U.S. patent application number 11/510860 was filed with the patent office on 2007-03-01 for method for forming a film of lithium metal or lithium alloys and an apparatus for the same.
Invention is credited to Eiji Fuchita, Yoshiyuki Honjo, Yukio Yamakawa.
Application Number | 20070048170 11/510860 |
Document ID | / |
Family ID | 37804379 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070048170 |
Kind Code |
A1 |
Fuchita; Eiji ; et
al. |
March 1, 2007 |
Method for forming a film of lithium metal or lithium alloys and an
apparatus for the same
Abstract
A lithium or lithium alloy film forming method comprises: the
step of heating and evaporating lithium or lithium alloy under an
atmosphere of inert gas in an ultra fine particle producing chamber
to produce ultra fine particles of lithium or lithium alloy
therein; the step of transporting the ultra fine particles through
a transfer pipe with the inert gas into a film forming chamber
under vacuum atmosphere; the step of jetting the ultra fine
particles onto a substrate arranged in the film forming chamber
from a nozzle; the step of moving a substrate holder holding the
substrate in the X-direction and/or Y-direction; the step of
preheating the substrate at a predetermined temperature within the
range of 100 to the melting point of lithium or lithium alloy: and
the step of forming a film of lithium or lithium alloy on the
substrate being moved with the substrate holder.
Inventors: |
Fuchita; Eiji; (Narita,
JP) ; Honjo; Yoshiyuki; (Osaka, JP) ;
Yamakawa; Yukio; (Osaka, JP) |
Correspondence
Address: |
Floyd B. Carothers;CAROTHERS AND CAROTHERS
Suite 500
445 Fort Pitt Boulevard
Pittsburgh
PA
15219
US
|
Family ID: |
37804379 |
Appl. No.: |
11/510860 |
Filed: |
August 28, 2006 |
Current U.S.
Class: |
419/28 ;
419/55 |
Current CPC
Class: |
C23C 14/564 20130101;
C22B 26/12 20130101; B22F 2201/20 20130101; B22F 2998/00 20130101;
C23C 14/228 20130101; B22F 9/12 20130101; C23C 14/22 20130101; B22F
9/12 20130101; B22F 7/08 20130101; B22F 2998/00 20130101; C23C
14/14 20130101 |
Class at
Publication: |
419/028 ;
419/055 |
International
Class: |
B22F 3/24 20060101
B22F003/24; C22C 33/02 20060101 C22C033/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 31, 2005 |
JP |
2005-250686 |
Aug 31, 2005 |
JP |
2005-250687 |
Claims
1. A lithium or lithium alloy film-forming method comprising: (a)
the step of heating and evaporating lithium or lithium alloy under
the atmosphere of an inert gas in an ultra fine particle producing
chamber to produce ultra fine particles of lithium or lithium alloy
therein; (b) the step of transporting said ultra fine particles
through a transfer pipe with said inert gas into a film forming
chamber under vacuum atmosphere; (c) the step of jetting said ultra
fine particles onto a substrate arranged in said film forming
chamber from a nozzle; (d) the step of moving a substrate holder
holding said substrate in the X-direction and/or the Y-direction;
(e) the step of heating said substrate at a predetermined
temperature within the range of 100.degree. C. to the melting point
of lithium or lithium alloy; and (f) the step of forming a film of
lithium or lithium alloy on said substrate while being moved with
said substrate holder.
2. A lithium or lithium alloy film forming method according to
claim 1 in which said inert gas is selected from the group
consisting of helium, neon, xenon and argon.
3. A lithium or lithium alloy film forming method according to
claim 1 in which a heating mechanism is included in said substrate
holder to heat said substrate.
4. A lithium or lithium alloy film forming method according to
claim 1 in which a thermocouple is attached to said substrate and
the output of said thermocouple is supplied to a control portion of
said substrate holder.
5. An apparatus for forming a lithium or lithium alloy film
comprising: (a) an ultra fine particle producing chamber including
a crucible containing lithium or lithium alloy; (b) a transfer pipe
vertically arranged directly above said crucible; (c) a nozzle
attached to a top end of said transfer pipe; (d) a film-forming
chamber including a substrate and a substrate holder holding said
substrate, said nozzle being arranged directly under said
substrate, and said holder being movable in the X-direction and/or
the Y-direction, in the plane of said substrate; (e) evacuating
means for evacuating said ultra fine particle producing chamber,
said transfer pipe and said film forming chamber; (f) means for
inductively heating and evaporating the lithium or lithium alloy in
said ultra fine particle producing chamber to produce ultra fine
particles; and (g) means for introducing and circulating inert gas
into and through said ultra fine particle producing chamber, said
transfer pipe and said film-forming chamber, whereby, after said
ultra fine particle producing chamber, said transfer pipe and said
film-forming chamber have been evacuated to a predetermined
pressure, and said inert gas is introduced into said ultra fine
particle producing chamber, said produced ultra fine particles are
transported through said transfer pipe with said inert gas, and are
jetted onto said substrate from said nozzle whereby a lithium or
lithium alloy film is formed onto said substrate being moved with
said holder, said predetermined pressure being lower than
5.times.10.sup.-4 Pa.
