U.S. patent application number 11/834717 was filed with the patent office on 2008-01-24 for thin-film disposition apparatus.
This patent application is currently assigned to CANON ANELVA CORPORATION. Invention is credited to Manabu Ikemoto, Masahiko Tanaka, Naoaki Yokogawa.
Application Number | 20080017500 11/834717 |
Document ID | / |
Family ID | 18688417 |
Filed Date | 2008-01-24 |
United States Patent
Application |
20080017500 |
Kind Code |
A1 |
Tanaka; Masahiko ; et
al. |
January 24, 2008 |
THIN-FILM DISPOSITION APPARATUS
Abstract
A dividing plate for a thin-film deposition apparatus divides
the interior of the vacuum reaction chamber into a plasma discharge
space and a film deposition process space, by fixing or connecting
a plurality of laminated plates together by securely bonding them
over the entire area of their interfacial surfaces, or a large
portion thereof.
Inventors: |
Tanaka; Masahiko; (Tokyo,
JP) ; Ikemoto; Manabu; (Kanakgawa-ken, JP) ;
Yokogawa; Naoaki; (Tokyo, JP) |
Correspondence
Address: |
BUCHANAN, INGERSOLL & ROONEY PC
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Assignee: |
CANON ANELVA CORPORATION
5-8-1, Yotsuya, Fuchu-shi
Tokyo
JP
183-8508
|
Family ID: |
18688417 |
Appl. No.: |
11/834717 |
Filed: |
August 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09862458 |
May 23, 2001 |
7267724 |
|
|
11834717 |
Aug 7, 2007 |
|
|
|
Current U.S.
Class: |
204/164 ;
118/719 |
Current CPC
Class: |
C23C 16/45574 20130101;
H01J 37/32623 20130101; C23C 16/452 20130101; C23C 16/45565
20130101 |
Class at
Publication: |
204/164 ;
118/719 |
International
Class: |
C23C 16/54 20060101
C23C016/54; C23C 16/00 20060101 C23C016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 23, 2000 |
JP |
2000-188667 |
Claims
1. A plasma apparatus comprising: a chamber comprising a first
inside-space, the first inside space including a first sub-space
and a second sub-space; means for evacuating the first inside-space
of the chamber; a member for separating the first sub-space from
the second sub-space, wherein said member comprises a first
sub-member facing the side of said first sub-space and a second
sub-member facing the side of said second sub-space; the chamber
further including a second inside-space between said first
sub-member and said second sub-member; said member has a first
though-hole which communicates said first sub-space and said second
sub-space in a non-contacting manner with the second inside-space;
said member has a second through-hole which communicates the second
inside-space and the second sub-space in a non-contacting manner
with the first inside-space; a first gas inlet for introducing a
first gas into the first sub-space; a second gas inlet for
introducing a second gas into the second inside-space; and means
for supplying a high frequency power in the first sub-space.
2. The plasma apparatus as claimed in claim 1, wherein said member
comprises two plates spaced from each other and a column structure
between the two plates and said first through-hole is pierced
through the column structure.
3. The plasma apparatus as claimed in claim 1, wherein said means
for supplying a high frequency power in the first sub-space
comprises an electrode having a hole.
4. The plasma apparatus as claimed in claim 1, wherein the means
for supplying a high frequency power in the first sub-space
comprises an electrode not having a hole.
5. The plasma apparatus as claimed in claim 1, wherein said means
for supplying a high frequency power in the first sub-space
comprises an electrode for supplying a high-frequency power.
6. The plasma apparatus as claimed in claim 1, wherein said first
gas comprises oxygen gas and said second gas comprises a precursor
gas.
7. An apparatus for making a thin-film comprising: a chamber
comprising a first inside-space having a first sub-space and a
second sub-space; means for evacuating the first inside-space of
the chamber; a member for separating the first sub-space from the
second sub-space, wherein said member comprises a first sub-member
facing the side of said first sub-space and a second sub-member
facing the side of said second sub-space; The chamber further
including a second inside-space between said first sub-member and
said second sub-member; said member has a first though-hole which
communicates said first sub-space and said second sub-space in a
non-contacting manner with the second inside-space; said member has
a second through-hole which communicates the second inside-space
and the second sub-space in a non-contacting manner with the first
inside-space; a first gas inlet for introducing a first gas into
the first sub-space; a second gas inlet for introducing a second
gas into the second inside-space; and means for providing a plasma
in the first sub-space.
8. A method for treating a substrate using said plasma apparatus of
claim 1.
9. A method for making a thin-film using said apparatus of claim 7.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No.
