U.S. patent application number 13/549166 was filed with the patent office on 2013-01-17 for deposition apparatus and method for manufacturing film by using deposition apparatus.
This patent application is currently assigned to Panasonic Corporation. The applicant listed for this patent is Kazuyoshi Honda, Shoichi Imashiku, Sadayuki Okazaki, Tomofumi Yanagi. Invention is credited to Kazuyoshi Honda, Shoichi Imashiku, Sadayuki Okazaki, Tomofumi Yanagi.
Application Number | 20130014699 13/549166 |
Document ID | / |
Family ID | 39759249 |
Filed Date | 2013-01-17 |
United States Patent
Application |
20130014699 |
Kind Code |
A1 |
Okazaki; Sadayuki ; et
al. |
January 17, 2013 |
DEPOSITION APPARATUS AND METHOD FOR MANUFACTURING FILM BY USING
DEPOSITION APPARATUS
Abstract
A vapor deposition device including an evaporation source for
evaporating a vapor-depositing material; a transportation section
including first and second rolls for holding the substrate in the
state of being wound therearound and a guide section for guiding
the substrate; and a shielding section, located in a vapor
deposition possible zone, for forming a shielded zone which is not
reachable by the vapor-depositing material from the evaporation
source. Vapor deposition zones include a planar transportation zone
for transporting the substrate such that the surface of the
substrate to be subjected to the vapor-depositing material is
planar; and the transportation section is located with respect to
the evaporation source such that the vapor-depositing material is
not incident on the substrate in a direction of the normal to the
substrate in the vapor deposition possible zone excluding the
shielded zone.
Inventors: |
Okazaki; Sadayuki; (Osaka,
JP) ; Honda; Kazuyoshi; (Osaka, JP) ; Yanagi;
Tomofumi; (Osaka, JP) ; Imashiku; Shoichi;
(Osaka, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Okazaki; Sadayuki
Honda; Kazuyoshi
Yanagi; Tomofumi
Imashiku; Shoichi |
Osaka
Osaka
Osaka
Osaka |
|
JP
JP
JP
JP |
|
|
Assignee: |
Panasonic Corporation
Osaka
JP
|
Family ID: |
39759249 |
Appl. No.: |
13/549166 |
Filed: |
July 13, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12516328 |
May 26, 2009 |
8241699 |
|
|
PCT/JP2008/000519 |
Mar 10, 2008 |
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13549166 |
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Current U.S.
Class: |
118/718 |
Current CPC
Class: |
Y02E 60/10 20130101;
C23C 14/02 20130101; H01M 4/0421 20130101; C23C 14/562 20130101;
H01M 10/052 20130101; C23C 14/226 20130101; H01M 4/1395
20130101 |
Class at
Publication: |
118/718 |
International
Class: |
C23C 16/54 20060101
C23C016/54 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2007 |
JP |
2007-059442 |
Apr 11, 2007 |
JP |
2007-103621 |
Apr 11, 2007 |
JP |
2007-103622 |
Oct 22, 2007 |
JP |
2007-273922 |
Claims
1-36. (canceled)
37. A vapor deposition device for moving a sheet-like substrate in
a roll-to-roll system in a chamber to continuously form a vapor
deposition film on the substrate, the vapor deposition device
comprising: an evaporation source for evaporating a
vapor-depositing material; a transportation section including first
and second rolls for holding the substrate in the state of being
wound therearound and a guide section for guiding the substrate,
wherein one of the first and second rolls supplies the substrate,
the guide section guides the supplied substrate, and the other of
the first and second rolls takes up the substrate, and thus the
substrate is transported so as to pass through a vapor deposition
possible zone to which the evaporated vapor-depositing material
reaches; and a shielding section, located in the vapor deposition
possible zone, for forming a shielded zone which is not reachable
by the vapor-depositing material from the evaporation source;
wherein: the guide section includes a first guide member for
guiding the substrate in the vapor deposition possible zone such
that a surface of the substrate to be subjected to the
vapor-depositing material is convexed toward the evaporation
source, and a second guide member, located on the second roll side
with respect to the first guide member on a substrate
transportation path, for guiding the substrate such that the
surface of the substrate to be subjected to the vapor-depositing
material is convexed toward the evaporation source; the shielding
section includes first and second shielding members respectively
located between the first and second guide members and the
evaporation source; the first guide member forms a first vapor
deposition zone located on the first roll side with respect to the
first shielding member on the substrate transportation path, and a
second vapor deposition zone located on the second roll side with
respect to the first shielding member on the substrate
transportation path; the second guide member forms a third vapor
deposition zone located on the first roll side with respect to the
second shielding member on the substrate transportation path, and a
fourth vapor deposition zone located on the second roll side with
respect to the second shielding member on the substrate
transportation path; the first through fourth vapor deposition
zones include a planar transportation zone for transporting the
substrate such that the surface of the substrate to be subjected to
the vapor-depositing material is planar; and the transportation
section is located with respect to the evaporation source such that
the vapor-depositing material is not incident on the substrate in a
direction of the normal to the substrate in the vapor deposition
possible zone excluding the shielded zone.
38. The vapor deposition device of claim 37, wherein the guide
section includes an inversion structure, provided between the
second vapor deposition zone and the third vapor deposition zone on
the substrate transportation path, for inverting the surface of the
substrate to be subjected to the vapor-depositing material.
39. The vapor deposition device of claim 37, wherein in a
cross-section which is vertical to the surface of the substrate and
includes a transportation direction of the substrate, the first
guide member and the second guide member are located on both sides
of the normal passing through the center of the evaporation source,
and the transportation section is located with respect to the
evaporation source such that any one of the first through fourth
vapor deposition zones crosses the normal passing through the
center of the evaporation source.
40. The vapor deposition device of claim 37, wherein a ratio of
film formation amounts in the first, second, third and fourth vapor
deposition zones is 1:2:2:1.
41. The vapor deposition device of claim 38, further comprising
first and second heating sections for heating the substrate to
200.degree. C. to 400.degree. C., wherein the first heating section
is located on the first roll side with respect to the first vapor
deposition zone on the substrate transportation path, and the
second heating section is located between the second vapor
deposition zone and the third vapor deposition zone on the
substrate transportation path.
42. The vapor deposition device of claim 38, further comprising
first, second, third and fourth heating sections for heating the
substrate to 200.degree. C. to 400.degree. C., wherein the first,
second, third and fourth heating sections are respectively located
in the vicinity of top ends of the first, second, third and fourth
vapor deposition zones.
43. The vapor deposition device of claim 37, wherein: the guide
section further includes in the vapor deposition possible zone: a
third guide member, located on the second roll side with respect to
the second guide member on the substrate transportation path, for
guiding the substrate such that the surface of the substrate to be
subjected to the vapor-depositing material is convexed toward the
evaporation source; and a fourth guide member, located on the
second roll side with respect to the third guide member on the
substrate transportation path, for guiding the substrate such that
the surface of the substrate to be subjected to the
vapor-depositing material is convexed toward the evaporation
source; the shielding section further includes a third shielding
member and a fourth shielding member respectively located between
the third and fourth guide members and the evaporation source; the
third guide member forms a fifth vapor deposition zone located on
the first roll side with respect to the third shielding member on
the substrate transportation path, and a sixth vapor deposition
zone located on the second roll side with respect to the third
shielding member on the substrate transportation path; and the
fourth guide member forms a seventh vapor deposition zone located
on the first roll side with respect to the fourth shielding member
on the substrate transportation path, and an eighth vapor
deposition zone located on the second roll side with respect to the
fourth shielding member on the substrate transportation path.
44. The vapor deposition device of claim 43, wherein the guide
section includes an inversion structure, provided between the
fourth vapor deposition zone and the fifth vapor deposition zone on
the substrate transportation path, for inverting the surface of the
substrate to be subjected to the vapor-depositing material.
45. The vapor deposition device of claim 43, wherein in a
cross-section which is vertical to the surface of the substrate and
includes a transportation direction of the substrate, the first and
second guide members, and the third and fourth guide members, are
located on both sides of the normal passing through the center of
the evaporation source, and the transportation section is located
with respect to the evaporation source such that one of the first
through eighth vapor deposition zones crosses the normal passing
through the center of the evaporation source.
46. The vapor deposition device of claim 43, wherein a ratio of
film formation amounts in the first, second, third, fourth, fifth,
sixth, seventh and eighth vapor deposition zones is
1:2:2:1:1:2:2:1.
47. The vapor deposition device of claim 44, further comprising
first and second heating sections for heating the substrate to
200.degree. C. to 400.degree. C., wherein the first heating section
is located on the first roll side with respect to the first vapor
deposition zone on the substrate transportation path, and the
second heating section is located so as to heat the substrate
between the fourth vapor deposition zone and the fifth vapor
deposition zone on the substrate transportation path.
48. The vapor deposition device of claim 44, further comprising
first, second, third and fourth heating sections for heating the
substrate to 200.degree. C. to 400.degree. C., wherein the first,
second, third and fourth heating sections are respectively located
in the vicinity of top ends of the first, fourth, fifth and eighth
vapor deposition zones.
49. The vapor deposition device of claim 43, wherein: the guide
section further includes in the vapor deposition possible zone: a
fifth guide member, located on to the second roll side with respect
to the fourth guide member on the substrate transportation path,
for guiding the substrate such that the surface of the substrate to
be subjected to the vapor-depositing material is convexed toward
the evaporation source; and a sixth guide member, located on the
second roll side with respect to the fifth guide member on the
substrate transportation path, for guiding the substrate such that
the surface of the substrate to be subjected to the
vapor-depositing material is convexed toward the evaporation
source; the shielding section further includes a fifth shielding
member and a sixth shielding member respectively located between
the fifth and sixth guide members and the evaporation source; the
fifth guide member forms a ninth vapor deposition zone located on
the first roll side with respect to the fifth shielding member on
the substrate transportation path, and a tenth vapor deposition
zone located on the second roll side with respect to the fifth
shielding member on the substrate transportation path; and the
sixth guide member forms an eleventh vapor deposition zone located
on the first roll side with respect to the sixth shielding member
on the substrate transportation path, and a twelfth vapor
deposition zone located on the second roll side with respect to the
sixth shielding member on the substrate transportation path.
50. The vapor deposition device of claim 49, wherein the guide
section includes an inversion structure, provided between the sixth
vapor deposition zone and the seventh vapor deposition zone on the
substrate transportation path, for inverting the surface of the
substrate to be subjected to the vapor-depositing material.
51. The vapor deposition device of claim 49, wherein in a
cross-section which is vertical to the surface of the substrate and
includes a transportation direction of the substrate, the first
through third guide members and the fourth through sixth guide
members are located on both sides of the normal passing through the
center of the evaporation source, and the transportation section is
located with respect to the evaporation source such that one of the
first through twelfth vapor deposition zones crosses the normal
passing through the center of the evaporation source.
52. The vapor deposition device of claim 50, wherein a ratio of
film formation amounts in the first, second, third, fourth, fifth,
sixth, seventh, eighth, ninth, tenth, eleventh and twelfth vapor
deposition zones is 1:2:2:2:2:1:1:2:2:2:2:1.
53. The vapor deposition device of claim 37, wherein in a
cross-section which is vertical to the surface of the substrate and
includes a transportation direction of the substrate, the
transportation section is located with respect to the evaporation
source such that a line connecting an arbitrary point on the
substrate passing through each vapor deposition zone and the center
of the vapor deposition source makes an angle of 45.degree. or
greater and 75.degree. or smaller with the direction of the normal
to the substrate.
54. The vapor deposition device of claim 37, wherein at least one
of the first through fourth vapor deposition zones includes a
curved transportation zone for transporting the substrate such that
the surface of the substrate to be subjected to the
vapor-depositing material is curved.
55. The vapor deposition device of claim 54, wherein: the at least
one of the first through fourth guide members is located in the
vapor deposition possible zone; and the curved transportation zone
includes a bottom end curved transportation zone for transporting
the substrate along a part of the at least one guide member which
is located in the vapor deposition possible zone.
56. The vapor deposition device of claim 55, further comprising an
inclination direction switching roller, provided in the at least
one vapor deposition zone, for forming two planar transportation
zones having different angles with respect to the normal passing
through the center of the evaporation source, wherein the curved
transportation zone includes an intermediate transportation zone
for transporting the substrate along the inclination direction
switching roller.
57. The vapor deposition device of claim 37, wherein the shielding
members further include at least one shielding plate having a wall,
and a surface of the wall faces the surface of the substrate, to be
subjected to the vapor-depositing material, passing through any of
the first through fourth vapor deposition zones.
58. The vapor deposition device of claim 57, wherein the surface of
the wall is located in the vapor deposition possible zone, and a
distance between the any vapor deposition zone and the surface of
the wall increases as being closer to the evaporation source.
59. The vapor deposition device of claim 57, further comprising a
nozzle section, provided in the vicinity of each of the guide
members in the vapor deposition possible zone, for supplying gas to
the two vapor deposition zones formed by each of the guide members,
wherein the wall causes the gas emitted from the nozzle section to
reside in the any vapor deposition zone.
60. The vapor deposition device of claim 57, wherein the surface of
the wall alleviates a temperature difference caused to the surface
by being subjected to the vapor-depositing material in the any
vapor deposition zone.
61. The vapor deposition device of claim 43, wherein the shielding
members further include at least one shielding plate having a wall,
and the surface of the wall faces the surface of the substrate, to
be subjected to the vapor-depositing material, passing through any
of the first through eighth vapor deposition zones.
62. The vapor deposition device of claim 61, wherein the surface of
the wall is located in the vapor deposition possible zone, and a
distance between the any vapor deposition zone and the surface of
the wall increases as being closer to the evaporation source.
63. The vapor deposition device of claim 61, further comprising a
nozzle section, provided in the vicinity of each of the guide
members in the vapor deposition possible zone, for supplying gas to
the two vapor deposition zones formed by each of the guide members,
wherein the wall causes the gas emitted from the nozzle section to
reside in the any vapor deposition zone.
64. The vapor deposition device of claim 61, wherein the surface of
the wall alleviates a temperature difference caused to the surface
by being subjected to the vapor-depositing material in the any
vapor deposition zone.
65. The vapor deposition device of claim 49, wherein the shielding
members further include at least one shielding plate having a wall,
and the surface of the wall faces the surface of the substrate, to
be subjected to the vapor-depositing material, passing through any
of the first through twelfth vapor deposition zones.
66. The vapor deposition device of claim 65, wherein the surface of
the wall is located in the vapor deposition possible zone, and a
distance between the any vapor deposition zone and the surface of
the wall increases as being closer to the evaporation source.
67. The vapor deposition device of claim 65, further comprising a
nozzle section, provided in the vicinity of each of the guide
members in the vapor deposition possible zone, for supplying gas to
the two vapor deposition zones formed by each of the guide members,
wherein the wall causes the gas emitted from the nozzle section to
reside in the any vapor deposition zone.
68. The vapor deposition device of claim 65, wherein the surface of
the wall alleviates a temperature difference caused to the surface
by being subjected to the vapor-depositing material in the any
vapor deposition zone.
Description
TECHNICAL FIELD
[0001] The present invention relates to a vapor deposition device
and a method for producing a film using the vapor deposition
device.
BACKGROUND ART
[0002] Recently, as the mobile devices provide higher and higher
level of performances and a wide and wider variety of functions, it
has been desired that cells used as power supplies of mobile
devices have larger capacities. As a secondary cell fulfilling such
a requirement, a nonaqueous electrolytic secondary cell is a target
of attention. In order to increase the capacitance of the
nonaqueous electrolytic secondary cell, it is proposed to use
silicon (Si), germanium (Ge), tin (Sn) or the like as an
electrolytic active material (hereinafter, referred to simply as
the "active material"). An electrode for a nonaqueous electrolytic
secondary cell using such an active material (hereinafter, referred
to simply as the "electrode") is generally formed by applying a
slurry containing an electrode active material, a binder and the
like to a current collector (hereinafter, an electrode thus
obtained will be referred to as the "application type electrode").
However, as the charge/discharge operation is repeated, the active
material drastically expands or contracts, and as a result, may be
pulverized or divided into tiny particles. When the active material
is pulverized or divided into tiny particles, the current
collectability of the electrode is decreased and also the contact
area of the active material and the electrolytic solution is
increased. Such an increase of the contact area promotes the
decomposition reaction of the electrolytic solution by the active
material, which results in a problem that a sufficient
charge/discharge cycle characteristic is not obtained. An
application type electrode contains a conductor, a binder and the
like therein and so it is difficult to increase the capacitance of
the electrode.
[0003] Under the circumstances, it has been studied to produce an
electrode by forming an active material layer on a current
collector using a vacuum process such as a vapor deposition method,
a sputtering method, a CVD method or the like, instead of the
application type electrode. As compared with the application type
electrode, an electrode formed by the vapor deposition method can
suppress the active material layer from being divided into tiny
particles and also can increase the adhesiveness between the
current collector and the active material layer. This improves the
electron conductivity in the electrode and also improves the
electrode capacitance and the charge/discharge cycle
characteristic. Whereas the application type electrode contains a
conductor, a binder and the like therein, formation of an active
material layer using the vapor deposition method can reduce the
amount of, or eliminate, the conductor or the binder present in the
electrode. Therefore, the capacitance of the electrode can be
essentially increased.
[0004] However, even when the vapor deposition method is used, the
current collector and the active material layer may be detached
from each other, or the current collector may be subjected to a
stress to possibly generate wrinkles, due to the expansion and
contraction of the active material at the time of charge/discharge.
These phenomena reduce the charge/discharge characteristic.
[0005] By contrast, Patent Documents 1 and 2 filed by the applicant
of the present application propose forming an active material layer
by vapor-depositing silicon particles in a direction inclined with
respect to the normal to the current collector (oblique vapor
deposition). Such an active material layer is formed using the
shadowing effect described later, and has a structure in which
column-like active material bodies inclined in one direction with
respect to the normal to the surface of the current collector are
located on the surface of the current collector. According to this
structure, a space for alleviating the expansion stress on silicon
can be secured between the active material bodies. Therefore, the
active material bodies can be suppressed from being detached from
the current collector, and the current collector can be suppressed
from being wrinkled. As a result, the charge/discharge
characteristic can be improved than by the conventional art.
[0006] Patent Document 2 proposes forming an active material body
grown zigzag by performing a plurality of stages of oblique vapor
deposition while switching the vapor deposition direction in order
to more efficiently alleviate the expansion stress applied on the
current collector. The zigzag active material body is formed as
follows, for example.
[0007] First, vapor deposition is performed in a first direction
inclined with respect to the normal to the current collector to
form a first part on the current collector (first stage vapor
deposition step). Then, vapor deposition is performed in a second
direction inclined oppositely to the first direction with respect
to the normal to the current collector to form a second part on the
first part (second stage vapor deposition step). Then, vapor
deposition is performed further in the first direction to form a
third part (third stage vapor deposition step). In this manner, the
vapor deposition step is repeated while switching the vapor
deposition direction until a desired stacking number is obtained.
Thus, an active material body is obtained.
[0008] Such an active material body can be formed using, for
example, a vapor deposition device described in Patent Document 2.
In the vapor deposition device described in Patent Document 2, a
fixing table for fixing the current collector is located above an
evaporation source. The fixing table is located such that a surface
thereof is inclined with respect to a plane parallel to the
vapor-depositing surface of the evaporation source (top surface of
the vapor-depositing material). Owing to such an arrangement, the
vapor-depositing material can be incident on the surface of the
current collector in a direction inclined by an arbitrary angle
with respect to the normal to the current collector. By switching
the inclination direction of the fixing table, the incidence
direction of the vapor-depositing material (vapor deposition
direction) can be switched. Accordingly, by repeating a plurality
of stages of vapor deposition while switching the inclination
direction of the fixing table, a zigzag active material body as
described above is obtained. It is also described that the
incidence direction of the vapor-depositing material is switched by
moving the evaporation source or using a plurality of evaporation
sources alternately, instead of switching the inclination direction
of the fixing table.
[0009] However, where the vapor deposition device described in
Patent Document 2 is used, vapor deposition is performed on a
current collector which is cut in advance into a prescribed size,
which decreases the productivity. Accordingly, it is difficult to
apply such a vapor deposition device to mass production
processes.
[0010] Patent Documents 3 through 6 disclose roll-to-roll system
vapor deposition devices preferably usable for mass production
processes.
[0011] Patent Document 3 proposes forming an active material layer
by oblique vapor deposition using a roll-to-roll system vapor
deposition device. With this vapor deposition device, a sheet-like
current collector runs from a supply roll to a take-up roll in a
chamber, and a vapor deposition film (active material film) can be
continuously formed on the running current collector in a
prescribed vapor deposition zone. In this vapor deposition zone,
the vapor-depositing material is incident on the surface of the
current collector in one direction inclined with respect to the
normal to the current collector. Therefore, column-like active
material bodies inclined in a particular direction with respect to
the normal to the current collector can be formed.
[0012] Patent Document 4 discloses various types of roll-to-roll
system vapor deposition devices as vapor deposition devices for
continuously producing an electrode material for electrolytic
capacitors. For example, in one of the disclosed structures, two
vapor deposition rolls are provided for one evaporation source, and
metal particles evaporated from the evaporation source are
vapor-deposited on the surface of the substrate on each vapor
deposition roll. Thus, two vapor deposition zones are provided for
one evaporation source.
[0013] However, it is difficult to continuously form active
material bodies grown zigzag as described in Patent Document 2
using the conventional roll-to-roll vapor deposition device
described in Patent Document 3 or 4.
[0014] As described above, the active material bodies described in
Patent Document 2 are formed by performing a plurality of stages of
vapor deposition while switching the incidence direction of the
vapor-depositing material (vapor deposition direction) to the
current collector. With the vapor deposition device described in
Patent Document 3, in order to switch the incidence direction of
the vapor-depositing material (vapor deposition direction) to the
current collector, the location of the vapor deposition zone with
respect to the evaporation source needs to be changed. Accordingly,
it is difficult to switch the vapor deposition direction in the
state where the chamber is kept vacuum. Therefore, a vapor
deposition film containing the active material bodies as described
above cannot be continuously formed.
[0015] The vapor deposition device described in Patent Document 4
is not structured so as to perform oblique vapor deposition from
the beginning. It is difficult to control the incidence direction
or the vapor deposition direction of the vapor-depositing material
with respect to the normal to the current collector. Therefore, it
is impossible form active material bodies grown zigzag by
controlling the vapor deposition direction thereof.
[0016] In addition, according to the conventional vapor deposition
devices described above, the vapor deposition zone is formed in
only a part of the zone in which the evaporated vapor-depositing
material is scattered (vapor deposition possible zone) in the
chamber. Therefore, the majority of the vapor-depositing material
scattered in the vapor deposition possible zone is not used for
vapor deposition. This presents a problem that the utilization
factor of the material is very low.
[0017] By contrast, Patent Documents 5 and 6 disclose a structure
of a roll-to-roll system vapor deposition device having a plurality
of vapor deposition zones with different vapor deposition
directions. Such a deposition device is provided for the purpose of
producing a magnetic tape. Using such a vapor deposition device, a
film including layers formed with different vapor deposition
directions can be produced.
[0018] According to the vapor deposition device shown in FIG. 4 of
Patent Document 5, a material substrate formed of a polymer
material is transported along three cylindrical rotatable cans
controlled to have a temperature of, for example, -10.degree. C. to
-15.degree. C. and vapor deposition is performed in two zones
(vapor deposition zones) on each rotatable can. In each vapor
deposition zone, vapor deposition is performed while a surface of
the material substrate opposite to the surface subjected to vapor
deposition is cooled by the rotatable can. Therefore, the
phenomenon that the material substrate is melted by the heat of the
vapor-depositing material can be prevented.
[0019] Patent Document 6 discloses a structure of a vapor
deposition device including a cooling device for directly cooling a
surface of the substrate on which vapor deposition is to be
performed. This cooling device is provided for the purpose of
preventing the material substrate of a magnetic tape (for example,
PET) from being melted.
[0020] Hereinafter, the structure of the vapor deposition device
disclosed in Patent Document 6 will be described in detail with
reference to the figure. FIG. 34 is a cross-sectional view showing
a conventional vapor deposition device disclosed in Patent Document
6.