6. An apparatus according to claim 5 in which said inert gas is of
purity of 99.9995% or more.
7. An apparatus according to claim 5 in which said evacuating means
includes a turbo-molecular pump.
8. An apparatus according to any one of claims 5 in which said
inert gas is selected from the group consisting of helium, argon,
xenon and argon.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a method for forming a film of
lithium metal or lithium alloy and an apparatus for the same.
[0003] 2. Description of the Prior Art
[0004] Publication J8-209330A discloses a pattern forming method
for a conductive metal thick film in which a conductive metal
material is heated and evaporated with high frequency induction
heat under an inert gas atmosphere, in an ultra fine particle
evaporation chamber, and produced ultra fine particles are
transported in a pipe, with the inert gas, into a film forming
chamber in a vacuum. The fine particles are jetted onto a
substrate, arranged in the film forming chamber, from a nozzle
heated at a temperature under the melting point of the ultra fine
particles, with the applied pressure of the inert gas. The nozzle
or the substrate is moved at an arbitrary speed and the thick film
of conductive metal is formed with a desired thickness in a desired
pattern.
[0005] However, in the above gazette publication, the conductive
metal is aluminum or an aluminum alloy. The aluminum alloys are
Al--Si, Al--Cu, Al--Si--Cu, Al--Si--Ti or Al--Cu--Ti.
[0006] On the other hand, JP2002-100346 discloses: [0007] a method
of producing a negative electrode for a lithium secondary cell
having a thin film made of an inorganic solid electrolyte,
comprising the steps of: [0008] placing a closed container
containing a negative electrode base material and a closed
container containing a source material for an inorganic solid
electrolyte, into a chamber space, which is substantially
inactivate to lithium and which is insulated from air and provided
adjacent to an apparatus for forming the thin film, the base
material having a surface made of a material selected from the
group consisting of lithium metal and lithium alloys; [0009] taking
out the base material and the source material from each container
in the chamber space; [0010] transferring the base material and the
source material into the apparatus without exposing them to air;
[0011] using the source material and forming a thin film made of an
inorganic solid electrolyte on the base material in the apparatus;
[0012] transferring the base material having the thin film formed
thereon, without exposing it to air, from the apparatus into a
chamber space, which is substantially inactivate to lithium and
which is insulated from air and positioned adjacent to the
apparatus; and [0013] placing the base material into a closed
container in the chamber space.
[0014] In the above mentioned method, the film of the material
selected from the group consisting of lithium metal and lithium
alloys is formed on the substrate by the gas phase deposition
method. Thus, the negative electrode is adjusted. The gas phase
deposition method is selected from the typical group consisting of
spattering, vacuum deposition, laser abrasion and ion plating. The
film is heated, and the film has a relatively high ion
conductivity.
SUMMARY OF THE INVENTION
[0015] However, ultra fine particles are not used for forming a
film in the gas phase deposition method of the above JP2002-100346A
reference, although they are used in the JP8-209330A reference. The
film forming principles are different between the above two patent
opening gazettes. Further the purity of the film of lithium is low
in the method of the JP2002-100346 publication. Thus, discharge
capacity is small. Thus, an ideal lithium electrode, which has high
discharging capacity, cannot be manufactured.
[0016] This invention has been conceived in consideration of the
above mentioned problem. The object of the invention is to provide
a method for forming lithium or lithium alloy film which can form a
lithium or lithium alloy film always having a high purity and an
apparatus for forming lithium or lithium alloy film which can form
a lithium or lithium alloy film always having high purity.
