U.S. patent application number 15/694306 was filed with the patent office on 2018-03-08 for vapor phase growth apparatus and vapor phase growth method.
The applicant listed for this patent is NuFlare Technology, Inc.. Invention is credited to Takashi HARAGUCHI, Yoshitaka ISHIKAWA, Yasushi IYECHIKA, Takehiko KOBAYASHI, Kiyotaka MIYANO, Hideshi TAKAHASHI.
Application Number | 20180066381 15/694306 |
Document ID | / |
Family ID | 61282452 |
Filed Date | 2018-03-08 |
United States Patent
Application |
20180066381 |
Kind Code |
A1 |
ISHIKAWA; Yoshitaka ; et
al. |
March 8, 2018 |
VAPOR PHASE GROWTH APPARATUS AND VAPOR PHASE GROWTH METHOD
Abstract
A vapor phase growth apparatus according to an embodiment
includes a reaction chamber, a holder provided in the reaction
chamber, the holder holding a substrate, a heater heating the
substrate, a first reflector facing the holder, the heater being
interposed between the first reflector and the holder, a second
reflector provided between the first reflector and the heater, the
second reflector having a compressive strength or a bending
strength equal to or less than 1000 MPa or a Vickers hardness equal
to or less than 8 GPa, the second reflector having a pattern, and a
rotating shaft fixed to the holder, the rotating shaft rotating the
holder.
Inventors: |
ISHIKAWA; Yoshitaka;
(Yokohama-shi, JP) ; KOBAYASHI; Takehiko;
(Sunto-gun, JP) ; TAKAHASHI; Hideshi;
(Yokohama-shi, JP) ; IYECHIKA; Yasushi;
(Matsudo-shi, JP) ; HARAGUCHI; Takashi;
(Fujisawa-shi, JP) ; MIYANO; Kiyotaka; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NuFlare Technology, Inc. |
Kanagawa |
|
JP |
|
|
Family ID: |
61282452 |
Appl. No.: |
15/694306 |
Filed: |
September 1, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/4584 20130101;
C30B 25/10 20130101; C23C 16/4586 20130101; C23C 16/46 20130101;
H01L 33/06 20130101; H01L 33/007 20130101; C30B 25/04 20130101 |
International
Class: |
C30B 25/04 20060101
C30B025/04; H01L 33/00 20060101 H01L033/00; C30B 25/10 20060101
C30B025/10; C23C 16/458 20060101 C23C016/458 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 5, 2016 |
JP |
2016-172860 |
May 30, 2017 |
JP |
2017-106795 |
Claims
1. A vapor phase growth apparatus comprising: a reaction chamber; a
holder provided in the reaction chamber, the holder holding a
substrate; a heater heating the substrate; a first reflector facing
the holder, the heater being interposed between the first reflector
and the holder; a second reflector provided between the first
reflector and the heater, the second reflector having a compressive
strength or a bending strength equal to or less than 1000 MPa or a
Vickers hardness equal to or less than 8 GPa, the second reflector
having a pattern; and a rotating shaft fixed to the holder, the
rotating shaft rotating the holder.
2. The vapor phase growth apparatus according to claim 1, wherein
at least one of the compressive strength, the bending strength, and
the Vickers hardness of the second reflector is less than that of
the first reflector.
3. The vapor phase growth apparatus according to claim 1, wherein
the first reflector and the second reflector are separated from
each other by a predetermined distance.
4. The vapor phase growth apparatus according to claim 1, wherein
the second reflector is made of a graphite sheet or graphite.
5. A vapor phase growth apparatus comprising: a reaction chamber; a
holder provided in the reaction chamber, the holder holding a
substrate; a heater heating the substrate; a first reflector facing
the holder, the heater being interposed between the first reflector
and the holder; a second reflector provided between the first
reflector and the heater, the second reflector including a first
portion with a first sub-pattern and a second portion with a second
sub-pattern, the first portion and the second portion being
relatively rotatable; and a rotating shaft fixed to the holder, the
rotating shaft rotating the holder.
6. The vapor phase growth apparatus according to claim 5, wherein
the first portion and the second portion are configured to rotate
relatively to change a degree of overlap between the first
sub-pattern and the second sub-pattern.
7. The vapor phase growth apparatus according to claim 5, wherein
the first portion and the second portion are configured to rotate
relatively to change an opening area of the second reflector.
8. The vapor phase growth apparatus according to claim 5, wherein
at least one of the first sub-pattern and the second sub-pattern
has a hole pattern, and the hole pattern does not have a
symmetrical axis passing through the rotation center of the
relative rotation between the first portion and the second
portion.
9. A vapor phase growth method comprising: heating a first
substrate using a heater and a first reflector, the heater being
interposed between the first reflector and the first substrate;
measuring a characteristic distribution of the first substrate
under predetermined process conditions; providing a second
reflector between the first reflector and the heater, the second
reflector having a pattern based on the characteristic
distribution, the second reflector having a compressive strength or
a bending strength equal to or less than 1000 MPa or a Vickers
hardness equal to or less than 8 GPa; heating a second substrate,
using the heater, the first reflector, and the second reflector;
and forming a film, on the second substrate under the predetermined
process conditions.
10. The vapor phase growth method according to claim 9, wherein at
least one of the compressive strength, the bending strength, and
the Vickers hardness of the second reflector is less than that of
the first reflector.
11. The vapor phase growth method according to claim 9, wherein the
first reflector and the second reflector are separated from, each
other by a predetermined distance.
12. The vapor phase growth method according to claim 9, wherein,
the second reflector is made of a graphite sheet or graphite.
13. The vapor phase growth method according to claim 9, wherein the
characteristic distribution is a temperature distribution.
14. A vapor phase growth method comprising: heating a first
substrate, using a heater and a reflector with a first pattern, the
heater being interposed between the reflector and the first
substrate; measuring a characteristic distribution of the first
substrate under predetermined process conditions; and forming a
film on a second substrate under the predetermined process
conditions, using the heater and the reflector changed to a second
pattern different from the first pattern on the basis of the
characteristic distribution.
15. The vapor phase growth method according to claim 14, wherein
the reflector is configured to attach and detach an adjuster, and
the adjuster is attached or detached to change the pattern of the
reflector from the first pattern to the second pattern.
16. The vapor phase growth method according to claim 14, wherein
the reflector includes a first portion with a first sub-pattern and
a second portion with a second sub-pattern, and the first portion
and the second portion are configured to rotate relatively to
change a pattern of the reflector from the first pattern to the
second pattern.
17. The vapor phase growth method according to claim 14, wherein
the characteristic distribution is a temperature distribution.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from Japanese Patent Applications No. 2016-172860, filed
on Sep. 5, 2016, and, Japanese Patent Applications No. 2017-106795,
filed on May 30, 2017, 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 and 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 holder in a reaction chamber
which is maintained at atmospheric 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 reaction
chamber to the surface of the wafer in the reaction chamber 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] The characteristics of the epitaxial single-crystal film
formed on the surface of the wafer, for example, the thickness,
chemical composition, and crystallinity of the epitaxial
single-crystal film depend on the temperature of the wafer during
deposition. Therefore, the characteristics of the film vary
depending on the temperature distribution of the wafer. For this
reason, it is preferable to easily adjust the temperature
distribution of the wafer to a desired temperature distribution. JP
2012-69689 discloses a vapor phase growth apparatus including a
reflector in which holes with different diameters are provided in
order to arbitrarily adjust the temperature distribution.
[0005] However, for example, when the temperature distribution of
the wafer is adjusted by the shape of a heater or the shape of a
reflector made of a material that is difficult to process, it takes
a long time to perform the adjustment and productivity is reduced.
For example, it takes a long time to change the design of a heater
or a reflector and to manufacture a new heater or a new
reflector.
SUMMARY OF THE INVENTION
[0006] According to an aspect of the invention, there is provided a
vapor phase growth apparatus including: a reaction chamber; a
holder provided in the reaction chamber, the holder holding a
substrate; a heater heating the substrate; a first reflector facing
the holder, the heater being interposed between the first reflector
and the holder; a second reflector provided between the first
reflector and the heater, the second reflector having a compressive
strength or a bending strength equal to or less than 1000 MPa or a
Vickers hardness equal to or less than 8 GPa, the second reflector
having a pattern; and a rotating shaft fixed to the holder, the
rotating shaft rotating the holder.
[0007] According to another aspect of the invention, a vapor phase
growth apparatus including: a reaction chamber;
[0008] a holder provided in the reaction chamber, the holder
holding a substrate; a heater heating the substrate; a first
reflector facing the holder, the heater being interposed between
the first reflector and the holder; a second reflector provided
between the first reflector and the heater, the second reflector
including a first portion with a first sub-pattern and a second
portion with a second sub-pattern, the first portion and the second
portion being relatively rotatable; and a rotating shaft fixed to
the holder, the rotating shaft rotating the holder.
[0009] According to still another aspect of the invention, there is
provided a vapor phase growth method including: heating a first
substrate using a heater and a first reflector, the heater being
interposed between the first reflector and the first substrate;
measuring a characteristic distribution of the first substrate
under predetermined process conditions; providing a second
reflector between the first reflector and the heater, the second
reflector having a pattern based on the characteristic
distribution, the second reflector having a compressive strength or
a bending strength equal to or less than 1000 MPa or a Vickers
hardness equal to or less than 8 GPa; heating a second substrate,
using the heater, the first reflector, and the second reflector;
and forming a film on the second substrate under the predetermined
process conditions.
