U.S. patent application number 15/295183 was filed with the patent office on 2017-04-27 for vertical heat treatment apparatus.
The applicant listed for this patent is TOKYO ELECTRON LIMITED. Invention is credited to Kohei FUKUSHIMA, Hiroki IRIUDA.
Application Number | 20170114464 15/295183 |
Document ID | / |
Family ID | 58561916 |
Filed Date | 2017-04-27 |
United States Patent
Application |
20170114464 |
Kind Code |
A1 |
IRIUDA; Hiroki ; et
al. |
April 27, 2017 |
VERTICAL HEAT TREATMENT APPARATUS
Abstract
A vertical heat treatment apparatus includes: a substrate holder
including a column, substrate holding parts configured to hold the
substrates, and gas flow guide parts installed in the column in a
corresponding relationship with the substrates; an elevator stand
configured to support the substrate holder and to load the
substrate holder into the reaction vessel from below the reaction
vessel; a rotating mechanism installed in the elevator stand and
configured to rotate the substrate holder about a vertical axis; a
process gas supply port and an exhaust port respectively formed at
a rear side and a front side of a substrate holding region; and a
plurality of baffle parts installed independently of the substrate
holder so that the baffle parts protrude from the outside toward
spaces between the gas flow guide parts adjoining each other and
run into the spaces.
Inventors: |
IRIUDA; Hiroki; (Nirasaki
City, JP) ; FUKUSHIMA; Kohei; (Oshu-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TOKYO ELECTRON LIMITED |
Tokyo |
|
JP |
|
|
Family ID: |
58561916 |
Appl. No.: |
15/295183 |
Filed: |
October 17, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/45591 20130101;
H01L 21/67109 20130101; C23C 16/4584 20130101; H01L 21/67309
20130101 |
International
Class: |
C23C 16/46 20060101
C23C016/46; C23C 16/455 20060101 C23C016/455; H01L 21/67 20060101
H01L021/67; C23C 16/458 20060101 C23C016/458 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 21, 2015 |
JP |
2015-207357 |
Claims
1. A vertical heat treatment apparatus for performing a process
with respect to a plurality of substrates disposed in a shelf-like
fashion within a vertical reaction vessel surrounded by a heating
part by forming a gas flow of a process gas flowing in a transverse
direction from one side toward the other side, comprising: a
substrate holder including a column, a plurality of substrate
holding parts installed along the column and configured to hold the
substrates, and a plurality of gas flow guide parts installed in
the column in a corresponding relationship with the substrates and
formed so that peripheral edge portions of the gas flow guide parts
protrude outward beyond the substrates; an elevator stand
configured to support the substrate holder and to load the
substrate holder into the reaction vessel from below the reaction
vessel; a rotating mechanism installed in the elevator stand and
configured to rotate the substrate holder about a vertical axis; a
process gas supply port and an exhaust port respectively formed at
a rear side and a front side of a substrate holding region where
the substrates are held; and a plurality of baffle parts installed
independently of the substrate holder at a left side and a right
side of the substrate holding region so that the baffle parts
protrude from the outside toward spaces between the gas flow guide
parts adjoining each other and run into the spaces.
2. The apparatus of claim 1, wherein the baffle parts are installed
in the elevator stand through support parts, and portions facing
the baffle parts in a sidewall of the reaction vessel bulge
outward.
3. The apparatus of claim 1, wherein the baffle parts are installed
in a sidewall of the reaction vessel, and on the basis of
orientation when the substrate holder moves up and down, cutouts
are formed in portions facing the baffle parts in the gas flow
guide parts when viewed from the top.
4. The apparatus of claim 1, wherein the baffle parts overlap with
the gas flow guide parts when viewed from the top.
5. The apparatus of claim 1, wherein the gas flow guide parts
correspond to peripheral edge portions of the substrate holding
parts.
6. The apparatus of claim 5, wherein the substrate holding parts
are formed in an annular shape along a circumferential direction of
the substrate holding parts.
7. The apparatus of claim 1, wherein the substrate holding parts
are installed in the column independently of the gas flow guide
parts.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Japanese Patent
Application No. 2015-207357, filed on Oct. 21, 2015, in the Japan
Patent Office, the disclosure of which is incorporated herein in
its entirety by reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a technique of performing
a heat treatment with respect to a plurality of substrates disposed
in a shelf-like fashion, within a vertical reaction vessel
surrounded by a heating part.
BACKGROUND
[0003] As one type of semiconductor manufacturing apparatuses, a
vertical heat treatment apparatus is used that performs a heat
treatment such as a film forming process or the like, with respect
to a plurality of substrates, which is held by a substrate holder
in a shelf-like fashion and is loaded into a vertical reaction
vessel surrounded by a heating part. As a method of forming a flow
of a process gas, a method is used having gas injectors and exhaust
ports disposed at a rear side and a front side of a substrate
holding region and forming a transverse flow (so-called cross flow)
of a process gas.
[0004] The aforementioned method is a technique which has been
studied on the basis of a concept of efficiently supplying a
process gas to individual substrates. Since the gap between the
substrates and the wall of the reaction vessel is wider than the
gap between the substrates, a process gas injected from individual
gas injection holes of a gas injector easily passes through the gap
existing at the outer side of the substrates. For that reason, the
gas supplied between the substrates is exhausted in a state close
to a diffusion flow at a low flow velocity.