[0021] A vapor deposition device 2000 includes rollers 1010 and
1012 for feeding out and taking in a material substrate, a cooling
device 1016 and a cooling support 1018 for cooling a material
substrate 1014 moving between the rollers 1010 and 1012, an
evaporation source 1020 located below a transportation path of the
material substrate 1014, and mask shielding plates 1022, 1024 and
1026 for defining a range in which vapor deposition is to be
performed on the material substrate 1014. In the vapor deposition
device 2000, the material substrate 1014 is fed out from the roller
1010 and cooled by the cooling device 1016. Then, the material
substrate 1014 is transported so as to be convexed toward the
evaporation source 1020 and is taken up by the roller 1012. The
cooling support 1018 is in contact with a rear surface (opposite to
a vapor deposition surface) of the material substrate 1014
transported as described above. In such a transportation path of
the material substrate 1014, oblique vapor deposition is performed
on the material substrate 1014 in a zone 1030 upstream to a part of
the material substrate 1014 closest to the evaporation source (the
apex of the convexed part) (such a zone will be referred to as the
"upstream vapor deposition zone") and a zone 1032 downstream to the
part (such a zone will be referred to as the "downstream vapor
deposition zone"). In the upstream vapor deposition zone 1030 and
the downstream vapor deposition zone 1032, the vapor-depositing
material is incident in directions different from each other with
respect to the normal to the material substrate 1014. Therefore, by
allowing the material substrate 1014 to pass through these zones,
two layers different in the vapor deposition directions can be
continuously formed on the material substrate 1014. A bottom end of
the vapor deposition zone 1030 (end on the evaporation source side)
is defined by the mask shielding plate 1022, and a top end thereof
(end on the roller 1010 side) is defined by the mask shielding
plate 1024. Similarly, a bottom end of the vapor deposition zone
1032 (end on the evaporation source side) is defined by the mask
shielding plate 1022, and a top end thereof (end on the roller 1010
side) is defined by the mask shielding plate 1026.
[0022] Patent Document 1: Pamphlet of International Publication
WO2007/015419
[0023] Patent Document 2: Pamphlet of International Publication
WO2007/052803
[0024] Patent Document 3: Japanese Laid-Open Patent Publication No.
2007-128659
[0025] Patent Document 4: Japanese Patent No. 2704023
[0026] Patent Document 5: Japanese Laid-Open Patent Publication No.
53-87706
[0027] Patent Document 6: Japanese Laid-Open Patent Publication No.
10-130815
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0028] As described above, the vapor deposition devices disclosed
in Patent Documents 5 and 6 each have a plurality of vapor
deposition zones with different vapor deposition directions, and so
are capable of continuously performing a plurality of stages of
vapor deposition with different vapor deposition directions.
[0029] However, the vapor deposition device of Patent Document 5
has a problem that each vapor deposition zone is formed on a
rotatable can and so cannot have a sufficient size. For this
reason, the ratio of the zone (including all the vapor deposition
zones) in which vapor deposition is performed with respect to a
vapor deposition possible zone in which the evaporated
vapor-depositing material is scattered is not sufficient.
Therefore, it is difficult to effectively improve the utilization
factor of the vapor-depositing material. There is another problem
that the vapor deposition angle in each vapor deposition zone
cannot be easily controlled. These problems will be described later
in detail with reference to figures.
[0030] As shown in FIG. 34, the vapor deposition device 2000 of
Patent Document 6 is capable of performing vapor deposition to the
material substrate 1014 transported in a V shape. Therefore, as
compared with the vapor deposition device of Patent Document 5, the
vapor deposition device 2000 increases the ratio of the zone in
which vapor deposition is performed with respect to the vapor
deposition possible zone and so has a higher possibility of
improving the utilization factor of the material. However, the
vapor deposition device 2000 performs vapor deposition on the
cooling support 1018 and so has the following problems.
[0031] The material substrate 1014 running between the vapor
deposition zones 1030 and 1032 is bent at an acute angle at a part
closest to the evaporation source. At this point, the rear surface
of the material substrate 1014 (surface opposite to the surface
subjected to vapor deposition) is rubbed by the cooling support
1018, which may damage the rear surface of the material substrate
1014 or wrinkle the material substrate 1014 during the
transportation. In addition, when being bent, the material
substrate 1014 may float from the cooling support 1018 and may not
be sufficiently cooled. As a result, the material substrate 1014
may be damaged, for example, may be ruptured. Furthermore, since
the vapor deposition is performed while the material substrate 1014
is transported such that the material substrate 1014 is in contact
with the cooling support 1018, the transportation path of the
material substrate 1014 is determined by the shape of the cooling
support 1018. This may reduce the freedom of selection regarding
the vapor deposition angle to the material substrate 1014.
[0032] The vapor deposition device 2000 has only two vapor
deposition zones 1030 and 1032 between the rollers 1010 and 1012.
Therefore, it is difficult to form a vapor deposition film having a
large stacking number efficiently.
[0033] The present invention made in light of the above-described
circumstances has an object of providing a vapor deposition device
which is capable of continuously performing oblique vapor
deposition while switching the vapor deposition direction with
respect to the normal to the substrate, does not damage the
substrate transported, is superb in utilization factor of the
vapor-depositing material and mass productivity, and is capable of
easily controlling the vapor deposition angle.
Means for Solving the Problems
[0034] A vapor deposition device according to the present invention
is for moving a sheet-like substrate in a roll-to-roll system in a
chamber to continuously form a vapor deposition film on the
substrate. The vapor deposition device comprising an evaporation
source for evaporating a vapor-depositing material; a
transportation section including first and second rolls for holding
the substrate in the state of being wound therearound and a guide
section for guiding the substrate, wherein one of the first and
second rolls supplies the substrate, the guide section guides the
supplied substrate, and the other of the first and second rolls
takes up the substrate, and thus the substrate is transported so as
to pass through a vapor deposition possible zone to which the
evaporated vapor-depositing material reaches; and a shielding
section, located in the vapor deposition possible zone, for forming
a shielded zone which is not reachable by the vapor-depositing
material from the evaporation source. The guide section includes a
first guide member for guiding the substrate in the vapor
deposition possible zone such that a surface of the substrate to be
subjected to the vapor-depositing material is convexed toward the
evaporation source, and a second guide member, located on the
second roll side with respect to the first guide member on a
substrate transportation path, for guiding the substrate such that
the surface of the substrate to be subjected to the
vapor-depositing material is convexed toward the evaporation
source. The shielding section includes first and second shielding
members respectively located between the first and second guide
members and the evaporation source. The first guide member forms a
first vapor deposition zone located on the first roll side with
respect to the first shielding member on the substrate
transportation path, and a second vapor deposition zone located on
the second roll side with respect to the first shielding member on
the substrate transportation path. The second guide member forms a
third vapor deposition zone located on the first roll side with
respect to the second shielding member on the substrate
transportation path, and a fourth vapor deposition zone located on
the second roll side with respect to the second shielding member on
the substrate transportation path. The first through fourth vapor
deposition zones include a planar transportation zone for
transporting the substrate such that the surface of the substrate
to be subjected to the vapor-depositing material is planar. The
transportation section is located with respect to the evaporation
source such that the vapor-depositing material is not incident on
the substrate in a direction of the normal to the substrate in the
vapor deposition possible zone excluding the shielded zone.
[0035] According to a vapor deposition device of the present
invention, a plurality of stages of vapor deposition steps can be
performed continuously while switching the vapor deposition
direction. Specifically, first and second vapor deposition zones
having different vapor deposition directions to each other are
formed in the chamber by the transportation section including the
first guide member and the first shielding member. In the first
vapor deposition zone, the vapor-depositing material can be
incident on the surface of the substrate in a direction inclined
with respect to the direction of the normal to the substrate; and
in the second vapor deposition zone, the vapor-depositing material
can be incident on the surface of the substrate in a direction
inclined oppositely to the inclination direction in the first vapor
deposition zone with respect to the direction of the normal to the
substrate. Thus, two layers having different growth directions are
formed on the surface of the substrate. After this, also in the
third and fourth vapor deposition zones formed by the second guide
member and the second shielding member, two layers having different
growth directions can be similarly formed. In this manner, during
the time in which the substrate is transported between the first
roll and the second roll, four stages of vapor deposition steps
with different vapor deposition directions can be continuously
performed. By repeating the vapor deposition while switching the
transportation direction of the substrate, a vapor deposition film
having a larger stacking number can be formed.
[0036] Accordingly, using the vapor deposition device of the
present invention, a plurality of active material bodies can be
grown zigzag on the surface of the substrate. As compared with an
electrode produced using a conventional roll-to-roll system vapor
deposition device described in each of Patent Document 3 and 4, an
electrode produced using the vapor deposition device according to
the present invention causes an expansion stress on the active
material bodies to be effectively alleviated. The vapor deposition
device according to the present invention can continuously form the
above-described active material bodies on the surface of a
sheet-like substrate. Therefore, as compared with the process of
controlling the vapor deposition direction by switching the
inclination direction of a table for fixing the current collector
as described in Patent Document 2, the process realized by the
vapor deposition device according to the present invention is
superb in mass productivity.
[0037] In the vapor deposition device according to the present
invention, the first and second vapor deposition zones include a
planar transportation zone for transporting the substrate such that
the surface of the substrate to be subjected to the
vapor-depositing material (hereinafter, referred to as the "vapor
deposition surface") is planar. As compared with the vapor
deposition device for performing vapor deposition only on a
rotatable can (roller) (for example, Patent Document 5), the vapor
deposition device according to the present invention can increase
the ratio of a zone in which vapor deposition is performed with
respect to the vapor deposition possible zone in which the
vapor-depositing material evaporated from the evaporation source is
scattered, and thus improves the utilization factor of the
vapor-depositing material.
[0038] In addition, the substrate is guided by a guide member to
two vapor deposition zones located on both sides of the guide
member. Therefore, the vapor deposition steps can be continuously
performed without damaging the substrate. Furthermore, the vapor
deposition angle in each vapor deposition zone can be easily
controlled with a higher degree of freedom than by the conventional
art.
Effects of the Invention
[0039] According to the present invention, in a substrate path
defined by the guide member to be convexed toward the evaporation
source, vapor deposition zones having different vapor deposition
directions can be formed on both sides of the guide member.
Accordingly, a vapor deposition device having superb mass
productivity which is capable of continuously performing a
plurality of vapor deposition steps with different vapor deposition
directions is provided. In addition, the utilization factor of the
vapor-depositing material can be improved as compared with by the
conventional art.
[0040] Using the vapor deposition device according to the present
invention, an electrode having a superb charge/discharge cycle
characteristic can be produced by a process having a superb
productivity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0041] [FIG. 1] FIG. 1 is a schematic cross-sectional view of a
vapor deposition device according to Embodiment 1 of the present
invention.
[0042] [FIG. 2] FIG. 2 is a cross-sectional view provided to
explain an angle at which a vapor-depositing material is incident
on a substrate (incidence angle) in the vapor deposition device in
Embodiment 1 of the present invention.
[0043] [FIG. 3] FIG. 3 is a schematic cross-sectional view of
active material bodies (stacking number n=2) formed using the vapor
deposition device in Embodiment 1 of the present invention.
[0044] [FIG. 4] FIG. 4 is a schematic cross-sectional view of
active material bodies (stacking number n=5) formed using the vapor
deposition device in Embodiment 1 of the present invention.
[0045] [FIG. 5] FIG. 5 is a cross-sectional view provided to
explain a structure of another vapor deposition device according to
Embodiment 1 of the present invention.
[0046] [FIG. 6] FIG. 6 is a schematic cross-sectional view of a
vapor deposition device according to Embodiment 2 of the present
invention. [FIG. 7] FIG. 7 is a schematic cross-sectional view of a
vapor deposition device according to Embodiment 3 of the present
invention.
[0047] [FIG. 8] FIG. 8 is a schematic cross-sectional view of
active material bodies (stacking number n=2) formed using the vapor
deposition device in Embodiment 3 of the present invention.
[0048] [FIG. 9] FIG. 9 is a cross-sectional view of a structure of
another vapor deposition device according to Embodiment 3 of the
present invention.
[0049] [FIG. 10] FIG. 10 is a schematic cross-sectional view of a
vapor deposition device according to Embodiment 4 of the present
invention.
[0050] [FIG. 11] FIG. 11 is a schematic cross-sectional view of
active material bodies (stacking number n=7) formed using the vapor
deposition device in Embodiment 4 of the present invention.
[0051] [FIG. 12] FIGS. 12(a) and (b) are top views showing an
example of films in Example 1 and Example 2 produced using a vapor
deposition device according to the present invention, and FIG.
12(c) is a schematic cross-sectional view of an active material
body in the films shown in FIGS. 12(a) and (b).
[0052] [FIG. 13] FIG. 13 is provided to explain the relationship
between the transportation number of times C of the substrate and
the stacking number n of the film (active material body); FIG.
13(a) is a cross-sectional view of an example of film (active
material body) formed by a vapor deposition device having a
V-shaped path, and FIGS. 13(b) and (c) are each a cross-sectional
views showing an example of film (active material body) formed by a
vapor deposition device having a W-shaped path.
[0053] [FIG. 14] FIG. 14 is a schematic cross-sectional view of a
vapor deposition device according to Embodiment 5 of the present
invention.
[0054] [FIG. 15] FIG. 15(a) is a schematic cross-sectional view of
a vapor deposition device according to Embodiment 6 of the present
invention, and FIG. 15(b) is a schematic cross-sectional view of a
vapor deposition film formed using the vapor deposition device
shown in FIG. 15(a). [FIG. 16] FIG. 16 is a schematic
cross-sectional view of a vapor deposition device according to
Embodiment 7 of the present invention.
[0055] [FIG. 17] FIG. 17(a) is a schematic cross-sectional view of
a vapor deposition device according to Embodiment 8 of the present
invention, and FIG. 17(b) is a schematic enlarged cross-sectional
view of vapor deposition zones in the vapor deposition device shown
in FIG. 17(a).
[0056] [FIG. 18] FIG. 18 is a schematic enlarged cross-sectional
view of vapor deposition zones in another vapor deposition device
according to Embodiment 8 of the present invention.
[0057] [FIG. 19] FIG. 19 is a schematic cross-sectional view of
still another vapor deposition device according to Embodiment 8 of
the present invention.
[0058] [FIG. 20] FIGS. 20(a) and (b) are each a schematic
cross-sectional view showing examples of vacuum vapor deposition
devices in Reference Embodiment A.
[0059] [FIG. 21] FIG. 21 is a schematic cross-sectional view of a
first vapor deposition section and a second vapor deposition
section in Reference Embodiment A.
[0060] [FIG. 22] FIG. 22 is a schematic cross-sectional view of
vapor deposition films formed by the vapor deposition device in
Reference Embodiment A.
[0061] [FIG. 23] FIG. 23 is a partial cross-sectional view
schematically showing a modification of the first vapor deposition
section and the second vapor deposition section in Reference
Embodiment A.
[0062] [FIG. 24] FIG. 24 is a partial cross-sectional view
schematically showing another modification of the first vapor
deposition section and the second vapor deposition section in
Reference Embodiment A.
[0063] [FIG. 25] FIG. 25 is a schematic cross-sectional view of a
vacuum vapor deposition device in Reference Embodiment B.
[0064] [FIG. 26] FIG. 26 is a schematic cross-sectional view of a
vapor deposition film formed by the vapor deposition device in
Reference Embodiment B.
[0065] [FIG. 27] FIG. 27 is a schematic cross-sectional view of a
vacuum vapor deposition device in Reference Embodiment C.
[0066] [FIG. 28] FIG. 28 is a schematic cross-sectional view of a
first vapor deposition section and a second vapor deposition
section in Reference Embodiment C.
[0067] [FIG. 29] FIG. 29 is a schematic cross-sectional view of a
vapor deposition film formed by the vapor deposition device in
Reference Embodiment C.
[0068] [FIG. 30] FIG. 30 is a partial cross-sectional view
schematically showing a modification of a first vapor deposition
section and a second vapor deposition section in Reference
Embodiment C.
[0069] [FIG. 31] FIG. 31 is a partial cross-sectional view
schematically showing another modification of the first vapor
deposition section and the second vapor deposition section in
Reference Embodiment C.
[0070] [FIG. 32] FIG. 32 is a schematic cross-sectional view of a
vacuum vapor deposition device in Reference Embodiment D.
[0071] [FIG. 33] FIG. 33 is a schematic cross-sectional view of a
vapor deposition film formed by the vapor deposition device in
Reference Embodiment D.
[0072] [FIG. 34] FIG. 34 is a cross-sectional view showing a
conventional vapor deposition device. [FIG. 35] FIG. 35(a) is a
schematic cross-sectional view showing an example of vapor
deposition zone formed of only a curved transportation zone, and
FIG. 35(b) is a schematic cross-sectional view showing an example
of vapor deposition zone including a planar transportation
zone.
DESCRIPTION OF THE REFERENCE NUMERALS
[0073] 1 Exhaust pump
[0074] 2 Chamber
[0075] 3, 8 Supply or take-up roll
[0076] 4 Substrate
[0077] 5a-5m Transportation roller
[0078] 6a-6d Guide member
[0079] 8 Evaporation source
[0080] 9s Evaporation surface
[0081] 10a, 10b Shielding plate
[0082] 11a, 11b Gas introduction pipe
[0083] 15a, 15b, 15c Shielding plate
[0084] 20a-20d Shielding member
[0085] 22 Nozzle section
[0086] 24 Nozzle section shielding plate
[0087] 28 Shutter
[0088] 60a-60h Vapor deposition zone
[0089] 100, 200, 300, 400, 500, 600, 700, 800 Vapor deposition
device
BEST MODE FOR CARRYING OUT THE INVENTION
[0090] Hereinafter, vapor deposition devices according to
embodiments of the present invention will be described with
reference to the figures.
Embodiment 1
[0091] In the vapor deposition device in this embodiment, a
sheet-like substrate is transported so as to be convexed toward an
evaporation source and vapor deposition is performed in zones on
both sides of the apex of the convexed part in the chamber.
<Structure of the Vapor Deposition Device>
[0092] First, FIG. 1 will be referred. FIG. 1 is a cross-sectional
view schematically showing a vapor deposition device according to
Embodiment 1 of the present invention. A vapor deposition device
100 includes a chamber (vacuum tank) 2, an exhaust pump 1 provided
outside the chamber 2 for exhausting the chamber 2, and gas
introduction pipes 11a and 11b for introducing gas such as oxygen
gas or the like from outside the chamber 2. The chamber 2
accommodates an evaporation source 9 for evaporating a
vapor-depositing material, a transportation section for
transporting a sheet-like substrate 4, a shielding section for
forming a shielded zone which is not reachable by the
vapor-depositing material evaporated from the evaporation source 9,
heating sections 16a and 16b for heating the substrate 4, and a
nozzle section 22 connected to the gas introduction pipes 11a and
11b for supplying gas to a surface of the substrate 4.
[0093] The evaporation source 9 includes a container such as, for
example, a crucible for accommodating a vapor deposition material
and a heating device for evaporating the vapor-depositing material.
The vapor-depositing material and the container are appropriately
attachable or detachable. Devices usable as the heating device
include, for example, a resistance heating device, an induction
heating device, an electronic beam heating device and the like. For
performing vapor deposition, the vapor-depositing material
accommodated in the crucible is heated by the heating device to be
evaporated from a top surface (evaporation source) 9s thereof and
is supplied to the surface of the substrate 4.
[0094] The transportation section includes first and second rolls 3
and 8 capable of holding the substrate 4 in the state where the
substrate 4 is wound therearound, and a guide section for guiding
the substrate 4. The guide section includes a first guide member
(here, a transportation roller) 6 and other transportation rollers
5a through 5d, and thus defines the transportation path of the
substrate 4 such that the substrate 4 passes through a zone reached
by the vapor-depositing material evaporated from the evaporation
surface 9a (such a zone will be referred to as the "vapor
deposition possible zone").
[0095] The first and second rolls 3 and 8, the transportation
rollers 5a through 5d and the first guide member 6 are cylindrical
with a length of, for example, 600 mm, and are located in the
chamber so as to be parallel to one another in a length direction
thereof (namely, a width direction of the substrate 4 to be
transported). FIG. 1 only shows the cross-sections of these
cylindrical members which are parallel to bottom surfaces
thereof.
[0096] The evaporation source 9 may also be formed such that, for
example, the evaporation surface 9s of the vapor-depositing
material has a sufficient length (for example, 600 mm or greater)
parallel to the width direction of the substrate 4 transported by
the transportation section. This allows vapor deposition to be
performed substantially uniformly in the width direction of the
substrate 4. The evaporation source 9 may include a plurality of
crucibles arranged in the width direction of the substrate 4 to be
transported.
[0097] In this embodiment, one of the first and second rolls 3 and
8 supplies the substrate 4, the transportation rollers 5a through
5d and the first guide member 6 guides the supplied substrate 4
along the transportation path, and the other of the first and
second rolls 3 and 8 takes up the substrate 4. When necessary, the
substrate 4 which is taken up is again supplied by the other roll
and transported along the transportation path in the opposite
direction. In this manner, the first and second rolls 3 and 8 in
this embodiment can act either as the supply roll or the take-up
roll depending on the transportation direction. By inverting the
transportation direction in repetition, the number of times the
substrate 4 passes through the vapor deposition zone can be
adjusted. Therefore, a prescribed number of vapor deposition steps
can be continuously carried out.
[0098] The transportation rollers 5a and 5b, the first guide member
6, and the transportation rollers 5c and 5d are sequentially
located in this order from the first roll side on the
transportation path of the substrate 4. In this specification, the
expression "the first roll side on the transportation path" means
the side of the first roll of the transportation path having the
first and second rolls 3 and 8 at both ends regardless of the
transportation direction of the substrate 4 or the spatial location
of the first roll. The first guide member 6 is located below the
transportation rollers 5b and 5c adjacent thereto, and guides the
substrate 4 such that the surface of the substrate 4 to be
subjected to the vapor-depositing material is convexed toward the
evaporation source 9. The expression "guide the substrate 4 such
that the substrate 4 is convexed toward the evaporation source 9"
means guiding the substrate 4 such that the substrate 4 is convexed
toward the evaporation surface 9s. Owing to this structure, the
path of the substrate 4 has the direction thereof changed by the
first guide member and has a V-shaped or U-shaped cross-section as
shown in the figure. In this specification, the V-shaped or
U-shaped path defined by the first guide member 6 will be referred
to as the "V-shaped path".
[0099] Between the first guide member 6 and the evaporation source
9 (evaporation surface 9s), a first shielding member 20 is located,
which prevents the vapor-depositing material evaporated from the
evaporation surface 9s from being incident in the direction of the
normal to the substrate 4 and also separates the vapor deposition
zone of the V-shaped path into two. Owing to such a structure, on
the transportation path of the substrate 4, a first vapor
deposition zone 60a located on the first roll side with respect to
the first shielding member 20 and a second vapor deposition zone
60b located on the second roll side with respect to the first
shielding member 20 are formed. In this specification, how each
vapor deposition zone is called does not depend on the positions of
the first and second rolls 3 and 8 in the chamber 2 or the
transportation direction of the substrate 4. A vapor deposition
zone which is on the first roll side with respect to the first
guide member 6 in the V-shaped path defined by the first guide
member 6 is called the "first vapor deposition zone 60a", and a
vapor deposition zone which is on the second roll side with respect
to the first guide member 6 in the V-shaped path is called the
"second vapor deposition zone 60b". Accordingly, the "first vapor
deposition zone 60a" only needs to be located on the first roll
side with respect to the first shielding member 20 on the
transportation path of the substrate 4. It does not matter even if,
for example, the distance in a straight line between the first roll
3 and the first vapor deposition zone 60a is longer than the
distance in a straight line between the first roll 3 and the first
guide member 6.
[0100] The shielding section is located in the vapor deposition
possible zone, and includes, in addition to the first shielding
member 20, shielding plates 10a and 10b located so as to cover the
evaporation source 9 and an exhaust opening (not shown) connected
to the exhaust pump 1, a nozzle section shielding plate 24 located
so as to cover the nozzle section 22, and shielding plates 15a and
15b respectively extending from a side wall of the chamber 2 toward
top ends of the first and second vapor deposition zones 60a and
60b. The shielding plates 15a and 15b are located so as to cover
the substrate 4 running in a vapor deposition possible zone on the
transportation path of the substrate 4 other than the vapor
deposition zones 60a and 60b, the first and second rolls 3 and 8,
the heating sections 16a and 16b, and the like, and prevents the
vapor-depositing material from reaching these elements.