[0010] According to yet another aspect of the invention, there is
provided a vapor phase growth method including: heating a first
substrate, using a heater and a reflector with a first pattern, the
heater being interposed between the reflector and the first
substrate; measuring a characteristic distribution of the first
substrate under predetermined process conditions; and forming a
film on a second substrate under the predetermined process
conditions, using the heater and the reflector changed to a second
pattern different from the first pattern on the basis of the
characteristic distribution.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a cross-sectional view schematically illustrating
a vapor phase growth apparatus according to a first embodiment;
[0012] FIGS. 2A and 2B are plan views schematically illustrating an
example of a reflector according to the first embodiment;
[0013] FIGS. 3A and 3B are cross-sectional views schematically
illustrating an example of the reflector according to the first
embodiment;
[0014] FIG. 4 is a cross-sectional view schematically illustrating
a vapor phase growth apparatus according to a third embodiment;
[0015] FIG. 5 is a plan view schematically illustrating an example
of a reflector according to the third embodiment;
[0016] FIGS. 6A and 6B are cross-sectional views schematically
illustrating an example of a reflector according to a fourth
embodiment;
[0017] FIGS. 7A and 7B are cross-sectional views schematically
illustrating an example of a reflector according to a fifth
embodiment;
[0018] FIG. 8 is a cross-sectional view schematically illustrating
an example of a reflector according to a sixth embodiment;
[0019] FIGS. 9A and 9B are plan views schematically illustrating an
example of a reflector according to a seventh embodiment;
[0020] FIGS. 10A and 10B are plan views schematically illustrating
an example of a reflector according to an eighth embodiment;
[0021] FIGS. 11A and 11B are plan views schematically illustrating
an example of the reflector according to the eighth embodiment;
[0022] FIG. 12 is a plan view schematically illustrating a
reflector according to Example 1;
[0023] FIG. 13 is a diagram illustrating the temperature
distributions of wafers according to Example 1 and Comparative
Example 1;
[0024] FIGS. 14A and 14B are plan views schematically illustrating
a reflector according to Example 2;
[0025] FIG. 15 is a plan view schematically illustrating the
reflector according to Example 2;
[0026] FIG. 16 is a diagram illustrating the emission wavelength
distributions of MQW layers according to Example 2, Example 3, and
Comparative Example 2;
[0027] FIGS. 17A, 17B, 17C, and 17D are diagrams schematically
illustrating an example of a reflector according to a ninth
embodiment;
[0028] FIGS. 18A, 18B, 18C, 18D, and 18E are diagrams illustrating
a change in a pattern of an adjustment reflector according to the
ninth embodiment;
[0029] FIGS. 19A, 19B, 19C, and 19D are diagrams schematically
illustrating an example of a reflector according to a tenth
embodiment;
[0030] FIGS. 20A, 20B, 20C, 20D, 20E, and 20F are diagrams
illustrating a change in a pattern of an adjustment reflector
according to the tenth embodiment;
[0031] FIGS. 21A and 21B are diagrams illustrating a change in the
pattern of the adjustment reflector according to the tenth
embodiment;
[0032] FIGS. 22A, 22B, 22C, and 22D are diagrams schematically
illustrating an example of a reflector according to an eleventh
embodiment;
[0033] FIGS. 23A, 23B, 23C, 23D, 23E, and 23F are diagrams
illustrating a change in a pattern of an adjustment reflector
according to the eleventh embodiment;
[0034] FIGS. 24A, 24B, 24C, 24D, and 24E are diagrams schematically
illustrating an example of a reflector according to a twelfth
embodiment; and
[0035] FIGS. 25A, 25B, 25C, and 25D are diagrams illustrating a
change in a pattern of an adjustment reflector according to the
twelfth embodiment.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0036] Hereinafter, embodiments of the invention will be described
with reference to the drawings.
[0037] In the specification, in some cases, the same or similar
members are denoted by the same reference numerals.
[0038] 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.
[0039] 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
[0040] A vapor phase growth apparatus according to this embodiment
includes: a reaction chamber; a holder which is provided in the
reaction chamber and on which a substrate is placed; a heater that
heats the substrate; a first reflector that is provided so as to
face the holder with the heater interposed therebetween; a second
reflector that is provided between the first reflector and the
heater, has a compressive strength or a bending strength equal to
or less than 1000 MPa or a Vickers hardness equal to or less than 8
GPa, and has a pattern; and a rotating shaft that is fixed to the
holder and rotates the holder.
[0041] In addition, a vapor phase growth method according to this
embodiment includes: heating a first substrate, using a heater and
a first reflector that is opposite to the first substrate with the
heater interposed therebetween; measuring a characteristic
distribution of the first substrate under predetermined process
conditions; providing a second reflector, which has a pattern based
on the characteristic distribution and has a compressive strength
or a bending strength equal to or less than 1000 MPa or a Vickers
hardness equal to or less than 8 GPa, between the first reflector
and the heater; heating a second substrate, using the heater, the
first reflector, and the second reflector; and forming a film on
the second substrate under the predetermined process
conditions.
[0042] In the manufacturing method according to this embodiment, an
example in which a "characteristic distribution" is a "temperature
distribution" will be described.
[0043] The above-mentioned configuration of the vapor phase growth
apparatus and the vapor phase growth method according to this
embodiment makes it possible to easily adjust the temperature
distribution of the substrate at a film forming process.
[0044] FIG. 1 is a cross-sectional view schematically illustrating
the vapor phase growth apparatus according to this embodiment. The
vapor phase growth apparatus according to this embodiment is, for
example, an epitaxial growth apparatus that uses a metal organic
chemical vapor deposition method (MOCVD method).
[0045] The vapor phase growth apparatus according to this
embodiment includes a reaction chamber 10, a first gas supply path
11, a second gas supply path 12, and a third gas supply path 13.
The reaction chamber 10 includes a ring-shaped holder 14, a
rotating unit 16, a rotating shaft 18, a rotating mechanism 20, a
shower plate 22, an in-heater 24, an out-heater 26, a standard
reflector (first reflector) 28, an adjustment reflector (second
reflector) 30, a support portion 32, a support column 34, a fixed
table 36, a fixed shaft 38, and a gas outlet 40.
[0046] The first gas supply path 11, the second gas supply path 12,
and the third gas supply path 13 supply process gas to the reaction
chamber 10.
[0047] The first gas supply path 11 supplies, for example, a first
process gas including organic metal, where the metal is a group-III
element, and carrier gas to the reaction chamber 10. The first
process gas is gas including a group-III element when a group III-V
semiconductor film is formed on a wafer.
[0048] 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).
[0049] The second gas supply path 12 supplies, for example, a
second process gas including ammonia (NH.sub.3) to the reaction
chamber 10. The second process gas is a source gas of a group-V
element or nitrogen (N) when a group III-V semiconductor film is
formed on a wafer.
[0050] The third gas supply path 13 supplies, for example, a
diluent gas which dilutes the first process gas and the second
process gas to the reaction chamber 10. 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 reaction chamber 10. The diluent gas is inert gas,
such as hydrogen gas, nitrogen gas, or argon gas, or a mixed gas
thereof.
[0051] The reaction chamber 10 includes, for example, a stainless
cylindrical wall surface 15. The shower plate 22 is provided in an
upper part of the reaction chamber 10. A plurality of gas ejection
holes are provided in the shower plate 22. The process gas is
supplied from the plurality of gas ejection holes to the reaction
chamber 10.
[0052] The ring-shaped holder 14 is provided in the reaction
chamber 10. A wafer (substrate) W can be placed on the ring-shaped
holder 14, An opening portion is provided at the center of the
ring-shaped holder 14.
[0053] The ring-shaped holder 14 is fixed to an upper part of the
rotating unit 16. The rotating unit 16 is fixed to the rotating
shaft 18. The ring-shaped holder 14 is indirectly fixed to the
rotating shaft 18.
[0054] The rotating shaft 18 can be rotated by the rotating
mechanism 20. The rotating mechanism 20 can rotate the rotating
shaft to rotate the ring-shaped holder 14. The ring-shaped holder
14 is rotated to rotate the wafer W placed on the ring-shaped
holder 14.
[0055] For example, the wafer W is rotated at a speed that is equal
to or greater than 50 rpm and equal to or less than 3000 rpm. The
rotating mechanism 20 includes, for example, a motor and a
bearing.
[0056] A heater that heats the wafer W from a lower surface (rear
surface) side includes the in-heater 24 and the out-heater 26. The
in-heater 24 and the out-heater 26 are provided below the
ring-shaped holder 14. The in-heater 24 and the out-heater 26 are
provided in the rotating unit 16. The out-heater 26 is provided
between the in-heater 24 and the ring-shaped holder 14.
[0057] The in-heater 24 and the out-heater 26 heat the wafer W held
by the ring-shaped holder 14 and the ring-shaped holder 14. The
in-heater 24 mainly heats a central portion of the wafer W. The
out-heater 26 mainly heats an outer circumferential portion of the
wafer W and the ring-shaped holder 14. The in-heater 24 has, for
example, a disk shape. The out-heater 26 has, for example, a ring
shape.
[0058] The standard reflector 28 is provided below the in-heater 24
and the out-heater 26. The in-heater 24 and the out-heater 26 are
provided between the standard reflector 28 and the ring-shaped
holder 14.
[0059] The standard reflector 28 reflects heat that is radiated
downward from, the in-heater 24 and the out-heater 26 to improve
the heating efficiency of the wafer W. In addition, the standard
reflector 28 prevents members below the standard reflector 28 from
being heated. The standard reflector 28 has, for example, a disk
shape.
[0060] The standard reflector 28 is made of a material with high
heat resistance. The standard reflector 28 has, for example,
resistance to a heat temperature of 1100.degree. C. or more.
[0061] The standard reflector 28 is fixed to the fixed table 36 by,
for example, a plurality of support columns 34. The fixed table 36
is supported by, for example, the fixed shaft 38.
[0062] The standard reflector 28 is made of ceramics or metal. The
standard reflector 28 can be made of ceramics, such as silicon
carbide (SiC), graphite, pyrolytic graphite (PG), pyrolytic boron
nitride (PBN), or tantalum carbide (TaC). In addition,
high-melting-point metal, such as tungsten, molybdenum, or rhenium,
can be used as metal. For example, a material obtained by coating a
base material, such as graphite, with SiC, PBN, PG, or TaC can be
used.