[0005] In the meantime, the design of a device becomes miniaturized
and complicated and a surface area of a processed surface of a
substrate, on which a film forming process is performed, becomes
larger. Thus, if a flow velocity of a process gas flowing along a
processed surface of a substrate is low, a difference in the
concentration of a film forming gas becomes larger between a region
close to gas injection holes and a region distant from the gas
injection holes. This may result in deterioration in the uniformity
of an in-plane film thickness distribution. In addition, the
deposition rate is low.
[0006] For example, there is known a structure in which, when the
direction facing from a gas supply pipe toward a center axis of
wafers is assumed to be from the side, arc-shaped partition plates
extending along the outer peripheral edges of the wafers are
disposed at the left and right sides of a wafer boat having columns
that hold the wafers in a shelf-like fashion. However, in this
structure, the space between the outer peripheral edges of the
wafers and the partition plates constitutes a so-called cavity over
an extent from the uppermost side to the lowermost side. It is
therefore impossible to sufficiently reduce the conductance in the
outer region of the wafers as compared to the conductance in the
regions between the wafers.
[0007] Furthermore, there is known a configuration which includes a
wafer boat having an outer ring portion positioned at the outer
side of wafers and an annular partition plate installed in an inner
wall of a reaction tube so as to face an outer end surface of the
outer ring portion. However, in this configuration, it is necessary
to set the gap between the outer ring portion and the annular
partition plate at a dimension anticipating the axis deflection of
the wafer boat so that the outer ring portion and the annular
partition plate do not collide with each other during rotation of
the wafer boat. It is therefore impossible to sufficiently reduce
the conductance in an outer region of the wafers.
SUMMARY
[0008] Some embodiments of the present disclosure provide a
vertical heat treatment apparatus capable of supplying a process
gas between substrates in an efficient manner and at a high flow
velocity.
[0009] According to one embodiment of the present disclosure, there
is provided a vertical heat treatment apparatus for performing a
process with respect to a plurality of substrates disposed in a
shelf-like fashion within a vertical reaction vessel surrounded by
a heating part by forming a gas flow of a process gas flowing in a
transverse direction from one side toward the other side,
including: a substrate holder including a column, a plurality of
substrate holding parts installed along the column and configured
to hold the substrates, and a plurality of gas flow guide parts
installed in the column in a corresponding relationship with the
substrates and formed so that peripheral edge portions of the gas
flow guide parts protrude outward beyond the substrates; an
elevator stand configured to support the substrate holder and to
load the substrate holder into the reaction vessel from below the
reaction vessel; a rotating mechanism installed in the elevator
stand and configured to rotate the substrate holder about a
vertical axis; a process gas supply port and an exhaust port
respectively formed at a rear side and a front side of a substrate
holding region where the substrates are held; and a plurality of
baffle parts installed independently of the substrate holder at a
left side and a right side of the substrate holding region so that
the baffle parts protrude from the outside toward spaces between
the gas flow guide parts adjoining each other and run into the
spaces.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The accompanying drawings, which are incorporated in and
constitute a part of the specification, illustrate embodiments of
the present disclosure, and together with the general description
given above and the detailed description of the embodiments given
below, serve to explain the principles of the present
disclosure.
[0011] FIG. 1 is a longitudinal sectional view of a vertical heat
treatment apparatus according to a first embodiment of the present
disclosure.
[0012] FIG. 2 is a longitudinal sectional view of the vertical heat
treatment apparatus.
[0013] FIG. 3 is a transverse plan view of the vertical heat
treatment apparatus.
[0014] FIG. 4 is a perspective view of a wafer boat which is loaded
into a reaction vessel installed in the vertical heat treatment
apparatus.
[0015] FIG. 5 is a longitudinal sectional view of the wafer boat
and the reaction vessel.
[0016] FIG. 6 is a schematic view showing a flow of a process gas
within the reaction vessel.
[0017] FIG. 7 is a transverse plan view of a vertical heat
treatment apparatus according to a modification of the first
embodiment.
[0018] FIG. 8 is a transverse plan view of a vertical heat
treatment apparatus according to a second embodiment of the present
disclosure.
[0019] FIG. 9 is a longitudinal sectional view of a wafer boat and
a reaction vessel that constitute the vertical heat treatment
apparatus according to the second embodiment.
[0020] FIG. 10 is a schematic longitudinal sectional view
illustrating another configuration of the wafer boat.
[0021] FIG. 11 is a schematic longitudinal sectional view
illustrating another configuration of the wafer boat.
[0022] FIG. 12 is a schematic longitudinal sectional view
illustrating another configuration of the wafer boat.
[0023] FIG. 13 is a schematic longitudinal sectional view
illustrating another configuration of the wafer boat.
[0024] FIG. 14 is a graph showing the results of evaluation
tests.
DETAILED DESCRIPTION
[0025] Reference will now be made in detail to various embodiments,
examples of which are illustrated in the accompanying drawings. In
the following detailed description, numerous specific details are
set forth in order to provide a thorough understanding of the
present disclosure. However, it will be apparent to one of ordinary
skill in the art that the present disclosure may be practiced
without these specific details. In other instances, well-known
methods, procedures, systems, and components have not been
described in detail so as not to unnecessarily obscure aspects of
the various embodiments.
