U.S. patent application number 11/706971 was filed with the patent office on 2007-09-06 for vapor phase deposition apparatus and support table.
This patent application is currently assigned to NuFLARE TECHNOLOGY, INC.. Invention is credited to Hironobu Hirata, Akira Jyogo, Yoshikazu Moriyama.
Application Number | 20070204796 11/706971 |
Document ID | / |
Family ID | 38470382 |
Filed Date | 2007-09-06 |
United States Patent
Application |
20070204796 |
Kind Code |
A1 |
Hirata; Hironobu ; et
al. |
September 6, 2007 |
Vapor phase deposition apparatus and support table
Abstract
A vapor phase deposition apparatus includes a chamber, a support
table arranged in the chamber, and having a first support unit
which is in contact with a back side surface of a substrate and on
which the substrate is placed and a second support unit which is
connected to the first support unit to support the first support
unit, a heat source arranged at a position having a distance from a
back side surface of the substrate, the distance being larger than
a distance between back side surface of the support table and the
heat source, and which heats the substrate, a first flow path
configured to supply a gas to form a film into the chamber, and a
second flow path configured to exhaust the gas from the
chamber.
Inventors: |
Hirata; Hironobu; (Shizuoka,
JP) ; Jyogo; Akira; (Shizuoka, JP) ; Moriyama;
Yoshikazu; (Shizuoka, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Assignee: |
NuFLARE TECHNOLOGY, INC.
|
Family ID: |
38470382 |
Appl. No.: |
11/706971 |
Filed: |
February 16, 2007 |
Current U.S.
Class: |
118/715 |
Current CPC
Class: |
C23C 16/4581 20130101;
C30B 29/06 20130101; C30B 35/00 20130101; C23C 16/481 20130101;
C23C 16/4585 20130101; C30B 25/10 20130101 |
Class at
Publication: |
118/715 |
International
Class: |
C23C 16/00 20060101
C23C016/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 21, 2006 |
JP |
2006-044068 |
Claims
1. A vapor phase deposition apparatus comprising: a chamber; a
support table arranged in the chamber, and having a first support
unit which is in contact with a back side surface of a substrate
and on which the substrate is placed and a second support unit
which is connected to the first support unit to support the first
support unit; a heat source arranged at a position having a
distance from a back side surface of the substrate, the distance
being larger than a distance between back side surface of the
support table and the heat source, and which heats the substrate; a
first flow path configured to supply a gas to form a film into the
chamber; and a second flow path configured to exhaust the gas from
the chamber.
2. The vapor phase deposition apparatus according to claim 1,
wherein a material of the first support unit uses a material having
a heat conductivity higher than that of a material used in the
second support unit.
3. The vapor phase deposition apparatus according to claim 2,
wherein silicon carbide (SiC) is used as a material of the first
support unit.
4. The vapor phase deposition apparatus according to claim 3,
wherein silicon nitride (Si.sub.3N.sub.4) is used as a material of
the second support unit.
5. The vapor phase deposition apparatus according to claim 2,
wherein a notched portion is formed on at least one upper surface
side of the first support unit and the second support unit at a
position which the first support unit and the second support unit
are connected to each other.
6. The vapor phase deposition apparatus according to claim 2,
wherein a notched portion is formed in the first support unit.
7. The vapor phase deposition apparatus according to claim 6,
wherein the notched portion is formed in a surface being in contact
with the back side surface of the substrate.
8. The vapor phase deposition apparatus according to claim 1,
wherein a notched portion is formed in the first support unit.
9. The vapor phase deposition apparatus according to claim 8,
wherein the notched portion is formed in a surface being in contact
with the back side surface of the substrate.
10. The vapor phase deposition apparatus according to claim 1,
wherein the first support unit has an annular projecting portion
extending on the back side at an outer peripheral portion, and the
second support unit has an opening formed on an inner peripheral
side, is in contact with a distal end portion of the projecting
portion on a bottom surface of the opening to support the first
support unit.
11. The vapor phase deposition apparatus according to claim 1,
wherein the first support unit has a plurality of projecting
portions formed on a back surface; the second support unit has an
opening formed on an inner peripheral side, is in contact with a
distal end portion of the projecting portion on a bottom surface of
the opening to support the first support unit.
12. The vapor phase deposition apparatus according to claim 11,
wherein the first support unit further has a plurality of second
projecting portions which are in contact with a side surface of the
opening when the first support unit substantially moves in a
horizontal direction and which extends to an outer peripheral
side.
13. The vapor phase deposition apparatus according to claim 11,
wherein the second support unit has a plurality of second
projecting portions which are in contact with a side surface of the
first support unit when the first support unit substantially moves
in a horizontal direction and which extend to an inner peripheral
side.