09/862,458, filed on May 23, 2007, and claims priority of Japanese
Patent Application No. 2000-188667, filed in Japan on Jun. 23,
2000, the entire contents of which are both hereby incorporated
herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a plasma apparatus, and in
particular, it relates to a chemical vapor deposition (CVD)
apparatus suitable for depositing films on large-scale flat panel
substrates.
[0004] 2. Description of Related Art
[0005] Known methods for the production of large-scale liquid
crystal displays include methods that use high-temperature
polysilicon TFTs (thin film transistors) and methods that use
low-temperature TFTs. In liquid crystal display production methods
that use low-temperature polysilicon TFTs, there is no need to use
expensive substrates such as quartz because all the processes can
be performed at a low temperature (e.g., 400.degree. C. or
less).
[0006] It is also possible to achieve cost reductions by increasing
the production yield if the drive circuits for driving the devices
in the liquid crystal displays, and like devices, are built into
the substrate at the same time. Since this also has the effect of
improving the TFT device characteristics, it makes it possible to
increase the degree of detail and achieve a larger aperture ratio.
Consequently, painstaking research is being undertaken with a view
to achieving improved performance, and the volume of production
itself is also increasing.
[0007] In the production of liquid crystal displays using
low-temperature polysilicon TFTs, plasma CVD is used for the
low-temperature deposition of polysilicon oxide films, which are
suitable for use as gate insulation films.
[0008] For such applications, a CVD apparatus proposed in a
previous patent application (U.S. patent application Ser. No.
09/435,625, the subject matter of which is hereby incorporated
herein by reference) involves producing a plasma inside a vacuum
enclosure to generate excited active species (referred to herein as
"radicals") and using these radicals and a precursor gas to deposit
a film on a substrate. Specifically, this apparatus uses a
technique whereby a dividing plate, having a plurality of holes
through which the radicals pass, is used to separate the interior
of the vacuum enclosure into a plasma discharge space and a film
deposition space. Radicals are generated from the plasma by
introducing a gas into the plasma discharge space, and these
radicals are introduced to the film deposition space through the
plurality of holes in the above-mentioned dividing plate.
Meanwhile, a precursor gas is directly introduced into the film
deposition space from outside the vacuum enclosure without coming
into contact with the above-mentioned plasma or radicals. The
precursor gas is allowed to react with the above-mentioned radicals
introduced into the film deposition space, whereby a film is
deposited on a substrate (e.g., on a glass substrate measuring 370
mm.times.470 mm) situated in the film deposition space.
[0009] An example of a thin-film deposition apparatus used for
plasma CVD that uses a dividing plate 24 to separate the interior
of the vacuum enclosure into a plasma discharge space and a film
deposition space is described using FIG. 1(a) and (b). FIG. 1(a) is
a cross-sectional view of a conventional dividing plate 24, and
FIG. 1 (b) is a plan view of the interior as seen from line X-X in
FIG. 1(a).
[0010] The dividing plate 24 consists of a three-plate laminated
structure where an intermediate diffusion plate 2 is sandwiched
between an upper plate 1 and a gas discharge plate 3 on the film
deposition side, and these three plates are fixed at their outer
perimeter. The fixing at the outer perimeter of these three plates
(upper plate 1, intermediate diffusion plate 2, and gas discharge
plate 3 on the film deposition side) can, for example, be achieved
by using screw fixing members 9 as shown in the figure, or by
welding or the like (not illustrated).
[0011] The dividing plate 24 consisting of three plates laminated
and fixed in this way has spaces provided in the interior thereof,
i.e., precursor gas primary diffusion spaces 4 and precursor gas
secondary diffusion spaces 5, and these internal spaces 4, 5 are
connected together by intermediate gas distribution holes 6. A
precursor gas, which is fed from outside into the vacuum enclosure
of the thin-film deposition apparatus, is uniformly diffused as it
passes through, in sequential order, the precursor gas primary
diffusion spaces 4, the intermediate gas distribution holes 6, and
the precursor gas secondary diffusion spaces 5, and is then guided
from the precursor gas discharge holes 7 into the film deposition
process chamber (the lower part in FIG. 1(a)).
[0012] Meanwhile, radical transit holes 8 are provided in the parts
where there are no spaces inside the dividing plate 24, and the
radicals produced in the plasma discharge space (i.e., above the
dividing plate 24) pass through these radical transit holes 8 and
are guided into the film deposition process space below the
dividing plate 24.