First Embodiment
[0026] A vertical heat treatment apparatus 1 according to a first
embodiment of the present disclosure will be described with
reference to FIGS. 1 and 2, which are longitudinal sectional view,
and FIG. 3, which is a transverse plan view. The vertical heat
treatment apparatus 1 is to form SiO.sub.2 (silicon oxide) films on
wafers W as circular substrates, using chemical vapor deposition
(CVD). In the drawings, reference numeral 11 designates a reaction
vessel made of, for example, quartz. The reaction vessel 11 is
formed in a vertical cylindrical shape with a roof. A lower end
portion of the reaction vessel 11 extends outward to form a flange
12. Specifically, FIGS. 1 and 2 illustrate longitudinal cross
sections taken at mutually-different positions in a circumferential
direction, FIG. 1 being a sectional view taken along line A-A in
FIG. 3 and FIG. 2 being a sectional view taken along line B-B in
FIG. 3.
[0027] A region surrounded by the flange 12 in the reaction vessel
11 is opened as a substrate loading/unloading opening 13 and is
air-tightly closed by a quartz circular lid 14 installed in a boat
elevator (not shown). A rotary shaft 15 extending in a vertical
direction (longitudinal direction) is installed to pass through the
central portion of the lid 14 used as an elevator stand. A wafer
boat 2 used as a substrate holder is supported on an upper end
portion of the rotary shaft 15.
[0028] The wafer boat 2 will be described with reference to the
perspective view of FIG. 4. The wafer boat 2 is made of quartz and
includes a horizontal circular top plate 21, a circular bottom
plate 22 disposed in parallel to the top plate 21, and four
vertical columns 23. The columns 23 are installed in a
mutually-spaced-apart relationship along peripheries of the top
plate 21 and the bottom plate 22 so that the wafers W can be
transferred from the lateral side of the wafer boat 2 to circular
ring plates 24 (to be described later). The columns 23 are merely
configured to interconnect the top plate 21, the bottom plate 22
and the ring plates 24. The number of the columns 23 installed in
the wafer boat 2 is not limited to four as in the example
illustrated in FIG. 4 but may be three or less, or five or
more.
[0029] A substrate holding region is defined between the top plate
21 and the bottom plate 22. The ring plates 24 which constitute
substrate holding parts are installed in the substrate holding
region in a mutually-spaced-apart relationship in multiple stages
along an up-down direction. The columns 23 penetrate peripheral
edge portions of the respective ring plates 24. Each of the ring
plates 24 is horizontally supported by the respective columns 23.
The outer circumference of each of the ring plates 24 is formed to
have a size larger than the diameter of the wafers W. The wafers W
are held on the ring plates 24 so that the centers of the wafers W
are aligned with the centers of the ring plates 24. Thus, the
peripheral edge portions of the ring plates 24 protrude outward
beyond the wafers W. As will be described later, the peripheral
edge portions of the ring plates 24 constitute gas flow guide parts
for guiding gas flows generated within the reaction vessel 11. For
the sake of convenience in illustration, only two of the ring
plates 24 are illustrated in FIG. 4.
[0030] The wafer boat 2 is configured to move up and down between a
process position (a position illustrated in FIGS. 1 to 3) at which
the wafer boat 2 is loaded into the reaction vessel 11 and the
substrate loading/unloading opening 13 of the reaction vessel 11 is
closed by the lid 14 and a substrate transfer position defined
below the reaction vessel 11. The substrate transfer position
refers to a position where the wafers W are transferred with
respect to the wafer boat 2 by a transfer mechanism (not shown)
installed within a loading area. The rotary shaft 15 is configured
to rotate about a vertical axis by a motor 17 that constitutes a
rotating mechanism installed in the lid 14. Upon rotating the
rotary shaft 15, the wafer boat 2 mounted on the rotary shaft 15
rotates about the centers of the respective wafers W held on the
wafer boat 2, namely about a vertical axis. In the drawings,
reference numeral 16 designates a heat insulation unit installed in
the lid 14. The heat insulation unit 16 is formed of a plurality of
ring-shaped plates which overlaps in a spaced-apart relationship in
an up-down direction and which surrounds the rotary shaft 15. The
heat insulation unit 16 provides heat insulation between the wafer
boat 2 and the lid 14.
[0031] In the sidewall of the reaction vessel 11, an expansion
region 31, an expansion region 32 and an expansion region 33, which
respectively bulge outward, are formed in a mutually-spaced-apart
relationship in the circumferential direction of the reaction
vessel 11 and are sequentially disposed clockwise when viewed from
the top. The expansion regions 31 to 33 are vertically-elongated
regions which are formed at the process position so as to extend
from the upper end portion of the wafer boat 2 to the lower end
portion of the reaction vessel 11. In the expansion region 32,
distal end portions of vertical gas injectors 41 and 42 formed in a
rod shape are installed in a mutually-spaced-apart relationship in
the circumferential direction of the reaction vessel 11. In the
distal end portions of the vertical gas injectors 41 and 42, a
plurality of gas injection holes 43 is formed in a spaced-apart
relationship in a vertical direction so that the gas injection
holes 43 can inject a process gas toward the central portions of
the respective wafers W held on the wafer boat 2 at the process
position.
[0032] A base end portion of the gas injector 41 is bent to
horizontally extend outward and to pass through the flange 12 in a
radial direction. The base end portion of the gas injector 41 is
coupled to a supply source 45 of a tetraethoxysilane (TEOS) gas via
a valve V1 and a mass flow controller 44 in the named order.
Similar to the base end portion of the gas injector 41, a base end
portion of the gas injector 42 is bent to horizontally extend
outward and to pass through the flange 12 in the radial direction.
The base end portion of the gas injector 42 is coupled to a supply
source 47 of an oxygen (O.sub.2) gas via a valve V2 and a mass flow
controller 46 in the named order. That is to say, a TEOS gas as a
process gas is injected from the gas injection holes 43 of the gas
injector 41 and an O.sub.2 gas as a process gas is injected from
the gas injection holes 43 of the gas injector 42.