[0101] In this embodiment, the shielding plates 15a and 15b
respectively include walls 15a' and 15b', which respectively have
surfaces (facing surfaces) Ya and Yb facing the vapor deposition
surface of the substrate 4 passing through the corresponding vapor
deposition zones 60a and 60b. As described below, since the facing
surfaces Ya and Yb facing the vapor deposition surface of the
substrate 4 are provided in the first and second vapor deposition
zones 60a and 60b, the difference in the amount of heat received by
the substrate 4 in the vapor deposition zones 60a and 60b can be
alleviated. This allows a vapor deposition film to be formed more
uniformly. In the case where the vapor deposition is performed
while gas is introduced from the nozzle section 22, the facing
surfaces Ya and Yb also provide an effect of efficiently causing
gas, emitted from a plurality of emission openings provided in side
surfaces of the nozzle section 22, to reside in the vapor
deposition zones 60a and 60b.
[0102] In this embodiment, the transportation section and the
shielding section are located with respect to the evaporation
source 9 so as to prevent the vapor-depositing material evaporated
from the evaporation surface 9s from being incident on the
substrate 4 in the normal direction to the substrate 4 running
along the transportation path. This allows vapor deposition to be
performed in a direction inclined with respect to the normal
direction to the substrate 4 (oblique vapor deposition). In the
vapor deposition device 100 shown in FIG. 1, the first shielding
member 20 and the nozzle section shielding plate 24 prevent the
vapor-depositing material from being incident on the substrate 4 in
the normal direction to the substrate 4. With another structure,
another shielding plate (for example, the shielding plate 15a, 15b,
etc.) may have substantially the same function.
[0103] In this embodiment, the nozzle section 22 is located between
the shielding plate 15b and the first guide member 15c. The nozzle
section 22 extends, for example, in the width direction of the
substrate 4 to be transported (the direction vertical to the
cross-section shown in FIG. 1), and may have a plurality of
emission openings on the side surfaces thereof for ejecting gas
toward the corresponding vapor deposition zones 60a and 60b. This
allows the gas to be supplied in the vapor deposition zones 60a and
60b substantially uniformly in the width direction of the substrate
4. The nozzle section 22 is preferably structured so as to eject
gas in parallel in the first and third vapor deposition zones 60a
and 60b. Owing to such a structure, the reaction ratio of oxygen
gas emitted from the nozzle section 22 and a vapor deposition
particles can be improved, and thus a vapor deposition film having
a high acidity can be formed without deteriorating the vacuum
pressure in the chamber 2.
[0104] The heating sections 16a and 16b are respectively located on
the first roll side and the second roll side of the V-shaped path.
Owing to such a structure, when the substrate 4 is transported from
the first roll 3 to the V-shaped path, the substrate 4 before
passing through the V-shaped path can be heated to 200.degree. C.
to 400.degree. C. (for example, 300.degree. C.) by the heating
section 16a; and when the substrate 4 is transported from the
second roll 8 to the V-shaped path, the substrate 4 before passing
through the V-shaped path can be heated to 200.degree. C. to
400.degree. C. (for example, 300.degree. C.) by the heating section
16b. By heating the substrate 4 to the above-described temperature,
organic substances adhering to the surface of the substrate 4 to be
subjected to vapor deposition can be removed and thus the adhesive
force between the substrate 4 and the vapor-depositing material
(for example, silicon particles) and the adhesive force of the
vapor-depositing material (among silicon particles) can be
improved.
<Operation of the Vapor Deposition Device>
[0105] Now, an operation of the vapor deposition device 100 will be
described. Here, an operation for forming a plurality of active
material bodies containing an oxide of silicon on the surface of
the substrate 4 using the vapor deposition device 100 will be
described.
[0106] First, the substrate 4 of a long strip type is wound around
one of the first and second rolls 3 and 8 (here, the first roll 3).
As the substrate 4, a metal foil such as a copper foil, a nickel
foil or the like is usable. As described later in more detail, in
order to provide a plurality of active material bodies with a
prescribed space therebetween on the surface of the substrate 4,
the shadowing effect provided by oblique vapor deposition needs to
be used. For this purpose, it is preferable that the surface of the
metal foil has a concave and convex pattern. According to the
concave and convex pattern used in this embodiment, quadrangular
prism-like projections having a diamond-shaped top surface
(diagonal lines: 20 .mu.m.times.10 .mu.m) and a height of 10 .mu.m
are regularly arranged. A distance between adjacent projections
along the longer diagonal line of the diamond shape is 20 .mu.m, a
distance between adjacent projections along the shorter diagonal
line of the diamond shape is 10 .mu.m, and a distance between
adjacent projections along the direction parallel to the sides of
the diamond shape is 10 .mu.m. The surface roughness Ra of the top
surface of each projection is, for example, 2.0 .mu.m.
[0107] A vapor-depositing material (for example, silicon) is
accommodated in the crucible in the evaporation source 9, and the
gas introduction pipes 11a and 11b are connected to an oxygen gas
tank or the like provided outside the vapor deposition device 100.
In this state, the chamber 2 is exhausted using the exhaust pump
1.
[0108] Next, the substrate 4 wound around the first roll 3 is fed
out and is transported toward the second roll 8. The substrate 4 is
first heated to a temperature of 200.degree. C. to 300.degree. C.
by the heating section 16a and then passes through the V-shaped
path including the first and second vapor deposition zones 60a and
60b. At this point, the silicon in the crucible in the evaporation
source 9 is evaporated by a heating device (not shown) such as an
electron beam heating device and supplied to the surface of the
substrate 4 passing through the first and second vapor deposition
zones 60a and 60b. At the same time, oxygen gas is supplied to the
surface of the substrate 4 from the nozzle section 22 via the gas
introduction pipes 11a and 11b. Thus, a compound containing silicon
and oxygen (an oxide of silicon) can be grown on the surface of the
substrate 4 by reactive vapor deposition. After the oxide of
silicon is vapor-deposited on the surface of the substrate 4 in the
vapor deposition zones 60a and 60b, the substrate 4 is taken up by
the second roll 8.
<Incidence Angle in the Vapor Deposition Zones>
[0109] Here, with reference to FIG. 2, an angle .theta. at which
the vapor-depositing material is incident on the substrate 4
(incidence angle) in the first and second vapor deposition zones
60a and 60b will be described. Herein, the "incidence angle
.theta." means an angle made by the normal to the substrate 4 and
the incidence direction of the vapor-depositing material.
[0110] FIG. 2 is a cross-sectional view schematically showing the
positional relationship between the first and second vapor
deposition zones 60a and 60b and the evaporation source 9 in the
chamber 2. For simplicity, identical elements with those in FIG. 1
bear identical reference numerals therewith, and descriptions
thereof will be omitted.
[0111] As shown in FIG. 2, the first and second vapor deposition
zones 60a and 60b are located on both sides of the first guide
member 6 in the V-shaped path described above. At this point, the
incidence angle .theta. of the vapor-depositing material in the
first vapor deposition zone 60a is in the range of equal to or
greater than an incidence angle .theta.2 of the vapor-depositing
material at a bottom end 62L of the first vapor deposition zone 60a
(end on the side of the first guide member 6) and equal to or
smaller than an incidence angle .theta.1 of the vapor-depositing
material at a top end 62U of the first vapor deposition zone 60a.
The incidence angle .theta.1 at the top end 62U is an angle made by
a straight line 32 vertical to the first vapor deposition zone 60a
and a straight line 30 connecting the top end 62U of the first
vapor deposition zone 60a and the center of the evaporation surface
9s. The incidence angle .theta.2 at the bottom end 62L is an angle
made by a straight line 36 vertical to the first vapor deposition
zone 60a and a straight line 34 connecting the bottom end 62L of
the first vapor deposition zone 60a and the center of the
evaporation surface 9s. Similarly, the incidence angle .theta. of
the vapor-depositing material in the second vapor deposition zone
60b is in the range of equal to or greater than an incidence angle
.theta.3 of the vapor-depositing material at a bottom end 64L of
the second vapor deposition zone 60b and equal to or smaller than
an incidence angle .theta.4 of the vapor-depositing material at a
top end 64U of the second vapor deposition zone 60b.
[0112] In this embodiment, it is preferable that the first guide
member 6, the transportation rollers 5b and 5c, the shielding
plates 15a and 15b, the shielding member 20 and the nozzle section
shielding plate 24 are located with respect to the evaporation
source 9 such that the incidence angles .theta.1 through .theta.4
are all 45.degree. or greater and 75.degree. or smaller. The reason
will be described below.
[0113] Where the incidence angles .theta.1 through .theta.4 are all
controlled to be 45.degree. or greater and 75.degree. or smaller,
the range of the incidence angle .theta. of silicon in both of the
first and second vapor deposition zones 60a and 60b is 45.degree.
or greater and 75.degree. or smaller. Where the incidence angle
.theta. of silicon is smaller than 45.degree., it is difficult to
allow the silicon to be incident on only projections 71 on the
substrate 4 using the shadowing effect. As a result, a sufficient
space may not be provided between the active material bodies. When
such active material bodies are used for a negative electrode of a
lithium secondary cell, the substrate 4 is likely to be wrinkled by
the expansion of each active material body during the charge of the
lithium secondary cell. By contrast, where the incidence angle
.theta. of silicon is larger than 75.degree., the growth direction
of the active material bodies is largely inclined toward the
surface of the substrate 4. As a result, the attaching force
between the surface of the substrate 4 and the active material
bodies is reduced, and thus the adhesiveness between the substrate
4 and the active material bodies is decreased. When such active
material bodies are used for a negative electrode of a lithium
secondary cell, the active material bodies are likely to be
detached from the substrate 4 as the charge/discharge of the
lithium secondary cell proceeds.
[0114] The incidence directions of the vapor-depositing material in
the first and second vapor deposition zones 60a and 60b are
inclined in opposite directions to each other with respect to the
normal to the substrate 4. Owing to this, the active material
bodies can be grown alternately in opposite inclination directions
with respect to the normal to the substrate 4. Therefore, the
zigzag active material bodies can be obtained as described
above.
[0115] In this embodiment, the incidence angle .theta. of the
vapor-depositing material (for example, silicon) in the first and
second vapor deposition zones 60a and 60b is controlled as follows.
The transportation rollers 5b and 5c and the first guide member 6
are located with respect to the evaporation source 9 such than the
incidence angle .theta. of silicon is in a desired range (for
example, 45.degree. or greater and 75.degree. or smaller,
preferably 60.degree. or greater and 75.degree. or smaller) in at
least a part of an area between the transportation roller 5b and
the first guide member 6 in the V-shaped path and at least a part
of an area between the first guide member 6 and the transportation
roller 5c in the V-shaped path. The shielding plates 15a and 15b,
the shielding member 20 and the nozzle section shielding plate 24
are located so as to shield silicon from being incident in an area
of the V-shaped path where the incidence angle .theta. is outside
the above-described range. This will be described specifically. In
the example shown in FIG. 2, the incidence angles .theta.1 and
.theta.3 at the top ends 62U and 64U in the first and second vapor
deposition zones 60a and 60b are respectively adjusted by the
shielding plates 15a and 15b. The incidence angles .theta.2 and
.theta.4 at the bottom ends 62L and 64L are respectively adjusted
by the shielding member 20 and the nozzle section shielding plate
24. The nozzle section shielding plate 24 may act as the shielding
member without providing the shielding member 20. Here, the
incidence angles .theta.1 through .theta.4 are respectively
75.degree., 60.degree., 60.degree., and 75.degree.
(.theta.1=75.degree., .theta.2=60.degree., .theta.3=60.degree.,
.theta.4=75.degree.).
[0116] As described above, according to this embodiment, the
incidence angle .theta. can be easily controlled by the positional
relationship among the transportation rollers 5b and 5c and the
guide member 6. In addition, in the planar transportation zones of
the vapor deposition zones 60a and 60b, a rear surface of the
substrate 4 (surface opposite to the vapor deposition surface) is
not in contact with any member such as a transportation section or
a cooling support. Therefore, the vapor deposition angle can be
selected at a higher degree of freedom than in the vapor deposition
device described in Patent Document 5 or 6.
<Facing Surfaces in the Vapor Deposition Device 100>
[0117] Now, advantages of providing the facing surfaces Ya and Yb
facing the vapor deposition surface of the substrate 4 passing
through the first and second vapor deposition zones 60a and 60b
will be described.
[0118] In the conventional vapor deposition device 2000 shown in
FIG. 34, at the bottom ends, of the vapor deposition zones 1030 and
1032, close to the evaporation source 1020, the material substrate
1014 receives a large amount of heat from the evaporation source
1020 and the vapor deposition particles. The amount of received
heat decreases as the material substrate 1014 is moved farther from
the evaporation source 1020, and is minimum at the top ends of the
vapor deposition zones 1030 and 1032. Therefore, a temperature
gradient is generated on the surface of the material substrate 1014
moving in the vapor deposition zones 1030 and 1032. This makes it
difficult to provide a film uniform in the thickness direction. The
rear surface of the material substrate 1014 moving in the vapor
deposition zones 1030 and 1032 is in contact with the cooling
support 1018. However, the cooling support 1018 becomes smaller as
approaching the evaporation source 1020, and it is difficult to
sufficiently alleviate, by the cooling support 1018, the difference
in the amount of heat received by the material substrate 1014
between the top ends and the bottom ends of the vapor deposition
zones 1030 and 1032.
[0119] By contrast, according to this embodiment, the amount of
heat received by the substrate 4 passing through the vapor
deposition zones 60a and 60b can be more averaged by radiant heat
from the facing surfaces Ya and Yb as described below, and
therefore a vapor deposition film more uniform in the thickness
direction can be provided.
[0120] Again, FIG. 2 will be referred to. In this specification,
the "facing surfaces Ya and Yb" facing the vapor deposition surface
of the substrate 4 in the vapor deposition zones 60a and 60b face
the surface of the substrate 4 (vapor deposition surface) passing
through the vapor deposition zones 60a and 60b and alleviate the
temperature difference which is caused to the vapor deposition
surface as a result of incidence of the vapor-depositing material.
In this embodiment, the facing surfaces Ya and Yb are located in
the vapor deposition possible zone, and further located so as to be
close to the vapor deposition surface at the ends 62U and 64U
farther from the evaporation source 9 (namely, the top ends) and
become farther from the vapor deposition surface as becoming closer
to the evaporation source 9. Accordingly, for example, in the
second vapor deposition zone 60b, a distance D.sub.Y between the
vapor deposition surface and the facing surface Ya is small in the
vicinity of the top end 64U and becomes larger as being closer to
the bottom end 64L. In other words, in the cross-section shown in
FIG. 2, each vapor deposition surface and the corresponding facing
surface Ya, Yb form an inverted V shape convexed upward. An angle
.theta..sub.Y made by each vapor deposition surface and the
corresponding facing surface Ya, Yb is equal to or smaller than
90.degree..
[0121] The vapor deposition surface of the substrate 4 passing
through the first and second vapor deposition zones 60a and 60b is
always subjected to the radiant heat and the vapor deposition
particles. In this embodiment, the amount of heat received by the
vapor deposition surface of the substrate 4 mainly includes the
amount of radiant heat generated by the evaporation source 9, the
amount of radiant heat from the facing surfaces Ya and Yb, and the
amount of heat of the vapor deposition particles. The amount of
radiant heat is in inverse proportion to the square of the distance
from the heat source. Therefore, the amount of radiant heat from
the evaporation source 9 is large in the vicinity of the
evaporation source 9 in the vapor deposition zones 60a and 60b, and
decreases as being farther from the evaporation source 9.
Similarly, the amount of heat of the vapor deposition particles is
large in the vicinity of the evaporation source 9 and decreases as
being farther from the evaporation source 9. By contrast, the
radiant amount of heat from the facing surface Ya, Yb is in inverse
proportion to the square of the distance D.sub.Y between the vapor
deposition surface and the facing surface Ya, Yb. As described
above, the distance D.sub.Y increases as being closer to the
evaporation source 9. Therefore, the amount of radiant heat from
the facing surface Ya, Yb is large in an area far from the
evaporation source 9 in the vapor deposition zones 60a and 60b, and
increases as being closer to the evaporation source 9. In this
manner, the temperature gradient generated in the surface of the
substrate 4 because of the amount of radiant heat from the facing
surface Ya, Yb is opposite to the temperature gradient generated
because of the amount of radiant heat from the evaporation source 9
and the amount of heat of the vapor deposition particles. For this
reason, the temperature difference caused to the substrate 4 by the
amount of radiant heat from the evaporation source 9 and the amount
of heat of the vapor deposition particles can be reduced.
[0122] The angle .theta..sub.Y made by the vapor deposition surface
and the facing surface Ya, Yb may be any angle which is equal to or
smaller than 90.degree., and is preferably 25.degree. or greater
and 70.degree. or smaller. Where the angle .theta..sub.Y is smaller
than 25.degree., the vapor deposition particles from the
evaporation source 9 are unlikely to reach the vapor deposition
surface, which may reduce the vapor deposition efficiency. Where
the angle .theta..sub.Y is larger than 70.degree., the heat cannot
be confined between these surfaces, which may reduce the effect
provided by the facing surfaces Ya and Yb of averaging the amount
of heat received by the vapor deposition surface. At least in the
vicinity of the top ends of the vapor deposition zones 60a and 60b,
the distance D.sub.Y between the facing surface Ya, Yb and the
vapor deposition surface needs to be set to be sufficiently small
such that the radiant heat from the facing surface Ya, Yb can be
received by the vapor deposition surface.
[0123] In the vapor deposition device 100, the shielding plates 15a
and 15b having the facing surfaces Ya and Yb respectively facing
the first and second vapor deposition zones 60a and 60b are
provided. The above-described effect is provided as long as the
shielding plate 15a or 15b having the facing surface Ya or Yb
facing at least one of the first and second vapor deposition zones
60a and 60b is provided.
[0124] In this embodiment, the shielding plates 15a and 15b are
used to provide the facing surfaces Ya and Yb facing the vapor
deposition surface of the substrate 4 passing through the first and
second vapor deposition zones 60a and 60b. The facing surfaces Ya
and Yb may be provided in other elements than the shielding plate
15a or 15b. The structure of the elements having the facing
surfaces Ya and Yb is not specifically limited.
[0125] The elements having the facing surfaces Ya and Yb may have a
structure for heating or cooling the facing surfaces Ya and Yb. For
example, such elements may have a heater for heating the facing
surfaces Ya and Yb or a cooling water path for cooling the rear
surfaces of the facing surfaces Ya and Yb with cooling water.
[0126] Where the facing surfaces Ya and Yb are heated by the heater
or the like, the vapor deposition particles flying toward the
facing surfaces Ya and Yb are partially reflected and incident on
the vapor deposition surface of the substrate 4 in the facing vapor
deposition zone. This improves the attaching efficiency (vapor
deposition efficiency) of the vapor deposition particles on the
vapor deposition surface of the substrate 4. Where the temperature
of the facing surfaces Ya and Yb is high, the vapor deposition
particles partially move on, and are fixed to, the facing surfaces
Ya and Yb. This increases the adhesive force between the facing
surfaces Ya and Yb and the vapor deposition particles attached to
the facing surfaces Ya and Yb. As a result, the vapor deposition
film deposited on the facing surfaces Ya and Yb during the vapor
deposition is unlikely to be detached from the facing surfaces Ya
and Yb. Where the adhesive force between the vapor deposition
particles and the facing surfaces Ya and Yb is small, the vapor
deposition film deposited on the facing surfaces Ya and Yb during
the vapor deposition is partially detached and falls on the
evaporation source 9, which may generate splash. By heating the
facing surfaces Ya and Yb, the adhesive force between the facing
surfaces Ya and Yb and the vapor deposition film can be increased
to suppress the splash. The term "splash" means that the
vapor-depositing material in the evaporation source 9 is not
gasified and flies to the vapor deposition possible zone in a
liquid state. Where the facing surfaces Ya and Yb are heated, the
amount of radiant heat received, by the substrate 4 in the vapor
deposition zones, from the facing surfaces Ya and Yb is increased
to raise the temperature of the vapor deposition surface of the
substrate 4. As a result, the vapor deposition particles move on,
and are fixed to, the vapor deposition surface, and therefore the
adhesiveness between the vapor deposition surface of the substrate
4 and the vapor deposition film can be improved. In the case where
the facing surfaces Ya and Yb are heated, the temperature thereof
is preferably, for example, 100.degree. C. or higher and
400.degree. C. or lower. This guarantees that the above-described
effects are provided more certainly.
[0127] Alternatively, the elements having the facing surfaces Ya
and Yb may be cooled. In the case where the facing surfaces Ya and
Yb are cooled by cooling water or the like, the following effects
are provided.
[0128] Organic substances attached to the vapor deposition surface
of the substrate 4 gather to a cool surface when being evaporated
by the radiant heat of the evaporation source 9. Therefore, the
evaporated organic substances may be vapor-deposited again on the
vapor deposition surface of the substrate 4 together with the vapor
deposition particles or may be attached to a cool surface of the
substrate 4. This may decrease the adhesiveness between the
substrate 4 and the vapor deposition particles. Where the facing
surfaces Ya and Yb are cooled, the evaporated organic substances
can be gathered to the facing surfaces Ya and Yb. Therefore, the
influence of the evaporated organic substances exerted on the vapor
deposition surface of the substrate 4 can be alleviated and thus
the adhesiveness between the vapor deposition surface and the vapor
deposition film can be improved. In the case where the facing
surfaces Ya and Yb are cooled, the temperature thereof is
preferably, for example, -20.degree. C. or higher and 20.degree. C.
or lower. This alleviates the influence of the evaporated organic
substances more effectively. When the facing surfaces Ya and Yb are
cooled, the amount of radiant heat from the facing surfaces Ya and
Yb is decreased, and so the effect of alleviating the temperature
difference of the substrate 4 may be reduced. However, even in such
a case, cooling the facing surfaces Ya and Yb is advantageous
because the above-described influence of the evaporated organic
substances can be alleviated.
[0129] In this embodiment, the structure of the facing surfaces Ya
and Yb is not limited to the above described structure. In this
embodiment, it is sufficient that the vapor deposition surface of
the substrate 4 passing through at least one of the first and
second vapor deposition zones 60a and 60b faces a facing surface
provided so as to alleviate, on the vapor deposition surface, the
temperature difference caused by the radiant heat generated by the
vapor-depositing material. As in embodiments described later, the
facing surfaces Ya and Yb may be formed during the vapor deposition
by the substrate 4 transported by the transportation section.
Specifically, another vapor deposition zone may be provided so as
to face at least one of the vapor deposition zones 60a and 60b, and
a transportation section may be provided such that the vapor
deposition surface of the substrate 4 passing through the another
vapor deposition zone faces the at least one of the vapor
deposition zones 60a and 60b and such that the vapor deposition
surface of the substrate 4 passing through the at least one of the
vapor deposition zones 60a and 60b faces the another vapor
deposition zone.
<Material Utilization Factor of the Vapor Deposition Device
100>
[0130] Here, the following angle ranges are set in any
cross-section which is vertical to the evaporation surface 9s of
the evaporation source 9 and includes a vapor deposition direction.
The angle range made by the straight line 30 connecting the top end
62U of the first vapor deposition zone 60a and the center of the
vaporization face 9s and the straight line 34 connecting the bottom
end 62L of the first vapor deposition zone 60a and the center of
the vaporization face 9s is labeled as A. The angle range made by
the straight line connecting the top end 64U of the second vapor
deposition zone 60b and the center of the vaporization face 9s and
the straight line connecting the bottom end 64L of the second vapor
deposition zone 60b and the center of the vaporization face 9s is
labeled as B. In the vapor deposition device 100, as shown in FIG.
2, silicon atoms emitted from the center of the evaporation surface
9s to the angle ranges A and B are usable for vapor deposition.
Accordingly, silicon atoms in a wider emission range are usable for
vapor deposition than in a vapor deposition device having only one
vapor deposition zone (for example, the vapor deposition device
described in Patent Document 3) or a vapor deposition device of
performing vapor deposition on a rotatably can (roller) described
in Patent Document 5. Therefore, the utilization factor of the
vapor-depositing material (silicon) can be improved and also the
vapor deposition efficiency can be improved.