14. The vapor phase deposition apparatus according to claim 1,
wherein the second support unit has an opening formed on an inner
peripheral side and a plurality of projecting portions formed on a
bottom surface of the opening, and is in contact with a back
surface of the first support unit at a distal end portion of the
projecting portion to support the first support unit.
15. The vapor phase deposition apparatus according to claim 14,
wherein the first support unit has a plurality of second projecting
portions which are in contact with a side surface of the opening
when the first support unit substantially moves in a horizontal
direction and which extend to an outer peripheral side.
16. The vapor phase deposition apparatus according to claim 14,
wherein the second support unit has a plurality of second
projecting portions which are in contact with a side surface of the
first support unit when the first support unit substantially moves
in a horizontal direction and which extend to an inner peripheral
side.
17. The vapor phase deposition apparatus according to claim 1,
wherein the first and second support units are formed as physically
different parts, and the first support unit is placed on a part of
the second support unit.
18. A vapor phase deposition apparatus comprising: a chamber; a
support table arranged in the chamber and formed a first opening
which a substrate is placed on its bottom surface, and a second
opening what is an annular opening and is located on an outer
peripheral side of the first opening and inside an outer peripheral
side; a heat source arranged at a position having a distance from
the back side surface of the substrate, the distance being larger
than a distance between the substrate and the support table, and
which heats the substrate; a first flow path configured to supply a
gas to form a film into the chamber; and a second flow path
configured to exhaust the gas from the chamber.
19. The vapor phase deposition apparatus according to claim 18,
wherein a thickness of a portion of the support table where the
second opening is formed is smaller than a thickness of an inner
portion of the second opening.
20. A support table for placing a substrate thereon in a chamber
held in a vapor phase deposition apparatus, comprising: a first
support unit being in contact with the substrate; and a second
support portion connected to the first support portion and made of
a material having a heat conductivity lower than that of a material
used in the first support unit.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from prior Japanese Patent Application No. 2006-044068
filed on Feb. 21, 2006 in Japan, the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a vapor phase deposition
apparatus and a support table. For example, the present invention
relates to a support member (support table) which supports a
substrate such as a silicon wafer in an epitaxial growth
apparatus.
[0004] 2. Related Art
[0005] In manufacture of semiconductor devices such as an
ultrahigh-speed bipolar transistor and an ultrahigh-speed CMOS, a
monocrystalline epitaxial growth technique in which an impurity
concentration and a film thickness are controlled is absolutely
necessary to improve the performance of devices. In epitaxial
growth for vapor-growing a monocrystalline thin film on a
semiconductor substrate such as a silicon wafer, an atmospheric
chemical vapor deposition method is generally used. Depending on
cases, a low-pressure chemical vapor deposition (LP-CVD) method is
used. A semiconductor substrate such as a silicon wafer is arranged
in a reaction chamber. The semiconductor substrate is heated and
rotated while keeping a normal-pressure atmosphere (0.1 MPa (760
Torr)) or a vacuum atmosphere having a predetermined degree of
vacuum in the reaction chamber. In this state, a silicon source and
a source gas containing a dopant such as a boric compound, an
arsenic compound, or a phosphorus compound are supplied. On the
surface of the heated semiconductor substrate, thermal
decomposition or hydrogen reduction reaction of the source gas is
performed. In this manner, a silicon epitaxial film doped with
boron (B), phosphorous (P), or arsenic (As) is manufactured by
deposition (see Japanese Patent Application, Publication No.
JP-A-09-194296, for example).
[0006] The epitaxial growth technique is also used in manufacture
of a power semiconductor, for example, manufacture of an IGBT
(Insulate Gate Bipolar Transistor). In the power semiconductor such
as the IGBT, a silicon epitaxial film having a thickness of several
10 .mu.m or more is required.
[0007] FIG. 25 is a top view showing an example of a state in which
a silicon wafer is supported by a holder.
[0008] FIG. 26 is a sectional view showing a section in a state in
which the silicon wafer is supported by the holder shown in FIG.
25.
[0009] In a holder 210 (also called a susceptor) serving as a
support member for the silicon wafer 200, a counterbore hole having
a diameter slightly larger than the diameter of the silicon wafer
200 is formed. The silicon wafer 200 may be placed to be fitted in
the counterbore hole. In this state, the holder 210 is rotated to
rotate the silicon wafer 200, so that a silicon epitaxial film is
grown by thermal decomposition or hydrogen reduction reaction of a
source gas supplied.