[0063] The adjustment reflector 30 is provided between the standard
reflector 28 and the in-heater 24. The adjustment reflector 30 has
a pattern. The pattern of the adjustment reflector 30 is adjusted
to easily adjust the temperature distribution of the wafer W.
[0064] The adjustment reflector 30 is made of a material with high
heat resistance. The adjustment reflector 30 has, for example,
resistance to a heat temperature of 1100.degree. C. or more.
[0065] The compressive strength or bending strength of the
adjustment reflector 30 is equal to or less than 1000 MPa, or the
Vickers hardness of the adjustment reflector 30 is equal to or less
than 8 GPa. The adjustment reflector 30 is made of a material that
has a compressive strength or a bending strength equal to or less
than 1000 MPa or a material that has a Vickers hardness equal to or
less than 8 GPa. At least one of the compressive strength, bending
strength, and Vickers hardness of the adjustment reflector 30 is
within the above-mentioned strength range. Since the strength of
the adjustment reflector 30 is within the above-mentioned strength
range, it is easy to process the adjustment reflector 30 in a
desired pattern, using, for example, drilling and bending.
[0066] In order to satisfy the above-mentioned strength range, the
adjustment reflector 30 can be made of, for example, graphite
sheet, graphite, pyrolytic graphite (PG), a carbon fiber reinforced
carbon composite (C/C composite), sintered boron nitride (hBN), or
a mixture of sintered boron nitride (hBN) and silicon nitride. It
is particularly preferable that the adjustment reflector 30 be made
of a graphite sheet or graphite since the graphite sheet or
graphite is easy to process and is inexpensive.
[0067] For example, at least one of the compressive strength,
bending strength, and Vickers hardness of the adjustment reflector
30 is less than that of the standard reflector 28.
[0068] For example, when the standard reflector 28 is made of
silicon carbide, the adjustment reflector 30 may be made of a
graphite sheet.
[0069] For example, a plurality of support portions 32 are provided
between the adjustment reflector 30 and the standard reflector 28.
The standard reflector 28 and the adjustment reflector 30 are
separated from each other by a predetermined distance, with the
plurality of support portions 32 interposed therebetween.
[0070] FIGS. 2A and 2B are plan views schematically illustrating an
example of the reflector according to this embodiment. FIG. 2A
illustrates the standard reflector 28 and FIG. 2B illustrates the
adjustment reflector 30. FIGS. 2A and 2B are top views illustrating
the reflectors.
[0071] As illustrated in FIG. 2A, the standard reflector 28 has,
for example, a disk shape. For example, three support portions 32
are provided on the standard reflector 28.
[0072] As illustrated in FIG. 2B, the adjustment reflector 30 has,
for example, a disk shape. The adjustment reflector 30 has, for
example, a plurality of inner-circumferential-side opening portions
(opening portions) 42 and a plurality of outer-circumferential-side
opening portions (opening portions) 44. The pattern of the
adjustment reflector 30 is formed by the plurality of
inner-circumferential-side opening portions 42 and the plurality of
outer-circumferential-side opening portions 44.
[0073] For example, the pattern of the adjustment reflector 30 is
rotationally symmetric. The pattern of the adjustment reflector 30
illustrated in FIG. 2B has fourfold symmetry.
[0074] FIGS. 3A and 3B are cross-sectional views schematically
illustrating an example of the reflector according to this
embodiment. FIG. 3A illustrates a state before the adjustment
reflector 30 is provided and FIG. 3B illustrates a state after the
adjustment reflector 30 is provided.
[0075] As illustrated in FIG. 3A, for example, the standard
reflector 28 are fixed by support shafts 35 provided in the support
columns 34, The support shaft 35 passes through a hole provided in
the standard reflector 28.
[0076] As illustrated in FIGS. 3A and 3B, the support portion 32
is, for example, a ring-shaped member through which the support
shaft 35 passes. The adjustment reflector 30 is fixed by, for
example, the support shafts 35 provided in the support columns 34.
The support shaft 35 passes through a hole provided in the
adjustment reflector 30, The adjustment reflector 30 is placed on
the support portions 32.
[0077] For example, a push-up pin (not illustrated) is provided in
the rotating unit 16 in order to attach or detach the wafer W to or
from the ring-shaped holder 14, The push-up pin passes through, for
example, the standard reflector 28, the adjustment reflector 30,
and the in-heater 24.
[0078] As illustrated in FIG. 1, the gas outlet 40 is provided in
the bottom of the reaction chamber 10. The gas outlet 40 discharges
a reaction product generated after source gas reacts on the surface
of the wafer W and process gas remaining in the reaction chamber 10
to the outside of the reaction chamber 10.
[0079] A wafer inlet and a gate valve (not illustrated) are
provided in a wall surface 15 of the reaction chamber 10. The wafer
W can be loaded to the reaction chamber 10 or can be unloaded from
the reaction chamber 10 through the wafer inlet and the gate
valve.
[0080] Next, a vapor phase growth method according to this
embodiment will be described. The vapor phase growth method
according to this embodiment uses the epitaxial growth apparatus
illustrated in FIG. 1.
[0081] An example in which a stacked film of a plurality of InGaN
(first nitride semiconductor) films and a plurality of GaN (second
nitride semiconductor) films is formed on a GaN base film will be
described. The stacked film is, for example, a multi-quantum well
(MQW) layer used in a light emitting layer of a light emitting
diode (LED). It has been known that the emission wavelength of the
MQW layer sensitively depends on temperature during deposition. The
uniform temperature distribution of a wafer during deposition is
important in order to achieve high productivity.
[0082] In the vapor phase growth method according to this
embodiment, first, a test wafer (first substrate) is loaded to the
reaction chamber 10. For example, a substrate that is used in the
actual process is preferably used as the test wafer. In the
following example, a case in which the actual process is performed
on a silicon substrate will be described. In the initial stage, the
adjustment reflector is not provided between the standard reflector
28 and the ring-shaped holder 14.
[0083] Then, the test wafer is placed on the ring-shaped holder 14.
The test wafer is heated by the in-heater 24 and the out-heater 26
while being rotated by the rotating mechanism 20. The temperature
distribution of the test wafer is measured while the test wafer is
being maintained under predetermined conditions including
temperature and a growth atmosphere which are adjusted to those in
the growth conditions of the MQW. The temperature distribution is
measured by, for example, a radiation thermometer.
[0084] After the temperature distribution of the test wafer is
measured, the test wafer is unloaded from the reaction chamber
10.
[0085] Next, the adjustment reflector 30 with a pattern is
manufactured on the basis of the measured temperature distribution
of the test wafer.
[0086] The adjustment reflector 30 is made of a material having a
compressive strength or a bending strength equal to or less than
1000 MPa or a material having a Vickers hardness equal to or less
than 8 GPa. In this case, a disk-shaped material is processed to
manufacture the adjustment reflector 30 having the plurality of
inner-circumferential-side opening portions 42 and the plurality of
outer-circumferential-side opening portions 44 illustrated in FIG.
2B. The pattern is processed by, for example, a cutter knife, a
scroll saw cutting machine, a gas cutting apparatus, or a laser
beam machining apparatus.
[0087] In the formation of the pattern of the adjustment reflector
30, for example, the adjustment reflector 30 is processed such that
an opening portion is located immediately below a region of the
wafer of which the temperature is to be lowered. However, the wafer
is rotated during the process. Therefore, the influence of the
opening portion provided in the adjustment reflector 30 is averaged
by the rotation of the wafer. The ratio of the length of the
opening portion provided in the adjustment, reflector 30 along the
rotation direction of the wafer to the length of a non-opening
portion is adjusted to finely adjust the temperature distribution
of the wafer.
[0088] Then, the adjustment reflector 30 is provided between the
standard reflector 28 and the in-heater 24, Then, a wafer (second
substrate) is loaded to the reaction chamber 10.
[0089] Then, the wafer is placed on the ring-shaped holder 14. The
wafer is heated by the in-heater 24 and the out-heater 26 while
being rotated by the rotating mechanism 20.
[0090] Then, AlN and AlGaN buffer layers are formed on the wafer,
using TMA, TMG, and ammonia, and a GaN base layer is grown. Then,
an InGaN layer and a GaN layer are alternately formed on the GaN
base layer to form an MQW layer.
[0091] When the InGaN layer is formed, for example, a mixed gas of
TMG and TMI having nitrogen gas as carrier gas is supplied from the
first gas supply path 11 to the reaction chamber 10. In addition,
for example, ammonia is supplied from the second gas supply path 12
to the reaction chamber 10. For example, nitrogen gas is supplied
as diluent gas from the third gas supply path 13 to the reaction
chamber 10.
[0092] When a GaN layer is formed, for example, TMG having nitrogen
gas as carrier gas is supplied from the first gas supply path 11 to
the reaction chamber 10. In addition, for example, ammonia is
supplied from the second gas supply path 12 to the reaction chamber
10. For example, nitrogen gas is supplied as diluent, gas from the
third gas supply path 13 to the reaction chamber 10.
[0093] After the MQW layer is formed, the wafer is unloaded from
the reaction chamber 10. While the MOW layer being formed as
described above, a temperature distribution of the wafer during the
deposition is more improved by the function of the adjustment
reflector 30 than that when the adjustment reflector is not
provided. Therefore, the uniformity of the emission wavelength is
higher than that when the adjustment reflector 30 is not used.
[0094] In the vapor phase growth apparatus and the vapor phase
growth method according to this embodiment, the adjustment
reflector 30 for adjusting the temperature distribution of the
wafer is made of a material that is easy to process. Specifically,
a material with a compressive strength or a bending strength equal
to or less than 1000 MPa or a material with a Vickers hardness
equal to or less than 8 GPa is used.
[0095] It is preferable that the adjustment reflector 30 be a
graphite sheet for ease of processing. The graphite sheet can be
processed by a cutter knife. Therefore, it is possible to
manufacture the adjustment reflector 30 with a pattern in a very
short time.