[0017] In accordance with an aspect of this invention: a lithium or
lithium alloy film forming method comprises: [0018] (a) the step of
heating and evaporating a lithium or lithium alloy under an
atmosphere of inert gas in an ultra fine particle producing chamber
to produce ultra fine particles of lithium or lithium alloy
therein; [0019] (b) the step of transporting the ultra fine
particles through a transfer pipe with the inert gas into a film
forming chamber under vacuum atmosphere; [0020] (c) the step of
jetting the ultra fine particles onto a substrate arranged in the
film forming chamber from a nozzle; [0021] (d) the step of moving a
substrate holder holding the substrate in the X-direction and/or
Y-direction; [0022] (e) the step of heating the substrate at a
predetermined temperature within the range of 100.degree. C. to the
melting point of lithium or lithium alloy; and [0023] (f) the step
of forming a film of lithium or lithium alloy on the substrate
being moved with the substrate holder.
[0024] In accordance with another aspect of this invention: an
apparatus is provided for forming a lithium or lithium alloy film
which comprises: [0025] (a) an ultra fine particle producing
chamber including a crucible containing lithium or lithium alloy;
[0026] (b) a transfer pipe vertically arranged directly above the
crucible; [0027] (c) a nozzle attached to a top end of the transfer
pipe; [0028] (d) a film-forming chamber including a substrate and a
substrate holder holding the substrate, the nozzle being arranged
directly under the substrate, and the holder being movable in the
X-direction and/or the Y-direction, in the plane of the substrate;
[0029] (e) evacuating means for evacuating the ultra fine particle
producing chamber, the transfer pipe and the film forming chamber;
and [0030] (f) means for introducing inert gas and circulating it
into and through the ultra fine particle producing chamber, the
transfer pipe and the film forming chamber, whereby, after the
ultra fine particle producing chamber, the transfer pipe and the
film forming chamber have been evacuated to a predetermined
pressure, lithium or lithium alloy in the crucible is heated and
evaporated in the ultra fine particle producing chamber to produce
ultra fine particles and the inert gas is introduced into the ultra
fine particle producing chamber, produced ultra fine particles are
transported through the transport pipe with the inert gas, and are
jetted onto the substrate from the nozzle, and a lithium or lithium
alloy film is formed onto the substrate being moved with the
holder, and wherein the predetermined pressure is lower than
5.times.10.sup.4 Pa.
[0031] The foregoing and other objects, features and advantages of
the present invention will be more readily understood upon
consideration of the following detailed description of the
preferred embodiments of the invention, taken in conjunction with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a schematic view of an apparatus for forming a
film of lithium according to a first embodiment of this
invention.
[0033] FIG. 2 is a schematic view for explaining operation of a
shutter system, FIG. 2A showing transport of ultra fine particles
and FIG. 2B showing cessation of transport.
[0034] FIG. 3 is a schematic view of an apparatus for forming a
lithium film according to a second embodiment of this
invention.
[0035] FIG. 4 is a schematic view for explaining operation of a
shutter system, FIG. 4A showing the situation during the transport
of the ultra fine particles and FIG. 4B showing the situation
during the cessation of the transport.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0036] Next, a gas deposition apparatus according to a first
embodiment of this invention will be described with reference to
the drawings.
First Embodiment
[0037] FIG. 1 shows a gas deposition apparatus A of the first
embodiment. Generally, it consists of an ultra fine particle
evaporation chamber 1, a transfer pipe 3, and a film forming
chamber 2, which are arranged in a vertical direction. A crucible 6
which is made of, for example, tantalum, the inner diameter and the
outer diameter of which are equal to 38mm(p and 40 mm.phi..
respectively, is arranged in the ultra fine particle evaporation
chamber 1. The height of the crucible 6 is equal to 40 mm.
Evaporation material 22 (Li) is contained in the crucible 6. An
electromagnetic coil 7C for heating inductively lithium 22 is wound
around the crucible 6. The coil 7C is connected to a radio (high)
frequency (150 kHz) electric power source 7 which is arranged
outside of the ultra fine particle evaporation chamber 1.
[0038] A helium (He) gas is introduced into the ultra fine particle
evaporation chamber 1 through a mesh-filter type introducing port
M, so that the ultra fine particle evaporation chamber 1 is
maintained at a predetermined pressure. The helium gas is used for
transporting the produced ultra fine particles. The mesh-filter
type introducing port M is of the type in which the area of the
filter and the aperture ratio can be changed. The helium gas flows
through a variable flow valve 12 from a helium gas source 18. The
gas flow is introduced into the ultra fine particle evaporation
chamber 1 through the mesh-filter type introducing port M that
adjusts the gas flow speed around the crucible 6. A pressure gauge
1G is installed on the ultra fine particle evaporation chamber
1.
[0039] The transfer pipe 3 is straight in the vertical direction.