[0010] In order to uniformly grow a silicon epitaxial film on the
substrate, the substrate is heated as described above, and heat
escapes through an edge portion of the substrate. For this reason,
in particular, the uniformity of the film thickness of the
substrate at an edge portion is disadvantageously deteriorated. For
this reason, although the support member is devised to be heated,
further improvement is desired.
BRIEF SUMMARY OF THE INVENTION
[0011] The present invention has as its object to provide a support
member to keep the temperature of a substrate edge uniform.
[0012] In accordance with embodiments consistent with the present
invention, there is provided a vapor phase deposition apparatus
including a chamber, a support table arranged in the chamber, and
having a first support unit which is in contact with a back side
surface of a substrate and on which the substrate is placed and a
second support unit which is connected to the first support unit to
support the first support unit, a heat source arranged at a
position having a distance from a back side surface of the
substrate, the distance being larger than a distance between back
side surface of the support table and the heat source, and which
heats the substrate, a first flow path configured to supply a gas
to form a film into the chamber, and a second flow path configured
to exhaust the gas from the chamber.
[0013] Also, in accordance with embodiments consistent with the
present invention, there is provided a vapor phase deposition
apparatus including a chamber, a support table arranged in the
chamber and formed a first opening which a substrate is placed on
its bottom surface, and a second opening what is an annular opening
and is located on an outer peripheral side of the first opening and
inside an outer peripheral side, a heat source arranged at a
position having a distance from the back side surface of the
substrate, the distance being larger than a distance between the
substrate and the support table, and which heats the substrate, a
first flow path configured to supply a gas to form a film into the
chamber, and a second flow path configured to exhaust the gas from
the chamber.
[0014] Further, in accordance with embodiments consistent with the
present invention, there is provided a support table for placing a
substrate thereon in a chamber held in a vapor phase deposition
apparatus, including a first support unit being in contact with the
substrate, and a second support portion connected to the first
support portion and made of a material having a heat conductivity
lower than that of a material used in the first support unit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a conceptual diagram showing a configuration of an
epitaxial growth apparatus according to a first embodiment;
[0016] FIG. 2 is a view showing an example of the appearance of an
epitaxial growth apparatus system;
[0017] FIG. 3 is a diagram showing an example of a unit
configuration of the epitaxial growth apparatus system;
[0018] FIG. 4 is a sectional view showing an example of a state in
which a silicon waver is supported by a holder;
[0019] FIG. 5 is a sectional view showing another example of the
state in which a silicon wafer is supported by a holder;
[0020] FIG. 6 is a sectional view showing still another example of
the state in which a silicon wafer is supported by a holder;
[0021] FIG. 7 is a conceptual diagram showing a configuration of an
epitaxial growth apparatus according to a second embodiment;
[0022] FIG. 8 is a conceptual view showing a sectional
configuration of a notched holder according to the second
embodiment;
[0023] FIG. 9 is a conceptual top view of the holder shown in FIG.
8;
[0024] FIG. 10 is a conceptual view showing a sectional
configuration of another notched holder according to the second
embodiment;
[0025] FIG. 11 is a conceptual top view of the holder shown in FIG.
10;
[0026] FIG. 12 is a conceptual diagram showing a configuration of
an epitaxial growth apparatus according to a third embodiment;
[0027] FIG. 13 is a conceptual view showing a sectional
configuration of a notched holder according to the third
embodiment;
[0028] FIG. 14 is a conceptual top view of the holder shown in FIG.
13;
[0029] FIG. 15 is a conceptual view showing a sectional
configuration of another notched holder according to the third
embodiment;
[0030] FIG. 16 is a conceptual top view of the holder shown in FIG.
15;
[0031] FIG. 17 is a conceptual view showing a sectional
configuration of an example of a holder according to a fourth
embodiment;
[0032] FIG. 18 is a conceptual view showing a sectional
configuration of an example of a holder according to a fifth
embodiment;
[0033] FIG. 19 is a conceptual view showing another example of a
holder according to a sixth embodiment when the holder is viewed
from the above;
[0034] FIG. 20 is a conceptual view showing a sectional structure
of the holder shown in FIG. 19;
[0035] FIG. 21 is a conceptual view showing still another example
of the holder according to the sixth embodiment;
[0036] FIG. 22 is a conceptual view showing a sectional
configuration of the holder shown in FIG. 21;
[0037] FIG. 23 is a conceptual view showing another example of a
sectional configuration of the holder;
[0038] FIG. 24 is a conceptual view showing another example of a
sectional configuration of the holder;
[0039] FIG. 25 is a top view showing an example of a state in which
a silicon wafer is supported by a holder; and
[0040] FIG. 26 is a sectional view showing a section in the state
in which the silicon wafer is supported by the holder shown in FIG.
