U.S. patent application number 15/244235 was filed with the patent office on 2017-03-02 for vapor phase growth apparatus and vapor phase growth method.
This patent application is currently assigned to NuFlare Technology, Inc.. The applicant listed for this patent is NuFlare Technology, Inc.. Invention is credited to Takanori Hayano, Hideki Ito, Yuusuke Sato, Hideshi Takahashi.
Application Number | 20170062212 15/244235 |
Document ID | / |
Family ID | 58010692 |
Filed Date | 2017-03-02 |
United States Patent
Application |
20170062212 |
Kind Code |
A1 |
Sato; Yuusuke ; et
al. |
March 2, 2017 |
VAPOR PHASE GROWTH APPARATUS AND VAPOR PHASE GROWTH METHOD
Abstract
A vapor phase growth apparatus according to an embodiment
includes, n reactors performing a deposition process for a
plurality of substrates at the same time, a first main gas supply
path distributing a predetermined amount of first process gas
including a group-III element to the n reactors at the same time, a
second main gas supply path distributing a predetermined amount of
second process gas including a group-V element to the n reactors at
the same time, a controller controlling a flow rate of the first
and second process gas, on the basis of control values of the flow
rates of the first and second process gas supplied to the n
reactors, and independently controlling predetermined process
parameter independently set for each of the n reactors on the basis
of control values, rotary drivers, and a heater.
Inventors: |
Sato; Yuusuke; (Bunkyo-ku,
JP) ; Takahashi; Hideshi; (Yokohama-shi, JP) ;
Ito; Hideki; (Yokohama-shi, JP) ; Hayano;
Takanori; (Yokohama-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NuFlare Technology, Inc. |
Yokohama-shi |
|
JP |
|
|
Assignee: |
NuFlare Technology, Inc.
Yokohama-shi
JP
|
Family ID: |
58010692 |
Appl. No.: |
15/244235 |
Filed: |
August 23, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C30B 25/165 20130101;
C23C 16/52 20130101; C23C 16/45574 20130101; H01L 21/0262 20130101;
C23C 16/45561 20130101; C30B 29/403 20130101; H01L 21/0254
20130101; C30B 25/10 20130101; C30B 29/406 20130101; C23C 16/45565
20130101; C23C 16/4412 20130101 |
International
Class: |
H01L 21/02 20060101
H01L021/02; C23C 16/458 20060101 C23C016/458; C30B 29/40 20060101
C30B029/40; C23C 16/44 20060101 C23C016/44; C30B 25/10 20060101
C30B025/10; C30B 25/16 20060101 C30B025/16; C23C 16/52 20060101
C23C016/52; C23C 16/46 20060101 C23C016/46 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 28, 2015 |
JP |
2015-168860 |
Claims
1. A vapor phase growth apparatus comprising: n (n is an integer
equal to or greater than 2) reactors performing a deposition
process for a plurality of substrates at the same time; a first
main gas supply path distributing a predetermined amount of first
process gas including a group-III element and supplying the first
process gas to the n reactors at the same time; a second main gas
supply path distributing a predetermined amount of second process
gas including a group-V element and supplying the second process
gas to the n reactors at the same time; a controller controlling a
flow rate of the first process gas and a flow rate of the second
process gas, on the basis of control values of flow rates of the
first process gas and the second process gas supplied to the n
reactors, the controller independently controlling at least one
predetermined process parameter in the n reactors, on the basis of
control values of the at least one predetermined process parameter
independently set for each of the n reactors; a rotary driver
provided in each of the n reactors and rotating each of the
plurality of substrates; and a heater provided in each of the n
reactors and heating each of the plurality of substrates.
2. The vapor phase growth apparatus according to claim 1, wherein
the at least one predetermined process parameter is selected from
concentration of the group-III element and the group-V element in
process gas supplied to the n reactors, rotation speed of the
substrates, temperature of the substrates, output of the heater,
and internal pressure of the reactors.
3. The vapor phase growth apparatus according to claim 1, wherein
the controller performs control such that an operation of starting
the first process gas supply, an operation of shutting off the
first process gas supply, an operation of starting second process
gas supply, and an operation of shutting off of the second process
gas supply are performed in the n reactors at the same time.
4. The vapor phase growth apparatus according to claim 2, further
comprising: n diluent gas supply lines supplying a diluent gas to
the n reactors, wherein the controller controls amount of diluent
gas supplied, on the basis of the control values of the
concentration of the group-III element and the group-V element, the
control values being independently set for the n reactors.
5. The vapor phase growth apparatus according to claim 1, wherein
each of the n reactors includes a film thickness measure capable of
measuring a thickness of a film being grown, and the controller
changes and adjusts the at least one of the control values of the
at least one predetermined process parameter independently for the
n reactors, on the basis of a measurement result of film thickness
by the film thickness measure during growth of the film.
6. The vapor phase growth apparatus according to claim 1, wherein
the controller includes a calculator calculating the control values
of the at least one predetermined process parameter from
information about correlation between characteristics of films
obtained in the n reactors and the at least one predetermined
process parameter in advance and the characteristics of the films
obtained in the n reactors in advance.
7. The vapor phase growth apparatus according to claim 1, further
comprising: n sub-gas exhaust paths connected to the n reactors and
discharging gas from the n reactors; n pressure adjusters connected
to the n sub-gas exhaust path; a main gas exhaust path connected to
the sub-gas exhaust paths; and a vacuum pump connected to the main
gas exhaust path.
8. The vapor phase growth apparatus according to claim 7, wherein
the controller independently sets pressure control values of the n
pressure adjuster.
9. A vapor phase growth method comprising: loading a plurality of
substrates to n reactors; distributing a predetermined amount of
first process gas including a group-III element and starting the
first process gas supply to the n reactors at the same time at a
flow rate controlled on the basis of control values of a first flow
rate; distributing a predetermined amount of second process gas
including a group-V element and starting second process gas supply
to the n reactors at the same time at a flow rate controlled on the
basis of control values of a second flow rate; controlling
independently at least one predetermined process parameter of the n
reactors, on the basis of control values of the at least one
predetermined process parameter, and growing films on the plurality
of substrates in the n reactors at the same time; shutting off the
first process gas supply to the n reactors at the same time; and
shutting off the second process gas supply to the n reactors at the
same time.
10. The vapor phase growth method according to claim 9, further
comprising: loading a plurality of test substrates to the n
reactors, distributing the predetermined amount of the first
process gas and starting the first process gas supply to the n
reactors at the same time at the flow rate controlled on the basis
of the control value of the first flow rate, distributing the
predetermined amount of second process gas and starting the second
process gas supply to the n reactors at the same time at the flow
rate controlled on the basis of the control value of the second
flow rate, controlling the at least one predetermined process
parameter on the basis of initial control values of the at least
one predetermined process parameter, and growing films on the
plurality of test substrates in the n reactors at the same time,
shutting off the first process gas supply to the n reactors at the
same time, shutting off the second process gas supply to the n
reactors at the same time, measuring characteristics of the films
grown on the plurality of test substrates, and calculating the
control values of the at least one predetermined process parameter
of the n reactors on the basis of the measured characteristics of
the films.
11. The vapor phase growth method according to claim 9, wherein the
at least one predetermined process parameter is selected from
concentration of the group-III element and the group-V element in
process gas supplied to the n reactors, rotation speed of the
substrates, temperature of the substrates, power of heater provided
in each of the n reactors, and internal pressure of the
reactors.
12. The vapor phase growth method according to claim 11, wherein
the at least one predetermined process parameter is the power of
the heater or the temperature of the substrates, and during the
growing films, stop the growth of the film in at least one of the n
reactors, the control value of the power of the heater or the
temperature of the substrates in the at least one of the n reactors
is set to be less than a control value when the film is grown on
the substrate.
13. The vapor phase growth method according to claim 9, wherein the
film is a stacked film of an indium gallium nitride film and a
gallium nitride film.
14. The vapor phase growth method according to claim 13, wherein
the at least one predetermined process parameter is the rotation
speed of the substrate.
15. The vapor phase growth method according to claim 13, wherein
the at least one predetermined process parameter is temperature of
the substrates.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Applications No. 2015-168860, filed
on Aug. 28, 2015, the entire contents of which are incorporated
herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a vapor phase growth
apparatus and a vapor phase growth method that supply gas to form a
film.