[0096] It is preferable that the adjustment reflector 30 be
provided between the standard reflector 28 and the in-heater 24 in
order to improve the uniformity of the temperature distribution of
the wafer.
[0097] It is preferable that the adjustment reflector 30 and the
standard reflector 28 be separated from each other by a
predetermined distance in order to improve the uniformity of the
temperature distribution of the wafer. It is preferable that the
distance between the adjustment reflector 30 and the standard
reflector 28 be equal to or greater than 1 millimeter and equal to
or less than 50 millimeters.
[0098] It is preferable that the center of gravity of the
adjustment reflector 30 be in the vicinity of the center of
rotation of the holder in order to prevent the non-uniform
deformation of the adjustment reflector 30 and to improve the
uniformity of the temperature distribution of the wafer. It is
preferable that the pattern of the adjustment reflector 30 be
rotationally symmetric in order to make the center of gravity of
the adjustment reflector 30 close to the center of rotation of the
holder.
[0099] The example in which at least one of the compressive
strength, bending strength, and Vickers hardness of the adjustment
reflector 30 is lower than that of the standard reflector 28 has
been described above. However, the adjustment reflector 30 and the
standard reflector 28 may have the same compressive strength,
bending strength, or Vickers hardness. The adjustment reflector 30
and the standard reflector 28 may be made of the same material.
[0100] The compressive strength or bending strength of the
adjustment reflector 30 is preferably equal to or less than 800 MPa
and is more preferably equal to or less than 500 MPa in order to
easily process the adjustment reflector 30.
[0101] Before the wafer (second substrate) is loaded into the
reaction chamber 10 after the adjustment reflector 30 is
manufactured and provided in the reaction chamber 10, the
temperature distribution of the test wafer may be measured again
and the pattern of the adjustment reflector 30 may be adjusted. The
measurement of the temperature distribution of the test wafer and
the adjustment of the pattern of the adjustment reflector 30 may be
repeatedly performed a plurality of times.
[0102] The example in which, when the temperature distribution of
the test wafer is measured first, the adjustment reflector 30 is
not provided between the standard reflector 28 and the in-heater 24
has been described above. However, when the temperature
distribution of the test wafer is measured first, the adjustment
reflector 30 with a predetermined pattern may be provided between
the standard reflector 28 and the in-heater 24 in advance.
[0103] As described above, according to the vapor phase growth
apparatus and the vapor phase growth method of this embodiment, it
is possible to easily adjust the temperature distribution of the
wafer to a desired temperature distribution.
Second Embodiment
[0104] A vapor phase growth method according to this embodiment
includes: loading a first substrate to a reaction chamber including
a holder, a heater, and a first reflector that is provided so as to
face the holder, with the heater interposed therebetween; placing
the first substrate on a holder; heating the first substrate with
the heater while rotating the first substrate; supplying process
gas to the reaction chamber to form a first film on the first
substrate; measuring a characteristic distribution of the first
film; manufacturing a second reflector with a pattern on the basis
of the measured characteristic distribution; providing a second
reflector between the first reflector and the heater; loading a
second substrate to the reaction chamber; placing the second
substrate on the holder; heating the second substrate with the
heater while rotating the second substrate; and supplying the
process gas to the reaction chamber to form, a second film on the
second substrate.
[0105] The vapor phase growth method according to this embodiment
differs from the vapor phase growth method according to the first
embodiment in that a "characteristic distribution" is a
"characteristic distribution of a film". Hereinafter, the
description of the same content as that in the first embodiment
will not be repeated.
[0106] Here, the characteristic distribution of the film is a
characteristic that depends on the temperature distribution of a
wafer. The characteristics of the first film are, for example, the
emission wavelength, thickness, chemical composition, and
crystallinity of an MQW layer.
[0107] The vapor phase growth method according to this embodiment
uses the epitaxial growth apparatus illustrated in FIG. 1.
Hereinafter, the vapor phase growth method according to this
embodiment will be described using, as an example, a case in which
an MQW layer obtained by stacking a plurality of InGaN layers,
which are first nitride semiconductor films, and a plurality of GaN
layers, which are second nitride semiconductor films, is formed on
a GaN base layer.
[0108] In the vapor phase growth method according to this
embodiment, first, a test wafer (first substrate) is loaded into
the reaction chamber 10. In this case, the adjustment reflector 30
is not provided between the standard reflector 28 and the
ring-shaped holder 14.
[0109] After buffer layer made of, for example, AlN or AlGaN is
formed on the test wafer on the basis of the actual process, the
GaN base layer is formed. Then, the InGaN layers and the GaN layers
are alternately stacked to form the MQW layer.
[0110] After the layers are formed, the test wafer is unloaded from
the reaction chamber 10 and the photo luminescence (PL) of the MQW
layer is measured.
[0111] The PL spectrum is measured by irradiating the MQW layer
with excitation light and measuring, for example, the wavelength
and intensity of fluorescent light emitted from the MQW layer.
[0112] Then, the adjustment reflector 30 is manufactured on the
basis of the emission wavelength distribution of the MQW layer on
the test wafer by PL measurement. It has been known that the
emission wavelength of the MQW layer in PL measurement becomes
shorter as the temperature during deposition increases. Therefore,
the pattern of the adjustment reflector 30 is adjusted such that a
portion with a shorter PL emission wavelength has a lower
temperature.
[0113] Then, the adjustment reflector 30 is provided between the
standard reflector 28 and the in-heater 24, Then, a wafer (second
substrate) is loaded into the reaction chamber 10.
[0114] Then, an MQW layer is formed on a GaN base layer of the
wafer, similarly to the test wafer, and PL measurement is
performed.
[0115] According to the vapor phase growth method of this
embodiment, the temperature distribution of a wafer is adjusted to
easily adjust the characteristic distribution of the film formed on
the wafer to a desired distribution.
Third Embodiment
[0116] A vapor phase growth apparatus according to this embodiment
further includes: a first, support portion that is provided between
the first reflector and the second reflector and supports the
second reflector such that the second reflector and the first
reflector are separated from each other by a predetermined
distance; and a second support portion that is provided between the
first reflector and the second reflector, supports the second
reflector such that the second reflector and the first reflector
are separated from each other by a predetermined distance, and is
closer to the center of rotation of the holder than the first
support portion. The vapor phase growth apparatus according to this
embodiment is the same as the vapor phase growth apparatus
according to the first embodiment except that it includes the
second support portion in addition to the first support portion.
Therefore, the description of the same content as that in the first
embodiment will not be repeated.
[0117] FIG. 4 is a cross-sectional view schematically illustrating
the vapor phase growth apparatus according to this embodiment. The
vapor phase growth apparatus according to this embodiment is, for
example, an epitaxial growth apparatus using an MOCVD method.
[0118] The vapor phase growth apparatus according to this
embodiment includes a first, support portion 32 and a second
support portion 33. The first support portion 32 and the second
support portion 33 are provided between the standard reflector
(first reflector) 28 and the adjustment reflector (second
reflector) 30.
[0119] The first support portion 32 and the second support portion
33 support the adjustment reflector 30. The second support portion
33 is provided at a position that is closer to the center of
rotation of the ring-shaped holder 14 than the first support
portion 32.
[0120] FIG. 5 is a plan view schematically illustrating an example
of the reflector according to this embodiment. FIG. 5 illustrates
the standard reflector 28.
[0121] As illustrated in FIG. 5, the standard reflector 28 has, for
example, a disk shape. For example, three first support portions 32
are provided in an outer circumferential portion of the standard
reflector 28. In addition, three second support portions 33 are
provided in an inner circumferential portion of the standard
reflector 28. In other words, the second support portion 33 is
provided at a position that is closer to the center of rotation (C
in FIG. 5) of the ring-shaped holder 14 than the first support
portion 32.
[0122] The first support portion 32 is, for example, a ring-shaped
member through which a support shaft 35 passes. The second support
portion 33 is, for example, a ring-shaped member through which a
push-up pin 37 used to attach and detach a wafer W passes. In FIG.
4, the push-up pin 37 is not illustrated.
[0123] The adjustment reflector is made of a material that is easy
to process. Therefore, in some cases, the adjustment reflector 30
is warped by its own weight. When the adjustment reflector 30
warps, it is difficult to stably adjust the temperature
distribution of a wafer or the characteristics of a film. In
particular, when the amount of warpage of the adjustment reflector
30 varies over time, the temperature distribution of a wafer or the
characteristics of a film become unstable.
[0124] According to the vapor phase growth apparatus of this
embodiment, since the second support portion 33 is provided inside
the first support portion 32, the warpage of the adjustment
reflector 30 is prevented. Therefore, it is possible to stably
adjust the temperature distribution of a wafer or the
characteristics of a film.
[0125] As described above, according to the vapor phase growth
apparatus and the vapor phase growth method of this embodiment, it
is possible to easily adjust the temperature distribution of a
wafer or the characteristics of a film to a desired distribution.
In addition, it is possible to stably adjust the temperature
distribution of a wafer or the characteristics of a film.
Fourth Embodiment
[0126] A vapor phase growth apparatus according to this embodiment
is the same as the vapor phase growth apparatus according to the
first embodiment except that a distance between a first reflector
and a second reflector is variable. Therefore, the description of
the same content as that in the first embodiment will not be
repeated.
[0127] FIGS. 6A and 6B are cross-sectional views schematically
illustrating an example of a reflector according to this
embodiment. FIG. 6A illustrates a case in which the distance
between the standard reflector (first reflector) 28 and the
adjustment reflector (second reflector) 30 is short. FIG. 6B
illustrates a case in which the distance between the standard
reflector 28 and the adjustment reflector 30 is long.
[0128] For example, a screw thread is provided on an outer surface
of a support shaft 35 provided in a support column 34. In addition,
a support portion 52 is a ring-shaped member and has a screw thread
provided on an inner surface. The support portion 52 is rotated to
change the distance between the support portion 52 and the standard
reflector 28.