25.
DETAILED DESCRIPTION OF THE INVENTION
First Embodiment
[0041] Film uniformity is required in process development for a
sheet-feeding epitaxial growth apparatus serving as an example of a
vapor phase deposition apparatus. It is apparent that as a point
which affects the film uniformity, the uniformity of a silicon
wafer edge is given. This is a specific phenomenon, which is
so-called an edge effect appearing at a wafer edge having several
mm and which is different from a phenomenon at a wafer central
portion. The phenomenon is very closely related to a temperature
distribution, and a temperature distribution near the edge must be
preferable. As will be described later, how to increase the
temperature of a part of the holder with which the edge is in
contact is a key to increase an edge temperature which tends to
decrease. The method of heating the holder is devised. The method
will be described below with reference to the drawings.
[0042] FIG. 1 is a conceptual diagram showing a configuration of an
epitaxial growth apparatus according to the first embodiment.
[0043] In FIG. 1, an epitaxial growth apparatus 100 serving as an
example of a vapor phase deposition apparatus includes a holder
(also called a susceptor) 110 serving as an example of a support
table, a chamber 120, a shower head 130, a vacuum pump 140, a
pressure control valve 142, an out-heater 150, an in-heater 160,
and a rotating member 170. A flow path 122 for supplying a gas and
a flow path 124 for exhausting a gas are connected to the chamber
120. The flow path 122 is connected to the shower head 130. In FIG.
1, a configuration required to explain the first embodiment is
shown. However, a reduction scale and the like are not conformed to
those of an actual apparatus (the same is also applied to the
following respective drawings).
[0044] The holder 110 has a first holder 112 which is arranged on
the inside to be in contact with a silicon wafer 101 serving as an
example of a substrate and a second holder 114 arranged on the
outside to be connected to the first holder 112. The first holder
112 serves as an example of the first support unit. The second
holder 114 serves as an example of a second support unit. In the
first holder 112, a penetrating opening having a predetermined
inner diameter is formed. On a bottom surface of a depressed
portion 116 dug from the upper surface side in a predetermined
depth at a right angle or a predetermined angle, the silicon wafer
101 is supported to be in contact with the back side surface of the
silicon wafer 101.
[0045] The second holder 114 is formed to have a circular
periphery. The second holder 114 is arranged on the rotating member
170 which is rotated by a rotating mechanism (not shown) about a
center line of the plane of the silicon wafer 101 perpendicular to
the plane of the silicon wafer 101. The holder 110 rotates together
with the rotating member 170 to make it possible to rotate the
silicon wafer 101.
[0046] The out-heater 150 and the in-heater 160 are arranged on the
back surface side of the holder 110. The out-heater 150 and the
in-heater 160 are arranged at a position having a distance from a
back side surface of the silicon wafer 101. The distance is larger
than a distance between back side surface of the holder 110 and the
heaters. The out-heater 150 can heat the outer peripheral portion
of the silicon wafer 101 and the holder 110. The in-heater 160 is
arranged under the out-heater 150 to make it possible to heat
portions except for the outer peripheral portion of the silicon
wafer 101. Independently of the in-heater 160, the out-heater 150
is arranged to heat the outer peripheral portion of the silicon
wafer 101 to make it easy to escape heat to the holder 110. In this
manner, a double-heater structure is employed to improve the
in-plane uniformity of the silicon wafer 101.
[0047] The holder 110, the out-heater 150, the in-heater 160, the
shower head 130, and the rotating member 170 are arranged in the
chamber 120. The rotating member 170 extends from the inside of the
chamber 120 to a rotating mechanism (not shown) outside the chamber
120. For the shower head 130, a piping extends from the inside of
the chamber 120 to the outside of the chamber 120.
[0048] The chamber 120 serving as a reaction vessel is kept at a
normal pressure or in a vacuum atmosphere having a predetermined
degree of vacuum by the vacuum pump 140. In this state, the silicon
wafer 101 is heated by the out-heater 150 and the in-heater 160.
With rotation of the holder 110, the silicon wafer 101 is rotated
at a predetermined rotating speed. While the silicon wafer 101 is
rotated, a source gas serving as a silicon source is supplied from
the shower head 130 into the chamber 120. Thermal decomposition or
hydrogen reduction of the source gas is performed on a surface of
the heated silicon wafer 101. In this manner, a silicon epitaxial
film is grown on the surface of the silicon wafer 110. A pressure
in the chamber 120 may be adjusted to a normal pressure or a vacuum
atmosphere having a predetermined degree of vacuum by using, for
example, the pressure control valve 142. Alternatively, when the
chamber 120 is used in the normal pressure, the vacuum pump 140 or
the pressure control valve 142 may not be used. In the shower head
130, the source gas supplied from the outside of the chamber 120
through the piping is discharged from a plurality of through holes
through a buffer inside the shower head 130. For this reason, the
source gas can be uniformly supplied onto the silicon wafer 101.