BACKGROUND OF THE INVENTION
[0003] As a method for forming a high-quality semiconductor film,
there is an epitaxial growth technique which grows a single-crystal
film on a substrate, such as a wafer, using vapor phase growth. In
a vapor phase growth apparatus using the epitaxial growth
technique, a wafer is placed on a support portion in a reactor
which is maintained at normal pressure or reduced pressure. Then,
process gas, such as source gas which will be a raw material for
forming a film, is supplied from an upper part of the reactor to
the surface of the wafer in the reactor while the wafer is being
heated. For example, the thermal reaction of the source gas occurs
in the surface of the wafer and an epitaxial single-crystal film is
formed on the surface of the wafer.
[0004] In recent years, as a material forming alight emitting
device or a power device, a gallium nitride (GaN)-based
semiconductor device has drawn attention. Metal organic chemical
vapor deposition (MOCVD) method is an epitaxial growth technique
that can form a GaN-based semiconductor film. In the organic metal
vapor phase growth method, organic metal, such as trimethylgallium
(TMG), trimethylindium (TMI), or trimethylaluminum (TMA), or
ammonia (NH.sub.3) is used as the source gas.
[0005] JP H10-158843A and JP 2002-212735A disclose a vapor phase
growth apparatus that includes a plurality of reactors in order to
improve productivity. In addition, JP 2003-49278A discloses a
method that changes the pressure control value of a reactor caused
a trouble when films are grown in a plurality of reactors.
SUMMARY OF THE INVENTION
[0006] According to an aspect of the invention, there is provided a
vapor phase growth apparatus including: n (n is an integer equal to
or greater than 2) reactors performing a deposition process for a
plurality of substrates at the same time; a first main gas supply
path distributing a predetermined amount of first process gas
including a group-III element and supplying the first process gas
to the n reactors at the same time; a second main gas supply path
distributing a predetermined amount of second process gas including
a group-V element and supplying the second process gas to the n
reactors at the same time; a controller controlling a flow rate of
the first process gas and a flow rate of the second process gas, on
the basis of control values of flow rates of the first process gas
and the second process gas supplied to the n reactors, the
controller independently controlling at least one predetermined
process parameter in the n reactors, on the basis of control values
of the at least one predetermined process parameter independently
set for each of the n reactors; a rotary driver provided in each of
the n reactors and rotating each of the plurality of substrates;
and a heater provided in each of the n reactors and heating each of
the plurality of substrates.
[0007] According to another aspect of the invention, there is
provided a vapor phase growth method including: loading a plurality
of substrates to n reactors; distributing a predetermined amount of
first process gas including a group-III element and starting the
first process gas supply to the n reactors at the same time at a
flow rate controlled on the basis of control values of a first flow
rate; distributing a predetermined amount of second process gas
including a group-V element and starting second process gas supply
to the n reactors at the same time at a flow rate controlled on the
basis of control values of a second flow rate; controlling
independently at least one predetermined process parameter of the n
reactors, on the basis of control values of the at least one
predetermined process parameter, and growing films on the plurality
of substrates in the n reactors at the same time; shutting off the
first process gas supply to the n reactors at the same time; and
shutting off the second process gas to the n reactors at the same
time.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a diagram illustrating the structure of a vapor
phase growth apparatus according to a first embodiment;
[0009] FIG. 2 is a cross-sectional view schematically illustrating
a reactor of the vapor phase growth apparatus according to the
first embodiment;
[0010] FIG. 3 is a diagram illustrating the function and effect of
the first embodiment;
[0011] FIG. 4 is a diagram illustrating the function and effect of
the first embodiment;
[0012] FIG. 5 is a diagram illustrating the function and effect of
the first embodiment;
[0013] FIG. 6 is a diagram illustrating the structure of a vapor
phase growth apparatus according to a second embodiment; and
[0014] FIG. 7 is a cross-sectional view schematically illustrating
a reactor of a vapor phase growth apparatus according to a third
embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0015] Hereinafter, embodiments of the invention will be described
with reference to the drawings.
[0016] In the specification, the direction of gravity in a state in
which a vapor phase growth apparatus is provided so as to form a
film is defined as a "lower" direction and a direction opposite to
the direction of gravity is defined as an "upper" direction.
Therefore, a "lower portion" means a position in the direction of
gravity relative to the reference and a "lower side" means the
direction of gravity relative to the reference. In addition, an
"upper portion" means a position in the direction opposite to the
direction of gravity relative to the reference and an "upper side"
means the direction opposite to the direction of gravity relative
to the reference. Furthermore, a "longitudinal direction" is the
direction of gravity.
[0017] In the specification, "process gas" is a general term of gas
used to form a film on a substrate. The concept of the "process
gas" includes, for example, source gas, carrier gas, and diluent
gas.
First Embodiment
[0018] A vapor phase growth apparatus according to this embodiment
includes, n (n is an integer equal to or greater than 2) reactors
performing a deposition process for a plurality of substrates at
the same time, a first main gas supply path distributing a
predetermined amount of first process gas including a group-III
element and supplying the first process gas to the n reactors at
the same time, a second main gas supply path distributing a
predetermined amount of second process gas including a group-V
element and supplying the second process gas to the n reactors at
the same time, a controller controlling a flow rate of the first
process gas and a flow rate of the second process gas, on the basis
of control values of the flow rates of the first process gas and
the second process gas supplied to the n reactors, and
independently controlling predetermined process parameters that are
independently set for each of the n reactors, on the basis of
control values of the predetermined process parameters, rotary
drivers provided in each of the n reactors and rotating each of the
plurality of substrates, and heaters provided in each of the n
reactors and heating the plurality of substrates.
[0019] A vapor phase growth method according to this embodiment
includes, loading a plurality of substrates to n reactors,
distributing a predetermined amount of first process gas including
a group-III element and starting the first process gas supply to
the n reactors at a flow rate that is controlled on the basis of a
control value of a first flow rate at the same time, distributing a
predetermined amount of second process gas including a group-V
element and starting the second process gas supply to the n
reactors at a flow rate that is controlled on the basis of a
control value of a second flow rate at the same time, independently
controlling predetermined process parameters of the n reactors, on
the basis of control values of the predetermined process parameters
of the n reactors, and growing films on the plurality of substrates
in the n reactors at the same time, shutting off the first process
gas supply to the n reactors at the same time, and shutting off the
second process gas supply to the n reactors at the same time.
[0020] According to the vapor phase growth apparatus and the vapor
phase growth method having the above-mentioned structure according
to this embodiment, when films are formed on substrates in a
plurality of reactors at the same time, it is possible to adjust
the characteristics of the films grown in each reactor. The
characteristics of the film are, for example, the thickness or
composition of the film.
[0021] FIG. 1 is a diagram illustrating the structure of the vapor
phase growth apparatus according to this embodiment. The vapor
phase growth apparatus according to this embodiment is an epitaxial
growth apparatus using a metal organic chemical vapor deposition
(MOCVD) method.
[0022] The vapor phase growth apparatus according to this
embodiment includes four reactors 10a, 10b, 10c, and 10d. Each of
the four reactors 10a, 10b, 10c, and 10d is, for example, a
vertical single-wafer-type epitaxial growth apparatus. The number
of reactors is not limited to 4 and two or more reactors may be
used. The number of reactors can be represented by n (n is an
integer equal to or greater than 2).
[0023] The vapor phase growth apparatus according to this
embodiment includes a first main gas supply path 11, a second main
gas supply path 21, and a third main gas supply path 31 which
supply process gas to the four reactors 10a, 10b, 10c, and 10d.
[0024] The first main gas supply path 11 supplies, for example, a
first process gas including organic metal, which is a group III
element, and carrier gas to the reactors 10a, 10b, 10c, and 10d.
The first process gas is gas including a group-III element when a
group III-V semiconductor film is formed on a wafer. The first main
gas supply path 11 distributes and supplies a predetermined amount
of first process gas including a group-III element to the four
reactors 10a, 10b, 10c, and 10d at the same time.
[0025] The group-III element is, for example, gallium (Ga),
aluminum (Al), or indium (In). In addition, the organic metal is,
for example, trimethylgallium (TMG), trimethylaluminum (TMA), or
trimethylindium (TMI).
[0026] The carrier gas is, for example, hydrogen gas. Only the
hydrogen gas may flow through the first main gas supply path
11.
[0027] A first main mass flow controller 12 is provided in the
first main gas supply path 11. The first main mass flow controller
12 controls the flow rate of the first process gas that flows
through the first main gas supply path 11.