[0129] As illustrated in FIG. 6A, the distance between the support
portion 52 and the standard reflector 28 is reduced to decrease the
distance between the standard reflector 28 and the adjustment
reflector 30. In addition, as illustrated in FIG. 6B, the distance
between the support portion 52 and the standard reflector 28 is
increased to increase the distance between the standard reflector
28 and the adjustment reflector 30.
[0130] The temperature distribution of a wafer also depends on the
distance between the standard reflector 28 and the adjustment,
reflector 30. In the vapor phase growth apparatus according to this
embodiment, the distance between the standard reflector 28 and the
adjustment, reflector 30 is variable. Therefore, it is easier to
adjust the temperature distribution of a wafer or the
characteristics of a film than that in the first embodiment or the
second embodiment.
Fifth Embodiment
[0131] A vapor phase growth apparatus according to this embodiment
is the same as the vapor phase growth apparatus according to the
fourth embodiment except that support portions with different
lengths are used to change the distance between the first reflector
and the second reflector. Therefore, the description of the same
content as that in the fourth embodiment will not be repeated.
[0132] FIGS. 7A and 7B are cross-sectional views schematically
illustrating an example of a reflector according to this
embodiment. FIG. 7A illustrates a case in which the distance
between the standard reflector 28 and the adjustment reflector 30
is short. FIG. 7B illustrates a case in which the distance between
the standard reflector 28 and the adjustment reflector 30 is
long.
[0133] For example, a short support portion 54 and a long support
portion 56 are prepared. The support portion 54 and the support
portion 56 are, for example, ring-shaped members through which
support shafts 35 pass.
[0134] As illustrated in FIG. 7A, the short support portion 54 is
used to reduce the distance between the standard reflector 28 and
the adjustment reflector 30. In addition, as illustrated in FIG.
7B, the long support portion 56 is used to increase the distance
between the standard reflector 28 and the adjustment reflector
30.
[0135] According to the vapor phase growth apparatus of this
embodiment, similarly to the fourth embodiment, it is easier to
adjust the temperature distribution of a wafer or the
characteristics of a film than that in the first embodiment or the
second embodiment.
Sixth Embodiment
[0136] A vapor phase growth apparatus according to this embodiment
is the same as the vapor phase growth apparatus according to the
first embodiment except that the second reflector is provided so as
to come into contact with the first reflector. Therefore, the
description of the same content as that in the first embodiment
will not be repeated.
[0137] FIG. 8 is a cross-sectional view schematically illustrating
an example of a reflector according to this embodiment. The
adjustment reflector (second reflector) 30 is provided so as to
come into contact with the standard reflector (first reflector)
28.
[0138] According to the vapor phase growth apparatus of this
embodiment, similarly to the first embodiment or the second
embodiment, it is easy to adjust the temperature distribution of a
wafer or the characteristics of a film.
Seventh Embodiment
[0139] A vapor phase growth apparatus according to this embodiment
is the same as the vapor phase growth apparatus according to the
third embodiment except that the shape of the second reflector is
different. Therefore, the description of the same content as that
in the third embodiment will not be repeated.
[0140] FIGS. 9A and 9B are plan views schematically illustrating an
example of a reflector according to this embodiment. FIG. 9A
illustrates a standard reflector 28. FIG. 9B illustrates a state in
which an adjustment reflector 30 is provided above the standard
reflector 28.
[0141] As illustrated in FIG. 9A, the standard reflector 28 has,
for example, a disk shape. For example, three first support
portions 32 are provided in an outer circumferential portion of the
standard reflector 28. In addition, three second support portions
33 are provided in an inner circumferential portion of the standard
reflector 28. In other words, the second support portion 33 is
provided at a position that is closer to the center of rotation (C
in FIG. 9) of the ring-shaped holder 14 than the first support
portion 32.
[0142] The first support portion 32 is, for example, a ring-shaped
member through which a support shaft 35 passes. The second support
portion 33 is, for example, a ring-shaped member through which a
push-up pin 37 used to attach and detach a wafer W passes.
[0143] As illustrated in FIG. 9B, the adjustment reflector 30
includes a plurality of disk-shaped reflectors. The adjustment
reflector 30 includes a first adjustment reflector 30c and a second
adjustment reflector 30d.
[0144] The first adjustment reflector 30c has a disk shape. The
second adjustment reflector 30d has a disk shape with a diameter
smaller than that of the first adjustment reflector 30c.
[0145] According to the vapor phase growth apparatus of this
embodiment, similarly to the first embodiment or the second
embodiment, it is easy to adjust the temperature distribution of a
wafer or the characteristics of a film.
Eight Embodiment
[0146] A vapor phase growth method according to this embodiment
includes: heating a first substrate, using a heater and a reflector
that has a first pattern and is opposite to the first substrate
with the heater interposed therebetween; measuring a characteristic
distribution of the first substrate under predetermined process
conditions; and forming a film on a second substrate under the
predetermined process conditions, using the heater and the
reflector which has been changed to a second pattern different from
the first pattern on the basis of the characteristic
distribution.
[0147] The vapor phase growth method according to this embodiment
differs from the vapor phase growth method according to the first
embodiment in that an adjustment member (adjuster) is attached or
detached to change the pattern of the adjustment reflector. In the
vapor phase growth method according to this embodiment, a reflector
has a detachable member and the member is attached or detached to
change the pattern of the reflector from a first pattern to a
second pattern. Hereinafter, the description of the same content as
that in the first embodiment will not be repeated.
[0148] Next, the vapor phase growth method according to this
embodiment will be described. The vapor phase growth method
according to this embodiment uses the epitaxial growth apparatus
illustrated in FIG. 1.
[0149] In the vapor phase growth method according to this
embodiment, first, a test wafer (first substrate) is loaded into
the reaction chamber 10. For example, a substrate that is used for
the actual process is preferably used as the test wafer.
Hereinafter, an example in which the actual process is performed on
a silicon substrate will be described.
[0150] First, an adjustment reflector (reflector) 130 with the
first pattern is provided between the standard reflector 28 and the
ring-shaped holder 14. For convenience, a disk shape without an
opening portion is also referred to as the first pattern.
[0151] Then, the test wafer is placed on the ring-shaped holder 14.
The test wafer is heated by the in-heater 24 and the out-heater 26
while being rotated by the rotating mechanism 20. The temperature
distribution of the test wafer is measured while the test wafer is
being maintained under predetermined conditions including
temperature and a growth atmosphere which are adjusted to those in
the growth conditions of the MQW. The temperature distribution is
measured by, for example, a radiation thermometer.
[0152] After the temperature of the test wafer is measured, the
test wafer is unloaded from the reaction chamber 10.
[0153] Then, the pattern of the adjustment reflector 130 is changed
from the first pattern to the second pattern different from the
first pattern, on the basis of the measured temperature
distribution of the test wafer.
[0154] FIGS. 10A and 10B are plan views schematically illustrating
an example of a reflector according to this embodiment. FIGS. 10A
and 10B illustrate the adjustment reflector 130. FIG. 10A
illustrates a state in which an adjustment member 130a (adjuster)
is completely removed from the adjustment reflector 130. FIG. 10B
illustrates a state in which the adjustment, member 130a is
completely attached to the adjustment reflector 130.
[0155] As illustrated in FIG. 10A, for example, a plurality of
opening portions 130b are provided in the adjustment reflector 130.
A plurality of opening portions are not necessarily provided and
one opening portion may be provided. As illustrated in FIG. 10B,
the adjustment member 130a is attached to cover the plurality of
opening portions 130b.
[0156] The adjustment reflector 130 and the adjustment member 130a
are made of, for example, graphite coated with SiC.
[0157] FIGS. 11A and 11B are plan views schematically illustrating
an example of the reflector according to this embodiment. FIG. 11A
illustrates a state in which outermost-circumferential opening
portions 130b of an adjustment reflector 130 are covered by an
adjustment member 130a. FIG. 11B illustrates a state in which
opening portions 130b other than outermost-circumferential opening
portions 130b of an adjustment reflector 130 are covered by an
adjustment member 130a.
[0158] For example, the pattern illustrated in FIG. 10A is used as
the first pattern. When the temperature distribution of the test
wafer is measured and the user wants to relatively increase, for
example, the temperature of the outer circumference of the test
wafer, the pattern illustrated in FIG. 11A is used as the second
pattern. For example, when the user wants to relatively reduce the
temperature of the outer circumference of the test wafer, the
pattern illustrated in FIG. 11B is used as the second pattern.
[0159] For example, the pattern illustrated in FIG. 10B, FIG. 11A,
or FIG. 11B may be used as the first pattern.
[0160] Then, the wafer is placed on the ring-shaped holder 14. The
wafer is heated by the in-heater 24 and the out-heater 26 while
being rotated by the rotating mechanism 20.
[0161] Then, AlN and AlGaN buffer layers are formed on the wafer,
using TMA, TMG, and ammonia, and a GaN base layer is grown. Then,
an InGaN layer and a GaN layer are alternately formed on the GaN
base layer to form an MQW layer.
[0162] After the MQW layer is formed, the wafer is unloaded from
the reaction chamber 10. In the MQW layer formed as described
above, a temperature distribution during deposition is more
improved by the function of the adjustment reflector 130 than that
when the pattern of the adjustment reflector is the first pattern.
Therefore, the uniformity of the emission wavelength is higher than
that when the adjustment reflector 130 is not used.
[0163] The shape of the adjustment member 130a and the opening
portion 130b is not limited to a circle. For example, the
adjustment member 130a and the opening portion 130b may have shapes
other than the circular shape, such as a triangular shape, a
rectangular shape, and other polygonal shapes.
[0164] The example in which the adjustment member 130a is attached
to or detached from the opening portion 130b to change the pattern
of the adjustment reflector 130 from the first pattern to the
second pattern has been described. However, for example, a
sheet-shaped adjustment member 130a that has been prepared in
advance may be attached to or detached from the surface of a
disk-shaped adjustment reflector 130 to change the pattern from the
first pattern to the second pattern.