OBJECTS AND SUMMARY
[0013] In the above-mentioned conventional dividing plate
structure, since the plurality of plates constituting the dividing
plate (upper plate 1, intermediate diffusion plate 2, and gas
discharge plate 3 on the film deposition side) are fixed at the
outer perimeter thereof, there have been cases where gaps have
appeared between plates (e.g., between upper plate 1 and
intermediate diffusion plate 2, or between intermediate diffusion
plate 2 and gas discharge plate 3 on the film deposition side) in
regions close to the central part of the plates, where the plates
are not fixed. In such cases, the radicals that pass through the
radical transit holes 8 running through the said plurality of
plates (upper plate 1, intermediate diffusion plate 2, and gas
discharge plate 3 on the film deposition side) may penetrate
through these gaps into the interior of the dividing plate. If this
happens, the radicals that have penetrated through the gaps will
come into contact with the precursor gas in places such as the
precursor gas primary diffusion spaces 4 and precursor gas
secondary diffusion spaces 5, and a reaction will take place inside
the dividing plate. The products of this reaction can lead to the
generation of particles, and this has led to problems in that it
becomes impossible to provide an adequate supply of radicals into
the film deposition process space.
[0014] The present invention provides a plasma apparatus
incorporating a dividing plate equipped with radical passage holes
and which has improved bonding between the plurality of plates
constituting the dividing plate, and wherein--when radicals pass
through from the plasma discharge space to the film deposition
process space--there is little or no danger of radicals penetrating
into the interior of the dividing plate. In one embodiment of the
invention, the plasma apparatus may be a thin-film deposition
apparatus.
[0015] A thin-film deposition apparatus according to the present
invention produces a plasma inside a vacuum enclosure to generate
active species and uses these active species and a precursor gas to
deposit a film on a substrate.
[0016] In a thin-film deposition apparatus according to an
embodiment of the present invention, the interior of the vacuum
reaction chamber is divided by a dividing plate into a plasma
discharge space and a film deposition process space. This dividing
plate has internal spaces that are separated from the plasma
discharge space and are connected to the film deposition process
space. A plurality of holes pass through the dividing plate from
the plasma discharge space to the film deposition process space. A
gas is introduced into the plasma discharge space, where radicals
are generated by the plasma, and these radicals are introduced into
the film deposition process space via the plurality of holes in the
dividing plate. Also, in this apparatus, a precursor gas is
introduced directly into the film deposition process space from
outside the vacuum enclosure, without coming into contact with the
plasma or radicals, and in the film deposition process space, the
radicals and precursor gas introduced thereto react together and a
film is thereby deposited on a substrate positioned in the film
deposition process space.
[0017] In the above-mentioned dividing plate, the plurality of
laminated plates may be fixed or connected together by securely
bonding them over either the entire area of their interfacial
surfaces or over a large portion of their interfacial surfaces
sufficient to prevent radicals from entering the internal
spaces.
[0018] By securely bonding the plurality of laminated plates over
the entire area or a large portion of their interfacial surfaces,
this means that apart from the parts where the above-mentioned
internal spaces and the above-mentioned plurality of holes are
provided in the dividing plate, the plates are fixed or connected
together in such a way that they are securely bonded together at
all, or most of, the mutually contacting surfaces of mutually
contacting plates.
[0019] In this way, since the plurality of laminated plates
constituting the dividing plate are fixed or connected by securely
bonding them together over the entire area or a large portion of
their interfacial surfaces, it is possible to prevent or reduce the
penetration of radicals from the plurality of holes connecting the
plasma discharge space with the film deposition space, which are
formed by piercing through the above-mentioned plurality of
laminated plates, and it is thereby possible to prevent or reduce
the radicals and precursor gas from coming into contact with each
other inside the dividing plate.
[0020] Above, where it says fixed by securely bonding over the
entire area or a large portion of their interfacial surfaces, this
means that instead of just fixing the plates of the dividing plate
together at the outer periphery thereof, it is possible to fix the
plates together with metal fixings (e.g. rivets 11, metal fixings
12), which have holes in their interior to connect the plasma
discharge space with the film deposition process space, located at
positions over the entire dividing plate area, except where the
above-mentioned interior spaces are provided inside the dividing
plate, in such a way that the film deposition performance--e.g.,
the film deposition rate or uniformity--is made as uniform as
possible.
[0021] Also, where it says connected together by securely bonding
over the entire area or a large portion of their interfacial
surfaces, this means that instead of just fixing the plates of the
dividing plate together at the outer periphery thereof, it is
possible to connect the plates together by vacuum soldering,
pressure welding or the like at the interfacial surfaces over the
entire dividing plate or a large portion thereof, except at parts
where the above-mentioned plurality of holes connecting the plasma
discharge space and the film deposition process space--which are
disposed at positions chosen so as to optimize the film deposition
performance such as the film deposition rate and uniformity--and
the internal spaces are provided inside the dividing plate.