[0131] Here, the advantages of the vapor deposition device 100 over
a structure of performing vapor deposition on a rotatable can such
as the vapor deposition device described in Patent Document 5 or
the like will be described in detail. In the vapor deposition
device described in Patent Document 5, vapor deposition is
performed only in a zone where a surface of the substrate which is
subjected to the vapor-depositing material is transported on a
curved surface along the rotatable can (hereinafter, such a zone
will be referred to as the "curved transportation zone"). By
contrast, in this embodiment, vapor deposition can be performed in
a zone in which the substrate 4 is transported such that the
surface thereof subjected to the vapor-depositing material is
planar (hereinafter, such a zone will be referred to as the "planar
transportation zone"). Therefore, the vapor-depositing material
emitted to a wider range is usable for vapor deposition as
described below with reference to the figures. The vapor deposition
zones 60a and 60b in the vapor deposition device 100 both include
only planar transportation zones. The vapor deposition zones 60a
and 60b only need to include at least planar transportation zones.
For example, as in embodiments described below, the vapor
deposition zones 60a and 60b may include a curved transportation
zone in which the substrate 4 is transported along a guide
member.
[0132] FIG. 35(a) is a schematic cross-sectional view showing an
example of vapor deposition zone in the case where vapor deposition
is performed only on a rotatable can, namely, an example of vapor
deposition zone formed of a curved transportation zone. FIG. 35(b)
is a schematic cross-sectional view showing an example of vapor
deposition zone including a planar transportation zone. For
simplicity, in these figures, identical elements with those in FIG.
2 bear identical reference numerals therewith, and descriptions
thereof will be omitted.
[0133] As seen from FIG. 35(a), in the case where vapor deposition
is performed on a rotatable can 1040, two vapor deposition zones
1042 and 1044 are formed in a part, of a surface of the rotatable
can 1040, which is within an angle range Z.sub.0 (vapor deposition
possible zone) in which the vapor-depositing material are
scattered. An angle range made by a straight line connecting a top
end of the vapor deposition zone 1042 and the center of the
evaporation surface 9 and a straight line connecting a bottom end
of the vapor deposition zone 1042 and the evaporation surface 9 is
labeled as Z.sub.1. An angle range made by a straight line
connecting a top end of the vapor deposition zone 1044 and the
center of the evaporation surface 9 and a straight line connecting
a bottom end of the vapor deposition zone 1044 and the evaporation
surface 9 is labeled as Z.sub.2. Then, the ratio of the emission
angle range of the vapor-depositing material usable for vapor
deposition, with respect to the angle range in which the
vapor-depositing material is scattered, is represented by
(Z.sub.1+Z.sub.2)/Z.sub.0. This ratio is determined by the size
(diameter) and the number of the rotatable can(s) 1040, the
distance between the rotatable can(s) 1040 and the evaporation
source 9 and the like. It is very difficult to increase the ratio
while controlling the vapor deposition angle in each of the vapor
deposition zones 1042 and 1044.
[0134] By contrast, according to this embodiment, as shown in FIG.
35(b), the angle ranges A and B can be arbitrarily set regardless
of the diameter of the guide member 6. Therefore, the ratio of the
emission angle ranges A and B of the vapor-depositing material
usable in the vapor deposition zones 60a and 60b, with respect to
the angle range Z.sub.0 in which the vapor-depositing material is
scattered, i.e., (A+B)/Z.sub.0, can be made larger than the
above-described ratio (Z.sub.1+Z.sub.2)/Z.sub.0 in the conventional
vapor deposition device. In addition, this embodiment is
advantageous because the vapor deposition angle in each of the
vapor deposition zones 60a and 60b can be more easily controlled by
the location of the transportation rollers or the like. In order to
further improve the utilization factor of the vapor-depositing
material, a plurality of V-shaped paths may be provided by locating
a plurality of guide members 6 in the vapor deposition possible
zone as in embodiments described later. In addition to performing
vapor deposition in the planar transportation zones, vapor
deposition may also be performed on the guide member 6.
[0135] Moreover, in the case where vapor deposition is performed on
the rotatable can 1040, the diameter of the rotatable can 1040
needs to be large to some extent in order to form the vapor
deposition zones 1042 and 1044 having a sufficient size. This makes
it difficult to provide many rotatable cans in the vapor deposition
possible zone. By contrast, in the case where vapor deposition is
performed in planar transportation zones, many planar
transportation zones can be formed for one evaporation source as in
embodiments described later. Therefore, the vapor deposition steps
with different vapor deposition directions can be performed
efficiently.
<Production Steps of the Film>
[0136] Hereinafter, with reference to the figures, steps of forming
a vapor deposition film in the first and second vapor deposition
zones 60a and 60b will be described in detail. Here, silicon is
used as the vapor-depositing material and vapor deposition is
performed while oxygen is supplied from the nozzle section 22, so
as to form a film of an oxide of silicon (SiO.sub.x, 0<x<2)
as the vapor deposition film.
[0137] FIG. 3 schematically shows an example of vapor deposition
film (film of an oxide of silicon) and shows a cross-section which
is vertical to the substrate 4 and includes an incidence direction
(vapor deposition direction) of silicon.
[0138] First, in the first vapor deposition zone 60a, silicon is
incident on the surface of the substrate 4 in a direction 42
inclined with respect to the direction of normal M to the substrate
4 at an angle of 60.degree. or greater and 75.degree. or smaller.
At this point, silicon is likely to be vapor-deposited on
projections 72 located on the surface of the current collector 4,
and therefore an oxide of silicon grows like columns on the
projections 72. In the meantime, on the surface of the current
collector 4, areas are formed which are shadowed by the projections
72 and the oxide of silicon growing like the columns, and on which
Si atoms are not incident and the oxide of silicon is not
vapor-deposited (shadowing effect). In the example shown in FIG. 3,
because of the shadowing effect, Si atoms are not attached and an
oxide of silicon do not grow on grooves between adjacent
projections 72 on the surface of the current collector 4. As a
result, the oxide of silicon is selectively grown like columns on
the projections 72 on the current collector 4, and thus a first
part p1 is obtained (first stage vapor deposition step). A growth
direction G1 of the first part pl is inclined with respect to the
normal direction M to the substrate 4.
[0139] Then, the substrate 4 is transported to the second vapor
deposition zone 60b. In the second vapor deposition zone 60b,
silicon is incident on the surface of the substrate 4 in a
direction 44 inclined in the opposite direction to the direction 42
with respect to the normal direction M to the substrate 4 at an
angle of 60.degree. or greater and 75.degree. or smaller. At this
point, silicon is selectively incident on the first part p1 formed
on the current collector 4 because of the above-described shadowing
effect. As a result, a second part p2 having a growth direction G2
inclined with respect to the normal direction M to the current
collector 4 is obtained on the first part p1 (second stage vapor
deposition step).
[0140] The growth directions G1 and G2 of the first and second
parts p1 and p2 are respectively determined by the incidence
directions 42 and 44 of silicon. Accordingly, in this embodiment,
the growth direction G2 of the second part p2 is inclined in the
opposite direction to the growth direction G1 of the first part p1
with respect to the normal direction M to the current collector 4.
Here, an angle (growth angle) made by each of the growth directions
G1 and G2 of the first and second parts p1 and p2 and the normal
direction M to the substrate 4 is labeled as .alpha..sub.(p1),
.alpha..sub.(.sub.p2). An angle (incidence angle) made by the
normal direction M to the substrate 4 and each of the incidence
directions 42 and 44 of silicon is labeled as .theta..sub.(p1),
.theta..sub.(p2). Then, these angles fulfill the relationships of 2
tan .alpha..sub.(p1)=tan .theta..sub.(p1) and 2 tan
.alpha..sub.(p2)=tan .theta..sub.(p2).
[0141] In this manner, two-layer active material bodies 40
(stacking number=2) including two parts of different growth
directions are formed. Since one active material body 40 is
provided on each projection 72 formed on the surface of the current
collector 4, a sufficient space can be secured between adjacent
active material bodies 40. Hence, the problem of electrode
deformation caused by the expansion stress on the active material
body 40 or the like can be solved.
[0142] In the case where the stacking type active material bodies
40 as shown in the figure are formed, it is preferable that the
incidence angles .theta.2 and .theta.3 of the vapor-depositing
material at the bottom ends 62L and 64L of the first and second
vapor deposition zones 60a and 60b are substantially equal to each
other. The reason for this will be described, hereinafter.
[0143] The concentration of the vapor-depositing material
evaporated from evaporation surface 9s is higher as being closer to
the line extending from the center of the evaporation surface 9s
vertical to the evaporation surface 9s (hereinafter, referred to
simply as the "normal passing through the center of the evaporation
surface 9s") and as being closer to the evaporation surface 9s.
Therefore, in the vapor deposition zone 60a, the vapor deposition
amount is larger in the vicinity of the bottom end 62L than in the
vicinity of the top end 62U. As a result, the growth direction G1
of the first part p1 formed in the first vapor deposition zone 60a
is mainly determined by the incidence angle .theta.2. Similarly,
the growth direction G2 of the second part p2 formed in the second
vapor deposition zone 60b is mainly determined by the incidence
angle .theta.3 at the bottom end 64U, in the vicinity of which the
vapor deposition amount is large. At this point, where the
incidence angles .theta.2 and .theta.3 are substantially equal to
each other, the parts p1 and p2 included in the active material
body 40 can be inclined at a substantially equal angle opposite to
each other with respect to the normal direction to the substrate 4.
This is advantageous because the active material body 40 as a whole
can be grown along the normal direction to the substrate 4.
[0144] Now, the shapes of the first and second parts p1 and p2 will
be described in more detail. Referring to FIG. 3, the growth
directions G1 and G2 of the first part p1 and the second part p2
represent the growth directions of the first part p1 and the second
part p2 as straight lines obtained by averaging the growth
directions. In actuality, the growth direction of each of the first
part p1 and the second part p2 changes as the corresponding part
grows. Specifically, as represented by arrows G1' and G2', the
angle (growth angle) .alpha. made by the growth direction of the
first part p1 and the normal direction M is actually large during
the initial period of the first stage vapor deposition step and
decreases as the first part p1 grows. The reason is as follows.
During the first stage vapor deposition step, vapor deposition is
performed on the substrate 4 moving toward the evaporation source 9
from the top end to the bottom end of the first vapor deposition
zone 60a. As the substrate 4 becomes closer to the evaporation
source 9, the incidence angle .theta. of the vapor-depositing
material with respect to the normal direction M to the substrate 4
decreases (see FIG. 2). For example, the growth direction G1' of
the first part p1 in the vicinity of the substrate 4 is determined
by the incidence angle .theta. at the top end of the vapor
deposition zone 60a (.theta.1, .theta.4 shown in FIG. 2), whereas
the growth direction G1' of the first part p1 at and in the
vicinity of a top surface of the first part p1 is determined by the
incidence angle .theta. at the bottom end of the vapor deposition
zone 60a (.theta.2, .theta.3 shown in FIG. 2; .theta.2<.theta.1,
.theta.3<.theta.4). Therefore, the growth angle of the first
part p1 in the vicinity of the substrate 4 is larger than the
growth angle thereof in the vicinity of the top end of the first
part p1.
[0145] By contrast, the growth angle .alpha. made by the growth
direction of the second part p2 and the normal direction M is
actually small during the initial period of the second stage vapor
deposition step and increases as the second part p2 grows. The
reason is as follows. During the second stage vapor deposition
step, vapor deposition is performed on the substrate 4 moving away
from the evaporation source 9 from the bottom end to the top end of
the second vapor deposition zone 60b. As the substrate 4 becomes
farther from the evaporation source 9, the incidence angle .theta.
of the vapor-depositing material with respect to the normal
direction M to the substrate 4 increases.
[0146] Accordingly, in the cross-section shown in FIG. 3, the first
part p1 is warped upward (in the direction of rising) along the
actual growth direction G1', whereas the second part p2 is warped
downward along the actual growth direction G2'.
[0147] The first part p1 has a width which increases as the first
part p1 grows. The reason is as follows. As described above, the
concentration of the vapor-depositing material is higher as being
closer to the evaporation source 9. Therefore, as the first stage
vapor deposition step proceeds and as the substrate 4 becomes
closer to the evaporation source 9, the amount of the
vapor-depositing material incident on the substrate 4 (vapor
deposition amount) increases. By contrast, the second part p2 has a
width which decreases as the second part p2 grows. The reason is as
follows. As the second stage vapor deposition step proceeds and as
the substrate 4 becomes farther from the evaporation source 9, the
vapor deposition amount on the substrate 4 decreases.
[0148] In the above, the two-layer active material bodies 40 are
described with reference to FIG. 3. By repeating the vapor
deposition while inverting the transportation direction of the
substrate 4, active material bodies having three or more layers can
be formed. For example, after the second stage vapor deposition
step is finished, the substrate 4 taken up by the second roll 8 is
transported toward the first roll 3 to further perform vapor
deposition. By allowing the substrate 4 to pass through the first
and second vapor deposition zones 60a and 60b a plurality of times
by switching the transportation direction, active material bodies
having an arbitrary stacking number n can be formed.
[0149] FIG. 4 is a cross-sectional view showing an example of vapor
deposition film including active material bodies having five layers
(stacking number n=5) formed using the vapor deposition device 100.
Active material bodies 75 shown in FIG. 4 are formed as follows,
for example.
[0150] First, the above-described first and second stage vapor
deposition steps are carried out. As a result, the first part p1
inclined with respect to the normal direction M to the substrate 4
and a lower layer p2L of a second part inclined oppositely to the
first part p1 with respect to the normal direction M to the
substrate 4 are formed. After the second stage vapor deposition
step, the substrate 4 is taken up by the second roll 8.
[0151] Next, the substrate 4 is fed out from the second roll 8 and
heated by the heating section 16b. Then, the substrate 4 is guided
to the second vapor deposition zone 60b. In the second vapor
deposition zone 60b, silicon atoms are incident in the
above-described direction 44. Therefore, the oxide of silicon is
further grown on the lower layer p2L of the second part in
substantially the same direction as the growth direction G2 of the
second part p2. Thus, an upper layer p2U of the second part is
formed (third stage vapor deposition step). As a result, the second
part p2 including the lower layer p2L and the upper layer p2U is
obtained.
[0152] Next, the substrate 4 is guided to the first vapor
deposition zone 60a. In the first vapor deposition zone 60a, a
lower layer p3L of a third part growing parallel to the growth
direction G1 of the first part p1 is formed on the second part p2
(fourth stage vapor deposition step). After this, the substrate 4
is taken up by the first roll 3. The transportation direction is
inverted, and the substrate 4 is guided to the first vapor
deposition zone 60a and vapor deposition is performed to obtain an
upper layer p3U of the third part (fifth stage vapor deposition
step). By repeating the vapor deposition until the eighth stage
vapor deposition step is performed while switching the
transportation direction, active material bodies 75 (stacking
number n=5) can be obtained.
[0153] In the case where the vapor deposition is repeated while
switching the transportation direction, it is preferable that the
lengths and the positions of the first and second vapor deposition
zones 60a and 60b are adjusted such that the ratio of the film
formation amount in the first vapor deposition zone 60a (for
example, the thickness of the first part p1) and the film formation
amount in the second vapor deposition zone 60b (for example, the
thickness of the lower layer p2L of the second part p2) is
substantially 1:1. Where the ratio is significantly different from
1:1, the active material bodies as a whole are inclined in one
direction. As a result, the space between adjacent active material
bodies becomes smaller as being closer to the surface of the
current collector. Hence, the active material bodies collide
against each other at the time of charge, which causes a problem
that the substrate is likely to be wrinkled. By contrast, where the
transportation section is located such that the ratio is 1:1, the
active material bodies 75 as a whole can be grown substantially in
the normal direction to the surface of the substrate 4. Therefore,
the above-described problem can be solved.
[0154] Although not shown in FIG. 4 for simplicity, active material
bodies having three or more layers may also be formed. Like the
first part p1 described above with reference to FIG. 3, the parts
p1, p2U, p3U and p4U obtained by the step of performing vapor
deposition while moving the substrate 4 toward the evaporation
source 9 become wider and warped upward (in the direction of
rising) as growing. Like the second part p2 described above with
reference to FIG. 3, the parts p2L, p3L, p4L and p5 obtained by the
step of performing vapor deposition while moving the substrate 4
away from the evaporation source 9 become narrower and warped
downward as growing. Note that the "warp" and the change in the
width of each part may not occasionally be confirmed by observing
the cross-section depending on the stacking number n of the active
material body or the thickness of each part.
[0155] The film obtained using the vapor deposition device in this
embodiment has the following advantages over the film obtained by
the batch system vapor deposition device as described in, for
example, Patent Document 2. In the batch system vapor deposition
device, oblique vapor deposition is performed while the fixing
table for fixing the substrate is inclined so as to have a
prescribed angle with respect to the evaporation source. As
necessary, a plurality of stages of vapor deposition may be
performed while switching the inclination direction of the fixing
table. However, with such a vapor deposition device, the fixing
table is usually located such that a central part of the surface of
the substrate is located on the normal to the center of the
evaporation source. Therefore, even when the inclination direction
of the fixing table is switched, only the central part of the
surface of the substrate is always in a zone having the highest
concentration of the vapor-depositing material. For this reason,
the vapor deposition amount is large in the central part of the
surface of the substrate and is small in the vicinity of the ends
of the surface of the substrate. It is difficult to form a vapor
deposition film having a uniform thickness. By contrast, using the
vapor deposition device in this embodiment, a film having a uniform
thickness (height of the active material bodies) over the entirety
of the sheet-like substrate 4 can be formed. In addition, a film
obtained by the batch system vapor deposition device, unlike the
film formed using the vapor deposition device in this embodiment,
is not "warped", is changed in the width, or does not have a
stacking structure described later with reference to FIG. 13.
[0156] In this embodiment, in order that the temperature of the
substrate 4 heated by the heating sections 16a and 16b does not
exceed 500.degree. C. while the substrate 4 passes through the
vapor deposition zones 60a and 60b respectively, it is preferable
that the transportation rollers (including the first guide member
6), except for the transportation rollers along which the substrate
4 passes immediately after being heated by the heating sections 16a
and 16b, are cooled. The transportation speed of the substrate 4 by
the transportation section and the vapor deposition rate are
appropriately adjusted such that the temperature of the substrate 4
does not exceed 500.degree. C.
[0157] As described above, by adjusting the temperature of the
substrate 4 running in the first and second vapor deposition zones
60a and 60b to the range of, for example, 200.degree. C. or higher
and lower than 500.degree. C., the growth angle .alpha. of the
active material bodies (angle made by the normal direction M to the
substrate 4 and the growth directions G1 and G2) can be adjusted.
As described above, the growth angle .alpha. of the active material
bodies is determined by the incidence angle .theta. of the
vapor-depositing material (2 tan .alpha.=tan .theta.; hereinafter,
referred to as the "tan rule"). When the incidence angle .theta. is
60.degree. or larger, the growth angle .alpha. tends to be smaller
than the angle determined by the tan rule. In this case, if the
temperature of the substrate 4 is lower than the above-described
range, the growth angle .alpha. is especially small. Where the
zigzag active material bodies are formed at a small growth angle
.alpha., the active material bodies are wider than the active
material bodies grown at a growth angle conformed to the tan rule.
As a result, a sufficient space between the active material bodies
cannot be secured. Where such active material bodies are used to
form an electrode, the active material bodies collide against each
other at the time of charge, which may buckle or wrinkle the
substrate, for example. The term "buckle" means that the substrate
(electrode substrate) is bent by an expansion stress. When buckle
occurs, the cross-section of the electrode is waved. By controlling
the temperature of the substrate 4 to the range of 200.degree. C.
or higher, the growth angle .alpha. of the active material bodies
can be made closer to the growth angle determined by the tan rule
and thus a sufficient space can be secured between the active
material bodies. By contrast, where the temperature of the
substrate 4 is lower than 500.degree. C., the substrate 4 can be
prevented from being wrinkled by thermal deformation thereof. In
the case where a copper substrate is used as the substrate 4,
diffusion of silicon in the copper substrate can be prevented at
such a temperature.
[0158] In this embodiment, the heating sections 16a and 16b are
located outside the vapor deposition zones to heat the substrate 4
before the substrate 4 reaches the vapor deposition zones 60a and
60b. The heating sections 16a and 16b may be located in the first
and second vapor deposition zones 60a and 60b. Note that it is
preferable to locate the heating sections 16a and 16b so as to heat
the substrate 4 immediately before the substrate 4 reaches the
first and second vapor deposition zones 60a and 60b as in this
embodiment because the temperature of the substrate 4 before vapor
deposition can be controlled more accurately.
[0159] Instead of the structure shown in FIG. 2, as shown in FIG.
5, the first and second vapor deposition zones 60a and 60b may be
formed so as to be line-symmetrical with respect to the normal N
passing through the center of the evaporation surface 9s in the
cross-section. This structure has the following advantages. The
incidence angles .theta.2 and .theta.3 in the vapor deposition
zones 60a and 60b can be easily made equal to each other
(.theta.2=.theta.3), and also the amount vapor-deposited in the
vapor deposition zones 60a and 60b (vapor deposition amount) can be
easily adjusted to be substantially equal to each other. As a
result, the active material body as a whole can be easily grown
substantially in the normal direction to the substrate 4.
Meanwhile, with the structure shown in FIG. 1 and FIG. 2, a zone
with a high concentration of the vapor-depositing material
evaporated from the evaporation surface 9s (a central zone
including the normal N passing through the center of the
evaporation surface 9s) in the vapor deposition possible zone is
usable for vapor deposition. Thus, the structure shown in FIG. 1
and FIG. 2 has an advantage that the vapor-depositing material can
be efficiently usable.
[0160] Using the vapor deposition device in this embodiment, an
arbitrary stacking number n of the active material bodies can be
formed continuously on the surface of the sheet-like substrate 4.
In the case of forming active material bodies having a stacking
number n of 30 or greater, the cross-section of each active
material body may not be zigzag or inclined along the growth
direction but may be like a column standing upright along the
normal direction to the substrate 4. Even in this case, it can be
confirmed that the active material body grows zigzag from the
bottom surface to the top surface thereof regardless of the
cross-sectional shape by, for example, observing the cross-section
by an SEM.
[0161] These active material bodies are located with a prescribed
space provided therebetween on the surface of the substrate 4.
Therefore, the space between adjacent active material bodies is
usable as an expansion space for accommodating the expansion of the
active material bodies during the charge/discharge. Accordingly,
the stress on the active material bodies is alleviated so as to
suppress the shortcircuiting between the positive and negative
electrodes. As a result, a cell having a high charge/discharge
cycle characteristic can be obtained.
[0162] The operation of the vapor deposition device 100 has been
described in the case of forming active material bodies of an oxide
of silicon. The vapor-depositing material to be used or the use of
the vapor deposition film are not limited to those in this example.
In the above, the vapor deposition film is formed by reacting the
vapor-depositing material evaporated from the evaporation source 9
(silicon atoms) with the gas supplied from the nozzle section 22
(oxygen gas). Alternatively, only the vapor-depositing material may
be grown on the surface of the substrate 4 without supplying
gas.
Embodiment 2
[0163] Hereinafter, a vapor deposition device according to
Embodiment 2 of the present invention will be described with
reference to the figure. In this embodiment, two V-shaped substrate
paths (V-shaped paths) as described in EMBODIMENT 1 are provided in
the vapor deposition possible zone in the chamber; namely, four
vapor deposition zones in total are provided.
[0164] FIG. 6 is a cross-sectional view schematically showing a
vapor deposition device according to EMBODIMENT 2 of the present
invention. For simplicity, identical elements with those of the
vapor deposition device 100 in FIG. 1 bear identical reference
numerals therewith, and descriptions thereof will be omitted. A
vapor deposition device 200 shown in FIG. 6 includes a
transportation section including first and second rolls 3 and 8,
transportation rollers 5a through 5c, and first and second guide
members (transportation rollers) 6a and 6b, and thus defines a
transportation path of the substrate 4.
[0165] The transportation rollers 5a, 6a, 5b, 6b and 5c are
sequentially located in this order from the first roll side on the
transportation path of the substrate 4. In this embodiment, the
first guide member 6a is located below the transportation rollers
5a and 5b adjacent thereto, and guides the substrate 4 such that
the surface of the substrate 4 to be subjected to the
vapor-depositing material is convexed toward the evaporation source
9. Thus, a V-shaped path is formed. Between the first guide member
6a and the evaporation source 9, a first shielding member 20a is
located, which prevents the vapor-depositing material evaporated
from the evaporation surface 9s of the evaporation source 9 from
being incident in the normal direction to the substrate 4 and also
separates the vapor deposition zone of the V-shaped path into two.