[0033] A region facing the expansion region 32 in the sidewall of
the reaction vessel 11 is opened and configured as an exhaust port
51. The exhaust port 51 is formed in a rectangular slit shape so as
to extend in an up-down direction and is formed to extend from a
height level of the top plate 21 of the wafer boat 2 to a height
level of the bottom plate 22. By performing an exhaust operation
through the exhaust port 51 and supplying the respective process
gases from the gas injectors 41 and 42, it is possible to form a
transverse flow (cross flow) of the process gases.
[0034] A roofed outer tube 52 configured to surround the reaction
vessel 11 is installed outside the reaction vessel 11. A lower end
of the outer tube 52 is connected to the flange 12 of the reaction
vessel 11. In FIGS. 1 and 2, reference numeral 53 designates a
support plate that surrounds the periphery of the outer tube 52.
The outer tube 52 and the reaction vessel 11 are supported by the
support plate 53. A upstream end of an exhaust pipe 54 is connected
to the outer tube 52 at the lower side of the exhaust port 51. A
downstream end of the exhaust pipe 54 is coupled to an exhaust
mechanism 56 which is configured by a vacuum pump or the like,
through an exhaust amount adjustment part 55 which is configured by
a valve or the like. A buffer space 57 defined between the outer
tube 52 and the reaction vessel 11 is exhausted through the exhaust
pipe 54, whereby the exhaust operation through the exhaust port 51
is performed. In FIGS. 1 and 2, reference numeral 59 designates a
heater as a heating part. The heater 59 is installed above the
support plate 53 so as to surround the lateral periphery of the
outer tube 52 and is configured to heat the interior of the
reaction vessel 11 so that the wafers W have a predetermined
temperature. In FIG. 3, the heater 59 is not shown.
[0035] Hereinafter, for the sake of convenience, the vertical heat
treatment apparatus 1 will be described under the assumption that a
side at which the expansion region 32 is formed is a front side and
a side at which the exhaust port 51 is formed is a rear side. The
expansion regions 31 and 33 will be additionally described. The
expansion regions 31 and 33 are formed at the front side of the
reaction vessel 11 in an arc shape when viewed from the top.
[0036] Two pillars 61 as support parts are installed in the lid 14
so as to extend vertically upward. A transfer mechanism gains
access to the wafer boat 2 existing in the substrate transfer
position below the reaction vessel 11 from the rear side and
performs the transfer of the wafers W. To do this, the respective
pillars 61 are installed at the front side of the lid 14 so as not
to hinder the transfer of the wafers W and are configured so that
the pillars 61 are accommodated in the respective expansion regions
31 and 33 when the wafer boat 2 is loaded toward the process
position. In this embodiment, the pillars 61 are formed in an arc
shape when viewed from the top so as to extend along lateral
peripheral surfaces of the respective expansion regions 31 and
33.
[0037] Horizontal baffle plates 62 as baffle parts are installed in
the respective pillars 61 in multiple stages. The baffle plates 62
are formed in an arc shape so as to extend along the respective
expansion regions 31 and 33 when viewed from the top. The baffle
plates 62 horizontally protrude from the pillars 61 toward the
center of the reaction vessel 11 and are installed in multiple
stages. Accordingly, the expansion regions 31 and 33 are regions
which are formed by causing portions facing the baffle plates 62 in
the sidewall of the reaction vessel 11 to bulge outward. While the
wafer boat 2 is rotatable with respect to the lid 14, the baffle
plates 62 are fixedly secured to the lid 14. In other words, the
baffle plates 62 are installed independently of the lid 14. The
baffle plates 62 and the ring plates 24 serve to reduce gaps formed
at outer sides of the wafers W, thus reducing the conductance of
the process gases at the outer sides of the wafers W.
[0038] The positional relationship between the reaction vessel 11,
the wafer boat 2 existing at the process position and the baffle
plates 62 will be described with reference to the longitudinal
sectional view of FIG. 5. The baffle plates 62 are respectively
positioned at the height levels differing from the height levels of
the wafers W and the ring plates 24. A distal end of each of the
baffle plates 62 runs toward and extends into the gap between the
top plate 21 of the wafer boat 2 and the ring plate 24 positioned
just below the top plate 21, the gaps between the adjoining ring
plates 24, and the gap between the bottom plate 22 and the ring
plate 24 positioned just above the bottom plate 22. A distance L1
between the lateral peripheral surfaces of the expansion regions 31
and 33 and the pillars 61 in the reaction vessel 11 is, for
example, 9.0 mm Horizontal distance L2 between the peripheral ends
of the ring plates 24 and the distal ends of the baffle plates 62
is, for example, 10.0 mm. That is to say, the ring plates 24 and
the baffle plates 62 overlap each other when viewed from the top.
In the mutually-adjoining baffle plates 62 and the ring plates 24
extending between the baffle plates 62, a height H1 of each of gaps
formed between the respective ring plate 24 and the baffle plates
62 is, for example, 3 mm. If the distance L2 grows larger and if
the height H1 grows smaller, the gap formed at the outer side of
the wafers W becomes smaller. Thus, it is possible to reliably
restrict the flow of the process gases, which will be described
later.