Furthermore, the internal pressures and the external pressures of
the holder 110 and the rotating member 170 are make equal to each
other (a pressure of a front-surface-side atmosphere of the silicon
wafer 101 and a pressure of a back surface-side atmosphere of the
silicon wafer 101 are made equal to each other). In this manner,
the source gas can be prevented from entering the inside of the
rotating member 170 or the inside of the rotating mechanism.
Similarly, a purge gas or the like on the rotating mechanism (not
shown) side can be prevented from leaking into the chamber
(front-surface-side atmosphere of the silicon wafer 101). In this
case, the chamber 120 is exhausted by the vacuum pump 140. However,
the exhausting means is not limited to the vacuum pump 140. Any
means which can exhaust the chamber 120 may be used. For example,
when the chamber 120 may be set at a normal-pressure atmosphere or
a vacuum atmosphere having a pressure close to a normal pressure,
the chamber 120 is exhausted by a blower or the like.
[0049] FIG. 2 is a view showing an example of the appearance of an
epitaxial growth apparatus system.
[0050] As shown in FIG. 2, an epitaxial growth apparatus system 300
is entirely surrounded by a housing.
[0051] FIG. 3 is a diagram showing an example of a unit
configuration of the epitaxial growth apparatus system.
[0052] In the epitaxial growth apparatus system 300, a cassette is
arranged on a cassette stage (C/S) 310 or a cassette stage (C/S)
312. The silicon wafer 101 set in the cassette is conveyed, or
"transferred" into a load/lock (L/L) chamber 320 by a transfer
robot 350. The silicon wafer 101 is conveyed from the L/L 320 into
a transfer chamber 330 by a transfer robot 332 arranged in the
transfer chamber 330. The conveyed the silicon wafer 101 is
conveyed into the chamber 120 of the epitaxial growth apparatus
100. A silicon epitaxial film is formed on a surface of the silicon
wafer 101 by an epitaxial growth method. The silicon wafer 101 on
which the silicon epitaxial film is formed is conveyed from the
epitaxial growth apparatus 100 into the transfer chamber 330 by the
transfer robot 332 again. The conveyed silicon wafer 101 is
conveyed into the L/L chamber 320. Thereafter, the transfer robot
350 returns the silicon wafer 101 from the L/L chamber 320 into a
cassette arranged on the cassette stage (C/S) 310 or the cassette
stage (C/S) 312. In the epitaxial growth apparatus system 300 shown
in FIG. 3, two chambers 120 and two L/L chambers 320 for the
epitaxial growth apparatus 100 are arranged. In this manner, a
throughput can be increased.
[0053] FIG. 4 is a sectional view showing an example of a state in
which a silicon wafer is supported by a holder.
[0054] In the first embodiment, as a material of the first holder
112 being in contact with a substrate, a material having a heat
conductivity .lamda. higher than that of a material used in the
second holder 114 is used. More specifically, this configuration is
designed to make a heat conductivity .lamda..sub.1 of the material
of the first holder 112 higher than a heat conductivity
.lamda..sub.2 of the material of the second holder 114. For
example, silicon carbide (SiC) is preferably used as the material
of the first holder 112, and silicon nitride (Si.sub.3N.sub.4) is
preferably used as the material of the second holder 114. The
ceramic materials such as SiC and Si.sub.3N.sub.4 are used without
using metal materials to make it possible to avoid metal
contamination. The materials are preferably selected such that the
heat conductivity .lamda..sub.1 of the material of the first holder
112 is twice or more the heat conductivity .lamda..sub.2 of the
material of the second holder 114.
[0055] As described above, the heat conductivity of the internal
member being in contact with the substrate is made high to make the
heat conductivity of the external member relatively low, so that
heat generated from a heat source is conducted from the first
holder 112 to the silicon wafer 101. On the other hand, the second
holder 114 can be suppressed from generating heat. Therefore, heat
received from the out-heater 150 serving as a heat source can be
conducted to the silicon wafer 101 without loading a heater serving
as a heating device (heat source). In contrast to this, heat
radiated from the silicon wafer 101 can be prevented from being
externally escaped. As a consequence, a temperature near the edge
of the silicon wafer 101 can be more increased, and a temperature
distribution near the edge of the silicon wafer 101 can be kept
uniform. As a result, the film thickness uniformity of the edge
portion of the silicon wafer 101 can be improved.