Owing to such a structure, on this V-shaped path, a first vapor
deposition zone 60a located on the first roll side with respect to
the first shielding member 20a and a second vapor deposition zone
60b located on the second roll side with respect to the first
shielding member 20a are formed. Similarly, the second guide member
6b is located below the transportation rollers 5b and 5c adjacent
thereto, and guides the substrate 4 such that the surface of the
substrate 4 to be subjected to the vapor-depositing material is
convexed toward the evaporation source 9. Thus, a V-shaped path is
formed. Between the second guide member 6b and the evaporation
source 9, a first shielding member 20b is located, which prevents
the vapor-depositing material evaporated from the evaporation
surface 9s of the evaporation source 9 from being incident in the
normal direction to the substrate 4 and also separates the vapor
deposition zone of the V-shaped path into two. Owing to such a
structure, on this V-shaped path, a third vapor deposition zone 60c
located on the first roll side with respect to the first shielding
member 20b and a fourth vapor deposition zone 60d located on the
second roll side with respect to the first shielding member 20b are
formed. The incidence directions of the vapor-depositing material
in the vapor deposition zones 60a through 60d are controlled to be
inclined by an angle of 45.degree. or greater and 75.degree. or
smaller with respect to the normal direction to the substrate 4. In
the case where the surface of the substrate 4 to be subjected to
the vapor-depositing material is transported in two V-shaped paths
continuously, namely, in a W-shaped manner as in this embodiment,
the transportation path may be occasionally referred to as the
"W-shaped path".
[0166] In the vapor deposition device 200 in this embodiment, four
vapor deposition zones are formed in the vapor deposition possible
zone. Therefore, the vapor-depositing material emitted to a wider
angle is usable for vapor deposition and thus the utilization
factor of the vapor-depositing material can be further improved. In
addition, after four stages of vapor deposition are continuously
performed on the surface of the substrate 4 while switching the
vapor deposition direction, the transportation direction may be
switched to further perform multiple stages of vapor deposition.
Accordingly, active material bodies having an arbitrary stacking
number n (for example, n=30 to 40) can be continuously formed on
the surface of the substrate 4.
[0167] The vapor deposition device 200 preferably includes
shielding plates 15a and 15b having walls facing the vapor
deposition surface of the substrate 4 passing through the first and
fourth vapor deposition zones 60a and 60d. Owing to this, gas
emitted from a plurality of emission openings provided in side
surfaces of the nozzle section 22 can be efficiently caused to
reside in the vapor deposition zones 60a and 60d.
[0168] It is preferable that the surface of the wall of each of the
shielding plates 15a and 15b acts as a facing surface for
alleviating the temperature difference caused, by the radiant heat
from the evaporation surface 9, to the vapor deposition surface of
the substrate 4 passing through the corresponding vapor deposition
zone. It is preferable that the vapor deposition surface of the
substrate 4 passing through the second vapor deposition zone 60b
and the vapor deposition surface of the substrate 4 passing through
the third vapor deposition zone 60c face each other and each acts
as a facing surface for alleviating the temperature difference
caused, by the radiant heat from the evaporation surface 9, to the
facing vapor deposition surface. Owing to such a structure, the
temperature difference can be reduced in all the vapor deposition
zones 60a through 60d to form a more uniform vapor deposition film.
It is not absolutely necessary that the vapor deposition device in
this embodiment includes the shielding plates 15a and 15b having
the walls or that the vapor deposition surfaces of the substrate 4
passing through the facing vapor deposition zones act as the
"facing surfaces" to each other. However, it is advantageous that
the vapor deposition surface of the substrate 4 passing through at
least one of the vapor deposition zones is structured to face a
surface, which is the target of alleviation of the temperature
difference caused by the radiant heat from the evaporation source
9, because this can suppress the uniformity of the vapor deposition
film from being deteriorated by the temperature difference.
[0169] Hereinafter, a method for forming a vapor deposition film
using the vapor deposition device 200 will be described.
[0170] First, the substrate 4 is transported from the first roll 3
to the first vapor deposition zone 60a. Next, in the first vapor
deposition zone 60a, while the substrate 4 is moved toward the
evaporation source 9, the vapor-depositing material evaporated from
the evaporation source 9 is incident on the surface of the
substrate 4 in a direction inclined with respect to the normal to
the surface of the substrate 4 (incidence direction) to deposit the
vapor-depositing material (first stage vapor deposition step). As a
result, a first film is formed on the surface of the substrate
4.
[0171] Next, the substrate 4 is transported to the second vapor
deposition zone 60b. In the second vapor deposition zone 60b, while
the substrate 4 is moved away from the evaporation source 9, the
vapor-depositing material is incident on the surface of the
substrate 4 in a direction inclined oppositely to the incidence
direction in the first stage vapor deposition step with respect to
the normal to the surface of the substrate 4 (second stage vapor
deposition step). As a result, a second film is formed on the first
film.
[0172] Then, the substrate 4 is transported to the third vapor
deposition zone 60c. In the third vapor deposition zone 60c, while
the substrate 4 is moved toward the evaporation source 9, the
vapor-depositing material is incident on the surface of the
substrate 4 in a direction inclined on the same side as the
incidence direction in the first stage vapor deposition step with
respect to the normal to the surface of the substrate 4 (third
stage vapor deposition step). As a result, a third film is formed
on the second film.
[0173] Then, the substrate 4 is transported to the fourth vapor
deposition zone 60d. In the fourth vapor deposition zone 60d, while
the substrate 4 is moved away from the evaporation source 9, the
vapor-depositing material is incident on the surface of the
substrate 4 in a direction inclined oppositely to the incidence
direction in the first stage vapor deposition step with respect to
the normal to the surface of the substrate 4 (fourth stage vapor
deposition step). As a result, a fourth film is formed on the third
film.
[0174] After the first through fourth films are formed, the
substrate 4 is taken up by the second roll 8. In this manner, a
film having a stacking structure (stacking number n: 4) is
formed.
[0175] After the fourth stage vapor deposition step, the substrate
4 may be transported from the second roll 8 to the first roll 3 to
perform another four stages of vapor deposition.
[0176] In this case, the substrate 4 is first transported to the
fourth vapor deposition zone 60d. In the fourth vapor deposition
zone 60d, while the substrate 4 is moved toward the evaporation
source 9, the vapor-depositing material is incident on the
substrate 4 to form a fifth film on the fourth film (fifth stage
vapor deposition step).
[0177] Next, the substrate 4 is transported to the third vapor
deposition zone 60c. In the third vapor deposition zone 60c, while
the substrate 4 is moved away from the evaporation source 9, the
vapor-depositing material is incident on the substrate 4 to form a
sixth film on the fifth film (sixth stage vapor deposition
step).
[0178] Then, similarly, in the second vapor deposition zone 60b,
while the substrate 4 is moved toward the evaporation source 9, a
seventh stage vapor deposition step is carried out. In the first
vapor deposition zone 60a, while the substrate 4 is moved away from
the evaporation source 9, an eighth stage vapor deposition step is
carried out. Then, the substrate 4 is taken up by the first roll
3.
[0179] The incidence direction and the incidence angle of the
vapor-depositing material are determined by the angle made by the
normal to the substrate 4 and the normal to the center of the
evaporation source 9 in the vapor deposition zones 60a through 60d.
Therefore, in the case where vapor deposition is performed in the
same vapor deposition zone, the incidence direction and the
incidence angle of the vapor-depositing material are the same
regardless of the transportation direction of the substrate 4. For
example, the fourth and fifth stage vapor deposition steps are both
carried in the fourth vapor deposition zone 60d, and so the
incidence direction and the incidence angle of the vapor-depositing
material are the same.
[0180] Even after the eighth stage vapor deposition step, when
necessary, the transportation direction of the substrate 4 may be
switched to transport the substrate 4 sequentially from the first
through fourth vapor deposition zones 60a through 60d and thus to
further repeat substantially the same vapor deposition steps as the
first through fourth stage vapor deposition steps. In this manner,
an arbitrary number of stages of vapor deposition steps can be
performed while the transportation direction of the substrate 4 is
switched.
[0181] The vapor deposition device 200 further includes heating
sections 16a and 16b respectively on the first roll side with
respect to the first vapor deposition zone 60a and on the second
roll side with respect to the fourth vapor deposition zone 60d for
heating the substrate 4 to the range of 200.degree. C. to
400.degree. C. Owing to such a structure, when the substrate 4 is
transported from the first roll 3 toward the second roll 8 via the
W-shaped path, the substrate 4 can be heated by the heating section
16a before reaching the W-shaped path. When the substrate 4 is
transported in the opposite direction, the substrate 4 can be
heated by the heating section 16b before reaching the W-shaped
path.
[0182] In the case where vapor deposition is repeated while
switching the transportation direction of the substrate 4, it is
preferable that the ratio among the film formation amounts in the
first, second, third and fourth vapor deposition zones 60a, 60b,
60c and 60d is 1:2:2:1. Where the film formation amount in the
first and fourth vapor deposition zones 60a and 60d through which
the substrate 4 may possibly pass twice in a row is set to be 1/2
of the film formation amount in the other vapor deposition zones
(the second and third vapor deposition zones 60b and 60c), the
thickness of the parts of the zigzag active material body can be
made substantially uniform. Thus, the active material body as a
whole can be grown in the normal direction to the substrate 4. The
expression "the substrate 4 passes through the vapor deposition
zone twice in a row" means that the substrate 4 passes through the
vapor deposition zone to form a vapor deposition film in a
prescribed direction, and then, without a vapor deposition film
being formed on the formed vapor deposition film in another
direction in another vapor deposition zone, the substrate 4 passes
through the same vapor deposition zone again by the transportation
direction being switched and vapor deposition is performed.
Embodiment 3
[0183] Hereinafter, a vapor deposition device according to
Embodiment 3 of the present invention will be described with
reference to the figures. In this embodiment, two V-shaped
substrate paths (V-shaped paths) are provided as in Embodiment 1;
namely, four vapor deposition zones (first through fourth vapor
deposition zones) 60a through 60d in total are provided. Note that
unlike in the Embodiment 1, the transportation section in this
embodiment is structured to put the substrate 4 upside down after
the substrate 4 passes through the first and second vapor
deposition zones 60a and 60b and to guide the substrate 4 to the
third and fourth vapor deposition zones 60c and 60d.
[0184] FIG. 7 is a cross-sectional view showing an example of vapor
deposition device in this embodiment. For simplicity, identical
elements with those of the vapor deposition device 200 shown in
FIG. 6 bear identical reference numerals therewith, and
descriptions thereof will be omitted.
[0185] In a vapor deposition device 300, the transportation path of
the substrate 4 is defined by the first and second rolls 3 and 8,
the transportation rollers 5a through 5f, and first and second
guide members 6a and 6b. The transportation rollers 5c through 5e
are located between the second vapor deposition zone 60b and the
third vapor deposition zone 60c on the transportation path of the
substrate 4 so as to surround the second roll 8 (inversion
structure). Owing to such a structure, the surface of the substrate
4 to face the evaporation source 9 can be inverted. Accordingly,
while the substrate 4 passes through the first and second vapor
deposition zones 60a and 60b, vapor deposition can be performed on
one of the surfaces of the substrate 4 (this surface will be
referred to as the "first surface"). While the substrate 4 passes
through the third and fourth vapor deposition zones 60c and 60d,
vapor deposition can be performed on the other surface of the
substrate 4 (this surface will be referred to as the "second
surface"). Therefore, using the vapor deposition device 300, vapor
deposition films can be continuously formed on both surfaces of the
substrate 4 while the chamber 2 is kept vacuum.
[0186] In this embodiment, the second vapor deposition zone 60b and
the fourth vapor deposition zone 60d are formed to face each other.
Between these vapor deposition zones 60b and 60d, a shielding plate
15c is provided so as to cover the transportation rollers 5b and
5f. The shielding plate 15c prevents the vapor-depositing material
from being incident on the transportation rollers 5b and 5f and
also controls the incidence angle at the top ends of the vapor
deposition zones 60b and 60d.
[0187] In this embodiment, in a cross-section which is vertical to
the surface of the substrate 4 and includes the transportation
direction of the substrate 4, the first guide member 6a and the
second guide member 6b are located on both sides of the normal N
passing through the center of the evaporation surface 9s. The
transportation section is located with respect to the evaporation
source 9 such that one of the first through fourth vapor deposition
zones 60a through 60d (in the example shown in the figure, the
vapor deposition zone 60b) crosses the normal N passing through the
center of the evaporation surface 9s. This is advantageous because
a zone having a high concentration of the vapor-depositing material
in the vapor deposition possible zone is usable to the maximum
possible degree to perform vapor deposition. In the vapor
deposition device 300 shown in the figure, the second vapor
deposition zone 60b and the fourth vapor deposition zone 60d are
formed to face each other at substantially the center of the vapor
deposition possible zone. In this specification, the vapor
deposition zone are assigned reference numerals in accordance with
the transportation path. Hence, the other vapor deposition zones
may face each other at the center of the vapor deposition possible
zone depending on the arrangement of the transportation section. In
either case, substantially the same effect as described above is
provided as long as one of the two vapor deposition zones facing
each other at substantially the center of the vapor deposition
possible zone is located so as to cross the normal N.
[0188] In the vicinity of the top ends of the vapor deposition
zones 60a through 60d, heating sections 16a through 16d are
respectively located for heating the substrate 4 to the range of,
for example, 200.degree. to 400.degree. C. The expression that the
heating sections 16a through 16d are respectively "located in the
vicinity of the top ends of the vapor deposition zones 60a through
60d" means that each heating section is provided at a position
which is in a vapor deposition zone other than the corresponding
vapor deposition zone and at which the substrate 4 is heated
immediately before reaching the corresponding vapor deposition
zone. Owing to such a structure, when the substrate 4 is
transported from the first roll 3 toward the second roll 8, the
substrate 4 can be heated by the heating sections 16a and 16c
before reaching the corresponding V-shaped path. When the substrate
4 is transported in the opposite direction, the substrate 4 can be
heated by the heating sections 16b and 16d before reaching the
corresponding V-shaped path. The vapor deposition zone 300 includes
four heating sections, but the number of the heating sections may
be two in the case where, for example, the transportation direction
does not need to be switched. In such a case, the heating section
16a located on the first roll side with respect to the first vapor
deposition zone 60a on the transportation path of the substrate 4,
and the heating section 16c located between the second vapor
deposition zone 60b and the third vapor deposition zone 60c on the
transportation path of the substrate 4, may be provided.
[0189] FIG. 8 is a cross-sectional view showing an example of vapor
deposition films formed on both surfaces of the substrate 4 using
the vapor deposition device 300. The vapor deposition films shown
here include a plurality of active material bodies formed by
transporting the substrate 4 from the first roll 3 to the second
roll 8 and arranged with a space provided therebetween.
[0190] In this embodiment, a metal foil having a concave and convex
pattern on both surfaces (first surface and second surface) S1 and
S2 thereof is used as the substrate 4. The pattern formed on the
surfaces S1 and S2 is substantially the same as that described
above in Embodiment 1 and will not be described here.
[0191] On the first surface S1 of the substrate 4, a plurality of
active material bodies 90 including two layers having different
growth directions are formed. Each active material body 90 includes
a first part p1 formed in the first vapor deposition zone 60a and a
second part p2 formed on the first part p1 in the second vapor
deposition zone 60b. On the second surface S2 of the substrate 4
also, a plurality of active material bodies 92 having substantially
the same two-layer structure are formed. Each active material body
92 includes a first part q1 and a second part q2 respectively
formed in the third and fourth vapor deposition zones 60c and
60d.
[0192] In this embodiment, it is preferable that the transportation
section and the shielding section are located such that the ranges
of incidence angle .theta. of the vapor-depositing material in the
first through fourth vapor deposition zones 60a through 60d are
substantially equal to one another. It is also preferable that the
film formation amounts in the first through fourth vapor deposition
zones 60a through 60d are substantially equal to one another. Owing
to this, the active material bodies 90 and 92 having substantially
the same shape and thickness can be formed on both surfaces of the
substrate 4. When such a substrate 4 is used to produce an
electrode for a lithium secondary cell, the stress applied on the
first surface S1 of the substrate 4 by the expansion of the active
material bodies 90 and the stress applied on the second surface S2
of the substrate 4 by the expansion of the active material bodies
92 can be made substantially equal to each other. As a result, the
substrate 4 can be effectively prevented from being curved due to
the stress difference when the charge/discharge cycle is
repeated.
[0193] In the vapor deposition device 300 shown in FIG. 7, a single
shielding plate 15c is provided for the transportation rollers 5b
and 5f. Alternatively, one single shielding plate may be provided
for each of the transportation rollers 5b and 5f. A vapor
deposition device of such a structure is shown in FIG. 9. For
simplicity, identical elements with those in FIG. 7 bear identical
reference numerals therewith, and descriptions thereof will be
omitted.
[0194] In a vapor deposition device 300' shown in FIG. 9, in order
to effectively prevent the vapor-depositing material from being
attached to the transportation rollers 5b and 5f, shielding plates
15d and 15e are provided along the transportation rollers 5b and 5c
respectively. Accordingly, the top ends of the vapor deposition
zones 60b and 60d are defined by the shielding plates 15d and 15e.
A shielding plate 15e is provided above the gap between the
transportation rollers 5b and 5f and prevents the vapor-depositing
material, which has passed through the gap between transportation
rollers 5b and 5f, from being attached to the substrate located
above the gap. Such a structure of the shielding plates is
preferably applicable to a vapor deposition device which requires
two or more transportation rollers to be provided between facing
vapor deposition zones for the purpose of forming an inversion
structure. The structure of the shielding plates is not limited to
that shown in FIG. 7 or FIG. 9. For example, the shielding plates
15a and 15b do not need to have a wall having a function of
alleviating the temperature difference on the substrate 4.
Embodiment 4
[0195] Hereinafter, a vapor deposition device according to
Embodiment 4 of the present invention will be described with
reference to the figures. In the vapor deposition device in this
embodiment, the transportation section has two W-shaped substrate
paths (W-shaped paths) as described in Embodiment 2 with reference
to FIG. 6 and is structured to have an inversion structure for
inverting the surface of the substrate 4 to be subjected to the
vapor-depositing material between the W-shaped paths. The W-shaped
path may have a structure substantially the same as that described
in Embodiment 3 with reference to FIG. 7.
[0196] FIG. 10 is a cross-sectional view schematically showing a
vapor deposition device in this embodiment. For simplicity,
identical elements with those of the vapor deposition devices 100,
200 and 300 described in the above embodiments bear identical
reference numerals therewith, and descriptions thereof will be
omitted.
[0197] A vapor deposition device 400 shown in FIG. 10 includes a
transportation section including first and second rolls 3 and 8,
transportation rollers 5a through 5m, and first through fourth
guide members 6a through 6d, and thus defines a transportation path
of the substrate 4. In addition, shielding plates 15a through 15e
and first through fourth shielding members 6a through 6b are
provided so as to prevent the vapor-depositing material evaporated
from the vapor deposition surface 9s from being incident on the
substrate 4 in the normal direction to the substrate 4.
[0198] The transportation rollers 5a through 5m are sequentially
located in this order from the first roll side on the
transportation path of the substrate 4. The first through fourth
guide members (transportation rollers) 6a through 6d are
sequentially located in this order from the first roll side on the
transportation path of the substrate 4. Like in the above
embodiments, the guide members 6a through 6d guide the substrate 4
such that the surface of the substrate 4 to be subjected to the
vapor-depositing material is convexed toward the evaporation source
9 and thus a V-shaped path is formed. Between the guide members 6a
through 6d and the evaporation source 9, the first through fourth
shielding members 20a through 20d are respectively located. Each of
the shielding members 20a through 20d prevents the vapor-depositing
material evaporated from the evaporation surface 9s of the
evaporation source 9 from being incident in the normal direction to
the substrate 4 and also separates the corresponding vapor
deposition zone of the V-shaped path into two. Owing to such a
structure, on the V-shaped path formed by the first guide member
6a, a first vapor deposition zone 60a located on the first roll
side with respect to the first shielding member 20a and a second
vapor deposition zone 60b located on the second roll side with
respect to the first shielding member 20a are formed. Similarly, on
the V-shaped path formed by the second guide member 6b, a third
vapor deposition zone 60c located on the first roll side with
respect to the first shielding member 20b and a fourth vapor
deposition zone 60d located on the second roll side with respect to
the first shielding member 20b are formed. On the V-shaped path
formed by the third guide member 6c, a fifth vapor deposition zone
60e located on the first roll side with respect to the first
shielding member 20c and a sixth vapor deposition zone 60f located
on the second roll side with respect to the first shielding member
20c are formed. On the V-shaped path formed by the fourth guide
member 6d, a seventh vapor deposition zone 60g located on the first
roll side with respect to the first shielding member 20d and an
eighth vapor deposition zone 60h located on the second roll side
with respect to the first shielding member 20d are formed. Between
the first through eighth vapor deposition zones 60a through 60h and
the evaporation surface 9s, a shutter 28 is provided.
[0199] In this embodiment, the transportation section and the
shielding section are located with respect to the evaporation
source 9 such that the incidence direction of the vapor-depositing
material in the first through eighth vapor deposition zones 60a
through 60h is inclined by an angle of, for example, 45.degree. or
greater and 75.degree. or smaller with respect to the normal
direction to the substrate 4.
[0200] In this embodiment, the transportation rollers 5f through 5h
are located between the fourth vapor deposition zone 60d and the
fifth vapor deposition zone 60e on the transportation path of the
substrate 4 so as to surround the second roll 8 (inversion
structure). Owing to such a structure, the substrate 4 after
passing through the W-shaped path including the first through
fourth vapor deposition zones 60a through 60d can be inverted to be
guided to the fifth through eighth vapor deposition zones 60e
through 60h. Therefore, vapor deposition films can be continuously
formed on both surfaces of the substrate 4 while the chamber 2 is
kept vacuum.
[0201] The vapor deposition device 400 also includes four heating
sections 16a through 16d located outside the corresponding vapor
deposition zones for heating the substrate 4 to the range of
200.degree. to 400.degree. C. The heating sections 16a through 16d
are respectively located in the vicinity of the top ends of the
first, fourth, fifth and eighth vapor deposition zones 60a, 60d,
60e and 60h. Owing to such a structure, when the substrate 4 is
transported from the first roll 3 toward the second roll 8, the
substrate 4 can be heated by the heating sections 16a and 16c
immediately before reaching the corresponding W-shaped path. When
the substrate 4 is transported in the opposite direction, the
substrate 4 can be heated by the heating sections 16b and 16d
before reaching the corresponding W-shaped path. The vapor
deposition zone 400 includes four heating sections, but the number
of the heating sections may be two in the case where, for example,
the transportation direction does not need to be switched. In such
a case, the heating section 16a located on the first roll side with
respect to the first vapor deposition zone 60a on the
transportation path of the substrate 4, and the heating section 16c
located between the fourth vapor deposition zone 60d and the fifth
vapor deposition zone 60e on the transportation path of the
substrate 4, may be provided.
[0202] The vapor deposition device 400 allows a plurality of stages
of vapor deposition steps to be continuously performed on both
surfaces of the substrate 4 while the vapor deposition direction is
switched. In addition, since eight vapor deposition zones are
formed in the vapor deposition possible zone, the vapor-depositing
material emitted to a wider angle is usable for vapor deposition,
which can further improve the utilization factor of the
vapor-depositing material.
[0203] Hereinafter, a method for forming a film using the vapor
deposition device 400 will be described.
[0204] First, substantially the same vapor deposition steps as
those in the first through fourth stage vapor deposition steps
described above with reference to FIG. 6 are performed in the first
through fourth vapor deposition zones 60a through 60d to form first
through fourth films.