[0028] In addition, the first main gas supply path 11 is branched
into three first sub-gas supply paths 13a, 13b, and 13c and one
second sub-gas supply path 13d at a position that is closer to the
reactors 10a, 10b, 10c, and 10d than to the first main mass flow
controller 12. The first sub-gas supply paths 13a, 13b, and 13c and
the second sub-gas supply path 13d supply the distributed first
process gases to the four reactors 10a, 10b, 10c, and 10d,
respectively.
[0029] A first manometer 41 is provided in the first main gas
supply path 11. The first manometer 41 is provided between the
first main mass flow controller 12 and the position where the first
main gas supply path 11 is branched into the three first sub-gas
supply paths 13a, 13b, and 13c and the one second sub-gas supply
path 13d. The first manometer 41 monitors the pressure of the first
main gas supply path 11.
[0030] First sub-mass flow controllers 14a, 14b, and 14c are
provided in the three first sub-gas supply paths 13a, 13b, and 13c,
respectively. The first sub-mass flow controllers 14a, 14b, and 14c
control the flow rate of the first process gas that flows through
the first sub-gas supply paths 13a, 13b, and 13c, respectively. The
first sub-mass flow controllers 14a, 14b, and 14c are a flow rate
control type.
[0031] A fourth sub-mass flow controller 14d of an opening position
control type is provided in the one second sub-gas supply path 13d.
The second sub-gas supply path 13d supplies the first process gas
to one reactor 10d other than three reactors 10a, 10b, and 10c to
which the first sub-gas supply paths 13a, 13b, and 13c supply the
first process gas, respectively. In the total amount of first
process gas supplied from the first main gas supply path 11, the
remainder of the first process gas which does not flow through the
first sub-gas supply paths 13a, 13b, and 13c flows from the second
sub-gas supply path 13d to the reactor 10d.
[0032] Specifically, the degree of opening of the fourth sub-mass
flow controller 14d is controlled on the basis of the measurement
result of the pressure of the first main gas supply path 11
monitored by the first manometer 41. For example, the degree of
opening of the fourth sub-mass flow controller 14d is controlled
such that the pressure monitored by the first manometer 41 is zero.
According to this structure, in the total amount of first process
gas supplied from the first main gas supply path 11, the remainder
of the first process gas which does not flow through the first
sub-gas supply paths 13a, 13b, and 13c can flow from the second
sub-gas supply path 13d to the reactor 10d.
[0033] For example, the second main gas supply path 21 supplies a
second process gas including ammonia (NH.sub.3) to the reactors
10a, 10b, 10c, and 10d. The second process gas is a source gas of a
group-V element and nitrogen (N) when a group III-V semiconductor
film is formed on a wafer. The second main gas supply path 21
distributes and supplies a predetermined amount of second process
gas including a group-V element to the four reactors 10a, 10b, 10c,
and 10d at the same time.
[0034] Only hydrogen gas may flow through the second main gas
supply path 21.
[0035] A second main mass flow controller 22 is provided in the
second main gas supply path 21. The second main mass flow
controller 22 controls the flow rate of the second process gas that
flows through the second main gas supply path 21.
[0036] In addition, the second main gas supply path 21 is branched
into three third sub-gas supply paths 23a, 23b, and 23c and one
fourth sub-gas supply path 23d at a position that is closer to the
reactors 10a, 10b, 10c, and 10d than to the second main mass flow
controller 22. The third sub-gas supply paths 23a, 23b, and 23c and
the fourth sub-gas supply path 23d supply the distributed second
process gases to the four reactors 10a, 10b, 10c, and 10d,
respectively.
[0037] A second manometer 51 is provided in the second main gas
supply path 21. The second manometer 51 is provided between the
second main mass flow controller 22 and the position where the
second main gas supply path 21 is branched into the three third
sub-gas supply paths 23a, 23b, and 23c and the one fourth sub-gas
supply path 23d. The second manometer 51 monitors the pressure of
the second main gas supply path 21.
[0038] Second sub-mass flow controllers 24a, 24b, and 24c are
provided in the three third sub-gas supply paths 23a, 23b, and 23c,
respectively. The second sub-mass flow controllers 24a, 24b, and
24c control the flow rate of the second process gas that flows
through the third sub-gas supply paths 23a, 23b, and 23c,
respectively. The second sub-mass flow controllers 24a, 24b, and
24c are a flow rate control type.
[0039] A fifth sub-mass flow controller 24d of an opening position
control type is provided in the one fourth sub-gas supply path 23d.
The fourth sub-gas supply path 23d supplies the second process gas
to one reactor 10d other than three reactors 10a, 10b, and 10c to
which the third sub-gas supply paths 23a, 23b, and 23c supply the
second process gas, respectively. In the total amount of second
process gas supplied from the second main gas supply path 21, the
remainder of the second process gas which does not flow through the
third sub-gas supply paths 23a, 23b, and 23c flows from the fourth
sub-gas supply path 23d to the reactor 10d.
[0040] Specifically, the degree of opening of the fifth sub-mass
flow controller 24d is controlled on the basis of the measurement
result of the pressure of the second main gas supply path 21
monitored by the second manometer 51. For example, the degree of
opening of the fifth sub-mass flow controller 24d is controlled
such that the pressure monitored by the second manometer 51 is
zero. According to this structure, in the total amount of second
process gas supplied from the second main gas supply path 21, the
remainder of the second process gas which does not flow through the
third sub-gas supply paths 23a, 23b, and 23c can flow from the
fourth sub-gas supply path 23d to the reactor 10d.
[0041] The third main gas supply path 31 supplies a diluent gas
which dilutes the first process gas and the second process gas to
the reactors 10a, 10b, 10c, and 10d. The first process gas and the
second process gas are diluted with the diluent gas to adjust the
concentration of the group-III element and the group-V element
supplied to the reactors 10a, 10b, 10c, and 10d. The diluent gas is
inert gas, such as hydrogen gas, nitrogen gas, or argon gas, or a
mixed gas thereof.
[0042] A third main mass flow controller 32 is provided in the
third main gas supply path 31. The third main mass flow controller
32 controls the flow rate of the diluent gas that flows through the
third main gas supply path 31.
[0043] In addition, the third main gas supply path 31 is branched
into three fifth sub-gas supply paths (diluent gas supply lines)
33a, 33b, and 33c and one sixth sub-gas supply path (diluent gas
supply line) 33d at a position that is closer to the reactors 10a,
10b, 10c, and 10d than to the third main mass flow controller 32.
The fifth sub-gas supply paths 33a, 33b, and 33c and the sixth
sub-gas supply path 33d supply the distributed diluent gases to the
four reactors 10a, 10b, 10c, and 10d, respectively. The three fifth
sub-gas supply paths and the one sixth sub-gas supply path are an
example of four diluent gas supply lines.
[0044] A third manometer 61 is provided in the third main gas
supply path 31. The third manometer 61 is provided between the
third main mass flow controller 32 and the position where the third
main mass flow controller 32 is branched into the three fifth
sub-gas supply paths 33a, 33b, and 33c and the one sixth sub-gas
supply path 33d. The third manometer 61 monitors the pressure of
the third main gas supply path 31.
[0045] Third sub-mass flow controllers 34a, 34b, and 34c are
provided in the three fifth sub-gas supply paths 33a, 33b, and 33c,
respectively. The third sub-mass flow controllers 34a, 34b, and 34c
control the flow rate of the diluent gas that flows through the
fifth sub-gas supply paths 33a, 33b, and 33c, respectively. The
third sub-mass flow controllers 34a, 34b, and 34c are a flow rate
control type.
[0046] A sixth sub-mass flow controller 34d of an opening position
control type is provided in the one sixth sub-gas supply path 33d.
The sixth sub-gas supply path 33d supplies the diluent gas to one
reactor 10d other than three reactors 10a, 10b, and 10c to which
the fifth sub-gas supply paths 33a, 33b, and 33c supply the diluent
gas, respectively. In the total amount of diluent gas supplied from
the third main gas supply path 31, the remainder of the diluent gas
which does not flow through the fifth sub-gas supply paths 33a,
33b, and 33c flows from the sixth sub-gas supply path 33d to the
reactor 10d.
[0047] Specifically, the degree of opening of the sixth sub-mass
flow controller 34d is controlled on the basis of the measurement
result of the pressure of the third main gas supply path 31
monitored by the third manometer 61. For example, the degree of
opening of the sixth sub-mass flow controller 34d is controlled
such that the pressure monitored by the third manometer 61 is zero.