[0022] In the thin-film deposition apparatus according to an
embodiment of the present invention, a dividing plate 124 adopts a
structure wherein, as shown in FIG. 2, the interfacial surfaces of
the plurality of laminated plates are securely bonded over their
entire area or a large portion of it by caulking with a plurality
of metal fixings (e.g. rivets 11), and the plurality of holes 108
provided in the dividing plate 124 can be provided by piercing
through the metal fixings (e.g., rivets 11).
[0023] A dividing plate 224 may also adopt a structure wherein, as
shown in FIG. 3, the interfacial surfaces of the above-mentioned
plurality of laminated plates are securely bonded over their entire
area or a large portion of it by screwing the plurality of
laminated plates together with a plurality of metal fixings 12
provided with threaded parts on the outside thereof, and the
plurality of holes 208 provided in dividing plate 224 can be
provided by piercing through the metal fixings 12.
[0024] Furthermore, the interfacial surfaces of the plurality of
laminated plates in a dividing plate 324 may be connected together
by securely bonding them over their interfacial entire area or a
large portion of it, as shown in FIG. 4, and the plurality of holes
308 provided in this dividing plate 324 can be formed by piercing
through it at positions where the above-mentioned internal spaces
4, 5 are not disposed.
[0025] In all the dividing plate structures in the thin-film
deposition apparatus according to the present invention, the
plurality of laminated plates constituting the dividing plate are
fixed by securely bonding them over the entire area of their
interfacial surfaces or a large portion thereof, and the plurality
of holes provided in the dividing plate connecting the plasma
discharge space and the film deposition process space are
preferably provided by piercing through each of the plurality of
metal fixings used to achieve secure bonding of the interfacial
surfaces of the plurality of laminated plates. Or alternatively,
the plurality of holes may be formed by piercing through at
positions where internal spaces are not disposed in the internal
wall, which is connected together by securely bonding a plurality
of laminated plates over their entire interfacial area, or a large
portion thereof. Therefore, there is little or no danger of
radicals penetrating into the interior of the dividing plate from
the holes through which the radicals pass while the radicals pass
through from the plasma discharge space to the film deposition
process space.
[0026] In the deposition of a thin film on substrate 21, the film
deposition performance, such as the film deposition rate and
uniformity, is affected by the holes through which the radicals
pass that are provided in dividing plate and disposed at positions
opposite substrate 21; specifically, the performance is affected by
the number and layout of the holes that connect the plasma
discharge space with the film deposition process space. However, in
a thin-film deposition apparatus according to the present
invention, as mentioned above, it is possible for the holes through
which the radicals pass to be provided at the same positions as
where the plurality of laminated plates constituting the dividing
plate are fixed together by a plurality of metal fixings.
Therefore, in the present invention, the layout of the holes
through which the radicals pass can be set by giving priority to
the film deposition performance over the entire area of dividing
plate, without being constrained by the positions at which the
plurality of laminated plates constituting the dividing plate are
fixed together, and it is possible to supply radicals to the film
deposition process space from the plasma discharge space without
them penetrating into the interior of dividing plate.
[0027] In the above-mentioned thin-film deposition apparatus
according to the present invention, the above-mentioned plurality
of holes through which the radicals pass are preferably formed so
as to satisfy the condition uL/D>1, where u is the velocity of
the gas flow inside these holes, L is the effective length of the
holes (in the embodiments shown in FIGS. 2, 3 and 4, this length is
equivalent to the thickness of dividing plate 24), and D is the gas
interdiffusion coefficient (the gas interdiffusion coefficient of
the two types of gas at both ends of the holes). In a thin-film
deposition apparatus according to the present invention, the plasma
discharge space and film deposition process space on either side of
the dividing plate are only connected through the holes provided in
the dividing plate, but as proposed in a previous patent
application (U.S. patent application Ser. No. 09/435,625), if these
holes satisfy the above-mentioned condition (uL/D>1), then it is
possible to prevent the precursor gas introduced into the film
deposition process space from diffusing back towards the plasma
discharge space.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] FIG. 1(a) is a cross-sectional view of the dividing plate in
a conventional thin-film deposition apparatus.
[0029] FIG. 1(b) is a partially simplified plan view of the
interior as seen from line X-X in FIG. 1(a).
[0030] FIG. 2 is a partially simplified cross-sectional view of a
dividing plate employed in a thin-film deposition apparatus
according to an embodiment of the present invention.
[0031] FIG. 3 is a partially simplified cross-sectional view of
another dividing plate employed in a thin-film deposition apparatus
according to an embodiment of the present invention.
[0032] FIG. 4 is a partially simplified cross-sectional view of a
further dividing plate employed in a thin-film deposition apparatus
according to an embodiment of the present invention.