[0205] Next, the vapor deposition surface of the substrate 4 is
inverted, and vapor deposition is performed in the fifth through
eighth vapor deposition zones 60e through 60h on the opposite
surface (rear surface) of the substrate 4 to the surface on which
the first through fourth films have been formed. Specifically, this
is performed as follows. In the fifth vapor deposition zone 60e,
while the substrate 4 is moved toward the evaporation source 9, the
vapor-depositing material evaporated from the evaporation source 9
is incident on the rear surface of the substrate 4 in a direction
inclined with respect to the normal to the surface of the substrate
4 (incidence direction) to form a 1'st film on the rear surface of
the substrate 4 (1'st stage vapor deposition step). Then, in the
sixth vapor deposition zone 60f, while the substrate 4 is moved
away from the evaporation source 9, the vapor-depositing material
is incident on the rear surface of the substrate 4 in a direction
inclined oppositely to the incidence direction in the 1'st stage
vapor deposition step with respect to the normal to the surface of
the substrate 4 to form a 2'nd film on the 1'st film (2'nd stage
vapor deposition step). Then, in the seventh vapor deposition zone
60g, while the substrate 4 is moved toward the evaporation source
9, the vapor-depositing material is incident on the rear surface of
the substrate 4 in a direction inclined on the same side as the
incidence direction in the 1'st stage vapor deposition step with
respect to the normal to the surface of the substrate 4 to form a
3'rd film on the 2'nd film (3'rd stage vapor deposition step).
Then, in the eighth vapor deposition zone 60h, while the substrate
4 is moved away from the evaporation source 9, the vapor-depositing
material is incident on the rear surface of the substrate 4 in a
direction inclined oppositely to the incidence direction in the
1'st stage vapor deposition step with respect to the normal to the
surface of the substrate 4 to form a 4'th film on the 3'rd film
(4'th stage vapor deposition step).
[0206] After this, the substrate 4 is once taken up by the second
roll 8 and then is transported to the eighth through fifth vapor
deposition zones 60h through 60e in this order to perform 5'th
through 8'th stage vapor deposition steps in the eighth through
fifth vapor deposition zones 60h through 60e. Specifically, this is
performed as follows. In the eighth vapor deposition zone 60h,
while the substrate 4 is moved toward the evaporation source 9, the
vapor-depositing material is incident on the substrate 4 to form a
5'th film on the 4'th film (5'th stage vapor deposition step).
Then, in the seventh vapor deposition zone 60g, while the substrate
4 is moved away from the evaporation source 9, the vapor-depositing
material is incident on the substrate 4 to form a 6'th film on the
5'th film (6'th stage vapor deposition step). Then, similarly, in
the sixth vapor deposition zone 60f, while the substrate 4 is moved
toward the evaporation source 9, a 7'th stage vapor deposition step
is carried out. In the fifth vapor deposition zone 60e, while the
substrate 4 is moved away from the evaporation source 9, an 8'th
stage vapor deposition step is carried out.
[0207] As described above, in the case where vapor deposition is
performed in the same vapor deposition zone, the incidence
direction and the incidence angle of the vapor-depositing material
are the same regardless of the transportation direction of the
substrate 4. For example, the 4'th and 5'th stage vapor deposition
steps are both carried in the eighth vapor deposition zone 60h, and
so the incidence direction and the incidence angle of the
vapor-depositing material are the same.
[0208] After the 8'th stage vapor deposition step, the vapor
deposition surface of the substrate 4 is again inverted and the
substrate 4 is transported to the fourth vapor deposition zone 60d.
After this, in the fourth through second vapor deposition zones 60d
through 60a, the fifth through eighth stage vapor deposition steps
are carried out on the surface of the substrate 4 on which the
first through fourth films have been formed. As a result, the fifth
through eighth films are formed. The fifth through eighth stage
vapor deposition steps are substantially the same as the fifth
through eighth stage vapor deposition steps described above with
reference to FIG. 6. After this, the substrate 4 is taken up by the
first roll 3.
[0209] Even after the eighth stage vapor deposition step, when
necessary, the transportation direction of the substrate 4 may be
switched to transport the substrate 4 sequentially to the first
through eighth vapor deposition zones 60a through 60h and thus to
further repeat substantially the same vapor deposition steps as the
first through fourth stage vapor deposition steps and the 1'st
through 4'th stage vapor deposition steps. By reciprocating the
substrate 4 an arbitrary number of times between the first roll 3
and the second roll 8 in this manner, a desired number of stages of
vapor deposition can be performed.
[0210] In this embodiment, it is preferable that in a cross-section
which is vertical to the surface of the substrate 4 and includes
the transportation direction of the substrate 4, the first and
second guide members 6a and 6b, and the third and fourth guide
members 6c and 6d, are preferably located on both sides of the
normal N passing through the center of the evaporation source 9. It
is also preferable that in the above-described cross-section, the
transportation section is located with respect to the evaporation
source 9 such that one of the first through eighth vapor deposition
zones 60a through 60h crosses the normal passing through the center
of the evaporation source 9. Owing to this, a zone having a high
concentration of the vapor-depositing material evaporated from the
evaporation source 9 in the vapor deposition possible zone is
usable for vapor deposition, and thus the utilization factor of the
vapor-depositing material can be improved.
[0211] The vapor deposition device 400 has an inversion structure
for inverting the substrate 4. However, a vapor deposition device
in this embodiment does not need to have an inversion structure. In
a vapor deposition device without the inversion structure, the
substrate 4 passes through two W-shaped paths and as a result,
active material bodies having eight layers (stacking number n=8)
are formed on only one surface of the substrate 4.
[0212] Now, an example of structure of the vapor deposition films
formed on both surfaces of the substrate 4 using the vapor
deposition device 400 will be described. FIG. 11 is a
cross-sectional view showing vapor deposition films obtained by
transporting the substrate 4 from the first roll 3 to the second
roll 8 (forward path) and then transporting the substrate 4 from
the second roll 8 to the first path 3 (return path). In this
example, the vapor deposition film formed on each surface of the
substrate 4 includes a plurality of active material bodies formed
with a space provided therebetween.
[0213] In this embodiment, as the substrate 4, a metal foil having
a concave and convex pattern on both surfaces (first surface and
second surface) S1 and S2 thereof is used. Here, the pattern formed
on the surfaces S1 and S2 is the same as the concave and convex
pattern described in Embodiment 1 and will not be described
again.
[0214] On the first and second surfaces S1 and S2 of the substrate
4, a plurality of active material bodies 94 and 96 are respectively
formed. Each active material body 94 has a structure in which seven
layers, i.e., first through seventh parts p1 through p7, are
stacked (stacking number n=7). The parts p1 through p7 have growth
directions inclined alternately in opposite directions with respect
to the normal direction to the first surface S1.
[0215] The active material bodies 94 and 96 are formed as follows,
for example. First, in the forward path, the substrate 4 fed out
from the first roll 3 passes through the first through fourth vapor
deposition zones 60a through 60d. As a result, the first part p1,
the second part p2, the third part p3 and a lower layer p4L of the
fourth part are stacked in this order on the first surface S1 of
the substrate 4 (first through fourth vapor deposition steps).
[0216] Next, the substrate 4 is inverted by the inversion structure
and passes through the fifth through eighth vapor deposition zones
60e through 60h. As a result, a first part q1, a second part q2, a
third part q3 and a lower layer 4qL of a fourth part are stacked in
this order also on the second surface S2 of the substrate 4 (1'st
through 4'th vapor deposition steps).
[0217] Then, the substrate 4 is once taken up by the second roll 8
and then is fed out toward the first roll 3 (return path). In the
return path, the substrate 4 first passes through the eighth vapor
deposition zone 60h. As a result, on the lower layer 4qL in the
fourth part formed in the forward path, an upper layer 4qU is grown
in substantially the same direction as that of the lower layer 4qL.
Thus, the fourth part q4 including the lower layer 4qL and upper
layer 4qU is obtained. Then, the substrate 4 passes through the
seventh, sixth and fifth vapor deposition zones 60g, 60f and 60e in
this order. As a result, fifth through seventh parts q5 through q7
are formed on the fourth part p4 (5'th through 8'th vapor
deposition steps). In this manner, the active material bodies 96
including the first through seventh parts q1 through q7 (stacking
number n: 7) are obtained.
[0218] Next, the substrate 4 is inverted by the inversion structure
to be guided to the fourth vapor deposition zone 60d. Here, on the
lower layer 4pL in the fourth part formed in the forward path, an
upper layer 4pU is grown. Thus, the fourth part p4 is obtained.
Then, the substrate 4 passes through the third, second and first
vapor deposition zones 60c, 60b and 60a in this order. As a result,
the fifth through seventh parts p5 through p7 are formed (fifth
through eighth vapor deposition steps). In this manner, the active
material bodies 94 including the first through seventh parts p1
through p7 (stacking number n: 7) are obtained.
[0219] In the case where the vapor deposition is repeated while
switching the transportation direction of the substrate 4, it is
preferable that the transportation section and the shielding
section are structured such that the ratio among the film formation
amounts in the first through eighth vapor deposition zones 60a
through 60h is 1:2:2:1:1:2:2:1. Owing to this, as described above
in Embodiment 2, the film formation amount in the vapor deposition
zones 60a, 60d, 60e and 60h through which the substrate 4 may
possibly pass twice in a row is set to be 1/2 of the film formation
amount in the other vapor deposition zones 60b, 60c, 60f and 60g.
Therefore, the thickness of the parts of the active material body
can be made substantially uniform (excluding the first part and the
uppermost layer). This will be specifically described regarding the
active material bodies shown in FIG. 11. The thickness of the
fourth part p4 formed by allowing the substrate 4 to pass through
the fourth vapor deposition zone 60d twice, and the thickness of
each of the second and third parts p2 and p3 formed by allowing the
substrate 4 to pass through each of the second and third vapor
deposition zones 60b and 60c, can be made substantially equal to
each other. Therefore, the active material bodies as a whole can be
prevented from being significantly inclined in one particular
direction. The same is applicable to the active material bodies 96.
Accordingly, where the film formation ratio is set as above, the
active material bodies as a whole can be grown in the normal
direction to the substrate 4 while using the oblique vapor
deposition.
EXAMPLE 1 AND EXAMPLE 2
[0220] In Examples 1 and 2, a substrate having projections formed
regularly on a surface thereof was transported between the first
roll 3 and the second roll 8 eight times (total of the forward path
and the return path), and first through 32nd stage vapor deposition
steps were performed using the vapor deposition device 400 to form
a film (stacking number n: 25). The vapor deposition conditions in
Examples 1 and 2 were the same except that the vapor deposition
angle (incidence angle of the vapor-depositing material with
respect to the normal to the substrate) .theta. in Example 1 was
larger than the vapor deposition angle in Example 2. In these
examples, a metal foil having column-like projections located
thereon was used as the substrate. Each projection had a
diamond-shaped top surface, and the diagonal lines had lengths of
20 .mu.m.times.10 .mu.m.
[0221] FIGS. 12(a) and (b) are top views showing an example of
films in Examples 1 and 2. FIG. 12(c) schematically shows a
cross-section of the active material body 97a, 97b shown in FIGS.
12(a) and (b) taken along line XIIa-XIIa and line XIIb-XIIb. Arrow
98 in FIGS. 12(a) and (b) represents a direction parallel to the
longer diagonal line of the diamond, and arrow 99 represents a
direction parallel to the shorter diagonal line of the diamond.
[0222] As shown in the figures, the films in Examples 1 and 2
respectively include a plurality of active material bodies 97a and
97b located with a space provided therebetween. Each of the active
material bodies 97a and 97b had a stacking number n of 25. The
relationship between the number of times the substrate 4 is
transported and the stacking number n will be described later.
[0223] From these results, it is understood that the active
material bodies 97a and 97b are formed with a space therebetween in
accordance with the arrangement of the projections on the substrate
4. Widths of the top surface of the active material body 97a in the
directions 98 and 99 (about 33 .mu.m and about 25 .mu.m) are
respectively larger than widths of the top surface of the active
material body 97b in the directions 98 and 99 (about 30 .mu.m and
about 20 .mu.m). Therefore, the space between adjacent active
material bodies 97b is larger than the space between adjacent
active material bodies 97a. From this, it is understood that where
the vapor deposition angle .theta. is larger, the widths of the
active material body are larger and accordingly, the space between
adjacent active material bodies is smaller. In addition, from FIG.
12(c), it is understood that the active material bodies 97a and 97b
each have a structure in which parts p1, p3, . . . deposited on the
projection 72 formed on the substrate 4 from left in the sheet of
FIG. 12(c) and parts p2, p4, . . . deposited from right in the
sheet of FIG. 12(c) are alternately stacked.
[0224] Here, with reference to FIGS. 13(a) through (c), the
relationship between the number of times the substrate is
transported between the first roll 3 and the second roll 8 for
forming a film using one of the vapor deposition devices 100
through 400 having a V-shaped or W-shaped path(s) (hereinafter, the
number of times will be referred to as the "transportation number
of times C") and the stacking number n of the film (active material
body) will be described. In the case where the transportation
direction is switched to perform vapor deposition, the total number
of times the substrate 4 is transported on the forward path and on
the return path is the "transportation number of times C".
[0225] First, FIG. 13(a) will be referred to. FIG. 13(a) is a
schematic cross-sectional view showing an active material body
formed using the vapor deposition device 100 having one V-shaped
path or the vapor deposition device 300 having two V-shaped paths
and an inversion structure.
[0226] In each of the vapor deposition devices 100 and 300, during
the first time in which the substrate is transported between the
first roll and the second roll (forward path), two parts p1 and p2L
having different growth directions are formed in this order in two
vapor deposition zones (for example, the first and second vapor
deposition zones 60a and 60b shown in FIG. 1). The growth
directions of these parts p1 and p2L are inclined oppositely to
each other with respect to the normal to the substrate. At this
point, the active material body has a two-layer structure (stacking
number n: 2) including a first layer formed of the part pl and a
second layer formed of the part p2L.
[0227] Next, the transportation direction is switched, and during
the second time in which the substrate is transported (return
path), a part p2U having the same growth direction as that of the
part p2L, and a part p3L having a growth direction inclined
oppositely to the part p2U with respect to the normal to the
substrate, are formed. At this point, the active material body has
a three-layer structure (stacking number n: 3) including the first
layer formed of the part p1, the second layer formed of the parts
p2L and p2U, and a third layer formed of the part p3L. The
transportation direction is switched again, and during the third
time in which the substrate is transported (forward path), parts
p3U and p4L are formed similarly. The stacking number n of the
active material body becomes 4. In this manner, the stacking number
n of the formed active material body is represented by the
following expression using the transportation number of times
C.
n=C+1
[0228] Between the parts p2L and p2U, and between the parts p3L and
p3U, a thin oxide film 101 is formed. The oxide film 101 is formed
as a result of the vapor deposition surface reacting with oxygen
while the transportation direction of the substrate is switched or
while the vapor deposition surface of the substrate is inverted.
Accordingly, in an active material body formed by each of the vapor
deposition devices 100 and 300, a thin oxide film 101 is formed in
each of the layers located between the first layer, i.e., the
lowermost layer and the uppermost layer (in the example shown in
the figure, the fourth layer formed of the part p4L) (hereinafter,
such layers will be referred to as the "intermediate layers"),
regardless of the stacking number n.
[0229] In the case where the film formation amounts in the vapor
deposition zones 60a and 60b are substantially equal to each other,
the thickness of the lowermost layer and the thickness of the
uppermost layer are each about 1/2 of the thickness of each
intermediate layer located therebetween.
[0230] FIG. 13(b) is a schematic cross-sectional view showing an
active material body formed using the vapor deposition device 200
having one W-shaped path or the vapor deposition device 400 having
two W-shaped paths and an inversion structure.
[0231] In each of the vapor deposition devices 200 and 400, during
the first time in which the substrate is transported between the
first roll and the second roll (forward path), four parts p1, p2,
p3 and p4L are formed in this order in four vapor deposition zones
(for example, the first through fourth vapor deposition zones 60a
through 60d shown in FIG. 6). The growth directions of these parts
p1, p2, p3 and p4L are inclined alternately in opposite directions
with respect to the normal to the substrate. At this point, the
active material body has a four-layer structure (stacking number n:
4) including first through third layers formed of the parts p1
through p3 and a fourth layer formed of the part p4L.
[0232] Next, the transportation direction is switched, and during
the second time in which the substrate is transported (return
path), four layers of p4U, p5, p6 and p7L are formed. The part p4U
has the same growth direction as that of the part p4L. At this
point, the active material body has a seven-layer structure
(stacking number n: 7) including the first through third layers
formed of the parts p1 through p3, the fourth layer formed of the
parts p4L and p4U, and fifth through seventh layers formed of the
parts p5 through p7L. The transportation direction is switched, and
during the third time in which the substrate is transported
(forward path), parts p7U, p8, p9 and p10L are formed similarly.
The stacking number n of the active material body becomes 10. The
stacking number n of the formed active material body is represented
by the following expression using the transportation number of
times C.
n=3.times.C+1
[0233] Between the parts p4L and p4U, and between the parts p7L and
p7U, a thin oxide film 101 is formed. In this manner, in an active
material body formed by each of the vapor deposition devices 200
and 400 having a W-shaped path(s), a layer including two parts and
an oxide film 101 between the two parts (hereinafter, such a layer
will be referred to as the "oxide film-containing layer") is formed
as every third layer. Such an oxide film-containing layer is formed
at every third layer from the fourth layer. In other words, the
oxide film-containing layer is formed at the (3.times.m+1)th layer
(m: an integer of 1 through (C-1); C: transportation number of
times C).
[0234] As described above, in the case where the ratio among film
formation amounts in the vapor deposition zones 60a through 60d is
1:2:2:1, the thicknesses of the intermediate layers are
substantially equal to one another. The thickness of each of the
lowermost layer formed of the part p1 and the uppermost layer (in
the example shown in the figure, the tenth layer formed of the part
p10L) is about 1/2 of the thickness of each intermediate layer.
[0235] In the case where the film formation amounts in the vapor
deposition zones 60a through 60d are substantially equal to one
another, as shown in FIG. 13(c), the thickness of each oxide
film-containing layer, such as the fourth layer or the seventh
layer is about twice the thickness of the other layers. By the
presence of such an oxide film-containing layer, the start position
of the layer formed on the oxide film-containing layer is shifted
to the same side as the growth direction of the oxide
film-containing layer. Accordingly, an active material body in
which the vapor deposition position is shifted alternately to the
opposite side at every third layer is formed.
Embodiment 5
[0236] Hereinafter, a vapor deposition device according to
Embodiment 5 of the present invention will be described with
reference to the figure. In the vapor deposition device in this
embodiment, the transportation section has two substrate
transportation paths, each including three V-shaped substrate paths
(hereinafter, referred to as the "V.times.3 path"), and is
structured to have an inversion structure for inverting the surface
of the substrate 4 to be subjected to the vapor-depositing material
between the V.times.3 paths. The inversion structure may be
substantially the same as the inversion structure described in
Embodiment 3 with reference to FIG. 7.
[0237] FIG. 14 is a cross-sectional view schematically showing a
vapor deposition device in this embodiment. For simplicity,
identical elements with those of the vapor deposition device 400
described in the above embodiment bear identical reference numerals
therewith, and descriptions thereof will be omitted.
[0238] A vapor deposition device 500 has substantially the same
structure as that of the vapor deposition device 400 described
above with reference to FIG. 10. Note that the number of guide
members is increased to six (guide members 6a through 6f) and the
number of the vapor deposition zones is increase to 12 because the
vapor deposition zones are formed on both sides of each of the six
guide members 6a through 6f. Accordingly, unlike the vapor
deposition device 400, during the time in which the substrate 4 is
transported from the first roll 3 to the second roll 8, a vapor
deposition film having a stacking number of 12 can be formed. This
is especially advantageous for forming a vapor deposition film
having a large stacking number.
[0239] An operation of the vapor deposition device 500 and a method
for forming a film using the vapor deposition device 500 are
substantially the same as those of the operation of the vapor
deposition device 400 and the method for forming a film using the
vapor deposition device 400.
Embodiment 6
[0240] Hereinafter, a vapor deposition device according to
Embodiment 6 of the present invention will be described with
reference to the figures.
[0241] FIG. 15 is a schematic cross-sectional view of a vapor
deposition device in this embodiment. A vapor deposition device 600
includes a supply section 601 for supplying a substrate (current
collector) 602, a take up section 606 for taking up the supplied
substrate 602, an evaporation source 604, a plurality of support
rolls 603a, 604b, 603c and 604d radially provided with respect to
the evaporation source 604, and shielding plates 613 respectively
provided between the support rolls 603a, 603b and 603c and the
evaporation source 604. In the vapor deposition device 600, the
support rolls 603a, 603b and 603c (hereinafter, referred to as the
"front support rolls") are located farther from the evaporation
source 604 than the support rolls 604d (hereinafter, referred to as
the "rear support rolls").
[0242] In this embodiment, the substrate 602 is fed out from the
supply section 602, passes alternately along the front support
rolls 603a, 603c and 603b radially located with respect to the
evaporation source 604 and along the rear support rolls 603d
radially located farther from the front support rolls, and is taken
up like a coil by the take-up section 606. The front support rolls
603a, 603b and 603c form a V-shaped path for transporting the
substrate 602 in a V-shaped manner. On both sides of the front
support rolls 603c located at the center among these front support
rolls, a plurality of vapor deposition zones 609b through 609e are
formed. Accordingly, the front support rolls 603c correspond to the
"guide members" in the above embodiments. A vapor deposition zone
609a is formed on the opposite side to the supply section 601 with
respect to the front support roll 603a, which is located closest to
the supply section 601 among the front support rolls. A vapor
deposition zone 609f is formed on the opposite side to the take-up
section 606 with respect to the front support roll 603b, which is
located closest to the take-up section 606 among the front support
rolls. In this embodiment, vapor deposition is not performed on the
supply section 601 side with respect to the support roll 603a or
the take-up section 606 side with respect to the support roll
603b.
[0243] In this embodiment, the plurality of vapor deposition zones
(vapor deposition forming section) 609a through 609f are formed for
one evaporation source 604 by the support rolls 603c and 603d.
Therefore, the vapor deposition device 600 is superb in mass
productivity. It is preferable that the vapor deposition surface of
the substrate 602 passing through the vapor deposition zone 609a
acts as the "facing surface" for the vapor deposition surface of
the substrate 602 passing through the vapor deposition zone 609b,
and that the vapor deposition surface of the substrate 602 passing
through the vapor deposition zone 609b acts as the "facing surface"
for the vapor deposition surface of the substrate 602 passing
through the vapor deposition zone 609a. The "facing surface" is as
described above with reference to FIG. 2. Owing to this, the
amounts of heat received by the substrate 602 in the vapor
deposition zones 609a and 609b can be averaged. Similarly, it is
preferable that the vapor deposition surfaces of the substrate 602
passing through the vapor deposition zones 609c and 609d act as the
facing surfaces for each other, and that the vapor deposition
surfaces of the substrate 602 passing through the vapor deposition
zones 609e and 609f act as the facing surfaces for each other. This
is advantageous because the difference in the amount of heat
received by the substrate 602 in all the vapor deposition zones
609a through 609f can be reduced without adding any member having a
facing surface.
[0244] Now, a method for producing a film using the vapor
deposition device 600 will be described. As the substrate 602, a
strip-like metal foil (current collector) processed to have
projections on a surface thereof is used. This substrate 602 is fed
out from the supply section 601 and passes alternately along the
front support rolls 603a, 603b and 603c radially located with
respect to the evaporation source 604 and along the rear support
rolls 603d also radially located with respect to the evaporation
source 604. Then, the substrate 602 is taken up like a coil by the
take-up section 606. Vapor deposition is performed on the running
substrate 604 in the vapor deposition zones 609a through 609f. The
support rolls 603a through 603d are located at the same angle with
respect to the evaporation source 604. Therefore, angles .theta.5
through .theta.7 of the vapor deposition surface of the substrate
602 in the vapor deposition zones 609a, 609c and 609e with respect
to the evaporation source 604 are equal to one another. For the
same reason, angles .theta.8 through .theta.10 of the vapor
deposition surface of the substrate 602 in the vapor deposition
zones 609b, 609d and 609f with respect to the evaporation source
604 are equal to one another. Where the angles .theta.5 through
.theta.7 are each .gamma., the angles .theta.8 through .theta.10
are each -.gamma.. The absolute values of the angles .theta.5
through .theta.10 are all equal.