According to this structure, in the total amount of diluent gas
supplied from the third main gas supply path 31, the remainder of
the diluent gas which does not flow through the fifth sub-gas
supply paths 33a, 33b, and 33c can flow from the sixth sub-gas
supply path 33d to the reactor 10d.
[0048] Four adjustment gas supply paths 131a, 131b, 131c, and 131d
are connected to the fifth sub-gas supply paths 33a, 33b, and 33c
and the sixth sub-gas supply path 33d, respectively. The adjustment
gas supply paths 131a, 131b, 131c, and 131d are connected to the
fifth sub-gas supply paths 33a, 33b, and 33c and the sixth sub-gas
supply path 33d at the positions that are closer to the reactors
10a, 10b, 10c, and 10d than to the third sub-mass flow controllers
34a, 34b, and 34c and the sixth sub-mass flow controller 34d,
respectively.
[0049] The adjustment gas supply paths 131a, 131b, 131c, and 131d
supply the diluent gas to the fifth sub-gas supply paths 33a, 33b,
and 33c and the sixth sub-gas supply path 33d, respectively. Inert
gas, such as hydrogen gas, nitrogen gas, or argon gas, is supplied
to the adjustment gas supply paths 131a, 131b, 131c, and 131d.
[0050] Adjustment mass flow meters 134a, 134b, 134c, and 134d are
provided in the adjustment gas supply paths 131a, 131b, 131c, and
131d, respectively. The adjustment mass flow meters 134a, 134b,
134c, and 134d adjust the amount of diluent gas supplied to the
fifth sub-gas supply paths 33a, 33b, and 33c and the sixth sub-gas
supply path 33d, respectively. The adjustment mass flow meters
134a, 134b, 134c, and 134d are, for example, a flow rate control
type.
[0051] The adjustment gas supply paths 131a, 131b, 131c, and 131d
independently adjust the flow rate of the diluent gas supplied to
the reactors 10a, 10b, 10c, and 10d. The concentration of the
group-III element and the group-V element in the process gas
supplied to the reactors can be independently adjusted by the
adjustment gas supply paths 131a, 131b, 131c, and 131d.
[0052] The vapor phase growth apparatus according to this
embodiment includes four sub-gas exhaust paths 15a, 15b, 15c, and
15d through which gas is discharged from the four reactors 10a,
10b, 10c, and 10d. In addition, the vapor phase growth apparatus
includes a main gas exhaust path 16 that is connected to the four
sub-gas exhaust paths 15a, 15b, 15c, and 15d. A vacuum pump 17 for
drawing gas is provided in the main gas exhaust path 16. The vacuum
pump 17 is an example of a pump.
[0053] In addition, the vapor phase growth apparatus according to
this embodiment includes a controller 19. The controller 19
controls the flow rate of the first process gas and the flow rate
of the second process gas, on the basis of the control values of
the flow rates of the first process gas and the second process gas
supplied to the four reactors 10a, 10b, 10c, and 10d. Furthermore,
the controller 19 independently controls predetermined process
parameters which are independently set for the four reactors 10a,
10b, 10c, and 10d, on the basis of the control values of the
predetermined process parameters.
[0054] The controller 19 can control the control values of the
process parameters of the four reactors 10a, 10b, 10c, and 10d
under the same conditions, that is, in the same process recipe, at
the same time. In addition, the controller 19 performs control such
that four operations, that is, a first process gas supply start
operation, a first process gas supply shut off operation, a second
process gas supply start operation, and a second process gas supply
shut off operation are performed in the four reactors 10a, 10b,
10c, and 10d at the same time.
[0055] The controller 19 can perform control such that the control
values of the predetermined process parameters of the four reactors
10a, 10b, 10c, and 10d are independently set for the four reactors
10a, 10b, 10c, and 10d and films are grown on the substrates at the
same time in the four reactors 10a, 10b, 10c, and 10d, in order to
match the characteristics of the films formed in the four reactors
10a, 10b, 10c, and 10d.
[0056] The predetermined process parameters which can be
independently set are at least one of the control values of the
concentration of the group-III element and the group-V element
supplied to the reactors, the rotation speed of the substrate, the
temperature of the substrate, and an output from a heater.
[0057] The controller 19 includes a calculator 19a. The calculator
19a has a function of calculating the control values of the
predetermined process parameters from information about the
correlation between the characteristics of the films obtained in
advance in the four reactors 10a, 10b, 10c, and 10d and the
predetermined process parameters and the characteristics of the
films obtained in advance in the four reactors 10a, 10b, 10c, and
10d.
[0058] The controller 19 is, for example, a controller. The
controller is, for example, hardware or a combination of hardware
and software.
[0059] The controller 19 controls the amount of diluent gas
supplied, on the basis of, for example, the control value of the
concentration of the group-III element and the group-V element
independently set for each of the four reactors 10a, 10b, 10c, and
10d.
[0060] FIG. 2 is a cross-sectional view schematically illustrating
the reactor of the vapor phase growth apparatus according to this
embodiment. FIG. 2 illustrates one of the four reactors 10a, 10b,
10c, and 10d, for example, the reactor 10a. The four reactors 10a,
10h, 10c, and 10d have the same structure.
[0061] As illustrated in FIG. 2, the reactor 10a according to this
embodiment includes, for example, a wall surface 100 of a stainless
cylindrical hollow body. A shower plate 101 is provided in an upper
part of the reactor 10a. The shower plate 101 supplies the process
gas into the reactor 10a.
[0062] The reactor 10a includes a support portion 112. A
semiconductor wafer (substrate) W can be placed on the support
portion 112. The support portion 112 is, for example, an annular
holder that has an opening formed at the center thereof or a
susceptor without an opening.
[0063] The first sub-gas supply path 13a, the third sub-gas supply
path 23a, and the fifth sub-gas supply path 33a are connected to
the shower plate 101. A plurality of gas ejection holes for
ejecting the first process gas, the second process gas, and the
diluent gas which are mixed in the shower plate 101 into the
reactor 10a are provided in the surface of the shower plate 101
close to the reactor 10a.
[0064] The reactor 10a includes a rotary driver 114. The support
portion 112 is provided above the rotary driver 114.
[0065] In the rotary driver 114, a rotating shaft 118 is connected
to a rotary driver 120. The rotary driver 120 can rotate the
semiconductor wafer W placed on the support portion 112 at a speed
that is, for example, equal to or greater than 50 rpm and equal to
or less than 3000 rpm. The rotary driver 120 is, for example, a
motor.
[0066] The rotary driver 114 includes a heater 116 that heats the
wafer W placed on the support portion 112. The heater 116 is, for
example, a heater.
[0067] The heater 116 is provided in the rotary driver 114 so as to
be fixed. Power is supplied to the heater 116 through an electrode
122 that passes through the rotating shaft 118 to control the
output of the heater 116 from 0% to 100%. In addition, a push up
pin (not illustrated) that passes through the heater 116 is
provided in order to attach or detach the semiconductor wafer W to
or from the support portion 112.
[0068] A gas discharge portion 126 is provided at the bottom of the
reactor 10a. The gas discharge portion 126 discharges a reaction
product obtained by the reaction of source gas on the surface of
the semiconductor wafer W and the process gas remaining in the
reactor 10a to the outside of the reactor 10a. The gas discharge
portion 126 is connected to the sub-gas exhaust path 15a (FIG.
1).
[0069] A wafer inlet and a gate valve (not illustrated) are
provided in the wall surface 100 of the reactor 10a. The
semiconductor wafer W can be loaded to or unloaded from the reactor
10a by the wafer inlet and the gate valve.
[0070] A vapor phase growth method according to this embodiment
uses the epitaxial growth apparatus illustrated in FIGS. 1 and 2.
Next, the vapor phase growth method according to this embodiment
will be described. An example in which a stacked film obtained by
stacking a plurality of first nitride semiconductor films including
indium (In) and gallium (Ga) and a plurality of second nitride
semiconductor films including gallium (Ga) is formed on a GaN film
will be described. The first nitride semiconductor film and the
second nitride semiconductor film are single-crystal films which
are formed by epitaxial growth. The stacked film is, for example, a
multi-quantum well (MQW) layer of a light emitting diode (LED).