[0165] The adjustment reflector 130 and the adjustment member 130a
may be made of the same material or different materials. For
example, a material with a reflectance different from the
reflectance of the material forming the adjustment reflector 130
may be applied to the adjustment member 130a.
[0166] As described above, according to the vapor phase growth
method of this embodiment, it is possible to easily adjust the
temperature distribution of a wafer to a desired temperature
distribution.
Ninth Embodiment
[0167] A vapor phase growth apparatus according to this embodiment
includes: a reaction chamber; a holder which is provided in the
reaction chamber and on which a substrate is placed; a heater that
heats the substrate; a first reflector that is provided so as to
face the holder with the heater interposed therebetween; a second
reflector that is provided between the first reflector and the
heater and includes a first portion with a first sub-pattern and a
second portion with a second sub-pattern, the first portion and the
second portion being relatively rotatable; and a rotating shaft
that is fixed to the holder and rotates the holder.
[0168] The vapor phase growth apparatus according to this
embodiment differs from the vapor phase growth apparatus according
to the first embodiment in that the second reflector includes a
first portion and a second portion which can be rotated relative to
each other. Hereinafter, the description of the same content as
that in the first embodiment will not be repeated.
[0169] A vapor phase growth method according to this embodiment
differs from the vapor phase growth method according to the eighth
embodiment in that a reflector has a first portion with a first
sub-pattern and a second portion with a second sub-pattern and the
pattern of the reflector is changed from a first, pattern to a
second pattern by the relative rotation between the first portion
and the second portion. Hereinafter, the description of the same
content as that in the eighth embodiment will not be repeated.
[0170] The vapor phase growth apparatus according to this
embodiment includes a standard reflector 28 (first reflector) and
an adjustment reflector 230 (second reflector). The standard
reflector 28 has the same structure as that in the first
embodiment.
[0171] FIGS. 17A, 17B, 17C, and 17D are diagrams schematically
illustrating an example of the adjustment reflector according to
this embodiment. FIGS. 17A, 17B, and 17C are top views illustrating
the reflector and FIG. 17D is a cross-sectional view taken along
the line AA' of FIG. 17C.
[0172] The adjustment reflector 230 includes a base reflector 231
(first portion) and a cover reflector 232 (second portion). The
adjustment reflector 230 includes a fixed shaft 234. The fixed
shaft 234 is the center of the relative rotation between the base
reflector 231 and the cover reflector 232.
[0173] The base reflector 231 and the cover reflector 232 are made
of, for example, ceramics or metal. The base reflector 231 and the
cover reflector 232 can be made of ceramics, such as silicon
carbide (SiC), graphite, pyrolytic graphite (PG), pyrolytic boron
nitride (PBN), sintered boron nitride (hBN), or tantalum carbide
(TaC). In addition, high-melting-point metal, such as tungsten,
molybdenum, or rhenium, can be used as metal. For example, a
material obtained by coating a base material, such as graphite,
with SiC, PBN, PG, or TaC can be used. Furthermore, a carbon fiber
reinforced carbon composite (C/C composite), sintered boron nitride
(hBN), or a mixture of sintered boron nitride (hBN) and silicon
nitride can be used.
[0174] FIG. 17A illustrates the base reflector 231 and FIG. 17B
illustrates the cover reflector 232. FIGS. 17C and 17D illustrate a
state in which the cover reflector 232 is superimposed on the base
reflector 231. The fixed shaft 234 passes through the cover
reflector 232.
[0175] As illustrated in FIG. 17A, the base reflector 231 has the
first sub-pattern. The first sub-pattern includes four-hole
patterns 231a. The hole patterns 2 31a have a symmetry axis X that
passes through the center of rotation. The hole patterns 231a are
line symmetric with respect to the symmetry axis X.
[0176] As illustrated in FIG. 17B, the cover reflector 232 has the
second sub-pattern. The second sub-pattern includes four hole
patterns 232a. The hole patterns 232a have a symmetry axis Y that
passes through the center of rotation. The hole patterns 232a are
line symmetric with respect to the symmetry axis Y.
[0177] As illustrated in FIG. 17C, the cover reflector 232 is
superimposed on the base reflector 231 such that the first
sub-pattern and the second sub-pattern overlap each other. In this
way, the pattern of the adjustment reflector 230 is formed.
[0178] FIGS. 18A, 18B, 18C, 18D, and 18E are diagrams illustrating
a change in the pattern of the adjustment reflector according to
this embodiment. FIGS. 18A, 18B, 18C, 18D, and 18E illustrate an
aspect in which the cover reflector 232 is rotated on the fixed
shaft 234 with respect to the base reflector 231 by a predetermined
rotation angle to change the pattern of the adjustment reflector
230.
[0179] FIG. 18A illustrates a state in which the hole pattern 231a
of the base reflector 231 and the hole pattern 232a of the cover
reflector 232 completely overlap each other. It is assumed that the
rotation angle of the pattern illustrated in FIG. 18A is 0 degree.
For example, the pattern illustrated in FIG. 18A is referred to as
the first pattern.
[0180] FIGS. 18B, 18C, 18D, and 18E illustrate patterns obtained by
rotating the cover reflector 232 in a counterclockwise direction by
10 degrees, 15 degrees, 20 degrees, and 30 degrees from the pattern
illustrated in FIG. 18A, respectively. For example, the patterns
illustrated in FIGS. 18A, 18B, 18C, 18D and 18E are referred to as
the second pattern.
[0181] The base reflector 231 and the cover reflector 232 are
relatively rotated to change the pattern of the adjustment
reflector 230 from the first pattern to the second pattern. The
base reflector 231 and the cover reflector 232 are relatively
rotated to change the degree of overlap between the first
sub-pattern and the second sub-pattern. The base reflector 231 and
the cover reflector 232 are relatively rotated to change the
opening area of the adjustment reflector 230.
[0182] In the case of the pattern illustrated in FIG. 18A, the
adjustment reflector 230 has the largest opening area. The opening
areas of the adjustment reflectors 230 are reduced in the order of
FIGS. 18B, 18C, and 18D. In the case of the pattern illustrated in
FIG. 18E, the adjustment reflector 230 does not have an opening
portion and has the smallest opening area.
[0183] According to the vapor phase growth apparatus and the vapor
phase growth method of this embodiment, since the pattern of the
adjustment reflector 230 is changed from the first pattern to the
second pattern, it is possible to easily adjust the characteristic
distribution of the wafer W. The characteristic distribution of the
wafer W is, for example, the temperature distribution of the wafer
W.
[0184] The base reflector 231 and the cover reflector 232 are
relatively rotated to continuously change the pattern of the
adjustment reflector 230. For example, the opening area of the
adjustment reflector 230 is continuously changed. Therefore, it is
easy to accurately adjust the characteristic distribution of the
wafer W.
[0185] The pattern of the adjustment reflector 230 is changed only
by relatively rotating the base reflector 231 and the cover
reflector 232. Therefore, for example, it is possible to change the
pattern of the adjustment reflector 230 from the first pattern to
the second pattern, without disassembling the in-heater 24 or the
out-heater 26. As a result, it is possible to adjust the
characteristic distribution of the wafer W in a short time.
[0186] The example in which the first sub-pattern of the base
reflector 231 is the hole pattern 231a has been described above.
However, the invention is not limited to the case in which the
first sub-pattern is the hole pattern 231a. For example, the first
sub-pattern may be formed by providing a pattern, which has a
reflectance different from that of other regions, in the surface of
the base reflector 231. The pattern having a reflectance different
from that of other regions is, for example, a pattern that is made
of a material different from that forming other regions.
Tenth Embodiment
[0187] A vapor phase growth apparatus and a vapor phase growth
method according to this embodiment differ from the vapor phase
growth apparatus and the vapor phase growth method according to the
ninth embodiment in that at least one of the first sub-pattern and
the second sub-pattern has a hole pattern and the hole pattern does
not have a symmetry axis which passes through the center of
rotation of the first portion or a symmetry axis which passes
through the center of rotation of the second portion. Hereinafter,
the description of the same content as that in the ninth embodiment
will not be repeated.
[0188] FIGS. 19A, 19B, 19C, and 19D are diagrams schematically
illustrating an example of an adjustment reflector according to
this embodiment. FIGS. 19A, 19B, and 19C are top views illustrating
a reflector and FIG. 19D is a cross-sectional view taken along the
line BB' of FIG. 19C.
[0189] An adjustment reflector 330 includes a base reflector 331
(first portion) and a cover reflector 332 (second portion). The
adjustment reflector 330 includes a fixed shaft 334. The fixed
shaft 334 is the center of the relative rotation between the base
reflector 331 and the cover reflector 332.
[0190] FIG. 19A illustrates the base reflector 331 and FIG. 19B
illustrates the cover reflector 332. FIGS. 19C and 19D illustrate a
state in which the cover reflector 332 is superimposed on the base
reflector 331.
[0191] As illustrated in FIG. 19A, the base reflector 331 has a
first sub-pattern. The first sub-pattern include four hole patterns
331a. The hole patterns 331a have a symmetry axis X that passes
through the center of rotation. The hole patterns 331a are line
symmetric with respect to the symmetry axis X.
[0192] As illustrated in FIG. 19B, the cover reflector 332 has a
second sub-pattern. The second sub-pattern includes four hole
patterns 332a. The hole patterns 332a do not have a symmetry axis
that passes through the center of rotation. In other words, the
hole patterns 332a are not line symmetric as viewed from the
circumferential direction of the cover reflector 332.
[0193] As illustrated in FIGS. 19C and 19D, the cover reflector 332
is superimposed on the base reflector 331 such that the first
sub-pattern and the second sub-pattern overlap each other. In this
way, the pattern of the adjustment reflector 330 is formed.
[0194] FIGS. 20A, 20B, 20C, 20D, 20E, 20F, 21A, and 21B are
diagrams illustrating a change in the pattern of the adjustment
reflector according to this embodiment. FIGS. 20A, 20B, 20C, 20D,
20E, 20F, 21A, and 21B illustrate an aspect in which the cover
reflector 332 is rotated on the fixed shaft 334 with respect to the
base reflector 331 by a predetermined rotation angle to change the
pattern of the adjustment reflector 330.