[0245] A cross-section of the film obtained using the vapor
deposition device 600 was observed with an SEM. FIG. 15(b) shows a
schematic view thereof. From this, it is understood that thin
layers 610a through 610f formed on the surface of the substrate 602
having projections 607 are inclined alternately in opposite
directions with respect to the normal to the substrate 602. This
occurs for the following reason. During the time in which the
substrate 602 fed out from the supply section 601 passes through
the vapor deposition zone 609a, the thin layer 610a is formed by
vapor deposition. The thin layer 610b is formed by vapor deposition
in the vapor deposition zone 609b, the thin layer 610c is formed by
vapor deposition in the vapor deposition zone 609c, the thin layer
610d is formed by vapor deposition in the vapor deposition zone
609d, the thin layer 610e is formed by vapor deposition in the
vapor deposition zone 609e, and the thin layer 610f is formed by
vapor deposition in the vapor deposition zone 609f. In this manner,
the angle of the vapor deposition surface with respect to the
evaporation source 604 is switched alternately between .gamma. and
-.gamma..
[0246] Next, an electrode plate having a plurality of electrode
active material thin films alternately formed on the concave and
convex part of the strip-like substrate 602 was formed, and
slit-processed to have a width defined by a cylindrical lithium ion
secondary cell (not shown) to produce an electrode for a lithium
ion secondary cell. The slit-processed electrode plate did not have
inconveniences such as warping or the like, and detachment of any
electrode active material thin film was not recognized.
[0247] As described above, according to this embodiment, a single
evaporation source 604 is used. Therefore, the deposition speed can
be easily controlled and the thin layers can be continuously formed
stably. Since the vapor deposition surfaces of the substrate 602
passing through adjacent vapor deposition zones face each other,
the amounts of heat received by the substrate 602 in the vapor
deposition zones can be averaged. By providing the shielding plates
613 between the evaporation source 604 and the front support rolls
603a through 603c facing the evaporation source 604, the support
rolls 603a through 603c can be prevented from being contaminated
with evaporated substances. This provides an advantage of
simplifying the cleaning work after the vapor deposition and
shortening the non-operation time of the vapor deposition device
600.
Embodiment 7
[0248] Hereinafter, a vapor deposition device according to
Embodiment 7 of the present invention will be described with
reference to the figure. In this embodiment, unlike in the
above-described embodiments, vapor deposition is performed on a
substrate transported in a curved state along a guide member as
well as a substrate transported in a planar state.
[0249] FIG. 16 is a cross-sectional view schematically showing a
vapor deposition device in this embodiment. For simplicity,
identical elements with those of the vapor deposition device 300'
(FIG. 9) in the embodiment described above bear identical reference
numerals therewith, and descriptions thereof will be omitted.
[0250] In a vapor deposition device 700, guide members 710a and
710b are partially located in the vapor deposition possible zone
without being shielded by shielding members 20a and 20b, and the
vapor-depositing material is incident on the substrate 4
transported on a curved path along the guide members 710a and 710b.
Accordingly, the vapor deposition zones 60a through 60d
respectively include curved transportation zones 720a through 720d
in which substrate 4 is transported in a curved state, as well as
the plane transportation zones in which the substrate 4 is
transported in a planar state. Except for this, the structure of
the vapor deposition device 700 is substantially the same as that
of the vapor deposition device 300' described above with reference
to FIG. 9.
[0251] Since the vapor deposition zones 60a through 60d
respectively include the curved transportation zones 720a through
720d, the surface area of the vapor deposition surface of the
substrate 4 can be increased in a zone which is close to the
evaporation source 9 and has the vapor-depositing material at a
high concentration, as compared with the case where each vapor
deposition zone includes only a planar transportation zone. This
significantly improves the utilization factor of the
vapor-depositing material. The deposition speed of the
vapor-depositing material on the substrate 4 is in inverse
proportion to the square of the distance between the substrate 4
and the evaporation source 9. In this embodiment, the distance
between the substrate 4 and the evaporation source 9 can be
shortened, and therefore the deposition speed of the
vapor-depositing material on the substrate 4 can be significantly
increased. In the cross-section shown in the figure, the curved
transportation zones 720a through 720d are represented with curved
lines, and so are occasionally referred to as the "curved running
sections". Advantages of performing vapor deposition in the curved
running sections 720a through 720d will also be described in
Reference Embodiment C provided later.
[0252] In the vapor deposition device 700, the curved
transportation zones 720a through 720d are provided in all the
vapor deposition zones 60a through 60d. The above-described effect
is provided as long as at least one vapor deposition zone includes
a curved transportation zone. For example, only the vapor
deposition zones 60b and 60d facing each other while having the
normal to the center of the evaporation source 9 therebetween may
include the curved transportation zones 720b and 720d.
[0253] Although not shown, the structure in this embodiment is also
applicable to the vapor deposition devices 100, 200, 300, 400, 500
and 600. Substantially the same effect as described above is
realized by providing a curved transportation zone in a vapor
deposition zone in these vapor deposition devices and performing
vapor deposition on a guide member.
Embodiment 8
[0254] Hereinafter, a vapor deposition device according to
Embodiment 8 of the present invention will be described with
reference to the figures. Unlike the vapor deposition device 700 in
Embodiment 7, in the vapor deposition device in this embodiment, an
inclination direction switching roller is provided on the substrate
transportation path in the vapor deposition zone and vapor
deposition is performed also on the inclination direction switching
roller.
[0255] FIG. 17(a) is a cross-sectional view schematically showing a
vapor deposition device in this embodiment. FIG. 17(b) is a
schematic enlarged cross-sectional view provided to explain a vapor
deposition zone in the vapor deposition device shown in FIG. 17(a).
For simplicity, identical elements with those of the vapor
deposition device 700 (FIG. 16) described in the above embodiment
bear identical reference numerals therewith, and descriptions
thereof will be omitted.
[0256] A vapor deposition device 800 includes an inclination
direction switching roller 750b located between the guide member
710a and the transportation roller 5b in the vapor deposition zone
60b and also includes an inclination direction switching roller
750d located between the guide member 710b and the transportation
roller 5f in the vapor deposition zone 60d. The inclination
direction switching rollers 750b and 750d respectively switch the
inclination direction of the substrate transportation path with
respect to the evaporation source 9 in the vapor deposition zones
60b and 60d (angle made by the substrate transportation path and
the normal N passing through the center of the evaporation source
9). As a result, in each of the vapor deposition zones 60b and 60d,
two planar transportation zones having different inclination angles
are formed; namely, one planar transportation zone is provided
upstream, and the other planar transportation zone is provided
downstream, with respect to the corresponding inclination direction
switching roller 750b, 750d.
[0257] Accordingly, in this embodiment, as shown in FIG. 17(b), the
vapor deposition zone 60b includes a curved transportation zone
720b along the guide member 710a (this curved transportation zone
is also referred to as the "bottom end curved transportation
zone"), a curved transportation zone 724b along the inclination
direction switching roller 750b (this curved transportation zone is
also referred to as the "intermediate curved transportation zone"),
a planar transportation zone 722b located between the guide member
710a and the inclination direction switching roller 750b, and a
planar transportation zone 726b located between the inclination
direction switching roller 750b and the transportation roller 5b.
Similarly, the vapor deposition zone 60d includes a bottom end
curved transportation zone 720d along the guide member 710b, an
intermediate curved transportation zone 724d along the inclination
direction switching roller 750d, a planar transportation zone 722d
located between the guide member 710b and the inclination direction
switching roller 750d, and a planar transportation zone 726d
located between the inclination direction switching roller 750d and
the transportation roller 5f.
[0258] According to this embodiment, as compared with the case
where the inclination direction switching rollers are not provided,
the distance between the substrate 4 and the evaporation source 9
in the planar transportation zone can be shortened. This improves
the deposition speed and the utilization factor of the
vapor-depositing material. The inclination direction switching
rollers also provide an advantage of suppressing the substrate 4
from being wrinkled during the transportation. In addition, by
cooling the inclination direction switching rollers 750b and 750d,
the heat received by the substrate 4 during the vapor deposition
can be alleviated and thus the thermal expansion of the substrate 4
can be suppressed. The advantages of providing the inclination
direction switching rollers 750b and 750d will also be described in
Reference Embodiment D provided later.
[0259] In the vapor deposition device 800, the inclination
direction switching rollers 750b and 750d are located in the two
vapor deposition zones 60d and 60d facing each other while having
the normal N to the substrate 4 therebetween. This is because in a
vapor deposition zone close to the normal N to the center of the
evaporation source 9, the vapor deposition angle of the planar
transportation zones formed upstream and downstream with respect to
the inclination direction switching roller can be easily controlled
to be a desired angle. It is sufficient that the inclination
direction switching roller is provided in at least one vapor
deposition zone, and the inclination direction switching roller may
be provided in each of all the vapor deposition zones 60a through
60d.
[0260] A plurality of inclination direction switching rollers may
be provided in one vapor deposition zone. For example, as shown in
FIG. 19, inclination direction switching rollers 750b and 760b may
be provided in the vapor deposition zone 60b, and inclination
direction switching rollers 750d and 760d may be provided in the
vapor deposition zone 60d. In the example shown in the figure, the
vapor deposition zones 60b and 60d each include a bottom curved
transportation zone, two intermediate curved transportation zones,
and three planar transportation zones.
[0261] The structure of this embodiment is also applicable to the
vapor deposition devices 100, 200, 300, 400, 500 and 600. FIG. 19
is a schematic cross-sectional view showing an example of structure
in which inclination direction switching rollers are provided in
the vapor deposition device 400 (FIG. 10). For simplicity,
identical elements with those of the vapor deposition device 400
bear identical reference numerals therewith, and descriptions
thereof will be omitted.
[0262] In a vapor deposition device 800' shown in FIG. 19,
inclination direction switching rollers 750b, 750c, 750f and 750g
are respectively located in the vapor deposition zones 60b, 60c,
60f and 60g. Vapor deposition is performed also on these
inclination direction switching rollers (intermediate curved
transportation zones). In the vapor deposition device 800', vapor
deposition is not performed on the guide members 6a through 6d.
Alternatively, vapor deposition may be performed on the guide
member(s).
[0263] The shape of the active material bodies formed using a vapor
deposition device according to the present invention is not limited
to the shapes described in Embodiments 1 through 8 provided above,
and may be appropriately selected in accordance with the designed
capacitance of the cell to which the active material bodies are to
be applied. For example, the stacking number n of each active
material body may also be appropriately selected. Note that the
stacking number n is preferably three or greater. Where the
stacking number n is two or smaller, the expansion of the active
material bodies in the width direction (lateral direction) may not
be sufficiently suppressed. The upper limit of the preferable
stacking number n is determined based on the total thickness of the
active material bodies (for example, 100 .mu.m or smaller) and the
thickness of each part of the active material bodies (for example,
2 .mu.m or greater). For example, the stacking number n is
preferably 50 (100 .mu.m/2 .mu.m). More preferably, the stacking
number n is 30 or greater and 40 or smaller.
[0264] As described above, according to a vapor deposition device
in embodiments of the present invention, an active material layer
including a plurality of active material bodies located with a
space provided therebetween can be formed on a surface of the
substrate 4. The substrate 4 having the active material layer is
cut into a prescribed size when necessary and used for a negative
electrode of a nonaqueous electrolytic secondary cell such as a
lithium secondary cell or the like. The negative electrode thus
obtained is protected against destruction of active material bodies
which would otherwise be caused by expansion of the active material
bodies, against deformation of the electrode plate, and against
deformation of the hole of the separator. Therefore, such a
negative electrode realizes superb charge/discharge cycle
characteristic.
[0265] The above-described negative electrode is applicable to
cylindrical, flat, coin-shaped, polygonal or many other shapes of
nonaqueous electrolytic secondary cells. A nonaqueous electrolytic
secondary cell can be produced by a known method, specifically as
follows. The negative electrode obtained using a vapor deposition
device according to the present invention is located to face a
positive electrode plate containing a positive electrode active
material in the state where a separator formed of microporous film
or the like is provided therebetween, to form an electrode
assembly. The electrode assembly is accommodated in a case together
with an electrolytic solution having lithium ion conductivity.
Thus, the nonaqueous electrolytic secondary cell is obtained. As
the positive electrode active material and the electrolytic
solution, materials generally used for lithium ion secondary cells
are usable. Materials usable as the positive electrode active
material include, for example, LiCoO.sub.2, LiNiO.sub.2,
LiMn.sub.2O.sub.4 and the like. An example of electrolytic solution
is obtained by dissolving lithium hexafluorophosphate or the like
in a cyclic carbonate such as ethylene carbonate, propylene
carbonate or the like. The sealing form of the cell is not
specifically limited.
Reference Embodiment A
[0266] Hereinafter, a vapor deposition device in Reference
Embodiment A will be described with reference to the figures.
[0267] FIG. 20(a) is a cross-sectional view schematically showing a
vapor deposition device in Reference Embodiment A.
[0268] A vapor deposition device 1000A in Embodiment A includes a
vacuum tank 802, an exhaust pump 801 provided outside the vacuum
tank 802, an assisting exhaust pump 831 communicated with an
assisting exhaust opening 830 of the vacuum tank 802, an
evaporation source 809 provided inside the vacuum tank 802 at a
position near the exhaust pump 801 for evaporating a
vapor-depositing material, shielding plates 810a and 810b provided
on both sides of the evaporation source 809, and gas introduction
pipes 811a and 811b acting as oxygen gas supply sections for
introducing oxygen gas into the vacuum tank 802. The shielding
plates 810a and 810b are located in a truncated inverted V shape so
as to cover the evaporation source 809 and the exhaust pump
801.
[0269] The vacuum tank 802 accommodates a supply roll 803 around
which a substrate 804 is wound, transportation rollers 805a through
805h, a take-up roll 808, a cylindrical first can 812, a
cylindrical second can 813, a cylindrical third can 814, and a
cylindrical fourth can 815. A first vapor deposition section 862 is
formed of the first can 812 and the second can 813. A first vapor
deposition zone 860 in the first vapor deposition section 862 is
formed of a vapor deposition surface of the substrate 804 between
the second can 813 and a contact point at which the first can 812
contacts a straight line extending from the center of the vapor
deposition surface of the evaporation source 809 through the end of
the gas introduction pipe 811a to the first can 812. A second vapor
deposition section 863 is formed of the third can 814 and the
fourth can 815. A second vapor deposition zone 861 in the second
vapor deposition section 863 is formed of the vapor deposition
surface of the substrate 804 between the fourth can 815 and a
contact point at which the third can 814 contacts a straight line
extending from the center of the vapor deposition surface of the
evaporation source 809 through the end of the gas introduction pipe
811b to the third can 814.
[0270] In order to effectively prevent the vapor-depositing
material from being attached to each can, as shown in FIG. 20(b),
shielding plates 810g, 810f, 810c and 810d may be respectively
provided for the first through fourth cans 812, 813, 814 and 815. A
shielding plate 811e may be provided above a gap between the second
and fourth cans 813 and 815.
[0271] FIG. 21 is a schematic view showing the positional
relationship among the first vapor deposition section 862, the
second vapor deposition section 863, and the evaporation source 809
in the vacuum tank 802. As shown in FIG. 21, the first vapor
deposition section 862 and the second vapor deposition section 863
are provided such that the vapor deposition surface of the first
vapor deposition zone 860 and the vapor deposition surface of the
second vapor deposition zone 861 face each other on both sides of
the normal passing through the center of the vapor deposition
surface of the evaporation source. In Embodiment A, the first can
812, the second can 813, the third can 814 and the fourth can 815
are located such that the incidence angle of the vapor-depositing
material on the substrate 804 is 45.degree. or greater and
75.degree. or smaller and such that .theta.11=45.degree.,
.theta.12=75.degree., .theta.13=45.degree. and .theta.14=75.degree.
are fulfilled. Referring to FIG. 21, .theta.11 is an angle made by
a straight line extending from the center of the vapor deposition
surface of the evaporation source 809 through the end of the gas
introduction pipe 811a to the first can 812 and the normal
extending from a point at which the straight line and the first can
812 cross each other. .theta.12 is an angle made by a straight line
extending from the center of the vapor deposition surface of the
evaporation source 809 to a point at which the substrate 804
contacts the second can 813 when leaving the second can 813 and the
normal extending from such a contact point of the straight line and
the second can 813. .theta.13 is an angle made by a straight line
extending from the center of the vapor deposition surface of the
evaporation source 809 through the end of the gas introduction pipe
811b to the third can 814 and the normal extending from a point at
which the straight line and the third can 814 cross each other.
.theta.14 is an angle made by a straight line extending from the
center of the vapor deposition surface of the evaporation source
809 to a point at which the substrate 804 contacts the fourth can
815 when leaving the fourth can 815 and the normal extending from
such a contact point of the straight line and the fourth can 815.
The fourth can 815 is located such that the second vaporization
zone 861 crosses the normal passing through the center of the vapor
deposition surface of the evaporation source. Owing to this, the
vapor-depositing material from the evaporation source 809 does not
directly exit toward the assisting exhaust opening 830 through the
gap between the first vaporization zone 860 and the second
vaporization zone 861.
[0272] Now, an operation of the vapor deposition device 1000A in
Embodiment A will be described. First, the substrate 804 is caused
to run. The substrate 804 of a long strip type fed out from the
supply roll 803 is guided along the transportation rollers 805a and
805b, the first can 812, the second can 813, the transportation
rollers 805c, 805d 805e, 805f and 805g, the third can 814, and the
fourth can 815, and then is taken up by the take-up roll 8. Since
the substrate 804 is used as a current collector of an electrode, a
film-type metal foil having a concave and convex pattern formed on
a top surface and a rear surface thereof is used as the substrate
804. The metal material of the metal foil is, for example, a
material fulfilling the electric conductivity required of a current
collector such as copper, nickel, aluminum or the like. The concave
and convex pattern is formed of diamond shapes, each of which has a
size of 20 .mu.m.times.20 .mu.m and a height of 10 .mu.m. The
arithmetic average roughness (Ra) of the surface of the concave and
convex pattern is 2.0 .mu.m. On the running substrate 804, the
vapor-depositing material evaporated from the evaporation source
809 is vapor-deposited to form a vapor deposition film (vapor
deposition particles). For the evaporation source 809, a crucible
or the like is used. The evaporation source 809 is heated by a
heating device (not shown) such as a resistance heating device, an
induction heating device, an electronic beam heating device or the
like, and silicon, for example, as the vapor-depositing material is
evaporated. Between the first can 812 and the second can 813, the
substrate 804 is exposed to the silicon evaporated from the
evaporation source 809, and as a result, a first active material
layer 821 of silicon is formed on one surface of the substrate 804.
Then, between the third can 814 and the fourth can 815, the
substrate 804 is exposed to the silicon evaporated from the
evaporation source 809, and as a result, a second active material
layer 823 of silicon is also formed on the other surface of the
substrate 804. For forming an active material layer of a compound
containing silicon and oxygen, oxygen gas is introduced through the
gas introduction pipes 811a and 811b, and silicon is evaporated
from the evaporation source 809 in an oxygen gas atmosphere. The
arithmetic average roughness (Ra) is defined in the Japanese
Industrial Standards (JISB 0601-1994), and may be measured by, for
example, a contact-system or laser-system surface roughness meter
or the like.
[0273] FIG. 22 is a schematic view of a vapor deposition film
formed on the substrate 804 by the above operation. The first
vaporization zone 860 and the second vaporization zone 861 are
located such that the incidence angle of the vapor-depositing
material particles evaporated from the center of the evaporation
source 809 on the substrate 804 is oblique. Therefore, a vapor
deposition film including column-like elements oblique with respect
to the substrate 804 as shown in FIG. 22 can be formed. As shown in
FIG. 20, the first film formation zone 860 and the second film
formation zone 861 are located on both sides of the evaporation
source 809. Therefore, vapor deposition can be performed in the two
film formation zones at the same time. As shown in FIG. 20, the
substrate 804 transported between the first can 812 and the second
can 813, and the substrate 804 transported between the third can
814 and the fourth can 815, are located on both sides of the
evaporation source 809. Therefore, vapor deposition can be
performed in the two film formation zones at the same time. The
growth direction of the first active material layer 821 and the
growth direction of the second active material layer 823 formed on
both surfaces of the substrate 804 are substantially symmetrical to
each other.
[0274] In the vapor deposition device 1000A in Embodiment A, the
fourth can 815 is located right above the evaporation source 809
with a gap from the second can 813 and the fourth can 815 and above
the second can 813. Owing to this, a reduction of the vacuum degree
can be prevented, and also an increase of probability of collision
of vapor deposition material particles which results in a decrease
of the attaching force can be prevented, in the vicinity of the
second can 813 and the fourth can 815. In addition, the second film
formation zone 861 is located at such a position that the incidence
angle of the vapor deposition particles on the substrate is
75.degree. and right above the evaporation source 809. Therefore,
film formation can be performed in a zone having the highest
concentration of the evaporated material. This occurs for the
following reason. The material heated in the vacuum atmosphere is
evaporated by the COS rule. Therefore, the vapor concentration is
higher in a zone closer to the normal to the evaporation source.
Thus, in such a zone, the utilization factor of the material can be
improved, and the direction right above the evaporation source can
be actively used. Substantially the same effect is provided where
the first vapor deposition zone 860 is located in the same manner
instead of the second vapor deposition zone 861.
[0275] Where .theta.11 and .theta.13 are smaller than 45.degree.,
the particles to be grown rise steeply, and hence, it is likely to
be difficult to form a vapor deposition film having a space between
the particles on the concaved and convexed surface of the substrate
804. As a result, the substrate is likely to be wrinkled by the
expansion of the particles at the time of charge/discharge. Where
.theta.12 and .theta.14 are larger than 75.degree., the particles
to be grown are inclined largely. This weakens the attachment of
the particles to the concaved and convexed surface of the
substrate, and as a result, a vapor deposition film having a weak
adhesiveness to the substrate is formed. As a result, the electrode
active material is likely to be detached from the substrate at the
time of charge/discharge. Accordingly, in the vapor deposition
device 1000A in Embodiment A, it is preferable that .theta.11,
.theta.12, .theta.13 and .theta.14 are set such that silicon
particles as the vapor deposition particles evaporated from the
center of the evaporation source 809 fly at an incidence angle in
the range of 45.degree. to 75.degree. on the substrate 804
transported between the first can 812 and the second can 813 and
between the third can 814 and the fourth can 815.
[0276] Outside the vacuum tank 802, the exhaust pump 801 and the
assisting exhaust pump 831 communicated with the assisting exhaust
opening 830 located above the vacuum tank 802 are provided. The
inside of the vacuum tank 802 is made vacuum by the exhaust pump
801 and the assisting exhaust opening 830. In the vapor deposition
device 1000A, when the pressure inside the vacuum tank 802 rises to
about 4.5.times.10.sup.-2 Pa, the pipe conductance is adjusted
using the assisting exhaust pump 831 having an exhaust speed of
5000 L/sec. such that the vacuum exhaust speed at the assisting
exhaust opening 830 is 2000 L/sec. In this manner, the vacuum
pressure is improved from about 4.5.times.10.sup.-2 Pa to about
3.0.times.10.sup.-2 Pa.
[0277] In order to improve the gas molecule exhaust capability, it
is desirable to provide a gap in the vicinity of the film formation
zones close to each other, namely, around a zone where the
incidence angle of the vapor deposition particles on the substrate
is 75.degree., thus to exhaust the introduced gas molecules. In
order to improve the gas molecule exhaust capability, it is
desirable to perform vacuum exhaust above the film formation zone.
Especially, where a vacuum exhaust opening is provided above such a
zone, the vapor-depositing material particles do not directly reach
the vacuum exhaust opening from the evaporation source 809.
Therefore, the vacuum pump does not need to be protected and so can
be installed at a highest exhaust efficiency. In addition, the
vapor-depositing material does not form a film around the vacuum
exhaust opening and so no substance is deposited. Therefore, there
is no risk that the deposited substance falls to contaminate the
substrate. Furthermore, since the vacuum degree in the vicinity of
the film formation zones close to each other can be improved, the
oxygen gas or evaporated particles of silicon having directivity
can be vapor-deposited as being distributed over the film formation
zones. Accordingly, a reduction of the space among the active
material particles caused by the reduction of the vacuum degree at
the time of vapor deposition and the expansion/contraction of the
electrode active material can be suppressed, and so a cell having a
high charge/discharge cycle characteristic is provided.
[0278] The space in the first active material layer 821 and the
second active material layer 823 formed in Embodiment A can be used
as an expansion space necessary when the electrode plate is
expanded by the charge/discharge, and allows the stress on the
electrode active material to be alleviated. Therefore, the
shortcircuiting between the positive electrode and the negative
electrode can be suppressed, which provides a cell having a high
charge/discharge cycle characteristic, needless to say.