[0071] In the vapor phase growth method according to this
embodiment, first, a variation in the characteristics of a film
which is formed on a substrate for a test (test substrate) in each
of the reactors 10a, 10b, 10c, and 10d is evaluated. The
characteristics of the film are the thickness and composition of
the film. When a film is grown on the test substrate, the
controller 19 controls the process parameters of the four reactors
10a, 10b, 10c, and 10d with the same initial control value.
[0072] First, a semiconductor wafer W2, which is an example of the
test substrate, is loaded to each of the four reactors 10a, 10b,
10c, and 10d. GaN films are formed on a plurality of semiconductor
wafers W2 in advance.
[0073] An indium gallium nitride (InGaN) film and a gallium nitride
(GaN) film are alternately grown on the GaN film of the
semiconductor wafer W2. When the InGaN film is formed, a mixed gas
(first process gas) of TMG and TMI having, for example, nitrogen
gas as carrier gas is supplied from the first main gas supply path
11 to each of the four reactors 10a, 10b, 10c, and 10d. In
addition, for example, ammonia (second process gas) is supplied
from the second main gas supply path 21 to each of the four
reactors 10a, 10b, 10c, and 10d.
[0074] When the GaN film is formed on the semiconductor wafer W2,
TMG (first process gas) having, for example, nitrogen gas as
carrier gas is supplied from the first main gas supply path 11 to
each of the four reactors 10a, 10b, 10c, and 10d. In addition, for
example, ammonia (second process gas) is supplied from the second
main gas supply path 21 to each of the four reactors 10a, 10b, 10c,
and 10d.
[0075] The first process gas, of which the flow rate has been
controlled by the first main mass flow controller 12, flows to the
first main gas supply path 11. The first process gas is distributed
and flows to the three first sub-gas supply paths 13a, 13b, and 13c
and the one second sub-gas supply path 13d which are branched from
the first main gas supply path 11.
[0076] The flow rates of the first process gases distributed to the
three first sub-gas supply paths 13a, 13b, and 13c are controlled
by the first sub-mass flow controllers 14a, 14b, and 14c,
respectively. For example, the flow rates of the first process
gases controlled by the first sub-mass flow controllers 14a, 14b,
and 14c are set such that a quarter (1/4) of the total amount of
first process gas set by the first main mass flow controller 12
flows.
[0077] In addition, the degree of opening of the fourth sub-mass
flow controller 14d is controlled such that the pressure of the
first main gas supply path 11 monitored by the first manometer 41
is zero. In this way, the remainder of the first process gas which
does not flow through the three first sub-gas supply paths 13a,
13b, and 13c, that is, the amount of first process gas which
corresponds to a quarter (1/4) of the total amount of first process
gas flows to the remaining one second sub-gas supply path 13d. The
first process gases distributed from the first main gas supply path
11 to the three first sub-gas supply paths 13a, 13b, and 13c and
the second sub-gas supply path 13d are supplied to the four
reactors 10a, 10b, 10c, and 10d, respectively.
[0078] A predetermined amount of first process gas is distributed
and the supply of the first process gas to each of the four
reactors 10a, 10b, 10c, and 10d at a flow rate that is controlled
on the basis of the control value of a first flow rate starts at
the same time.
[0079] The second process gas, of which the flow rate has been
controlled by the second main mass flow controller 22, flows to the
second main gas supply path 21. Then, the second process gas is
distributed and flows to three third sub-gas supply paths 23a, 23b,
and 23c and one fourth sub-gas supply path 23d which are branched
from the second main gas supply path 21.
[0080] The flow rates of the second process gases distributed to
the three third sub-gas supply paths 23a, 23b, and 23c are
controlled by the second sub-mass flow controllers 24a, 24b, and
24c, respectively. For example, the flow rates of the second
process gases controlled by the second sub-mass flow controllers
24a, 24b, and 24c are set such that a quarter (1/4) of the total
amount of second process gas set by the second main mass flow
controller 22 flows.
[0081] In addition, the degree of opening of the fifth sub-mass
flow controller 24d is controlled such that the pressure of the
second main gas supply path 21 monitored by the second manometer 51
is zero. In this way, the remainder of the second process gas which
does not flow through the three third sub-gas supply paths 23a,
23b, and 23c, that is, the amount of second process gas which
corresponds to a quarter (1/4) of the total amount of second
process gas flows to the remaining one fourth sub-gas supply path
23d. The second process gases distributed from the second main gas
supply path 21 to the three third sub-gas supply paths 23a, 23b,
and 23c and the fourth sub-gas supply path 23d are supplied to the
four reactors 10a, 10b, 10c, and 10d, respectively.
[0082] A predetermined amount of second process gas is distributed
and the supply of the second process gas to each of the four
reactors 10a, 10b, 10c, and 10d at a flow rate that is controlled
on the basis of the control value of a second flow rate starts at
the same time.
[0083] When an InGaN film and a GaN film are alternately grown on
the GaN film of the semiconductor wafer W2, the controller 19
performs control such that four operations, that is, the first
process gas supply start operation, the first process gas supply
shut off operation, the second process gas supply start operation,
and the second process gas supply shut off operation are performed
in the four reactors 10a, 10b, 10c, and 10d at the same time.
[0084] When an InGaN film and a GaN film are alternately grown on
the GaN film of the semiconductor wafer W2, the diluent gas is
supplied from the third main gas supply path 31 to the four
reactors 10a, 10b, 10c, and 10d on the basis of the same initial
control value.
[0085] When an InGaN film and a GaN film are alternately grown on
the GaN film of the semiconductor wafer W2, the initial control
values of three process parameters, that is, the concentration of
the group-III element and the group-V element supplied to the four
reactors 10a, 10b, 10c, and 10d, the rotation speed of the
semiconductor wafer W2, and the temperature of the semiconductor
wafer W2 are set to the same value for the four reactors 10a, 10b,
10c, and 10d and films are grown on a plurality of semiconductor
wafers W2 in the four reactors 10a, 10b, 10c, and 10d at the same
time.
[0086] The control value of the concentration of the group-III
element and the group-V element supplied to the four reactors 10a,
10b, 10c, and 10d is, for example, the flow rate control values of
the first main mass flow controller 12 and the second main mass
flow controller 22. The control value of the rotation speed of the
semiconductor wafer W2 is the rotation number control value of the
rotary driver 114. The control value of the temperature of the
semiconductor wafer W2 is, for example, the control value of power
supplied to the heater 116.
[0087] The first process gas, the second process gas, and the
diluent gas are supplied to each of the reactors 10a, 10b, 10c, and
10d by the above-mentioned method and a stacked film obtained by
alternately stacking the InGaN film and the GaN film is formed on
the semiconductor wafer W2.
[0088] Then, the semiconductor wafers W2 are unloaded from the four
reactors 10a, 10b, 10c, and 10d and the characteristics of the
films grown on the semiconductor wafer W2 are measured. The
characteristics of the film are, for example, the thickness and
composition of the film. For example, the thickness of the film can
be measured on an image captured by a transmission electron
microscope (TEM). The composition of the film can be measured by,
for example, a secondary ion mass spectrometry (SIMS).
[0089] In the subsequent process, when the same stacked film is
grown, the control values of the process parameters to be set are
determined on the basis of the characteristics of the films grown
on the test semiconductor wafer W2. The process parameters are the
concentration of the group-III element and the group-V element
supplied to the four reactors 10a, 10b, 10c, and 10d, the rotation
speed of the semiconductor wafer W2, and the temperature of the
semiconductor wafer W2.
[0090] For example, the calculator 19a of the controller 19
calculates the control values of the concentration of the group-III
element and the group-V element, the rotation speed of the
semiconductor wafer W2, and the temperature of the semiconductor
wafer W2 from information about the correlation among the thickness
and composition of the film obtained in advance in each of the four
reactors 10a, 10b, 10c, and 10d, the concentration of the group-III
element and the group-V element, the rotation speed of the
semiconductor wafer W2, and the temperature of the semiconductor
wafer W2 and the thickness and composition of the film obtained
from the semiconductor wafer W2.
[0091] The control values of the process parameters which are set
for each of the reactors 10a, 10b, 10c, and 10d are set such that
the films grown in the reactors 10a, 10b, 10c, and 10d have the
same thickness and composition.
[0092] Then, a semiconductor wafer W1 which is an example of the
substrate is loaded to each of the four reactors 10a, 10b, 10c, and
10d. A GaN film is formed on the semiconductor wafer W1 in
advance.