[0195] FIG. 20A illustrates a state in which the hole pattern 331a
of the base reflector 331 and the hole pattern 332a of the cover
reflector 332 overlap each other. It is assumed that the rotation
angle of the pattern illustrated in FIG. 20A is 0 degree. For
example, the pattern illustrated in FIG. 20A is referred to as a
first pattern.
[0196] FIGS. 20B, 20C, 20D, 20E, 20F, 21A, and 21B illustrate
patterns obtained by rotating the cover reflector 332 in a
counterclockwise direction by 10 degrees, 20 degrees, 30 degrees,
40 degrees, 50 degrees, 60 degrees, and 70 degrees from the pattern
illustrated in FIG. 20A, respectively. For example, the patterns
illustrated in FIGS. 20B, 20C, 20D, 20E, 20F, 21A, and 21B are
referred to as a second pattern.
[0197] The base reflector 331 and the cover reflector 332 are
relatively rotated to change the pattern of the adjustment
reflector 330 from the first pattern to the second pattern. The
base reflector 331 and the cover reflector 332 are relatively
rotated to change the degree of overlap between the first
sub-pattern and the second sub-pattern. The base reflector 331 and
the cover reflector 332 are relatively rotated to change the
opening area of the adjustment reflector 330.
[0198] In the case of the pattern illustrated in FIG. 20A, the
adjustment reflector 330 has the largest opening area. The opening
areas of the adjustment reflectors 330 are reduced in the order of
FIGS. 20B, 20C, 20D, 20E, 20F, and 21A. In the case of the pattern
illustrated in FIG. 21B, the adjustment reflector 330 does not have
an opening portion and has the smallest opening area.
[0199] According to the vapor phase growth apparatus and the vapor
phase growth method of this embodiment, the same effect as that in
the ninth embodiment is obtained. In addition, since the hole
pattern 332a of the cover reflector 332 is not line symmetric as
viewed from the circumferential direction of the cover reflector
332, the rate of change in the opening area of the adjustment
reflector 330 with respect to the rotation angle is not asymmetric.
For example, there is a difference between the rate of change in
the opening area respect to the rotation angle when the cover
reflector 332 is rotated in the counterclockwise direction and the
rate of change in the opening area respect to the rotation angle
when the cover reflector 332 is rotated in the clockwise direction.
The use of the asymmetry of the hole pattern 332a makes it possible
to achieve a complicated pattern change. Therefore, it is possible
to further improve the accuracy of adjusting the characteristic
distribution of the wafer W. In addition, the hole pattern 331a of
the base reflector 331 may not be line symmetric or both the hole
pattern 332a of the cover reflector 332 and the hole pattern 331a
of the base reflector 331 may not be line symmetric.
Eleventh Embodiment
[0200] A vapor phase growth apparatus and a vapor phase growth
method according to this embodiment differ from the vapor phase
growth apparatus and the vapor phase growth method according to the
ninth embodiment in that the second sub-pattern does not have a
hole pattern. Hereinafter, the description of the same content as
that in the ninth embodiment will not be repeated.
[0201] FIGS. 22A, 22B, 22C, and 22D are diagrams schematically
illustrating an example of an adjustment reflector according to
this embodiment. FIGS. 22A, 22B, and 22C are top views illustrating
a reflector and FIG. 22D is a cross-sectional view taken along the
line CC' of FIG. 22C.
[0202] An adjustment reflector 430 includes a base reflector 431
(first portion) and a cover reflector 432 (second portion).
[0203] FIG. 22A illustrates the base reflector 431 and FIG. 22B
illustrates the cover reflector 432. FIGS. 22C and 22D illustrate a
state in which the cover reflector 432 is superimposed on the base
reflector 431.
[0204] As illustrated in FIG. 22A, the base reflector 431 has a
first sub-pattern. The first sub-pattern is a hole pattern 431a.
The hole pattern 431a has a symmetry axis X that passes through the
center of the relative rotation between the base reflector 431 and
the cover reflector 432. The hole pattern 431a is line symmetric
with respect to the symmetry axis X. The center of the relative
rotation between the base reflector 431 and the cover reflector 432
is aligned with the center of the base reflector 431.
[0205] In addition, the base reflector 431 includes an inner
circumferential portion 431b and an outer circumferential portion
431c. The inner circumferential portion 431b has a concave shape.
The hole pattern 431a is provided in the inner circumferential
portion 431b.
[0206] As illustrated in FIG. 22B, the cover reflector 432 has a
second sub-pattern. The second sub-pattern has a cross shape that
covers the hole pattern 431a. The second sub-pattern does not nave
a hole pattern.
[0207] As illustrated in FIG. 22C, the cover reflector 432 is
fitted to the inner circumferential portion 431b of the base
reflector 431. The first sub-pattern and the second sub-pattern
overlap each other and the pattern of the adjustment reflector 430
is formed.
[0208] FIGS. 23A, 23B, 23C, 23D, 23E, and 23F are diagrams
illustrating a change in the pattern of the adjustment reflector
according to this embodiment. FIGS. 23A, 23B, 23C, 23D, 23E, and
23F illustrate an aspect in which the cover reflector 432 is
rotated with respect to the base reflector 431 by a predetermined
rotation angle to change the pattern of the adjustment reflector
330.
[0209] FIG. 23A illustrates a state in which the hole pattern 431a
of the base reflector 431 and the cross shape of the cover
reflector 432 overlap each other. It is assumed that the rotation
angle of the pattern illustrated in FIG. 23A is 0 degree. For
example, the pattern illustrated in FIG. 23A is referred to as a
first pattern.
[0210] FIGS. 23B, 23C, 23D, 23E, and 23F illustrate patterns
obtained by rotating the cover reflector 432 in a counterclockwise
direction by 10 degrees, 20 degrees, 30 degrees, 40 degrees, and 45
degrees from the pattern illustrated in FIG. 23A, respectively. For
example, the patterns illustrated in FIGS. 23B, 23C, 23D, 23E, and
23F are referred to as a second pattern.
[0211] The base reflector 431 and the cover reflector 432 are
relatively rotated to change the pattern of the adjustment
reflector 430 from the first pattern to the second pattern. The
base reflector 431 and the cover reflector 432 are relatively
rotated to change the degree of overlap between the first
sub-pattern and the second sub-pattern. The base reflector 431 and
the cover reflector 432 are relatively rotated to change the
opening area of the adjustment reflector 430.
[0212] In the pattern illustrated in FIG. 23A, the adjustment
reflector 430 does not have an opening portion. In the case of the
pattern illustrated in FIG. 23A, the adjustment reflector 430 has
the smallest opening area. The opening area of the adjustment
reflector 430 sequentially increases in the order of FIG. 23B, FIG.
23C, FIG. 23D, and FIG. 23E. In the pattern illustrated in FIG.
23F, the adjustment reflector 430 has the largest opening
portion.
[0213] According to the vapor phase growth apparatus and the vapor
phase growth method according to this embodiment, the same effect
as that in the ninth embodiment is obtained. In addition, the
adjustment reflector 430 has a simple structure in which the cover
reflector 432 is fitted to the inner circumferential portion 431b
of the base reflector 431. Therefore, manufacturing costs are
reduced.
Twelfth Embodiment
[0214] A vapor phase growth apparatus and a vapor phase growth
method according to this embodiment differ from the vapor phase
growth apparatus and the vapor phase growth method according to the
ninth embodiment in that the second reflector includes a third
portion that can be relatively rotated with respect to the first
portion and the second portion. Hereinafter, the description of the
same content as that in the ninth embodiment will not be
repeated.
[0215] FIGS. 24A, 24B, 24C, 24D, and 24E are diagrams schematically
illustrating an example of an adjustment reflector according to
this embodiment. FIGS. 24A, 24B, 24C, and 24D are top views
illustrating a reflector and FIG. 24E is a cross-sectional view
taken along the line DD' of FIG. 24D.
[0216] An adjustment reflector 530 includes a base reflector 531
(first portion), an outer cover reflector 532 (second portion), and
an inner cover reflector 533 (third portion). The adjustment
reflector 530 includes a fixed shaft 534. The fixed shaft 534 is
the center of the relative rotation between the base reflector 531,
the outer cover reflector 532, and the inner cover reflector 533.
The fixed shaft 534 passes through the inner cover reflector
533.
[0217] FIG. 24A illustrates the base reflector 531, FIG. 24B
illustrates the outer cover reflector 532, and FIG. 24C illustrates
the inner cover reflector 533. FIGS. 24D and 24E illustrate a state
in which the outer cover reflector 532 and the inner cover
reflector 533 are superimposed on the base reflector 531.
[0218] As illustrated in FIGS. 24D and 24E, the outer cover
reflector 532 is fitted to the outside of the inner cover reflector
533. The outer cover reflector 532 and the inner cover reflector
533 can be independently rotated with respect to the base reflector
531.
[0219] As illustrated in FIG. 24A, the base reflector 531 has a
first sub-pattern. The first sub-pattern includes eight hole
patterns 531a provided in an outer circumferential portion and four
hole patterns 531b provided in an inner circumferential portion.
The hole patterns 531a provided in the outer circumferential
portion have a symmetrical axis that passes through the center of
rotation. In contrast, the hole patterns 531b provided in the inner
circumferential portion does not have a symmetry axis that passes
through the center of rotation.
[0220] As illustrated in FIG. 24B, the outer cover reflector 532
has a second sub-pattern. The second sub-pattern is a ring-shaped
pattern that has eight protrusions 532a corresponding to the eight
hole patterns 531a provided in the outer circumferential portion of
the base reflector 531.
[0221] As illustrated in FIG. 24C, the inner cover reflector 533
has a third sub-pattern. The third sub-pattern includes four hole
patterns 533a that correspond to the four hole patterns 531b
provided in the inner circumferential portion of the base reflector
531.