[0033] FIG. 5 is a cross-sectional sketch illustrating one example
of a thin-film deposition apparatus according to an embodiment of
the present invention.
[0034] FIG. 6 is a cross-sectional sketch illustrating another
example of a thin-film deposition apparatus according to an
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0035] Preferred embodiments of the present invention are described
below with reference to the attached figures.
[0036] FIG. 2 is a cross-sectional view of a preferred embodiment
of a dividing plate 124, which divides the vacuum reaction chamber
of a thin-film deposition apparatus according to this invention (an
example of which is shown in FIG. 5) into a plasma discharge space
25 and a film deposition space 26.
[0037] Dividing plate 124 is formed by fixing together a plurality
of laminated plates (upper plate 101, intermediate diffusion plate
102, and gas discharge plate 103 on the film deposition side) by
securely bonding them over the entire area of their interfacial
surfaces or a large portion thereof (i.e., between upper plate 101
and intermediate diffusion plate 102, and between intermediate
diffusion plate 102 and gas discharge plate 103 on the film
deposition side) with a plurality of metal fixings, in this case by
caulking with rivets 10,11. As used herein, the term interfacial
surfaces refers to the portions of the laminated plates that are in
direct contact with a portion of an adjacent laminated plate.
[0038] Internal spaces (precursor gas primary diffusion spaces 104,
intermediate gas distribution holes 106, source gas secondary
diffusion spaces 105) are formed in dividing plate 124, which is
made as described above by laminating and fixing upper plate 101,
intermediate diffusion plate 102, and gas discharge plate 103 on
the film deposition side, in such a way that they are separated
from plasma discharge space 25 and connect with film deposition
process space 26.
[0039] Since a structure of this sort is employed, the gas supplied
from the outside first enters precursor gas primary diffusion
spaces 104 where it is diffused, after which it passes through
intermediate gas distribution holes 106 and enters source gas
secondary diffusion spaces 105; as it travels along this path, it
is uniformly diffused, and it is then guided directly from
precursor gas discharge holes 107 into film deposition process
space 26, i.e., without coming into contact with the plasma or
radicals.
[0040] Note that in FIG. 2, rivets 10 are used to perform fixing at
the outer perimeter of the plurality of laminated plates (upper
plate 101, intermediate diffusion plate 102, and gas discharge
plate 103 on the film deposition side), whereas rivets 11 are used
to fix the parts other than the periphery.
[0041] As FIG. 2 shows, in the dividing plate 124 of the thin-film
deposition apparatus according to this invention, the holes 108
that are pierced through it to allow the transit of radicals are
provided in the rivets 11 that fix the plurality of laminated
plates (upper plate 101, intermediate diffusion plate 102, and gas
discharge plate 103 on the film deposition side) together by
securely bonding them over the entire area of their interfacial
surfaces, except at the outer periphery thereof.
[0042] As a result, the holes 108 through which the radicals pass
are separated from the spaces inside dividing plate 124 (precursor
gas primary diffusion spaces 104, intermediate gas distribution
holes 106, source gas secondary diffusion spaces 105) by the
constituent outer walls of the rivets 11, and there is no
penetration of radicals into the spaces inside dividing plate 124
while the radicals are introduced from plasma discharge space 25
(at the top of FIG. 2) to film deposition process space 26 (at the
bottom of FIG. 2).
[0043] FIG. 3 shows a cross-sectional view of another preferred
embodiment of a dividing plate 124, which divides the vacuum
reaction chamber of a thin-film deposition apparatus according to
this invention into a plasma discharge space 25 (at the top of FIG.
3) and a film deposition process space 26 (at the bottom of FIG.
3).
[0044] The dividing plate 224 shown in FIG. 3 differs from that
shown in FIG. 2 in that the rivets 11 are replaced with metal
fixings 12 provided with threaded parts on the outside thereof, a
plurality of metal fixings 12 being used to screw together the
plurality of laminated plates (upper plate 201, intermediate
diffusion plate 202, and gas discharge plate 203 on the film
deposition side), thereby securely bonding these laminated plates
over the entire area of their interfacial surfaces or a large
portion thereof. The holes 208 through which the radicals pass are
provided by piercing through metal fixings 12.
[0045] In the embodiment shown in FIG. 3, female threaded parts are
provided in the gas discharge plate 203 on the film deposition
side, and using metal fixings 12 provided with male threaded parts
on the outside at the ends thereof, the metal fixings 12 which are
inserted from the top of the plurality of laminated plates (upper
plate 201, intermediate diffusion plate 202, and gas discharge
plate 203 on the film deposition side) are screwed into the female
threaded parts of the above-mentioned gas discharge plate 203 on
the film deposition side, whereby metal fixings 12 are screwed to
the plurality of laminated plates, and the plurality of laminated
plates (upper plate 201, intermediate diffusion plate 202, and gas
discharge plate 203 on the film deposition side) are thereby fixed
by securely bonding them over the entire area of their interfacial
surfaces.