The outer diameter of the transfer pipe 3 is equal to 1/4 inch. The
lower end portion of the transfer pipe 3 is inserted into the ultra
fine particle evaporation chamber 1. An inlet port 3a of the
transfer pipe 3 is located directly above the crucible 6, and an
inner diameter of the inlet port 3a of the transfer pipe 3 is equal
to 30 mm. The top portion of the transfer pipe 3 is inserted into
the film forming chamber 2. A nozzle 4, which ejects out ultra fine
particles, is connected to an outlet port 4 of the transfer pipe
3.
[0040] The nozzle 4 has a throat or narrow hole portion, the inner
diameter of which is equal to 1.0 mm. The transfer pipe 3 is
straight without bends. Accordingly, turbulence does not occur in
the transfer flow of the ultra fine particles through the transfer
pipe 3. Further, a nozzle heater 23, wound on the nozzle 4, is
heated with an AC power source 24.
[0041] Referring to FIG. 1, an inhalant or evacuation intake pipe
5, which is concentric with the transfer pipe 3, is located above
the inlet 3a of the transfer pipe 3, in the ultra fine particles
evaporation chamber 1, so that an annular space is formed between
the transfer pipe 3 and the intake pipe 5. The intake pipe 5 is so
arranged that it sucks in ultra fine particles drifting around the
crucible 6 in the ultra fine particle evaporation chamber 1. The
intake pipe 5 is directed separately from the transfer pipe 31
outside of the ultra fine particle evaporation chamber 1. It is
connected to a vacuum pump 16 through a vacuum valve 13.
[0042] A substrate 8 is arranged in the film forming chamber 2, and
is positioned at a right angle with respect to the nozzle 4. The
distance between the nozzle 4 and the substrate 8 is equal to 3 mm.
The substrate 8 is supported on an operating plate or holding plate
10 which is movable in the X-direction, the Y-direction and the Z
direction, which are at right angles with respect to each other.
The operating plate or holding plate 10 has a heating mechanism
(which is not shown) for heating the substrate 8. The film forming
chamber 2 is connected to a vacuum pump 15 through a vacuum valve
14. Further, a vacuum gauge 2G is attached to the film forming
chamber 2.
[0043] A shutter system 9 supports the crucible 6 at the bottom.
The shutter system 9 locates the crucible 6 at a position directly
under the transfer pipe 3 as shown in FIG. 2A, or locates the
crucible 6 at another position directly under the annular space
between the transport pipe 3 and the intake pipe 5 as shown in FIG.
2B. The distance between the one position and the other position is
equal to 50 mm in the direction as shown by the arrow a. Metal
vapor from the crucible 6 is cooled by the atmosphere of the
transport gas (helium gas) to thereby become ultra fine particles,
which are sucked into the transfer pipe 3, at the one position, and
the intake pipe 5 at the other position as shown in FIG. 2B. The
shutter system 9 is moved between the one position and the other
position in accordance with a program of a controller which is not
shown. Transport or non-transport of the ultra fine particles
through the transport pipe 3 is thus controlled.
[0044] The nozzle 4 of 1.0 mm.in inner diameter is inserted through
the top and the upper end portion of the transfer pipe 3. A nozzle
heater 23 is wound around the nozzle 4 and is electrically
connected to the outward alternative power source 24. The substrate
8 is arranged directly over the nozzle 4. It is held by the holder
10. The distance between the substrate 8 and the nozzle 4 is
variable within the range of 3 to 30 mm. The movement of the holder
or operating plate 10 is programmatically controlled by a
controller 11. The substrate 8 is moved in the plane of the
X-direction and Y-direction at the speed of 0.5 to 6 mm per
second.
[0045] According to this invention, the holder 10 includes a
heating mechanism which is controlled to heat the substrate 8 at a
predetermined temperature within the range of 100.degree. to
180.5.degree. C. (melting point of lithium metal) by a temperature
control portion of the controller 11. In this embodiment, the
substrate 8 is heated at the predetermined temperature of
100.degree. C. through the heating mechanism in the holder 10 with
the temperature control portion of the controller 11.
[0046] The discharge conduits of the vacuum pumps 15 and 16 are
combined to form one conduit and connected through a valve 19 to a
He gas purification recycle system 17. Output gas of the helium gas
purification system 17 is transported into the bottom of the ultra
fine particle producing chamber 1, which is further connected
through the valve 12 to the helium gas source 18. It contains
helium gas of a purity of 99.9999% or more. Discharge conduits of
the vacuum valves 15, 16 are combined with the conduit which is
further connected through a valve 20 to a divided conduit.