[0056] FIG. 5 is a sectional view showing another example of the
state in which a silicon wafer is supported by a holder.
[0057] In FIG. 5, as a material of a first holder 212 being in
contact with the substrate, a material having a heat conductivity
.lamda. higher than that of a material used in a second holder 214
is used. More specifically, this configuration is designed to make
a heat conductivity .lamda..sub.1 of the material of the first
holder 212 higher than a heat conductivity .lamda..sub.2 of the
material of the second holder 214. The first holder 212 and the
second holder 214 are connected to each other with a step. In other
words, the diameter of an upper portion of the second holder 214 on
the inner peripheral side is decreased to form a projecting portion
215 extending to the inner peripheral side at a lower portion of an
inner peripheral end. More specifically, a depressed portion is
formed on the inner peripheral side. On the other hand, the
diameter of the first holder 212 on the outer peripheral side is
decreased to form a projecting portion 213 extending to the outer
peripheral side at an upper portion of an outer peripheral end. An
arrangement is preferable in which a back surface of the projecting
portion 213 of the first holder 212 is placed on the bottom surface
of the projecting portion 215 on the inner peripheral side of the
second holder 214. At the connection positions, the bottom surface
of the projecting portion 215 serving as the depressed portion
formed on the inner peripheral side of the second holder 214 is in
reliable contact with the back surface of the projecting portion
213 on the outer peripheral side of the first holder 212 placed on
the bottom surface. A very small gap is formed between the outer
peripheral surface of the first holder 212 and the inner peripheral
surface of the second holder 214. This makes it possible to reduce
a contact area between the first holder 212 and the second holder
214. For this reason, heat transfer between the first holder 212
and the second holder 214 can be made poor. With this
configuration, furthermore, heat radiated from the silicon wafer
101 can be prevented from being externally escaped.
[0058] FIG. 6 is a sectional view showing still another example of
the state in which a silicon wafer is supported by a holder.
[0059] In FIG. 6, as a material of a first holder 222 being in
contact with a substrate, a material having a heat conductivity
.lamda. higher than that of a material used in a second holder 214
is used. More specifically, this configuration is designed to make
a heat conductivity .lamda..sub.1 of the material of the first
holder 222 higher than a heat conductivity .lamda..sub.2 of the
material of the second holder 224. A notched portion is formed on
at least one upper surface side of the first holder 212 and the
second holder 214 at a position which the first holder 212 and the
second holder 214 are connected to each other. The first holder 212
and the second holder 214 are connected to each other by forming a
space (notch) therebetween. In other words, the diameter of an
upper portion of the second holder 224 on the inner peripheral side
is decreased to form a projecting portion 225 extending to the
inner peripheral side. On the other hand, the diameter of the first
holder 222 on the outer peripheral side is also decreased to form a
projecting portion 223 extending to the outer peripheral side at an
outer peripheral end. A distal end face of the projecting portion
225 is connected to a distal end face of the projecting portion 223
to connect the first holder 222 and the second holder 224 to each
other. With this configuration, a contact area between the first
holder 222 and the second holder 224 can be decreased. For this
reason, heat transfer between the first holder 222 and the second
holder 224 can be made poor. With this configuration, heat radiated
from the silicon wafer 101 can be prevented from being externally
escaped.
[0060] As for the first holder 212 and the first holder 222, like
the first holder 112, silicon carbide (SiC) is preferable used as,
for example, the material of the first holder 112. As for the
second holder 214 and the second holder 224, like the second holder
114, silicon nitride (Si.sub.3N.sub.4) is preferably used as a
material. Similarly, the materials are desirably selected such that
the heat conductivities .lamda..sub.1 of the materials of the first
holder 212 and the first holder 222 are twice or more the heat
conductivities 12 of the materials of the second holder 214 and the
second holder 224.
[0061] In this manner, the heat conductivity of the internal member
being in contact with the substrate is increased to relatively
decrease the heat conductivity of the external member to make it
possible to easily conduct heat received from the out-heater 150
serving as a heat source to the silicon wafer 101. In contrast to
this, heat radiated from the silicon wafer 101 can be prevented
from being externally escaped. Furthermore, a heater serving as a
heating device (heat source) is not loaded. For this reason, a
temperature near the edge of the silicon wafer 101 can be more
increased. Therefore, the temperature distribution near the edge of
the silicon wafer 101 can be kept uniform. As a result, the film
thickness uniformity of the edge portion of the silicon wafer 101
can be improved.