[0222] As illustrated in FIG. 24D, the outer cover reflector 532
and the inner cover reflector 533 are superimposed on the base
reflector 531 such that the first sub-pattern overlaps the second
sub-pattern and the third sub-pattern. In this way, the pattern of
the adjustment reflector 530 is formed.
[0223] FIGS. 25A, 25B, 25C, and 25D are diagrams illustrating a
change in the pattern of the adjustment reflector according to this
embodiment. FIGS. 25A, 25B, 25C, and 25D illustrate an aspect in
which the outer cover reflector 532 and the inner-cover reflector
533 are independently rotated on the fixed shaft 534 with respect
to the base reflector 531 by a predetermined rotation angle to
change the pattern of the adjustment reflector 530.
[0224] FIG. 25A illustrates a state in which the eight hole
patterns 531a provided in the outer circumferential portion of the
base reflector 531 do not overlap the eight protrusions 532a of the
outer cover reflector 532 and the four hole patterns 531b provided
in the inner circumferential portion of the base reflector 531
overlap the four hole patterns 533a of the inner cover reflector
533. It is assumed that the rotation angle of the inner cover
reflector 533 in the pattern illustrated in FIG. 25A is 0 degree.
In addition, it is assumed that the rotation angle of the outer
cover reflector 532 in the pattern illustrated in FIG. 25A is 0
degree. For example, the pattern illustrated in FIG. 25A is
referred to as a first pattern.
[0225] FIGS. 25B, 25C, and 25D illustrate patterns obtained by
independently rotating the inner cover reflector 533 and the outer
cover reflector 532 in a counterclockwise direction from the
pattern illustrated in FIG. 25A. In FIG. 25B, the rotation angle of
the inner cover reflector 533 is 15 degrees and the rotation angle
of the outer cover reflector 532 is 10 degrees. In FIG. 25C, the
rotation angle of the inner cover reflector 533 is 45 degrees and
the rotation angle of the outer cover reflector 532 is 10 degrees.
In FIG. 25D, the rotation angle of the inner cover reflector 533 is
45 degrees and the rotation angle of the outer cover reflector 532
is 22.5 degrees. For example, the patterns illustrated in FIGS.
25B, 25C, and 25D are referred to as a second pattern.
[0226] The base reflector 531, the inner cover reflector 533, and
the outer cover reflector 532 are independently rotated relative to
each other to change the pattern of the adjustment reflector 530
from the first pattern to the second pattern. The base reflector
531, the inner cover reflector 533, and the outer cover reflector
532 are relatively rotated to change the degree of overlap between
the first sub-pattern, the second sub-pattern, and the third
sub-pattern. The base reflector 531, the inner cover reflector 533,
and the outer cover reflector 532 are relatively rotated to change
the opening area of the adjustment reflector 530.
[0227] In the case of the pattern illustrated in FIG. 25A, the
adjustment reflector 530 has the largest opening area. In the
pattern illustrated in FIG. 25D, the adjustment reflector 530 does
not have an opening portion and has the smallest opening area.
[0228] According to the vapor phase growth apparatus and the vapor
phase growth method of this embodiment, the same effect as that in
the ninth embodiment is obtained. In addition, since two cover
reflectors that are independently rotated, that is, the inner cover
reflector 533 and the outer cover reflector 532 are provided, it is
possible to achieve a complicated pattern change. Therefore, it is
possible to further improve the accuracy of adjusting the
characteristic distribution of the wafer W.
EXAMPLES
[0229] Next, examples of the invention will be described.
Example 1
[0230] The temperature distribution of a wafer was adjusted using
the vapor phase growth apparatus and the vapor phase growth method
according to the first embodiment.
[0231] FIG. 12 is a plan view schematically illustrating a
reflector according to Example 1. FIG. 12 illustrates an adjustment
reflector 30.
[0232] In Example 1, a disk-shape reflector is used as a standard
reflector 28. In addition, the reflector having the pattern
illustrated in FIG. 12 is used as the adjustment reflector 30.
Comparative Example 1
[0233] The temperature distribution of a wafer was measured by the
same method as that in Example 1 except that the adjustment
reflector 30 was not used and only the standard reflector 28 is
used as a reflector.
[0234] FIG. 13 is a diagram illustrating the temperature
distributions of the wafers according to Example 1 and Comparative
Example 1. FIG. 13 is a diagram illustrating the influence of the
adjustment reflector 30 on the temperature distribution of the
wafer. The horizontal axis indicates a distance from the center of
the wafer and the vertical axis indicates the temperature of the
wafer.
[0235] As can be seen from FIG. 13, the uniformity of the
temperature of the wafer is improved by the use of the adjustment
reflector 30.
Example 2
[0236] The temperature distribution of a wafer and the film
characteristics of the wafer were adjusted using the vapor phase
growth method according to the second embodiment,
[0237] FIGS. 14A and 14B and FIG. 15 are plan views schematically
illustrating a reflector according to Example 2. FIGS. 14A and 14B
and FIG. 15 illustrate an adjustment reflector 30.
[0238] FIG. 14A illustrates a first adjustment reflector 30a and
FIG. 14B illustrates a second adjustment reflector 30b. FIG. 15
illustrates a state in which the second adjustment reflector 30b is
superimposed on the first adjustment reflector 30a.
[0239] A disk-shape reflector was used as a standard reflector 28.
In addition, a reflector in which the first adjustment reflector
30a and the second adjustment reflector 30b illustrated in FIG. 15
overlap each other was used as the adjustment reflector 30.
[0240] The PL of an MQW layer formed on the wafer was measured and
an emission wavelength distribution was measured.
Example 3
[0241] An emission wavelength distribution was measured by the same
method as that in Example 2 except that the size of an
inner-circumferential-side opening portion 42 of a first adjustment
reflector 30a was reduced.
Comparative Example 2
[0242] Comparative Example 2 relates to a test wafer. An MQW layer
was formed under the same process conditions as those in Example 2
and Example 3 before the formation of a film on the wafer according
to Example 2 or Example 3. As a reflector, only the standard
reflector 28 was used. The PL of the formed MQW layer was measured
and an emission wavelength distribution was measured.
[0243] FIG. 16 is a diagram illustrating the emission wavelength
distributions of the MQW layers in Example 2, Example 3, and
Comparative Example 2. The horizontal axis indicates a distance
from the center of the wafer and the vertical axis indicates an
emission wavelength.
[0244] The object of Examples 2 and 3 is to further uniformize the
PL wavelength distribution of the MQW layer formed without the
adjustment reflectors 30a and 30b according to Comparative Example
2, In particular, the object is to improve the uniformity of the
wavelength in a radius range less than 50 mm.
[0245] As illustrated in FIG. 16, in Example 2 using the adjustment
reflectors 30a and 30b, the wavelength distribution in the PL
measurement in the radius range less than radius 50 mm is more
improved than that in Comparative Example 2. In addition, in growth
according to Example 3 in which the shape of the adjustment
reflector 30a is adjusted, a very uniform wavelength distribution
is obtained.
[0246] Similarly, the pattern of the adjustment reflectors 30a and
30b can be adjusted to improve the uniformity of the wavelength in
the PL measurement of the MQW layer in a portion with a radius
greater than 50 mm. In addition, the ratio of the power of an
in-heater to the power of an out-heater may be adjusted. However,
the temperature of a portion with a radius that is equal to or less
than 50 mm is mainly determined by a heating operation of the
in-heater. Therefore, in this case, the use of the ratio of the
power of the in-heater to the power of the out-heater for the
adjustment of the temperature distribution is not expected to have
a considerable effect. For this reason, it is important that the
adjustment reflectors 30a and 30b are adjusted to finely adjust the
temperature of a portion with a small radius.
[0247] The embodiments and the examples of the invention have been
described above with reference to specific examples. The
above-described embodiments and examples are illustrative and do
not limit the invention. In addition, the components according to
each embodiment may be appropriately combined with each other.
[0248] For example, in the above-described embodiments and
examples, the adjustment reflector (second reflector) 30 has a disk
shaped with an opening portion and the adjustment reflector has a
plurality of disks. However, the adjustment reflector 30 is not
limited to the above-mentioned shapes. The adjustment reflector 30
may have any shape as long as it has a pattern. The adjustment
reflector 30 may be, for example, a star-shaped plate, a polygonal
plate, or a plurality of rectangular plates.
[0249] In the above-mentioned example, one standard reflector 28 is
provided. However, two or more standard reflectors 28 may be
provided.
[0250] For example, in the above-described embodiments, a stacked
film of a plurality of InGaN films and a plurality of GaN films is
epitaxially grown on a GaN film. However, for example, the
invention can be applied to form, other group III-V nitride-based
semiconductor single-crystal films, such as an aluminum nitride
(AlN) film and an aluminum gallium nitride (AlGaN) film. In
addition, the invention can be applied to a group III-V
semiconductor such as GaAs. Furthermore, the invention can be
applied to form other films.
[0251] A case in which the process gas is mixed in the shower plate
has been described as an example. However, the process gas may be
mixed before it flows into the shower plate. In addition, the
process gas may be in a separated state until it is ejected from
the shower plate into the reaction chamber.
[0252] The ring-shaped holder 14 has been described as an example
of the wafer holder. However, the wafer holder may be a dish-shaped
susceptor without an opening portion at the center.
[0253] A case in which two types of heaters, that is, the in-heater
24 and the out-heater 26 are provided as the heater has been
described as an example. However, only one type of heater or more
than 2 types of heaters may be provided.
[0254] In the above-mentioned example, the temperature of a portion
of the substrate corresponding to the opening portion of the
adjustment reflector is less than that of the other portions.
However, a change in the temperature of the substrate may have an
opposite effect, depending on the reflectance of the reflector. In
this case, an opening portion may be provided at a position of the
adjustment reflector which corresponds to a portion of the
substrate of which the temperature is desired to be higher than
that of other portions.
[0255] In the above-described embodiments, for example, portions
which are not directly 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.
* * * * *