[0047] Next, there will be described the method of forming a
lithium metal film on the substrate 8 by using the above described
apparatus. In this embodiment, a copper foil is used as the
substrate 8, the thickness of which is exaggeratedly shown. The
thickness is equal to 10 mm.
[0048] Referring to FIG. 1, the ultra fine particle producing
chamber 1 and the film forming chamber 2 are evacuated to a
pressure of 10.sup.-4 Pa by the vacuum pumps 15, 16. The valves 13,
14 and 20 are opened and the valves 12 and 19 are closed. The
vacuum pumps 15 and 16 are continuously driven. The valve 20 is
closed. The valves 12 and 19 are opened. Helium gas of a purity of
99.9999% or more is introduced at a predetermined rate into the
ultra fine particle producing chamber 1 from the helium gas source
18. The opening of the valve 13 is so adjusted so as to maintain
the pressure of the ultra fine particle producing chamber 1 at 100
kPa. The introduced helium is sucked into the intake pipe 5 at the
rate of 30 SLM (number of liters per minute under standard
conditions). Helium gas is flowed through the transfer pipe 3 at
the rate of 10 SLM, into the film forming chamber 2. The helium gas
is introduced into the film forming chamber 2 and evacuated through
the valve 14. The pressure of the film forming chamber 2 is
maintained at about 300 Pa. The pressure difference between the
film forming chamber 2 and the ultra fine particle producing
chamber 1 becomes about 100 kPa. At that time, the valve 12 is
closed.
[0049] The reason why the flow amount into the intake pipe 5 is
larger, is as follows: when the ultra fine particles stay in the
ultra fine particle producing chamber 1 for some time, ultra fine
particles are apt to coagulate together and the coagulations might
be transferred in the transfer pipe 3. The coagulations have an
undesirable influence on the film being formed on the substrate.
The larger flow amount into the intake pipe 5 prevents the
formation of coagulation of the ultra fine particles.
[0050] When the above condition exists for longer than 30 minutes,
the helium gas discharged from the helium gas purification recycle
system 17 becomes purified at a purification of 99.9999% or more.
Helium gas of a purification of 99.9999% is circulated in the
direction as shown by the arrows.
[0051] After the above condition, the crucible 6 containing lithium
metal 22 is inductively heated with the high frequency power source
7. The metal 22 is heated at a temperature of 480.degree. C. and it
is evaporated from the crucible 6 and therefore ultra fine
particles are formed. Almost all of the formed ultra fine particles
are sucked into the transfer pipe 3 and they are jetted onto the
substrate 8 from the nozzle 4, which is heated at the temperature
of 100.degree. C. by the nozzle heater 23. The substrate 8 is
heated at the temperature of 100.degree. C. According to this
invention, it is preheated at the temperature of 100.degree. C.
with the heater unit included in the substrate holder 10 before
introducing the ultra fine particles into the film forming chamber
2. Thus, a lithium film is formed on the substrate 8.
[0052] The substrate 8 is moved in the X-direction and the
Y-direction in the plane of the substrate 8. The stop and start of
the transfer of the ultra fine particles is freely controlled with
the shutter system 9. An arbitrary pattern can be formed from one
arbitrary point to another arbitrary point.
[0053] The content of lithium in the film was measured
electrochemically.
[0054] The method of calculation of the content is shown in formula
3. Lithium amount obtained from the electrolysis (discharge) is
shown in formula 1. Lithium amount (theoretical capacity) obtained
from the weight (film thickness) is shown in formula 2. Formula
1/Formula 2.times.100=content [%]
[0055] [Formula 1]
Lithium amount obtained from the electrolysis
[0056] (Discharge time: t [sec], Constant current value: 0.001
[A/cm2]) G = t .function. [ sec ] .times. 0.001 .times. [ A .times.
/ .times. cm .times. .times. 2 ] 96487 .times. [ C .times. /
.times. mol ] .times. [ mol .times. / .times. cm .times. .times. 2
] ##EQU1##
[0057] [Formula 2]
Lithium amount obtained from the weight
[0058] (Lithium weight: W [g], Dimension: S [cm2]) M = W .function.
[ g ] 6.941 .times. [ g .times. / .times. mol ] .times. S
.function. [ cm .times. .times. 2 ] .times. [ mol .times. / .times.
cm .times. .times. 2 ] ##EQU2##
[0059] [Formula 3] G M .times. 100 = rate .times. .times. of
.times. .times. content .times. [ % ] ##EQU3##
[0060] In this embodiment, the substrate 8 is heated to the
predetermined temperature within the range of 100 to 180.5.degree.