[0093] An InGaN film and a GaN film are alternately grown on the
GaN film of the semiconductor wafer W1. When the InGaN film is
formed, a mixed gas (first process gas) of TMG and TMI having, for
example, nitrogen gas as carrier gas is supplied from the first
main gas supply path 11 to each of the four reactors 10a, 10b, 10c,
and 10d. In addition, for example, ammonia (second process gas) is
supplied from the second main gas supply path 21 to each of the
four reactors 10a, 10b, 10c, and 10d.
[0094] When the GaN film is formed on the semiconductor wafer W1,
TMG (first process gas) having, for example, nitrogen gas as
carrier gas is supplied from the first main gas supply path 11 to
each of the four reactors 10a, 10b, 10c, and 10d. In addition, for
example, ammonia (second process gas) is supplied from the second
main gas supply path 21 to each of the four reactors 10a, 10b, 10c,
and 10d.
[0095] The first process gas, of which the flow rate has been
controlled by the first main mass flow controller 12, flows to the
first main gas supply path 11. The first process gas is distributed
and flows to three first sub-gas supply paths 13a, 13b, and 13c and
one second sub-gas supply path 13d which are branched from the
first main gas supply path 11.
[0096] The flow rates of the first process gases distributed to the
three first sub-gas supply paths 13a, 13b, and 13c are controlled
by the first sub-mass flow controllers 14a, 14b, and 14c,
respectively. For example, the flow rates of the first process
gases controlled by the first sub-mass flow controllers 14a, 14b,
and 14c are set such that a quarter (1/4) of the total amount of
first process gas set by the first main mass flow controller 12
flows.
[0097] In addition, the degree of opening of the fourth sub-mass
flow controller 14d is controlled such that the pressure of the
first main gas supply path 11 monitored by the first manometer 41
is zero. In this way, the remainder of the first process gas which
does not flow through the three first sub-gas supply paths 13a,
13b, and 13c, that is, the amount of first process gas which
corresponds to a quarter (1/4) of the total amount of first process
gas flows to the remaining one second sub-gas supply path 13d. The
first process gases distributed from the first main gas supply path
11 to the three first sub-gas supply paths 13a, 13b, and 13c and
the second sub-gas supply path 13d are supplied to the four
reactors 10a, 10b, 10c, and 10d, respectively.
[0098] A predetermined amount of first process gas is distributed
and the supply of the first process gas to each of the four
reactors 10a, 10b, 10c, and 10d at a flow rate that is controlled
on the basis of the control value of a first flow rate starts at
the same time.
[0099] The second process gas, of which the flow rate has been
controlled by the second main mass flow controller 22, flows to the
second main gas supply path 21. Then, the second process gas is
distributed and flows to the three third sub-gas supply paths 23a,
23b, and 23c and the one fourth sub-gas supply path 23d which are
branched from the second main gas supply path 21.
[0100] The flow rates of the second process gases distributed to
the three third sub-gas supply paths 23a, 23b, and 23c are
controlled by the second sub-mass flow controllers 24a, 24b, and
24c, respectively. For example, the flow rates of the second
process gases controlled by the second sub-mass flow controllers
24a, 24b, and 24c are set such that a quarter (1/4) of the total
amount of second process gas set by the second main mass flow
controller 22 flows.
[0101] In addition, the degree of opening of the fifth sub-mass
flow controller 24d is controlled such that the pressure of the
second main gas supply path 21 monitored by the second manometer 51
is zero. In this way, the remainder of the second process gas which
does not flow through the three third sub-gas supply paths 23a,
23b, and 23c, that is, the amount of second process gas which
corresponds to a quarter (1/4) of the total amount of second
process gas flows to the remaining one fourth sub-gas supply path
23d. The second process gases distributed from the second main gas
supply path 21 to the three third sub-gas supply paths 23a, 23b,
and 23c and the fourth sub-gas supply path 23d are supplied to the
four reactors 10a, 10b, 10c, and 10d, respectively.
[0102] A predetermined amount of second process gas is distributed
and the supply of the second process gas to each of the four
reactors 10a, 10b, 10c, and 10d at a flow rate that is controlled
on the basis of the control value of a second flow rate starts at
the same time.
[0103] When an InGaN film and a GaN film are alternately grown on
the GaN film of the semiconductor wafer W1, the controller 19
performs control such that four operations, that is, the first
process gas supply start operation, the first process gas supply
shut off operation, the second process gas supply start operation,
and the second process gas supply shut off operation are performed
in the four reactors 10a, 10b, 10c, and 10d at the same time.
[0104] In addition, the control value of at least one process
parameter that is selected from the concentration of the group-III
element and the group-V element supplied to the reactors 10a, 10b,
10c, and 10d, the rotation speed of the semiconductor wafer W1, and
the temperature of the semiconductor wafer W1 is set for at least
one of the four reactors 10a, 10b, 10c, and 10d such that the
control value is different from those set for the other reactors
and films are grown on the semiconductor wafers W1 in the four
reactors 10a, 10b, 10c, and 10d at the same time.
[0105] The controller 19 independently sets and controls at least
one process parameter among the concentration of the group-III
element and the group-V element in the four reactors 10a, 10b, 10c,
and 10d, the rotation speed of the semiconductor wafer W1, and the
temperature of the semiconductor wafer W1, on the basis of the
control values of the concentration of the group-III element and
the group-V element in the four reactors 10a, 10b, 10c, and 10d,
the rotation speed of the semiconductor wafer W1, and the
temperature of the semiconductor wafer W1.
[0106] In this embodiment, the control values of the concentration
of the group-III element and the group-V element, the rotation
speed of the semiconductor wafer W1, and the temperature of the
semiconductor wafer W1 which have been determined on the basis of
the characteristics of the films grown on the test semiconductor
wafer W2 are applied.
[0107] For example, when the control value of the concentration of
the group-III element and the group-V element is set for a specific
reactor such that the control value is different from those set for
the other reactors, the control value of the flow rate of the
diluent gas which is supplied from the third main gas supply path
31 to the specific reactor is set such that the control value is
different from those set for the other reactors.
[0108] For example, when the control value of the concentration of
the group-III element and the group-V element in the reactor 10a is
less than those in the other three reactors 10b, 10c, and 10d, the
control value of the flow rate of gas adjusted by the adjustment
mass flow meter 134a among the four adjustment mass flow meters
134a, 134b, 134c, and 134d increases. The flow rate of the diluent
gas supplied to the fifth sub-gas supply path 33a increases and the
control value of the concentration of the group-III element and the
group-V element for the reactor 10a is less than those for the
other reactors 10b, 10c, and 10d.
[0109] For example, when the control value of the concentration of
the group-III element and the group-V element for the reactor 10a
is greater than those for the other three reactors 10b, 10c, and
10d, the control values of the flow rates of gas adjusted by three
adjustment mass flowmeter 134b, 134c, 134d among the four
adjustment mass flow meters 134a, 134b, 134c, and 134d are greater
than the control value of the flow rate of gas adjusted by the
adjustment mass flow meter 134a. The flow rate of the diluent gas
supplied to the fifth sub-gas supply path 33a decreases and the
control value of the concentration of the group-III element and the
group-V element for the reactor 10a is greater than those for the
other reactors 10b, 10c, and 10d.
[0110] For example, when the control value of the rotation speed of
the semiconductor wafer W1 for a specific reactor is set to be
different from those for the other reactors, the control value of
the rotation speed of the rotary driver 114 for the specific
reactor is set to be different from those for the other
reactors.
[0111] For example, when the control value of the temperature of
the semiconductor wafer W1 for a specific reactor is set to be
different from those for the other reactors, the control value of
power supplied to the heater 116 for the specific reactor is set to
be different from those for the other reactors.
[0112] The first process gas, the second process gas, and the
diluent gas are supplied to each of the reactors 10a, 10b, 10c, and
10d by the above-mentioned method and stacked films in which an
InGaN film and a GaN film are alternately stacked are formed on a
plurality of semiconductor wafers W1 at the same time.
[0113] Next, the function and effect of the vapor phase growth
apparatus and the vapor phase growth method according to this
embodiment will be described.
[0114] When films having the same characteristics are grown on a
plurality of substrates at the same time, using a plurality of
reactors, the process parameters of the reactors are set to the
same control values. When the process parameters of the reactors
are set to the same control values, it is possible to theoretically
grow films having the same characteristics on a plurality of
substrates at the same time.
[0115] In some cases, even if the process parameters of the
reactors are set to the same control values, a variation in the
characteristics of the films grown in each reactor occurs. The
variation in the characteristics of the film is caused by, for
example, the difference between the control value of each process
parameter and the actual value.