[0046] In the embodiment shown in FIG. 3, as in the embodiment
shown in FIG. 2, as the radicals are guided from plasma discharge
space 25 (at the top of FIG. 3) to the film deposition process
space 26 (at the bottom of FIG. 3), the holes 208 through which the
radicals pass are separated from the spaces inside dividing plate
224 (precursor gas primary diffusion spaces 204, intermediate gas
distribution holes 206, source gas secondary diffusion spaces 205)
by the constituent outer walls of metal fixings 12, and while the
radicals are introduced from plasma discharge space 25 to film
deposition process space 26, there is no penetration of radicals
into the spaces inside dividing plate 224.
[0047] In the embodiment shown in FIG. 3, to securely bond the
plurality of laminated plates (upper plate 201, intermediate
diffusion plate 202, and gas discharge plate 203 on the film
deposition side) at their interfacial surfaces, metal fixings 12
provided with threaded parts on the outside thereof are used to
screw the plurality of laminated plates together, and since these
metal fixings 12 can be attached and removed using screw-type
connections, the metal fixings 12 can be easily replaced.
Therefore, by suitably replacing metal fixings 12, it is easy to
modify the diameter or profile of the holes 208 through which the
radicals pass.
[0048] In the embodiments shown in FIGS. 2 and 3, cases were
described in which the length of metal fixings 12 and rivets 11,
which have holes 108, 208 through which the radicals pass, matches
the thickness of the plurality of laminated plates. However, this
does not necessarily have to be the case, and the same action and
effects may be obtained when the rivets 11 and metal fixings 12 are
shorter or longer than the thickness of the plurality of laminated
plates.
[0049] FIG. 4 shows a cross-sectional view of a further preferred
embodiment of dividing plate 324 where the vacuum reaction chamber
of the thin-film deposition apparatus of this invention is
separated into a plasma discharge space 25 (at the top of FIG. 4)
and a film deposition process space 26 (at the bottom of FIG.
4).
[0050] The dividing plate 324 shown in FIG. 4 is such that the
plurality of laminated plates (upper plate 301, intermediate
diffusion plate 302, and gas discharge plate 303 on the film
deposition side) are connected together by securely bonding over
the entire area of their interfacial surfaces (i.e., between upper
plate 301 and intermediate diffusion plate 302, and between
intermediate diffusion plate 302 and gas discharge plate 303 on the
film deposition side). Internal spaces (precursor gas primary
diffusion spaces 304, intermediate gas distribution holes 306,
source gas secondary diffusion spaces 305), which are separated
from the plasma discharge space 25 and connect with the film
deposition process space 26, are provided in the same way as in the
dividing plates 124, 224 shown in FIGS. 2 and 3, but here the
plurality of holes 308 through which the radicals pass are formed
by piercing through at positions where the above-mentioned internal
spaces are not disposed.
[0051] A method such as vacuum soldering, pressure welding or the
like can be used to achieve secure bonding over the entire area or
a large portion thereof of the interfacial surfaces of the
plurality of laminated plates (i.e. between upper plate 301 and
intermediate diffusion plate 302, and between intermediate
diffusion plate 302 and gas discharge plate 303 on the film
deposition side).
[0052] In FIG. 4, the parts identified by reference numeral 13
represent the connecting parts of the interfacial surfaces of upper
plate 301, intermediate diffusion plate 302, and gas discharge
plate 303 on the film deposition side.
[0053] As shown in FIG. 4, the closely bonded joints made over the
entire interfacial surface area (or a large portion thereof) of the
plates are preferably made by connecting the interfacial surfaces
of the plurality of laminated plates (upper plate 301, intermediate
diffusion plate 302, and gas discharge plate 303 on the film
deposition side) except at the parts where there are internal
spaces (precursor gas primary diffusion spaces 304, intermediate
gas distribution holes 306, source gas secondary diffusion spaces
305) in the dividing plate 324, so as to completely prevent or
minimize the penetration of radicals into the internal spaces in
dividing plate 324 from the holes 308 through which the radicals
pass.