C. by the substrate holder 10. When the substrate 8 is not heated,
the content is equal to 87%. However, when the substrate 8 is
heated to the temperature of 100.degree. C., it is equal to 96%,
according to this invention. The content of lithium or purity of
lithium is greatly raised. Accordingly, the electrical capacity of
the lithium can be widely improved.
[0061] The reason why the content or purity of lithium is greatly
raised, is considered to be that the surface of the substrate is
cleaned, or particularly that water is removed from the surface of
the substrate, or that various contaminants from the walls of the
vacuum chamber are eliminated from the surface of the substrate 8
by the heat.
[0062] Next, a gas deposition apparatus according to a second
embodiment of this invention will be described with reference of
FIG. 3 and FIG. 4.
Second Embodiment
[0063] FIG. 3 shows a gas deposition apparatus B of the second
embodiment. The parts which correspond to those in FIG. 1, are
denoted by the same, but primed, reference numerals. Generally, it
consists of an ultra fine particle evaporation chamber 1', a
transfer pipe 3', and a film forming chamber 2', which are arranged
in a vertical direction. A crucible 6', the inner diameter of which
is equal to 5.0 mm, is arranged in the ultra fine particle
evaporation chamber 1'. Evaporation material 22' (Li) is contained
in the crucible 6'. An electromagnetic coil 7C' for inductively
heating lithium in the crucible 6' is wound around the crucible 6'.
The coil 7C' is connected to a radio (high) frequency electric
power source 7' which is arranged outside of the ultra fine
particle evaporation chamber 1'.
[0064] A helium (He) gas is introduced into the ultra fine particle
evaporation chamber 1' through a mesh-filter type introducing port
M', so that the ultra fine particle evaporation chamber 1' is
maintained at a predetermined pressure. The helium gas is used for
transporting the produced ultra fine particles. The mesh-filter
type introducing port M is of the type in which the area of the
filter and the aperture ratio can be changed. The helium gas flows
through a variable flow valve 12' from a source 18'. The gas flow
is introduced into the ultra fine particle evaporation chamber 1'
through the mesh-filter type introducing port M' that adjusts the
gas flow speed around the crucible 6'. A pressure gauge 1G' is
installed on the ultra fine particle evaporation chamber 1'.
[0065] The transfer pipe 3' is straight in the vertical direction.
The inner diameter of the transfer pipe 3' is equal to 4.3 mm. The
lower end portion of the transfer pipe 3a' is inserted into the
ultra fine particle evaporation chamber 1'. An inlet port 3a' of
the transfer pipe 3' is located directly above the crucible 6' and
the inlet port 3a' of the transfer pipe 3' is equal to 30 mm. The
top portion of the transfer pipe 3' is inserted into the film
forming chamber 2'. A nozzle 4', which ejects ultra fine particles,
is connected to an outlet port 4' of the transfer pipe 3'.
[0066] The nozzle 4' has a throat or narrow passage portion, the
inner diameter of which is equal to 0.6 mm. The transfer pipe 3' is
straight without bends. Accordingly, turbulence does not occur in
the transfer flow of the ultra fine particles through the transfer
pipe 3'. Further, the nozzle 4' is heated with an alternating power
source 24'. A nozzle heater 23' wound on the nozzle 4' is connected
to the alternating power source 24'.
[0067] Referring to FIG. 3, an inhalant or evacuation intake pipe
5', which is concentric with the transfer pipe 3', is located above
the inlet 3a' of the transfer pipe 3', in the ultra fine particle
evaporation chamber 1', so that an annular space is formed between
the transfer pipe 3' and the intake pipe 5'. The intake pipe 5' is
so arranged that it sucks in ultra fine particles drifting around
the crucible 6' from the ultra fine particle evaporation chamber
1'. The intake pipe 5' is directed separately from the transfer
pipe 3' outside of the ultra fine particle evaporation chamber 1'.
It is connected through a vacuum valve 13', an F.Box and an FM to a
vacuum pump 16'.
[0068] A substrate 8' is arranged in the film forming chamber 2',
and makes a right angle with the nozzle 4'. The distance between
the nozzle 4 and the substrate 8' is equal to 3 mm. The substrate
8' is supported on an operating plate or a holder 10' which is
movable in the X-direction, the Y-direction and the Z direction,
which are at right angles with each other. The operating plate 10'
has a heating mechanism (which is not shown) for heating the
substrate 8'. The film forming chamber 2' is connected to a vacuum
pump 15' through a vacuum valve 14'. Further, a vacuum gauge 2G' is
attached to the film forming chamber 2'.