[0279] FIG. 23 is a partial schematic view showing a modification
of the first film formation zone 860 and the second film formation
zone 861 in the vapor deposition zones of the vapor deposition
device 1000A in Embodiment A. As shown in FIG. 23, it is possible
to provide an assisting can 850 between the first can 812 and the
second can 813 forming the first film formation zone 860, and also
between the third can 814 and the fourth can 815 forming the second
film formation zone 861. By providing the assisting cans 850, a
curved running section can be provided in the middle of the
straight running section of the substrate 804 in the first film
formation zone 860 and the second film formation zone 861, which
suppresses the slackening of the substrate 804 during the running.
This can suppress the substrate 804 from being wrinkled during the
running.
[0280] FIG. 24 is a partial schematic view showing another
modification of the first film formation zone 860 and the second
film formation zone 861 in the vapor deposition zones of the vapor
deposition device 1000A in Embodiment A. As shown in FIG. 24, it is
possible to provide the first can 812, the second can 813, the
third can 814, the fourth can 815, and a plurality of assisting
cans 850 as a cooling structure, and set each can to a temperature
range of -30.degree. C. to 20.degree. C. to cool the substrate 804.
Since the heat received by the substrate 804 during the vapor
deposition (radiant heat from the evaporation source 809, heat of
solidification of the vapor deposition particles, etc.) can be
alleviated, the thermal expansion of the substrate 804 during the
running can be suppressed and so substrate 804 can be suppressed
from being wrinkled during the running.
Reference Embodiment B
[0281] Now, a structure of a vapor deposition device 1000B in
Reference Embodiment B will be described. FIG. 25 is a schematic
cross-sectional view of the vapor deposition device 1000B in
Embodiment B. The vapor deposition device 1000B in Embodiment B has
almost the same structure as that of the vapor deposition device
1000A in Embodiment A except for the following. Unlike the vapor
deposition device 1000A, the vapor deposition device 1000B includes
a path, located on the path for guiding the substrate 804 from the
first film formation zone 860 to the second film formation zone
861, for allowing the substrate 804 to run such that a film is
formed on the same surface of the substrate 804 in the first film
formation zone 860 and the second film formation zone 861.
[0282] Now, an operation of the vapor deposition device 1000B in
Embodiment B will be described. The vapor deposition device 1000B
operates in almost the same manner as the deposition device 1000A
in Embodiment A. The difference is the following. A film is formed
on the same surface of the substrate 804 in the first film
formation zone 860 and the second film formation zone 861. The
rolled substrate 804 having the film formed thereon is set to the
supply roll 803 again, and the same operation is performed on the
surface of the substrate 804 on which no vapor deposition film has
been formed. Specifically, as shown in FIG. 25, the substrate 804
of a long strip type fed from the supply roll 803 in the vacuum
tank 802 is guided along the transportation rollers 805a and 805b,
the first can 812, the second can 813, the transportation rollers
805c, 805d and 805e, the fourth can 815, the third can 814, and the
transportation rollers 805g, 805f and 805h in this order, and then
is taken up by the take-up roll 808.
[0283] FIG. 26 is a cross-sectional view of a vapor deposition film
formed by the vapor deposition device 1000B in Embodiment B. While
the incidence direction of the evaporated vapor-depositing material
particles on the substrate 804 is changed, the film is formed on
the same surface of the substrate 804 in the first film formation
zone 860 and the second film formation zone 861. Therefore, the
first active material layer 821 and the second active material
layer 823 can be formed zigzag as shown in FIG. 7. In Embodiment B
also, the second film formation zone 861 is provided above the
evaporation source 809. Therefore, film formation can be performed
in a zone having a high concentration of the evaporated material,
and the utilization factor of the material can be improved,
needless to say.
[0284] The shape of an electrode 820 after the vapor deposition
film is formed in each of Embodiments A and B is not limited to the
above shape, and may be appropriately selected in accordance with
the designed capacitance of the cell.
[0285] Using the electrode 820 produced by each of vapor deposition
devices 1000A and 1000B, a nonaqueous electrolytic secondary cell
can be easily produced as follows. The electrode 820 is used
together with a positive electrode plate containing a positive
electrode active material generally usable for a lithium ion
secondary cell such as LiCoO.sub.2, LiNiO.sub.2, LiMn.sub.2O.sub.4
or the like, a separator formed of a microporous film or the like,
and an electrolytic solution having a generally known composition
and having lithium ion conductivity obtained by dissolving lithium
hexafluorophosphate or the like in a cyclic carbonate such as
ethylene carbonate, propylene carbonate or the like.
[0286] According to the vapor deposition devices 1000A and 1000B
described above, film formation can be performed in a zone right
above the evaporation source, where the concentration of the
evaporated vapor-depositing material is high and the incidence
angle of the vapor-depositing material is high. Accordingly, the
film formation can be performed in a zone having a high
concentration of the evaporated material supplied from the
evaporation source, although the structure of the vapor deposition
device is compact. Thus, the utilization factor of the evaporated
material can be improved, and a film which is not easily
deteriorated can be continuously formed by a highly productive
vapor deposition method.
Reference Embodiment C
[0287] FIG. 27 is a cross-sectional view schematically showing a
vapor deposition device 1000C in Reference Embodiment C. As shown
in FIG. 27, the vapor deposition device 1000C in Embodiment C
includes a vacuum tank 902, an exhaust pump 901 provided outside
the vacuum tank 902, an assisting exhaust pump 931 communicated
with an assisting exhaust opening 930 of the vacuum tank 902, an
evaporation source 909 provided inside the vacuum tank 902 at a
position near the exhaust pump 901 for evaporating a
vapor-depositing material, shielding plates 10a and 10b provided on
both sides of the evaporation source 909, and gas introduction
pipes 911a and 911b acting as oxygen gas supply sections for
introducing oxygen gas into the vacuum tank 902. The shielding
plates 910a and 910b are located in a truncated inverted V shape so
as to cover the evaporation source 909 and the exhaust pump
901.
[0288] The vacuum tank 902 accommodates a supply roll 903 around
which a substrate 904 is wound, transportation rollers 905a through
905h, a take-up roll 908, a cylindrical first can 912, a
cylindrical second can 913, a cylindrical third can 914, and a
cylindrical fourth can 915. A first vapor deposition section 962 is
formed of the first can 912 and the second can 913. A first vapor
deposition zone 960 in the first vapor deposition section 962 is
formed of a vapor deposition surface of the substrate 904 between
the second can 913 and a contact point at which the first can 912
contacts a straight line extending from the center of the vapor
deposition surface of the evaporation source 909 through the end of
the gas introduction pipe 911a to the first can 912. A second vapor
deposition section 963 is formed of the third can 914 and the
fourth can 915. A second vapor deposition zone 961 in the second
vapor deposition section 963 is formed of the vapor deposition
surface of the substrate 904 between the fourth can 915 and a
contact point at which the third can 914 contacts a straight line
extending from the center of the vapor deposition surface of the
evaporation source 909 through the end of the gas introduction pipe
911b to the third can 914. The first vapor deposition zone 960 and
the second vapor deposition zone 961 are located on both sides of
the normal passing through the center of the vapor deposition
surface of the evaporation source so as to face each other.
[0289] FIG. 28 is a schematic view showing the set positions of the
first vapor deposition section 962, the second vapor deposition
section 963, the evaporation source 909 and the like. As shown in
FIG. 28, the first vapor deposition zone 960 is formed of a first
curved running section 964 for allowing the substrate 904 to run
along the first can 912 and a first straight running section 965
for allowing the substrate 904 to run along a straight section
between the first can 912 and the second can 913. The second vapor
deposition zone 963 is formed of a second curved running section
966 for allowing the substrate 904 to run along the third can 914
and a second straight running section 967 for allowing the
substrate 904 to run along a straight section between the third can
914 and the fourth can 915. Referring to FIG. 28, .theta.21 is an
angle made by a straight line extending from the center of the
vapor deposition surface of the evaporation source 909 through the
end of the gas introduction pipe 911a to the first can 912 and the
normal extending from a point at which the straight line and the
first can 912 cross each other. .theta.22 is an angle made by the
normal extending from a point at which the substrate 904 leaves the
first can 912 and a straight line extending from the center of the
vapor deposition surface of the evaporation source 909 to such a
point. .theta.23 is an angle made by a straight line extending from
the center of the vapor deposition surface of the evaporation
source 909 to a point at which the substrate 904 contacts the
second can 813 when leaving the second can 813 and the normal
extending from such a contact point of the straight line and the
second can 913. The first can 912 and the second can 913 are
located such that .theta.21, .theta.22 and .theta.33 fulfill the
relationship of
45.degree..ltoreq..theta.21<.theta.22<.theta.23.ltoreq.75.degree.
(in this Embodiment C, .theta.21=45.degree., .theta.22=63.degree.,
and .theta.23=75.degree.). The third can 914 and the fourth can 915
are located line-symmetric to the first can 912 and the second can
913 with respect to the center line passing through the center of
the evaporation source 909.
[0290] Now, an operation of the vapor deposition device 1000C in
Embodiment C will be described. First, the substrate 904 is caused
to run. The substrate 904 of a long strip type fed out from the
supply roll 903 is guided along the transportation rollers 905a and
905b, the first can 912, the second can 913, the transportation
rollers 905c, 905d 905e, 905f and 905g, the third can 914, and the
fourth can 915, and then is taken up by the take-up roll 908. Since
the substrate 904 is used as a current collector of an electrode, a
film-type metal foil having a concave and convex pattern formed on
a top surface and a rear surface thereof is used as the substrate
904. The metal material of the metal foil is, for example, a
material fulfilling the electric conductivity required of a current
collector such as copper, nickel, aluminum or the like. The concave
and convex pattern is formed of diamond shapes, each of which has a
size of 20 .mu.m.times.20 .mu.m and a height of 10 .mu.m. The
arithmetic average roughness (Ra) of the surface of the concave and
convex pattern is 2.0 .mu.m. On the running substrate 904, the
vapor-depositing material evaporated from the evaporation source
909 is vapor-deposited to form a vapor deposition film (vapor
deposition particles). For the evaporation source 909, a crucible
or the like is used. The evaporation source 909 is heated by a
heating device (not shown) such as a resistance heating device, an
induction heating device, an electronic beam heating device or the
like, and silicon, for example, as the vapor-depositing material is
evaporated. In the first film formation zone 960 between the first
can 912 and the second can 913, the substrate 904 is exposed to the
silicon evaporated from the evaporation source 909, and as a
result, a first active material layer 921 of silicon is formed on
one surface of the substrate 904. Then, in the second film
formation zone 961 between the third can 914 and the fourth can
915, the substrate 904 is exposed to the silicon evaporated from
the evaporation source 909, and as a result, a second active
material layer 923 of silicon is also formed on the other surface
of the substrate 904. For forming an active material layer of a
compound containing silicon and oxygen, oxygen gas is introduced
through the gas introduction pipes 911a and 911b, and silicon is
evaporated from the evaporation source 909 in an oxygen gas
atmosphere. The arithmetic average roughness (Ra) is defined in the
Japanese Industrial Standards (JISB 0601-1994), and may be measured
by, for example, a contact-system or laser-system surface roughness
meter or the like.
[0291] FIG. 29 is a schematic view of a vapor deposition film
formed on the substrate 904 by the above operation. The first
vaporization zone 960 and the second vaporization zone 961 are
located such that the incidence angle of the vapor-depositing
material particles evaporated from the center of the evaporation
source 909 on the substrate 904 is oblique. Therefore, a vapor
deposition film including column-like elements oblique with respect
to the substrate 904 as shown in FIG. 29 can be formed.
[0292] In the vapor deposition device 1000C in Embodiment C, the
first film formation zone 960 and the second film formation zone
961 are located such that silicon particles as the vapor deposition
particles evaporated from the center of the evaporation source 909
fly at an incidence angle in the range of 45.degree. to 75.degree.
on the substrate 904 transported between the first can 912 and the
second can 913 and between the third can 914 and the fourth can
915. This is for the following reason. In vapor deposition, the
material heated in the vacuum atmosphere is evaporated by the COS
rule. Therefore, the vapor concentration is higher in a zone closer
to the normal to the evaporation source 909. Thus, in such a zone,
the utilization factor of the material is improved. Where the angle
with respect to the normal to the evaporation source 909 is defined
as the vaporization angle, the utilization factor of the material
can be adjusted in the range of the vaporization angle of the vapor
deposition particles. Namely, where the range of the vaporization
angle is the same, as the distance from the evaporation source is
shorter, the deposition speed of the material evaporated from the
evaporation source on the substrate 904 is higher. For this reason,
in order to raise the productivity, it is important to widen the
vaporization angle and shorten the distance from the evaporation
source 909 to the substrate 904. This is why the first film
formation zone 960 and the second film formation zone 961 are
located as described above. However, in the case where the film
formation zone includes only a zone where the substrate 904 runs
straight, a film formation zone with a large incidence angle
unavoidably needs to be located far from the evaporation source
909. For this reason, in the vapor deposition device 1000C in
Embodiment C, the first vapor deposition zone 960 is formed of the
first curved running section 964 for allowing the substrate 904 to
run along the first can 912 and the first straight running section
965 for allowing the substrate 904 to run along the straight
section provided by the first can 912 and the second can 913. The
second vapor deposition zone 963 is formed of the second curved
running section 966 for allowing the substrate 904 to run along the
third can 914 and the second straight running section 967 for
allowing the substrate 904 to run along the straight section
provided by the third can 914 and the fourth can 915. The first
curved running section 964 and the second curved running section
966 form a film formation zone with an incidence angle of about
45.degree. to 63.degree., and therefore a film formation zone with
an incidence angle of about 75.degree. can be provided near the
evaporation source. For example, assuming that a vaporization angle
of 2.degree. to 32.degree. and a vaporization angle of -32.degree.
to -2.degree. are used, a zone with an incidence angle of
45.degree. to 63.degree. is provided above the first can 912 and
the third can 914, and a zone with an incidence angle of 63.degree.
to 75.degree. is provided linearly. In this case, as compared with
the case where a film formation zone with an incidence angle of
45.degree. to 75.degree. is provided linearly, the position of an
incidence angle of 75.degree. can be closer by 7/10 to the
evaporation source. Since the deposition speed on the substrate is
in inverse proportion to the square of the distance between the
evaporation source and the substrate, the material deposition speed
on the substrate can be increased about twice as higher. The zone
with an incidence angle of 45.degree. to 63.degree. is close to the
evaporation source 909, and so the temperature of the substrate in
this zone is increased as a result of the influence of the radiant
heat and the energy of the vapor-depositing material. By allowing
the substrate to be in contact with the can, heat can be removed
from the substrate, which provides an effect of suppressing a
temperature rise of the substrate.
[0293] Where .theta.21 is smaller than 45.degree., the particles to
be grown rise steeply, and hence, it is likely to be difficult to
form a vapor deposition film having a space between the particles
on the concaved and convexed surface of the substrate 904. As a
result, the substrate is likely to be wrinkled by the expansion of
the particles at the time of charge/discharge. Where .theta.23 is
larger than 75.degree., the particles to be grown are inclined
largely. This weakens the attachment of the particles to the
concaved and convexed surface of the substrate, and as a result, a
vapor deposition film having a weak adhesiveness to the substrate
is formed. As a result, the electrode active material is likely to
be detached from the substrate at the time of charge/discharge.
Accordingly, in the vapor deposition device 1000C in Embodiment C,
it is preferable that .theta.21 and .theta.23 are set such that
silicon particles as the vapor deposition particles evaporated from
the center of the evaporation source 909 fly at an incidence angle
in the range of 45.degree. to 75.degree. on the substrate 904
transported between the first can 912 and the second can 913 and
between the third can 914 and the fourth can 915.
[0294] In the vapor deposition device 1000C in Embodiment C, when
the pressure inside the vacuum tank 902 rises to about
4.5.times.10.sup.-2 Pa, the pipe conductance is adjusted using the
assisting exhaust pump 931 having an exhaust speed of 5000 L/sec.
such that the vacuum exhaust speed at the assisting exhaust opening
930 is 2000 L/sec. In this manner, the vacuum pressure is improved
from about 4.5.times.10.sup.-2 Pa to about 3.0.times.10.sup.-2
Pa.
[0295] The vacuum exhaust capability can be improved as follows.
The first film formation zone 960 and the second film formation
zone 961 of the substrate 904 located obliquely are located
symmetrical with respect to the evaporation source 909, and the
assisting exhaust opening 930 is provided in the vicinity of a zone
where the incidence angle of the vapor deposition particles on the
substrate is 75.degree., i.e., in the vicinity of the
above-mentioned film formation zones close to each other. Owing to
this, the vacuum degree in the vicinity of the film formation zones
close to each other can be improved, and the oxygen gas or
evaporated particles of silicon having directivity can be
vapor-deposited as being distributed over the film formation zones.
Accordingly, a reduction of the space among the active material
particles caused by the reduction of the vacuum degree at the time
of vapor deposition and the expansion/contraction of the electrode
active material can be suppressed, and so a cell having a high
charge/discharge cycle characteristic is provided.
[0296] The space in the first active material layer 921 and the
second active material layer 923 formed in Embodiment C can be used
as an expansion space necessary when the electrode plate is
expanded by the charge/discharge, and allows the stress on the
electrode active material to be alleviated. Therefore, the
shortcircuiting between the positive electrode and the negative
electrode can be suppressed, which provides a cell having a high
charge/discharge cycle characteristic, needless to say.
[0297] FIG. 30 is a partial schematic view showing a modification
of the first vapor deposition zone 960 and the second vapor
deposition zone 961 in the vapor deposition zones of the vapor
deposition device 1000C in Embodiment C. As shown in FIG. 30, it is
possible to provide an assisting can 950 in a middle part of the
first film formation zone 960 and in a middle part of the second
film formation zone 961. By providing the assisting cans 950, the
first film formation zone 960 is formed of a first curved running
section 964, a first intermediate straight running section 970, a
first intermediate curved running section 968 and a first straight
running section 965. Also by providing the assisting cans 950, The
second film formation zone 961 is formed of a second curved running
section 966, a second intermediate straight running section 970, a
second intermediate curved running section 969 and a second
straight running section 967. Owing to this structure, in the first
film formation zone 960 and the second film formation zone 961,
slackening of the substrate 804 cab be suppressed during the
running. This can suppress the substrate 804 from being wrinkled
during the running.
[0298] By providing the first intermediate curved running section
968 and the second intermediate curved running section 969, zones
having a high incidence angle in the first straight running section
965 and the second straight running section 967 can be made closer
to the evaporation source 909. Thus, film formation can be
performed fulfilling the conditions on both the incidence angle and
the vaporization angle, which improves the utilization factor of
the material.
[0299] By allowing the first intermediate curved running section
968 and the second intermediate curved running section 969 to be
cooled, heat can be removed from the substrate, which provides an
effect of suppressing a temperature rise of the substrate. For
example, the temperature of each can may be set to the range of
-30.degree. C. to 20.degree. C. to cool the substrate 904. Since
the heat received by the substrate 904 during the vapor deposition
(radiant heat from the evaporation source 909, heat of
solidification of the vapor deposition particles, etc.) can be
alleviated, the thermal expansion of the substrate 904 during the
running can be suppressed and so substrate 904 can be suppressed
from being wrinkled during the running.
[0300] FIG. 31 is a partial schematic view showing another
modification of the first vapor deposition zone 960 and the second
vapor deposition zone 961 in the vapor deposition zones of the
vapor deposition device 1000C in Embodiment C. As shown in FIG. 31,
it is possible to provide two assisting cans 950 in each of the
first film formation zone 960 and the second film formation zone
961.
[0301] Owing to this structure, zones having a high incidence angle
in the first straight running section 965 and the second straight
running section 967 can be made still closer to the evaporation
source 909. Thus, film formation can be performed fulfilling the
conditions on both the incidence angle and the vaporization angle,
which improves the utilization factor of the material.
Reference Embodiment D
[0302] Now, a structure of a vapor deposition device 1000D in
Reference Embodiment D will be described. FIG. 32 is a
cross-sectional view schematically showing the vapor deposition
device 1000D in Embodiment D. The vapor deposition device 1000D in
Embodiment D has almost the same structure as that of the vapor
deposition device 1000C in Embodiment C except for the following.
Unlike the vapor deposition device 1000C, the vapor deposition
device 1000D includes a path, located on the path for guiding the
substrate 904 from the first film formation zone 960 to the second
film formation zone 961, for allowing the substrate 904 to run such
that a film is formed on the same surface of the substrate 904 in
the first film formation zone 960 and the second film formation
zone 961.
[0303] Now, an operation of the vapor deposition device 1000D in
Embodiment D will be described. The vapor deposition device 1000D
in Embodiment D operates in almost the same manner as the
deposition device 1000C shown in Embodiment C. The difference is
the following. A film is formed on the same surface of the
substrate 904 in the first film formation zone 960 and the second
film formation zone 961. The rolled substrate 904 having the film
formed thereon is set to the supply roll 903 again, and the same
operation is performed on the surface of the substrate 904 on which
no vapor deposition film has been formed. Specifically, as shown in
FIG. 32, the substrate 904 of a long strip type fed from the supply
roll 903 in the vacuum tank 902 is guided along the transportation
rollers 905a and 905b, the first can 912, the second can 913, the
transportation rollers 5c, 5d and 5e, the fourth can 915, the third
can 914, and the transportation rollers 905g, 905f and 905h in this
order, and then is taken up by the take-up roll 909.
[0304] FIG. 33 is a cross-sectional view of a vapor deposition film
formed by the vapor deposition device 1000D in Embodiment D. While
the incidence direction of the evaporated vapor-depositing material
particles on the substrate 904 is changed, the film is formed on
the same surface of the substrate 904 in the first film formation
zone 960 and the second film formation zone 961. Therefore, the
first active material layer 921 and the second active material
layer 923 can be formed zigzag as shown in FIG. 33. Like in
Embodiment C, in Embodiment D also, the first curved running
section 964 and the first straight running section 965 are provided
in the first vapor deposition zone 960, and the second curved
running section 966 and the second straight running section 967 are
provided in the second vapor deposition zone 961. Thus, the
relative distance between the vapor deposition zones in which the
vapor deposition particles are vapor-deposited on the substrate 904
obliquely and the evaporation source 909 is shortened. Therefore,
needless to say, the utilization factor of the material can be
improved.
[0305] The shape of an electrode 20 after the vapor deposition film
is formed in each of Embodiments C and 2 is not limited to the
above shape, and may be appropriately selected in accordance with
the designed capacitance of the cell.
[0306] Using the electrode 920 produced by each of the vapor
deposition devices 1000C and 200, a nonaqueous electrolytic
secondary cell can be easily produced as follows. The electrode 920
is used together with a positive electrode plate containing a
positive electrode active material generally usable for a lithium
ion secondary cell such as LiCoO.sub.2, LiNiO.sub.2,
LiMn.sub.2O.sub.4 or the like, a separator formed of a microporous
film or the like, and an electrolytic solution having a generally
known composition and having lithium ion conductivity obtained by
dissolving lithium hexafluorophosphate or the like in a cyclic
carbonate such as ethylene carbonate, propylene carbonate or the
like.
[0307] According to Embodiments C and D, the vapor deposition zone
can be enlarged without increasing the size of the vacuum tank of
the vapor deposition device. Thus, a vapor deposition film can be
formed at a higher efficiency. In addition, the distance from the
substrate in the vicinity of a zone, where the incidence angle from
the evaporation source on the surface of the substrate is
75.degree., to the evaporation source can be shortened.
Accordingly, the deposition speed of the vapor deposition particles
on the substrate can be increased. Thus, the utilization factor of
the evaporated material can be improved, and a film which is not
easily deteriorated can be continuously formed by a highly
productive vapor deposition method.
INDUSTRIAL APPLICABILITY
[0308] A vapor deposition device according to the present invention
is usable for producing various devices using vapor deposition
films, for example, electrochemical devices such as cells and the
like; optical devices such as photonic elements, optical circuit
components and the like; and various other devices such as sensors
and the like. The present invention is generally applicable to
electrochemical elements, and is especially advantageously
applicable to production of electrode plates for cells using active
materials which are largely expanded and contracted by
charge/discharge. When being applied to production of such
elements, the present invention provides an electrode plate having
a high energy density with deformation or generation of wrinkles
caused by expansion of the active material being suppressed.
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