[0039] It is conceivable that the deflection of an elevator shaft
of the lid 14 occurs due to, for example, the limit in the
operation accuracy of the vertical heat treatment apparatus 1. The
expansion regions 31 and 33 described above are provided in order
to prevent the pillars 61 under the vertical movement from
interfering with the inner periphery of the reaction vessel 11 when
the shaft deflection has occurred. In other words, the expansion
regions 31 and 33 are provided in order to obtain the distance L1
between the reaction vessel 11 and the pillars 61 needed for the
installation of the baffle plates 62, while realizing the
configuration in which the baffle plates 62 are disposed at the
outer side of the wafers W. In a case where the ring plates 24 and
the baffle plates 62 are disposed at the same height, it is
necessary to consider the deflection of the rotary shaft of the lid
14 as described in the Background section of the present
disclosure. Thus, the positions of the distal ends of the baffle
plates 62 are significantly limited in order to prevent the
interference between the baffle plates 62 and the ring plates 24.
However, since the baffle plates 62 are disposed at a height
differing from the height of the ring plates 24 as described above,
it may be possible to configure the baffle plates 62 so as to
relatively largely protrude toward the center of the reaction
vessel 11 so that the distal ends of the baffle plates 62 are
positioned in the vicinity of the peripheral ends of the wafers W.
That is to say, by disposing the baffle plates 62 at a height
differing from the height of the ring plates 24, it is possible to
further reduce the gap of the outer periphery of the reaction
vessel 11. This makes it possible to reliably restrict the flow of
the process gases, which will be described later.
[0040] As illustrated in FIGS. 1 and 2, the vertical heat treatment
apparatus 1 includes a control part 5 configured by a computer. The
control part 5 is configured to control the up-down movement of the
lid 14, the temperature of the wafers W heated by the heater 59,
the supply amount of the respective process gases regulated by the
mass flow controllers 44 and 46 and valves V1 and V2, the exhaust
amount adjusted by the exhaust amount adjustment part 55, the
rotation of the rotary shaft 15 caused by the motor 17, and other
operations. The control part 5 includes step groups which are
combined so as to perform a series of processes which will be
described later. A program is stored in the control part 5 in a
state where the program is recorded in a memory medium such as, for
example, a hard disc, a flexible disc, a compact disc, a
magneto-optical disc (MO) or a memory card.
[0041] Next, descriptions will be made on a film forming process
performed in the vertical heat treatment apparatus 1. First of all,
the wafers W are transferred to the wafer boat 2 which is supported
on the rotary shaft 15 and located at the substrate transfer
position below the reaction vessel 11. The wafers W are held on the
respective ring plates 24 in a shelf-like fashion. Thereafter, the
lid 14 is moved upward. The wafer boat 2 is moved up to the process
position from below the reaction vessel 11. The pillars 61 and the
baffle plates 62 are accommodated within the expansion regions 31
and 33. The substrate loading/unloading opening 13 is closed. Then,
the interior of the reaction vessel 11 is evacuated by the exhaust
through the exhaust port 51 so that the interior of the reaction
vessel 11 becomes a vacuum atmosphere having a predetermined
pressure. The wafers W are heated to a predetermined temperature by
the heater 59. Furthermore, the wafer boat 2 is rotated through the
rotary shaft 15 by the motor 17.
[0042] Thereafter, a TEOS gas and an O.sub.2 gas as process gases
are injected from the respective injection holes 43 of the gas
injectors 41 and 42 toward the central portions of the surfaces of
the respective wafers W. Since the exhaust is performed through the
exhaust port 51, the TEOS gas and the O.sub.2 gas flow in the
transverse direction from the front side toward the rear side
within the reaction vessel 11. In FIG. 6, the flow of the process
gases is indicated by white arrows. A dashed arrow in FIG. 6
indicates the rotation direction of the wafers W.
[0043] The peripheral edge portions of the ring plates 24 are
positioned in the outer peripheries of the wafers W. Furthermore,
the baffle plates 62 oriented toward the inner side of the ring
plates 24 are installed so as to extend from the expansion regions
31 and 33 between the mutually-adjoining ring plates 24. Thus, when
viewed from the respective process gases injected as above, the
gaps of the left and right outer peripheries of the wafers W are
kept small. This suppresses the process gases from diffusing to the
outer peripheries of the wafers W, thus efficiently supplying the
process gases to the gaps between the adjoining wafers W. When
viewed from the process gases supplied to the gaps between the
wafers W, the gaps in the circumferential direction of the wafers W
are kept relatively small by the baffle plates 62. Thus, the
diffusion of the process gases in the circumferential direction of
the wafers W is suppressed. As a result, the process gases flow
toward the exhaust port 51 across the wafers W at a relatively high
flow velocity. Then, the process gases are exhausted from the
exhaust port 51.
[0044] The process gases (the TEOS gas and the O.sub.2 gas) flowing
along the surfaces of the wafers W make a chemical reaction due to
the heat of the wafers W. Thus, the molecules of SiO.sub.2 are
deposited on the surfaces of the wafers W so that a SiO.sub.2 film
is formed on each of the surfaces of the wafers W. If the
deposition of the molecules of SiO.sub.2 proceeds and if the
thickness of the SiO.sub.2 film reaches a predetermined thickness,
the supply of the process gases from the gas injectors 41 and 42 is
stopped. The lid 14 is moved downward. The wafer boat 2 is unloaded
from the reaction vessel 11. Thus, the film forming process is
completed.