[0069] A shutter system 9' is connected to the lower end of the
transfer pipe 3'. The shutter system 9' locates the transfer pipe
3' at a position directly above the crucible 6' as shown in FIG. 4A
or locates the transfer pipe 3' at another position shifted from
the crucible 6' in FIG. 4B. The distance between the one position
and the other position is equal to 50 mm in the direction as shown
by the arrow. Metal vapor from the crucible 6' is cooled by the
atmosphere of the transport gas (helium gas) to become ultra fine
particles and is sucked into the transfer pipe 3' at the one
position and the intake pipe 5' at the other position as shown in
FIG. 4B. The shutter system 9' is moved between the one position
and the other position in accordance with a program of a controller
which is not shown. Transport or non-transport of the ultra fine
particles through the transfer pipe 3' is thus controlled.
[0070] The nozzle 4' of 1.0 mm inner diameter is inserted through
the top and the upper end portion of the transfer pipe 3.' A nozzle
heater 23' is wound around the nozzle 4' and is electrically
connected to the outward alternative power source 24'. A substrate
8' is arranged directly over the nozzle 4'. It is held by the
holder 10'. The distance between the substrate 8' and the nozzle 4'
is variable within the range of 3 to 30 mm. The holder 10' is
programmatically controlled by a controller 11'. The substrate 8'
is moved in the plane of the X-direction and the Y-direction at a
speed of 0.5 to 6 mm per sec.
[0071] The discharge conduits of the vacuum pumps 15' and 16' are
combined to one conduit and connected through a valve 19' to an He
gas circulation system 17'. Output gas of helium gas circulation
system 17' is transported into the bottom of the ultra fine
particle producing chamber 1', which is further connected through a
valve 12' to a helium gas source 18'. It contains helium gas of
purity 99.9999% or more. Discharge conduits of the vacuum pumps
15', 16' are combined to the conduit which is connected through a
valve 20' to a divided conduit.
[0072] Further, in this embodiment, a turbo molecular pump (TMP) 34
and a rotary pump 35 are connected through valves 30 and 31 to the
film forming chamber 2' and through valves 32 and 33 to the ultra
fine particle producing chamber 1'.
[0073] In this embodiment, a shutter system 9' is fixed to the
lower end of the transfer pipe 3' as shown in FIG. 4. FIG. 4A shows
one position at which the crucible 6' is direct under the transfer
pipe 3'. The evaporation 20' is almost sucked into the transfer
pipe 3'. In FIG. 4B, the transfer pipe 3' is shifted leftwards by
the shutter system 9'. The evaporation 20' is always sucked into
the intake pipe 5'.
[0074] Next, there will be described the method of forming a
lithium metal film on the substrate 8' by using the above described
apparatus. In this embodiment, a copper foil is used as the
substrate 8', the thickness of which is exaggeratedly shown. The
thickness is equal to 10 m.
[0075] The ultra fine particle producing chamber 1' and the film
forming chamber 2' are evacuated to high vacuum with the turbo
molecular pump (TMP) 34 and the rotary pump 35. According to this
invention, the film forming chamber 2' is evacuated to lower than
5.times.10.sup.-4 Pa, which is measured with pressure gauge 2G'. In
other words, the ultimate vacuum is lower than 5.times.10.sup.-4
Pa.
[0076] Next, the valves 31 and 32 are closed, and the rotary vacuum
pumps 15 and 16 and the mechanical booster pomp (MBP) are driven.
The valves 14 and 13 are opened and also the valves 12' and 19' are
opened. The helium gas of purity higher than 99.9995% is introduced
into the ultra fine particle producing chamber 1' at a
predetermined rate. The pressure of the ultra fine particle
producing chamber 1' is maintained at the pressure of 100 kPa. The
introduced helium gas is flowed into the intake pipe 5' at the rate
of 5 to 30 SLM (Standard litters per minute), and it is flowed
thorough the transfer pipe 3' at the rate of 2 to 10 SLM into the
film forming chamber 2'. The helium gas is discharged through the
valve 14'. The pressure of the film forming chamber 2' is
maintained at a pressure of about 300 Pa. The pressure difference
between the ultra fine particle producing chamber 1' and the film
forming chamber 2' is equal to about 100 kPa. At that time, the
valve 12' is closed. "F.M" is a helium gas flow meter which is
operated at the same time as the MBP. "F.BOX" represents a particle
trap.