[0054] In the embodiment shown in FIG. 4, the plurality of holes
308 through which the radicals pass are formed by piercing through
at positions where internal spaces (precursor gas primary diffusion
spaces 304, intermediate gas distribution holes 306, source gas
secondary diffusion spaces 305) are not disposed in the plurality
of laminated plates (upper plate 301, intermediate diffusion plate
302, and gas discharge plate 303 on the film deposition side) that
are laminated and connected together by securely bonding them over
the interfacial surface area, but as mentioned above, since the
entire interfacial surfaces of the plurality of laminated plates
may be connected except at parts where there are internal holes
inside dividing plate 324, there is little or no penetration of the
radicals passing through holes 308 into the internal spaces in
dividing plate 324, and there is little or no danger of radicals
coming into contact with the precursor gas in the spaces inside
dividing plate 324.
[0055] With the embodiment shown in FIG. 4, since there is no need
for members such as rivets 11 or metal fixings 12 to connect
together the plurality of laminated plates (upper plate 301,
intermediate diffusion plate 302, and gas discharge plate 303 on
the film deposition side) by closely bonding them over the entire
interfacial area (or a large part thereof) as in the embodiments
shown in FIGS. 2 and 3, it is possible to provide a dividing plate
at lower cost. Furthermore, there is no need for a process to
attach the plurality of rivets or metal fixings, and it can instead
be bonded together with a single operation, allowing a dividing
plate to be provided with more stable quality.
[0056] Note that in each of the above-mentioned embodiments, if the
holes 8, 108, 208, 308 through which the radicals pass are formed
so as to satisfy the condition uL/D>1, where u is the gas flow
velocity inside these holes, L is the effective length of the holes
(in the above-mentioned embodiments, this length is equivalent to
the thickness of dividing plate), and D is the gas interdiffusion
coefficient (the gas interdiffusion coefficient of the two types of
gas at both ends of the holes), then this is advantageous because
it is possible to prevent the reverse diffusion of precursor gas
introduced into film deposition process space 26 towards plasma
discharge space 25.
[0057] FIG. 5 shows a rough view of one example of a thin-film
deposition apparatus according to the present invention wherein the
interior of the vacuum reaction chamber 22 is divided into two
chambers by the above-mentioned dividing plate 124 shown in FIG. 2.
The thin-film deposition apparatus shown in FIG. 5 deposits a
silicon oxide film as a gate insulation film on the surface of a
glass substrate 21 as normally used for TFTs (e.g., a glass
substrate measuring 370 mm.times.470 mm), preferably using silane
as the precursor gas. In this figure, however, dividing plate
24--which is the characteristic structural part in the thin-film
deposition apparatus according to the present invention--is shown
expanded in relation to the other parts, and the parts other than
dividing plate 124 are only shown in sketch form.
[0058] An embodiment of the thin-film deposition apparatus
according to the present invention is described with reference to
FIG. 5.
[0059] The interior of vacuum reaction chamber 22 is divided into
two (upper and lower) chambers by a dividing plate 124 (shown in
FIG. 2) held at ground potential, the upper chamber forming a
plasma discharge space 25, and the lower chamber forming a film
deposition process space 26. A planar electrode (high frequency
electrode) 30 is attached in such a way that the sides around its
perimeter come into contact with the upper insulating member 34 of
the insulating members 34, 35 interspersed between the upper
enclosure constituting vacuum reaction chamber 22, and the lower
part of its perimeter comes into contact with the lower insulating
member 35. Dividing plate 124 has the desired characteristic
thickness and has an overall flat shape, and has a planar profile
resembling the horizontal cross-sectional profile of vacuum
reaction chamber 22.
[0060] In the thin-film deposition apparatus shown in FIG. 5, the
region in which an oxygen plasma 32 is produced inside plasma
discharge space 25 is formed by the dividing plate 124, the upper
part of the enclosure constituting vacuum reaction chamber 22, and
from electrode 30 which is disposed more or less centrally between
them. A plurality of holes 30a are formed in electrode 30.
[0061] A glass substrate 21 is carried into the interior of vacuum
reaction chamber 22 by a transfer robot (not illustrated), and is
placed on a substrate holding assembly 27 which is held at earth
potential, which is the same potential as vacuum enclosure 22. The
substrate holding assembly 27 provided in film deposition process
space 26 is already held at the prescribed temperature because a
current is made to flow through a heater 28.
[0062] The interior of vacuum reaction chamber 22 is pumped down,
depressurized and held at the prescribed vacuum state by a pumping
mechanism 23.
[0063] Next, oxygen gas is introduced into the plasma discharge
space 25 through an oxygen gas inlet pipe 29.
[0064] Meanwhile, the precursor gas (e.g., silane) is introduced
into source gas primary diffusion spaces 4 of dividing plate 24
through source gas inlet pipe 33. The silane first enters precursor
gas primary diffusion spaces 4 where it is diffused, after which it
passes through intermediate gas distribution holes 6 and enters
source gas secondary diffusion space 5, during the course of which
it is uniformly diffused, and it is then introduced directly into
film deposition process space 26 from precursor gas discharge holes
7, i.e., it is introduced into film deposition process space 26
without coming into contact with the plasma or radicals.