[0045] In the vertical heat treatment apparatus 1, the process is
performed using the wafer boat 2 in which the ring plates 24
respectively holding the wafers W and having the peripheral edge
portions protruding outward beyond the wafers W are installed in
the columns 23 in multiple stages. The baffle plates 62 independent
of the wafer boat 2 are installed so that the baffle plates 62
protrude from the left and right outer sides of the wafer boat 2 at
the process position within the reaction vessel 11 toward the gaps
between the mutually-adjoining ring plates 24 and run into the
gaps. With this configuration, it is possible to restrain the
process gases injected from the gas injectors 41 and 42 from
passing through the outer peripheries of the wafers W and moving
toward the exhaust port 51. This makes it possible to supply the
process gases to the surfaces of the respective wafers W in an
efficient manner and at a relatively high flow velocity. By
efficiently supplying the process gases in this way, it is possible
to enhance the deposition rate (the increment amount of a film
thickness per unit time) and to increase the throughput of the
vertical heat treatment apparatus 1. Furthermore, by supplying the
process gases to the wafers W at a relatively high flow velocity,
it is possible to suppress generation of a deviation in the supply
amount of the process gases in the front-rear diametrical direction
of the rotating wafers W. This makes it possible to improve the
film thickness uniformity in the wafers W.
[0046] As described above, the baffle plates 62 are installed in
order to reduce the gaps existing at the outer side of the wafers W
and to restrict the flow of the process gases. As illustrated in
FIG. 5, the baffle plates 62 are configured so that the distal ends
of the baffle plates 62 extend between the adjoining ring plates
24. This makes it possible to significantly reduce the gaps. It is
therefore possible to reliably achieve the aforementioned effects.
Even if the baffle plates 62 are installed so as not to extend into
the gaps between the adjoining ring plates 24, the gaps existing at
the outer side of the wafers W become smaller as compared with a
case where the baffle plates 62 are not installed. Thus, the
effects of the present disclosure are achieved. Accordingly, the
baffle plates 62 may be formed so that the distal ends of the
baffle plates 62 and the peripheral ends of the ring plates 24
overlap with each other, namely so that the distance L2 in FIG. 5
becomes 0 mm. In some embodiments, the baffle plates 62 may be
formed so that the distal ends of the baffle plates 62 are spaced
apart from the peripheral ends of the ring plates 24 toward the
peripheral end of the reaction vessel 11.
Modification of First Embodiment
[0047] A vertical heat treatment apparatus 6 according to a
modification of the first embodiment will be described with
reference to a transverse plan view of FIG. 7, with a focus on the
differences from the vertical heat treatment apparatus 1. In the
vertical heat treatment apparatus 6, baffle plates 63 having an arc
shape when viewed from the top and extending along semicircles of
the respective ring plates 24 are installed in place of the baffle
plates 62. Each end of the arc is respectively disposed at the left
and right sides of the reaction vessel 11. The longitudinal center
portion of the arc is disposed at the front side within the
reaction vessel 11. That is to say, the baffle plates 63 are formed
in an arc shape when viewed from the top so as to become longer
than the baffle plates 62. Except for the difference in shape, the
baffle plates 63 are configured similar to the baffle plates 62.
The baffle plates 63 are supported by, for example, rod-shaped
vertical pillars 64 installed in a spaced-apart relationship along
the circumferential direction of the reaction vessel 11. Except for
the difference in the shape when viewed from the top, the pillars
64 are configured similar to the pillars 61 described above.
[0048] A region facing the baffle plates 63 in the sidewall of the
reaction vessel 11 constitutes a first expansion region 65 bulging
outward. The first expansion region 65 is configured similar to the
expansion regions 31 and 33 except that the shape of the first
expansion region 65 when viewed from the top differs from the shape
of the expansion regions 31 and 33 when viewed from the top.
Furthermore, the front side of the sidewall of the reaction vessel
11 defining the first expansion region 65 locally bulges outward of
the reaction vessel 11 to form a second expansion region 66.
Similar to the expansion region 32 described above, the gas
injectors 41 and 42 are installed in the second expansion region
66. The injection holes 43 of the gas injectors 41 and 42 are
opened so as to inject process gases between the adjoining ring
plates 24.
[0049] Since the gaps formed at the outer side of the wafers W are
kept relatively small by the ring plates 24 and the baffle plates
62, the process gases injected between the adjoining ring plates 24
are restrained from flowing toward the outer peripheries of the
wafers W and are moved toward the exhaust port 51. Thus, according
to the vertical heat treatment apparatus 6, similar to the vertical
heat treatment apparatus 1, it is possible to supply the process
gases to the respective wafers W in an efficient manner and at a
relatively high flow velocity.
Second Embodiment
[0050] Next, a vertical heat treatment apparatus 7 according to a
second embodiment will be described with reference to a transverse
plan view of FIG. 8 and a longitudinal sectional view of FIG. 9,
with a focus on the differences from the vertical heat treatment
apparatus 1. In the vertical heat treatment apparatus 7, the
expansion regions 31 and 33, the pillars 61 and the baffle plates
62 are not installed. Instead, baffle plates 71 corresponding to
the baffle plates 62 are installed. Similar to the baffle plates
62, the baffle plates 71 are installed in multiple stages. Each of
the baffle plates 71 protrude from four regions of the inner
circumferential wall of the reaction vessel 11 spaced apart in the
circumferential direction toward the gaps between the adjoining
ring plates 24 of the wafer boat 2 disposed in the process
position, so that the baffle plates 71 run into the gaps. In this
embodiment, the baffle plates 71 are respectively installed at the
front left and right sides and at the rear left and right sides
within the reaction vessel 11.