Second Embodiment
[0062] In the first embodiment, a material of a holder on which the
silicon wafer 101 is placed is improve to increase the temperature
of the wafer edge without loading a heater serving as a heating
device. A second embodiment explains a configuration in which the
shape of a holder is improved without improving the material of the
holder to increase the temperature of a wafer edge without loading
a heater serving as a heating device.
[0063] FIG. 7 is a conceptual diagram showing a configuration of an
epitaxial growth apparatus according to the second embodiment.
[0064] In FIG. 7, the same configuration as that in FIG. 1 is used
except for the holder (also called a susceptor) 110 serving as an
example of a support table. In the second embodiment, the same
configuration as that in the first embodiment is used except for
the configuration of the holder 110.
[0065] A penetrating opening having a predetermined inner diameter
is formed in the holder 110 shown in FIG. 7. On a bottom surface of
a depressed portion 116 dug from an upper surface side in a
predetermined depth at a right angle or a predetermined angle, the
holder 110 is in contact with a back side surface of the silicon
wafer 101 to support the silicon wafer 101.
[0066] FIG. 8 is a conceptual view showing a sectional
configuration of a notched holder according to the second
embodiment.
[0067] FIG. 9 is a conceptual top view of the holder shown in FIG.
8.
[0068] The holder 110 is formed to have a circular periphery. The
first holder 110 is arranged on a rotating member 170. On the
bottom surface of the depressed portion 116 of the holder 110 on
which the silicon wafer 101 is placed, notched portions 50 which
are uniformly radially formed at predetermined intervals as shown
in FIGS. 8 and 9 are formed. More specifically, the notched
portions 50 are formed on the surface of the holder 110 being in
contact with the back side surface of the silicon wafer 101. In
this manner, the silicon wafer 101 can directly receive heat
radiated from the out-heater 150 or the in-heater 160 serving as a
heat source through spaces of the notched portions 50 without
passing through the holder 110. With the configuration, in
particular, radiant heat from the out-heater 150 or the in-heater
160 can be easily received by the edge of the silicon wafer 101.
Furthermore, the notched portions 50 are formed to make a contact
area to the silicon wafer 101 small. Therefore, an area for
radiating heat from the silicon wafer 101 to the holder 110 can be
decreased. Therefore, an amount of radiated heat can be suppressed.
A notched area of the notched portion 50 is especially preferably
set at 30% or more the area of a surface on which the silicon wafer
101 is placed. In this case, a notch pattern of the notched portion
50 is not limited to the above-described pattern. A notch pattern
having another shape will be explained below.
[0069] FIG. 10 is a conceptual view showing a sectional
configuration of another notched holder according to the second
embodiment.
[0070] FIG. 11 is a conceptual top view of the holder shown in FIG.
10.
[0071] In this case, on the bottom surface of the depressed portion
116 of the holder 110 on which the silicon wafer 101 is placed,
notched portions 52 are formed at predetermined intervals as shown
in FIGS. 10 and 11. The notched portion 52 is formed to have a
shape uniformly gradually curved from a notch start position in a
circumferential direction. The configuration is preferably used.
The notched portion is gradually curved from the notch start
position in the circumferential direction to make it possible to
decrease deviation of a space in which the silicon wafer 101 is
directly heated by the out-heater 150 or the in-heater 160. The
notch pattern of the notched portions 50 shown in FIGS. 8 and 9 has
some position to which heat is not directly conducted at all in the
radial direction of the silicon wafer 101. However, when the notch
patterns shown in FIGS. 10 and 11 are used, positions to which heat
is not directly conducted at all in the radial direction can be
decreased or eliminated. A notch area of the notched portions 52 is
especially preferably set at 30% or more the area of the surface on
which the silicon wafer 101 is place as described above. In this
case, although a pattern having a shape gradually curved from a
notch start position in the circumferential direction is used, the
pattern is not limited to this shape. For example, the pattern may
be sharply bent from a straight line. Any shape which decreases or
eliminates portions to which heat is not directly conducted at all
in the radial direction may be used.
[0072] As described above, notches are formed on a counterbore
surface of the holder 110 on which the silicon wafer 101 is placed.
In this manner, radiant heat from a heater is easily received by
the edge of the silicon wafer 101. Therefore, the silicon wafer 101
can be directly heated by the heat source. As a result, the
temperature of the wafer edge can be increased. Furthermore, since
a contact area between the holder 110 and the silicon wafer 101
decreases, heat radiated from the silicon wafer 101 can be
suppressed. Consequently, a temperature distribution near the edge
of the silicon wafer 101 can be kept uniform. For this reason, the
film thickness uniformity of the edge portion of the silicon wafer
101 can be improved.