[0077] The reason why the flow amount into the intake pipe 5' is
larger, is as follows. When the ultra fine particles stay in the
ultra fine particle producing chamber 1' for some time, the ultra
fine particles are apt to coagulate together and the coagulations
might be transferred in the transfer pipe 3'. The coagulations have
an undesirable influence on the film being formed on the substrate.
The larger flow amount into the intake pipe 5' prevents the
formation of coagulations of the ultra fine particles.
[0078] When the above condition continues for longer than 30
minutes, the helium gas discharged from the helium gas purification
recycle system 17' becomes purified at a purification of 99.9999%
or more. Helium gas of purification of 99.9999% is circulated in
the direction as shown by the arrows.
[0079] After the above condition is attained, the crucible 6'
containing lithium metal 22' is inductively heated with the high
frequency power source 7'. The metal 22' is heated at a temperature
of 480.degree. C. and it is evaporated from the crucible 6',
thereby forming ultra fine particles. Almost all of the formed
ultra fine particles are sucked into the transfer pipe 3' and they
are jetted onto the substrate 8' from the nozzle 4', which is
heated to a temperature of 100.degree. C. by the nozzle heater 23'.
The substrate 8' is heated to a temperature of 100.degree. C. It is
preheated to a temperature of 100.degree. C. with the heater unit
included in the substrate holder 10. Thus, a lithium film is formed
on the substrate 8'.
[0080] The substrate 8' is moved in the X-direction and the
Y-direction in the plane of the substrate 8'. The stop and start of
the transfer of the ultra fine particles is freely controlled with
the shutter system 9'. An arbitrary pattern can be formed from one
arbitrary point to another arbitrary point
[0081] The content of lithium in the film was measured
electrochemically.
[0082] The calculation method of the content is shown in formula 3.
Lithium amount obtained from the electrolysis (discharge) is shown
in formula 1. Lithium amount (theoretical capacity) obtained from
the weight (film thickness) is shown in formula 2. Formula
1/Formula 2.times.100=content [%]
[0083] [Formula 1]
Lithium amount obtained from the electrolysis
[0084] (Discharge time: t [sec], Constant current value: 0.001
[A/cm2]) G = t .function. [ sec ] .times. 0.001 .times. [ A .times.
/ .times. cm .times. .times. 2 ] 96487 .times. [ C .times. /
.times. mol ] .times. [ mol .times. / .times. cm .times. .times. 2
] ##EQU4##
[0085] [Formula 2]
Lithium amount obtained from the weight
[0086] (Lithium weight: W [g], Dimension: S [cm2]) M = W .function.
[ g ] 6.941 .times. [ g .times. / .times. mol ] .times. S
.function. [ cm .times. .times. 2 ] .times. [ mol .times. / .times.
cm .times. .times. 2 ] ##EQU5##
[0087] [Formula 3] G M .times. 100 = rate .times. .times. of
.times. .times. content .times. [ % ] ##EQU6##
[0088] Also in this embodiment, it has been proved that the
purification of the lithium is greatly raised, and that it is more
than 95% of the theoretical electric capacity. Thus, the electrical
capacity of the lithium is greatly raised.
[0089] The reason why the theoretical electrical capacity is
greatly raised, is considered to be that, before a lithium film is
formed, the surface of the substrates 8' is cleaned with the
lowering of the ultimate vacuum, and particularly that the water
content is removed and contaminants from the walls of vacuum
chamber are eliminated from the surface of the substrate.
[0090] While the preferred embodiments of the Invention have been
described, without being limited to this, variations thereto will
occur to those skilled in the art within the scope of the present
inventive concepts that are delineated by the following claims.
[0091] For example, in the above embodiments, helium gas of purity
of 99.9999% or more is used as the inert gas, however argon, neon
or xenon may be used as the inert gas.
[0092] Furthermore, in the first embodiment, the predetermined
heating temperature is 100.degree. C. It may be higher than
100.degree. C., but lower than the melting point of lithium or
lithium alloy.
[0093] Furthermore, in the above embodiments, the shutter system is
used. However, it is not always necessary. The ON/OFF of the
transport of the ultra fine particles may be effected by any other
means.
[0094] Further, in the above embodiment, lithium or lithium alloy
in the crucible, is heated inductively with the coil. Instead, the
crucible may be heated by a resistance heating method, wherein the
crucible is directly heated by Joule heat.
[0095] Furthermore, the heating mechanism may be included in the
substrate 8.
* * * * *