[0116] Among the characteristics of the film to be grown, necessary
characteristics are the thickness and composition of the film. When
films having the same characteristics are grown on a plurality of
substrates at the same time, using a plurality of reactors, it is
assumed that the processing time of each reactor is constant. In
other words, the process gas supply start time and the process gas
supply shutoff time are the same in all of the reactors.
[0117] Therefore, for example, when there is only the difference in
the film thickness between one reactor and the other reactors, it
is necessary to change only the thickness of the film in the same
processing time, without changing the composition of the film, in
order to obtain the same film thickness in the reactors.
[0118] When the control value of the flow rate of the process gas
supplied to a plurality of reactors is changed for each reactor to
independently control the flow rate of the process gas in each
reactor, the structure of the vapor phase growth apparatus becomes
complicated, which is not preferable.
[0119] Therefore, it is preferable that the control value of the
flow rate of the process gas supplied to each reactor is not
independently set. In addition, it is preferable that the control
value of the flow rate of the process gas supplied to each reactor
is not independently controlled.
[0120] FIG. 3 is a diagram illustrating the function and effect of
the vapor phase growth apparatus and the vapor phase growth method
according to this embodiment. FIG. 3 is a diagram illustrating the
relationship among the total flow rate of the process gas, an MQW
period, and the indium composition of films when an InGaN film and
a GaN film are alternately grown to form an MQW.
[0121] The InGaN film is formed using a mixed gas (first process
gas) of TMG and TMI having nitrogen gas as carrier gas and ammonia
(second process gas). The GaN film is formed using TMG (first
process gas) having nitrogen gas as carrier gas and ammonia (second
process gas).
[0122] The flow rate of the diluent gas is changed to change the
total gas flow rate. Therefore, when the total gas flow rate is
high, the concentration of the group-III element and the group-V
element which are supplied is low. In contrast, when the total gas
flow rate is low, the concentration of the group-III element and
the group-V element which are supplied is high.
[0123] The MQW period is a total film thickness when one InGaN film
and one GaN film are formed.
[0124] As can be seen from FIG. 3, the dependence of a change in
the MQW period on a change in the total gas flow rate is large and
the dependence of a change in the composition of indium in the film
on the change in the total gas flow rate is small. When the total
gas flow rate is changed, the thickness and composition of the film
are changed in different ways. Therefore, for example, the flow
rate of the diluent gas can be changed to change only the thickness
of the film in the same processing time, without changing the
composition of the film.
[0125] FIG. 4 is a diagram illustrating the function and effect of
the vapor phase growth apparatus and the vapor phase growth method
according to this embodiment. FIG. 4 is a diagram illustrating the
relationship among the rotation speed of the substrate, an MQW
period, and the indium composition of films when an InGaN film and
a GaN film are alternately grown to form an MQW. In FIG. 4, the
process gas used to form the film is the same as that in FIG.
3.
[0126] As can be seen from FIG. 4, the dependence of a change in
the MQW period on a change in the rotation speed of the substrate
is large and the dependence of a change in the indium composition
of the film on the change in the rotation speed of the substrate is
small. When the rotation speed is changed, the thickness and
composition of the film are changed in different ways. Therefore,
for example, the rotation speed can be changed to change only the
thickness of the film in the same processing time, without changing
the composition of the film.
[0127] FIG. 5 is a diagram illustrating the function and effect of
the vapor phase growth apparatus and the vapor phase growth method
according to this embodiment. FIG. 5 is a diagram illustrating the
relationship among the temperature of the substrate, an MQW period,
and the indium composition of films when an InGaN film and a GaN
film are alternately grown to form an MQW. In FIG. 5, the process
gas used to form the film is the same as that in FIG. 3.
[0128] As can be seen from FIG. 5, the dependence of a change in
the MQW period on a change in the temperature of the substrate is
small and the dependence of a change in the indium composition of
the film on the change in the temperature of the substrate is
large. When the temperature of the substrate is changed, the
thickness and composition of the film are changed in different
ways. Therefore, for example, the temperature of the substrate can
be changed to change only the composition of the film in the same
processing time, without changing the thickness of the film.
[0129] The vapor phase growth apparatus and the vapor phase growth
method according to this embodiment perform control such that the
control value of at least one process parameter selected from the
concentration of the group-III element and the group-V element
supplied to the reactors, the rotation speed of the substrate, and
the temperature of the substrate is independently set for the n
reactors and films are formed on the substrates in the n reactors
at the same time. Therefore, when films are formed on a plurality
of substrates in a plurality of reactors, the characteristics of
the films grown in each reactor can be adjusted so as to be matched
with each other.
Second Embodiment
[0130] A vapor phase growth apparatus according to this embodiment
further includes pressure adjusters which are provided in each of n
sub-gas exhaust paths. A controller performs control such that the
control value of pressure is independently set for the n reactors
and films are grown on substrates in the reactors at the same time.
This is the difference between the vapor phase growth apparatus
according to this embodiment and the vapor phase growth apparatus
according to the first embodiment.
[0131] A vapor phase growth method according to this embodiment
differs from the vapor phase growth method according to the first
embodiment in that the control value of pressure in at least one of
the n reactors is set to be different from the control values of
pressure in the other reactors and films are grown on substrates in
the n reactors at the same time.
[0132] The description of the same parts as those in the first
embodiment will not be repeated.
[0133] FIG. 6 is a diagram illustrating the structure of the vapor
phase growth apparatus according to this embodiment.
[0134] The vapor phase growth apparatus according to this
embodiment includes four sub-gas exhaust paths 15a, 15b, 15c, and
15d that discharge gas from four reactors 10a, 10b, 10c, and 10d.
In addition, the vapor phase growth apparatus includes a main gas
exhaust path 16 that is connected to the four sub-gas exhaust paths
15a, 15b, 15c, and 15d. A vacuum pump 17 for drawing gas is
provided in the main gas exhaust path 16. The vacuum pump 17 is an
example of a pump.
[0135] Pressure adjusters 18a, 18b, 18c, and 18d are provided in
the four sub-gas exhaust paths 15a, 15b, 15c, and 15d,
respectively. The pressure adjusters 18a, 18b, 18c, and 18d adjust
the internal pressure of the reactors 10a, 10b, 10c, and 10d to a
predetermined value, respectively. The pressure adjusters 18a, 18b,
18c, and 18d are, for example, throttle valves.
[0136] A controller 19 performs control such that the control value
of pressure in the four reactors 10a, 10b, 10c, and 10d is
independently set for the four reactors 10a, 10b, 10c, and 10d and
films are grown on substrates in the four reactors 10a, 10b, 10c,
and 10d at the same time.
[0137] In the vapor phase growth method according to this
embodiment, the controller 19 sets the pressure control value of at
least one of the pressure adjusters 18a, 18b, 18c, and 18d so as to
be different from the pressure control values of the other pressure
adjusters. Therefore, the controller 19 performs control such that
the control value of pressure in at least one of the four reactors
10a, 10b, 10c, and 10d is different from the control values of
pressure in the other reactors. Then, films are grown on substrates
in the four reactors 10a, 10b, 10c, and 10d at the same time.
[0138] The vapor phase growth apparatus and the vapor phase growth
method according to this embodiment can independently control the
internal pressure of the n reactors at the same time. Therefore,
when films are formed on a plurality of substrates in a plurality
of reactors at the same time, the characteristics of the films
grown in each reactor can be adjusted so as to be matched with each
other.
Third Embodiment
[0139] A vapor phase growth apparatus according to this embodiment
includes a film thickness measure that can measure the thickness of
a film that is being grown in a reactor. A controller independently
sets at least one of the control values of the concentration of a
group-III element and a group-V element supplied to the reactor,
the rotation speed of a substrate, and the temperature of the
substrate for n reactors, on the basis of the measurement result of
the film thickness by the film thickness measure during the growth
of the film. This is the difference from the vapor phase growth
apparatus according to the first embodiment.
[0140] A vapor phase growth method according to this embodiment
differs from the vapor phase growth method according to the first
embodiment in that at least one of the control values of the
concentration of the group-III element and the group-V element
supplied to the reactor, the rotation speed of a substrate, and the
temperature of the substrate for at least one of the n reactors is
changed to a value that is different from those for the other
reactors, on the basis of the measurement result of the film
thickness by the film thickness measure during the growth of the
film, and films are grown on the substrates in the n reactors at
the same time.