[0065] In the above-mentioned state, high-frequency electrical
power is supplied to electrode 30 via an electric power feed rod 31
which is insulated from the other metal parts. This high-frequency
electrical power gives rise to a discharge, and an oxygen plasma 32
is produced around electrode 30 inside plasma discharge space 25.
By producing oxygen plasma 32, radicals (excited active species),
which are a neutral excited species, are produced, and these are
introduced into the film deposition process space 26 through the
plurality of holes 8 provided in dividing plate 124. Meanwhile, the
precursor gas is introduced into the film deposition process space
26 through precursor gas primary diffusion spaces 4, intermediate
gas distribution holes 6, precursor gas secondary diffusion spaces
5, and precursor gas discharge holes 7.
[0066] As a result, these radicals come into contact with the
precursor gas for the first time inside film deposition process
space 26, whereupon a chemical reaction takes place, and silicon
oxide material accumulates on the surface of glass substrate 21,
whereby a thin film is formed.
[0067] FIG. 6 shows a sketch of another embodiment of a thin-film
deposition apparatus according to the present invention, where the
interior of vacuum reaction chamber 22 is divided into two chambers
by the dividing plate 124 shown in FIG. 2. The characteristic
constitution of the embodiment shown in FIG. 6 is that an
insulating member 34 is provided inside the ceiling part of the
upper enclosure constituting vacuum reaction chamber 22, and that
electrode 30 is disposed therebelow. Electrode 30 has the form of a
single-layer planar electrode without holes 30a formed therein as
in the case of the embodiment shown in FIG. 5. Plasma discharge
space 25 is formed by a parallel planar electrode structure from
electrode 30 and dividing plate 124. The other constituent parts
are essentially the same as in the configuration of the embodiment
shown in FIG. 5. Therefore, all elements in FIG. 6 that are
essentially the same as those in FIG. 5 are identified with the
same reference numerals, and their detailed descriptions will not
be repeated here. Furthermore, since the action and advantages of
the thin-film deposition apparatus according to the embodiment
shown in FIG. 6 are the same as those of the above-mentioned
embodiment shown in FIG. 5, their description will not be repeated
here.
[0068] In the above-mentioned preferred embodiments of the present
invention, the plurality of laminated plates constituting dividing
plate 124, 224, 324 are configured from three plates (upper plate
101, 201, 301, intermediate plate 102, 202, 302 and gas discharge
plate 103, 203, 303 on the film deposition side), but the
embodiments of the present invention are not limited to this
number. As long as the dividing plate has internal spaces formed
therein (e.g., precursor gas primary diffusion spaces 104, 204,
304, intermediate gas distribution holes 106, 206, 306, source gas
secondary diffusion spaces 105, 205, 305, and the like) which are
separated from the plasma discharge space 25 and connected with
film deposition process space 26, it is possible to use a dividing
plate 124, 224, 324 that is laminated from two plates that are
fixed or connected by securely bonding them over their entire
interfacial surface area, or a large portion thereof, and it is
also possible to configure dividing plate 124, 224, 324 from 4 or 5
plates.
[0069] The present invention relates to a thin-film deposition
apparatus wherein the interior of the vacuum reaction chamber is
divided into a plasma discharge space and a film deposition process
space by a dividing plate having a plurality of holes through which
radicals pass, radicals are generated from the plasma by
introducing a gas into the plasma discharge space, these radicals
are introduced into the film deposition process space through the
plurality of holes in the above-mentioned dividing plate, and a
precursor gas is introduced into the film deposition process space,
whereby the above-mentioned introduced radicals react with the
precursor gas in the film deposition process space and a film is
deposited on a substrate disposed in the film deposition process
space, and it is able to prevent the radicals produced in the
plasma discharge space from penetrating into the spaces inside the
dividing plate, which would result in the radicals coming into
contact with the precursor gas inside the internal spaces of the
dividing plate.
[0070] That is, with the present invention, it is not only possible
to solve the problem of radicals penetrating the internal spaces of
the dividing plate (which causes problems by generating particles
that block the precursor gas discharge holes 7), but it is also
possible to solve the problem of precursor gas leaking into the
plasma discharge space, and as a result it is possible to prevent
excessive breakdown of the precursor gas and it is possible to
obtain thin films with favorable film quality.
[0071] Although preferred embodiments of the present invention have
been described above with reference to the accompanying figures,
the present invention is not limited to these embodiments, and can
be modified in a variety of ways within the scope of the art as
understood from the scope of the patent claims.
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