[0051] Four cutouts 25 corresponding to the baffle plates 71 are
formed in each of the ring plates 24 along the circumferential
direction. When the wafer boat 2 is loaded into and unloaded from
the reaction vessel 11, the lid 14 is moved up and down in a state
where the orientation of the wafer boat 2 is adjusted by the motor
17 so that the cutouts 25 face the respective baffle plates 71 as
illustrated in FIG. 8. Thus, the baffle plates 71 pass through the
cutouts 25. The cutouts 25 are formed so as to prevent interference
between the ring plates 24 and the baffle plates 71 even when the
deflection of the elevator shaft of the wafer boat 2 occurs as
described earlier.
[0052] In the vertical heat treatment apparatus 7, similar to the
vertical heat treatment apparatus 1, a gas flow is formed by
supplying and exhausting process gases and the wafer boat 2 is
rotated. Thus, the wafers W are subjected to a film forming
process. Due to the rotation of the wafer boat 2, the film forming
process is performed while alternately repeating a state in which
the distal end portions of the baffle plates 71 and the peripheral
end portions of the ring plates 24 do not overlap with each other
when viewed from the top (a state illustrated in FIG. 8) and a
state in which the distal end portions of the baffle plates 71 and
the peripheral end portions of the ring plates 24 overlap with each
other when viewed from the top. Due to the installation of the ring
plates 24 and the baffle plates 71, when viewed from the process
gases injected into the reaction vessel 11, the gaps formed at the
outer side of the wafers W is relatively small. Thus, in the
vertical heat treatment apparatus 7, similar to the vertical heat
treatment apparatus 1, it is possible to restrain the process gases
from flowing toward the outer peripheries of the wafers W. When the
baffle plates 71 and the ring plates 24 overlap with each other,
the gaps existing at the outer side of the wafers W, which are
viewed from the process gases, is very small. It is therefore
possible to reliably restrain the process gases from flowing toward
the outer peripheries of the wafers W.
[0053] By restricting the flow of the process gases in the
aforementioned manner, the vertical heat treatment apparatus 7 may
achieve the same effects as achieved by the vertical heat treatment
apparatus 1. The baffle plates 71 of the vertical heat treatment
apparatus 7 are fixed to the reaction vessel 11. It is therefore
possible to install the baffle plates 71 regardless of the
direction in which the wafer transfer mechanism gains access to the
wafer boat 2. That is to say, the baffle plates 71 may be disposed
in a free layout at the front, rear, left and right sides within
the reaction vessel 11.
[0054] In the above embodiments, it is only necessary for the ring
plates 24 of the wafer boat 2 to reduce the gaps existing at the
outer side of the wafers W. Thus, the ring plates 24 need not be
necessarily circular. As illustrated in the second embodiment, the
cutouts 25 may be formed in the ring plates 24. The ring plates 24
may have, for example, an elliptical shape or a rectangular shape.
Furthermore, the exhaust port 51 may be formed in an arbitrary
shape in order to adjust the in-plane pressure between the
respective wafers W. For example, the exhaust port 51 may be formed
in a downwardly-tapered wedge-like slit shape. Alternatively, the
exhaust port 51 may have a configuration in which a plurality of
holes is formed in a spaced-apart relationship in an up-down
direction so that the holes existing at the lower side have a
smaller diameter. An exhaust flow path existing at the downstream
side of the exhaust port 51 is not limited to the aforementioned
configuration example. For example, instead of installing the outer
tube 52, it may be possible to employ a configuration in which the
exhaust port 51 is covered by a cover outside of the reaction
vessel 11 and a space covered by the cover is exhausted through the
exhaust pipe 54. In addition, it may be possible to employ a
configuration in which the upstream end of the exhaust pipe 54 is
connected to the front side of the outer tube 52 so that the
process gases introduced into the exhaust port 51 pass through the
upper side of the ceiling plate of the reaction vessel 11 and flow
into the exhaust pipe 54.
[0055] Furthermore, the configuration of the wafer boat is not
limited to the aforementioned example. FIGS. 10 to 13 are schematic
longitudinal sectional views illustrating wafer boats differing in
configuration from the wafer boat 2. Hereinafter, the wafer boats
illustrated in FIGS. 10 to 13 will be described with a focus on the
differences from the wafer boat 2. In FIG. 10, there is illustrated
a configuration example of the wafer boat 73 in which circular
plates 72 are installed in place of the ring plates 24. Similar to
the peripheral edge portions of the ring plates 24, peripheral edge
portions of the circular plates 72 protrude outward beyond the
peripheral edges of the wafers W mounted on the circular plates 72.
In FIG. 11, there is illustrated a wafer boat 75 in which
ring-shaped protrusions 74 are formed to extend along the inner
peripheral edges of the ring plates 24. The wafers W are held on
the respective protrusions 74.
[0056] A wafer boat 76 illustrated in FIG. 12 includes holder
bodies 77 protruding from the respective columns 23 toward the
central portion of the region surrounded by the columns 23. The
peripheral edge portions of the wafers W are held on the holder
bodies 77. In the wafer boat 76, horizontal circular ring plates 78
are installed in multiple stages at a height differing from the
height of the holder bodies 77 and the wafers W. The inner
peripheral edges of the ring plates 78 are supported by the
respective columns 23. Similar to the peripheral edge portions of
the ring plates 24, the ring plates 78 are configured to restrict
gas flow within the reaction vessel 11. That is to say, in the
wafer boat 76, substrate holding parts and gas flow guide parts are
installed independently of each other. A wafer boat 79 illustrated
in FIG. 13 is configured substantially similar to the wafer boat
76. A difference resides in that horizontal circular plates 70 are
installed in place of the ring plates 78.