[0141] The description of the same parts as those in the first
embodiment will not be repeated.
[0142] FIG. 7 is a diagram schematically illustrating the reactor
of the vapor phase growth apparatus according to this
embodiment.
[0143] The vapor phase growth apparatus according to this
embodiment includes a film thickness measure 150 that is provided
on a shower plate 101. The film thickness measure 150 can measure
the thickness of a film that is being grown on a wafer W. For
example, the film thickness measure 150 monitors light interference
to measure the thickness of the film that is grown on the
substrate.
[0144] The controller 19 (FIG. 1) independently sets at least one
of the control values of the concentration of the group-III element
and the group-V element supplied to four reactors 10a, 10b, 10c,
and 10d, the rotation speed of the wafer W, and the temperature of
the wafer W for the four reactors 10a, 10b, 10c, and 10d, on the
basis of the measurement result of the film thickness by the film
thickness measure 150 during the growth of the film.
[0145] In the vapor phase growth method according to this
embodiment, the controller 19 changes at least one of the control
values of the concentration of the group-III element and the
group-V element supplied to four reactors 10a, 10b, 10c, and 10d,
the rotation speed of the wafer W, and the temperature of the wafer
W for at least one of the four reactors 10a, 10b, 10c, and 10d to a
value that is different from the control values for the other
reactor, on the basis of the measurement result of the film
thickness by the film thickness measure 150 during the growth of
the film. Then, films are grown on substrates in the four reactors
10a, 10b, 10c, and 10d, on the basis of the changed control
value.
[0146] The vapor phase growth apparatus and the vapor phase growth
method according to this embodiment change the control value of at
least one process parameter among the concentration of the
group-III element and the group-V element supplied to the reactors,
the rotation speed of the wafer W, and the temperature of the wafer
W, on the basis of the measurement result of the film thickness by
the film thickness measure 150 during the growth of the film. Then,
control is performed such that films are grown on substrates in the
n reactors at the same time on the basis of the changed control
value. Therefore, even if it is determined that there is an error
in the thickness of the film which is being grown, a variation in
the characteristics of the films between the reactors can be
adjusted such that the characteristics of the films are matched
with each other.
Fourth Embodiment
[0147] A vapor phase growth apparatus according to this embodiment
has the same structure as the vapor phase growth apparatus
according to the first embodiment, but a vapor phase growth method
according to this embodiment differs from the vapor phase growth
method according to the first embodiment in that the control value
of the power of the heater is reduced to stop a deposition process
in at least one of n reactors. The description of the same parts as
those in the first embodiment will not be repeated.
[0148] In the vapor phase growth method according to this
embodiment, similarly to the first embodiment, a deposition process
is performed in advance on a semiconductor wafer W1, which is an
example of a substrate, in each of four reactors 10a, 10b, 10c, and
10d on the basis of the control value of each process
parameter.
[0149] When a trouble occurs in the reactor 10a during the
deposition process and it is difficult to continuously perform the
deposition process, the control value of the power of the heater
116 is reduced to 0 kW to stop the deposition process while the
process gas is flowing and the deposition process is continuously
performed in the reactors 10b, 10c, and 10d without any trouble,
similarly to the first embodiment.
[0150] As in the vapor phase growth apparatus according to this
embodiment, in a case in which a predetermined amount of process
gas is distributed and supplied to the reactors at the same time,
when the supply of the process gas to the reactor with a trouble is
stopped, various problems arise. Specifically, for example, it is
difficult to adjust the flow rate due to the lower limit of the
control of the mass flow controller. In addition, a reaction
product is accumulated in, for example, an exhaust valve. As a
result, gas flows out of the reactor 10a or gas flows backward from
the exhaust valve, due to the outflow (internal leakage) of gas
from the valve. Therefore, it is necessary to provide a valve on
the exhaust side. In addition, it is necessary to change the total
flow rate of the process gas and to readjust the control values.
Furthermore, since there is a dead space on the upstream pipe side,
it is necessary to provide a valve in a branch portion.
[0151] However, in this embodiment, even if a trouble occurs in any
one of the reactors, the process gas continuously flows to all of
the reactors. Therefore, it is possible to prevent the
above-mentioned problems.
[0152] In this case, even if a trouble occurs in two or more of the
reactors, it is possible to continuously perform the deposition
process in the other reactors. When the wafer W can be rotated in a
reactor with a trouble, the wafer W may be maintained in a rotated
state or the rotation of the wafer W may be stopped. When the
heater can be turned on, the control value of the power of the
heater is not necessarily reduced to 0 kW in order to stop the
formation of a film on the wafer W and the wafer W may be heated at
a low temperature. That is, the control value of the output of the
heater may be set to a value which is less than the control value
in the deposition process and at which a process gas reaction does
not occur (for example, 0 kW to 5 kW) to stop the formation of a
film. Alternatively, the control value of the temperature of the
substrate is set to the temperature which is less than the control
value in the deposition process and at which a process gas reaction
does not occur (for example, a room temperature to 300.degree. C.)
to stop the formation of a film.
[0153] In this embodiment, control is independently performed for
the reactor with a trouble. However, the invention can be applied
to a case in which there is an odd lot (for example, when one lot
includes 25 wafers and there are four reactors, the remainder is
1). That is, when a new wafer W is processed, the control value of
the power of the heater 116 in the reactor in which the deposition
process is not performed may be set to 0 kW or a small value or the
control value of the temperature of the substrate may be set to a
value that is equal to or greater than the room temperature, while
the process gas is flowing to all of the reactors. In this case, it
is not necessary to readjust the control values of parameters in
the lot and to continuously perform a series of deposition
processes.
[0154] In this case, it is preferable to place a dummy wafer on the
support portion 112 in the reactor in which the deposition process
is not performed, in order to prevent the process gas from flowing
into the rotary driver.
[0155] The embodiments of the invention have been described above
with reference to examples. The above-described embodiments are
illustrative examples and do not limit the invention. In addition,
the components according to each embodiment may be appropriately
combined with each other.
[0156] For example, in the above-described embodiments, examples of
the process parameters have been described. However, the process
parameters are not necessarily limited to the examples. For
example, any process parameters can be used as long as they can be
independently controlled in each reactor at a predetermined time
when the deposition process is performed in the n reactors. That
is, process parameters other than time can be used.
[0157] For example, when the remainder of the process gas which
does not flow to (n-1) sub-gas supply paths is supplied from one
sub-gas supply path to one reactor other than (n-1) reactors,
structures other than the embodiments can be used.
[0158] For example, in the embodiments, the stacked film in which a
plurality of first nitride semiconductor films including indium
(In) and gallium (Ga) and a plurality of second nitride
semiconductor films including gallium (Ga) are stacked on the GaN
film is epitaxial grown. However, for example, the invention can be
applied to form other group III-V nitride-based semiconductor
single-crystal films, such as aluminum nitride (AlN), aluminum
gallium nitride (AlGaN), and indium gallium nitride (InGaN)
single-crystal films. In addition, the invention can be applied to
a group III-V semiconductor such as GaAs.
[0159] In the above-described embodiments, hydrogen gas (H.sub.2)
is used as the carrier gas. However, nitrogen gas (N.sub.2), argon
gas (Ar), helium gas (He), or a combination of the gases can be
applied as the carrier gas.
[0160] In the above-described embodiments, the process gases are
mixed in the shower plate. However, the process gases may be mixed
before they flow into the shower plate. In addition, the process
gases may be in a separated state until they are ejected from the
shower plate into the reactor.
[0161] In the above-described embodiments, the epitaxial apparatus
is the vertical single wafer type in which the deposition process
is performed for each wafer in the n reactors. However, the
application of the n reactors is not limited to the
single-wafer-type epitaxial apparatus. For example, the invention
can be applied a horizontal epitaxial apparatus or a planetary CVD
apparatus that simultaneously forms films on a plurality of wafers
which revolve on their own axes and around the apparatus.
[0162] In the above-described embodiments, for example, portions
which are not necessary to describe the invention, such as the
structure of the apparatus or a manufacturing method, are not
described. However, the necessary structure of the apparatus or a
necessary manufacturing method can be appropriately selected and
used. In addition, all of the vapor phase growth apparatuses and
the vapor phase growth methods which include the components
according to the invention and whose design can be appropriately
changed by those skilled in the art are included in the scope of
the invention. The scope of the invention is defined by the scope
of the claims and the scope of equivalents thereof.
* * * * *