[0057] As the transfer mechanism which transfers the wafers W to
each of the wafer boats, a transfer mechanism having an arbitrary
configuration may be used as long as the transfer mechanism is
capable of transferring the wafers W to the wafer boat described
above. For example, it may be possible to use a transfer mechanism
including grippers that grip each of the wafers W by pressing the
mutually-spaced-apart different positions of the side surface of
each of the wafers W toward the center of each of the wafers W.
[0058] The vertical heat treatment apparatus 1 is not limited to an
apparatus which performs a CVD-based film formation but may be an
apparatus which performs an ALD (atomic layer deposition)-based
film formation. In addition, it may be possible to install a plasma
mechanism which converts the process gases injected from the gas
injectors 41 and 42 to plasma and generates radicals until the
process gases are supplied to the wafers W, so that active species
such as the radicals or the like are supplied to the wafers W. In
this case, the process gases pass between the adjoining wafers W at
a relatively high flow velocity as described above. It is therefore
possible to restrain the active species from being deactivated
until the active species reach the respective portions of the
surfaces of the wafers W. This makes it possible to enhance the
throughput of the apparatus and to achieve process uniformity
within the planes of the wafers W. Furthermore, the vertical heat
treatment apparatus 1 is not limited to a film forming apparatus
which performs a film forming process but may be configured as a
modification apparatus which modifies the surfaces of the wafers W
by heating the wafers W while supplying an inert gas such as, for
example, a N.sub.2 (nitrogen) gas or the like. Moreover, the
configurations of the respective embodiments described above may be
appropriately combined. For example, the pillars 64 of the vertical
heat treatment apparatus 6 may be used as the pillars of the
vertical heat treatment apparatus 1 which support the baffle plates
62.
[0059] In the examples illustrated in FIGS. 3 and 8, the peripheral
edge portions of the ring plates 24 of the wafer boat 2 are formed
to protrude outward from the entire circumferences of the wafers W
beyond the peripheral edges of the wafers W. However, it is only
necessary for the ring plates 24 to have an action of restricting
the gas flow as described above. The ring plates 24 are not limited
to the configuration in which the peripheral edge portions of the
ring plates 24 protrude outward from the entire circumferences of
the wafers W. For example, cutouts may be formed in the peripheral
edge portions of the ring plates 24 so that the cutouts face the
centers of the ring plates 24 and so that the distal ends of the
ring plates 24 are positioned inward of the peripheral edges of the
wafers W. The ring plates 24 may be configured so that, when viewed
from the top, the peripheral edge portions of the ring plates 24
protrude outward of the wafers W from the majority of the entire
circumferences of the wafers W, for example, from the region of 70%
or more of the entire circumferences of the wafers W. The cutouts
are formed in a plurality of regions of the peripheral edge
portions of the ring plates 24 so that, for example, when a
transfer mechanism including a plurality of claws for supporting a
plurality of mutually-spaced-apart regions of the peripheral edge
portions of the rear surfaces of the wafers W moves up and down
with respect to the ring plates 24 and transfers the wafers W to
the ring plates 24, the claws can pass through the cutouts.
(Evaluation Test)
[0060] As evaluation test 1, there was conducted a simulation which
perform a film forming process with respect to the wafers W having
a diameter of 300 mm using the vertical heat treatment apparatus 1
described above. Then, a distribution of flow velocities of a
process gas in the gaps between the adjoining wafers W under the
film forming process was acquired. As comparative test 1, a
simulation was conducted under the same conditions as those of
evaluation test 1 except that the baffle plates 62, the pillars 61
and the expansion regions 31 and 32 are not formed. Similar to
evaluation test 1, a distribution of flow velocities of a process
gas was acquired.
[0061] A graph of FIG. 14 shows the distributions of flow
velocities in the gaps between the wafers W, which were acquired on
a diametrical line extending in a left-right direction of the
wafers W. The distribution of flow velocities acquired in
evaluation test 1 is indicated by a solid line. The distribution of
flow velocities acquired in comparative test 1 is indicated by a
dotted line. The horizontal axis in the graph indicates the
distance (unit: m) from the center (0 mm) of the wafer W to the
position where the flow velocity is detected. The right side of the
reaction vessel 11 is indicated by positive values and the left
side of the reaction vessel 11 is indicated by negative values. The
vertical axis in the graph indicates the detected flow velocity
(unit: m/second). A character "a" in the vertical axis is a
positive number. From this graph, it can be noted that the flow
velocity in the same position is larger in evaluation test 1 than
in comparative test 1. Thus, the effects of the present disclosure
mentioned above were confirmed from the results of evaluation
tests.
[0062] According to the present disclosure in some embodiments, gas
flow guide parts having peripheral edge portions protruding outward
beyond substrates are installed in columns of a substrate holder
for each of the substrates. Further, baffle parts are installed
independently of the substrate holder at left and right sides of a
substrate holding region so that the baffle parts protrude from the
outer side toward a space between the mutually-adjoining gas flow
guide parts and run into the space. It is therefore possible to
supply a process gas between the substrates in an efficient manner
and at a high flow velocity.
[0063] While certain embodiments have been described, these
embodiments have been presented by way of example only, and are not
intended to limit the scope of the disclosures. Indeed, the
embodiments described herein may be embodied in a variety of other
forms. Furthermore, various omissions, substitutions and changes in
the form of the embodiments described herein may be made without
departing from the spirit of the disclosures. The accompanying
claims and their equivalents are intended to cover such forms or
modifications as would fall within the scope and spirit of the
disclosures.
* * * * *