Third Embodiment
[0073] A third embodiment will describe a configuration of a
combination between the first and second embodiments.
[0074] FIG. 12 is a conceptual diagram showing a configuration of
an epitaxial growth apparatus according to the third
embodiment.
[0075] In FIG. 12, the same configuration as that in FIG. 1 is used
except for the holder (also called a susceptor) 110 serving as an
example of a support table. In the third embodiment, the same
configuration as that in Embodiment 1 is used except for the
configuration of the holder 110.
[0076] The holder 110 has a first holder 118 (example of a first
support unit) being in contact with the silicon wafer 101 serving
as an example of a substrate on the internal side and a second
holder 114 (example of a second support unit) connected to a first
holder 118 on the external side. A penetrating opening having a
predetermined inner diameter is formed in the first holder 112. On
a bottom surface of a depressed portion 116 dug from the upper
surface side in a predetermined depth at a right angle or a
predetermined angle, the silicon wafer 101 is supported to be in
contact with the back side surface of the silicon wafer 101. The
second holder 114 is formed to have a circular periphery. The
second holder 114 is arranged on a rotating member 170.
[0077] FIG. 13 is a conceptual diagram showing a sectional
configuration of a notched holder according to the third
embodiment.
[0078] FIG. 14 is a conceptual top view of the holder shown in FIG.
13.
[0079] As in the first embodiment, as a material of a first holder
118 being in conduct with the substrate, a material having a heat
conductivity .lamda. higher than that of a material used in a
second holder 214 is used. More specifically, this configuration is
designed to make a heat conductivity .lamda..sub.1 of the material
of the first holder 118 higher than a heat conductivity
.lamda..sub.2 of the material of the second holder 114. For
example, silicon carbide (Si.sub.3N.sub.4) is preferably used as
the material of the first holder 118. Silicon nitride
(Si.sub.3N.sub.4) is preferably used as the material of the second
holder 114. The ceramic materials such as SiC and Si.sub.3N.sub.4
are used without using metal materials to make it possible to avoid
metal contamination. The materials are preferably selected such
that the heat conductivity .lamda..sub.1 of the material of the
first holder 118 is twice or more the heat conductivity
.lamda..sub.2 of the material of the second holder 114. The first
holder 118 and the second holder 114 are preferably connected to
each other to decrease a contact area as described in FIGS. 5 and
6.
[0080] As described above, the heat conductivity of the internal
member being in contact with the substrate is made high to make the
heat conductivity of the external member relatively low, so that
heat generated from the out-heater 150 serving as a heat source can
be easily conducted to the silicon wafer 101. Furthermore, the
heater serving as a heating device (heat source) is not loaded. In
contrast to this, heat radiated from the silicon wafer 101 can be
prevented from being escaped. In this manner, the temperature near
the edge of the silicon wafer 101 can be further increased.
[0081] Furthermore, notched portions 50 which are uniformly
radially formed at predetermined intervals as shown in FIGS. 13 and
14 are formed on the bottom surface of the depressed portion 116 of
the first holder 118 on which the silicon wafer 101 is placed. More
specifically, the notched portions 50 are formed on the surface of
the holder 118 being in contact with the back side surface of the
silicon wafer 101. As a consequence, the silicon wafer 101 can
directly receive heat radiated from the out-heater 150 or the
in-heater 160 serving as a heat source through spaces of the
notched portions 50 without passing through the holder 110. With
the configuration, in particular, radiant heat from the out-heater
150 or the in-heater 160 can be easily received by the edge of the
silicon wafer 101. Furthermore, as in the second embodiment, the
notch area of the notched portions 50 is especially preferably set
at 30% or more of an area of a surface on which the silicon wafer
101 is place. In this case, a notch pattern of the notched portion
50 is not limited to the above-described pattern. A notch pattern
having another shape will be explained.
[0082] FIG. 15 is a conceptual view showing a sectional
configuration of another notched holder according to the third
embodiment.
[0083] FIG. 16 is a conceptual top view of the holder shown in FIG.
15.
[0084] As in the second embodiment, on the bottom surface of the
depressed portion 116 of the holder 110 on which the silicon wafer
101 is placed, notched portions 52 are formed at predetermined
intervals as shown in FIGS. 10 and 11. The notched portion 52 is
formed to have a shape uniformly gradually curved from a notch
start position in a circumferential direction. The configuration is
also preferably used. The notched portion is gradually curved from
the notch start position in the circumferential direction to make
it possible to decrease deviation of a space in which the silicon
wafer 101 is directly heated by the out-heater 150 or the in-heater
160. With the configuration, positions to which heat is not
directly conducted at all in the radial direction can be decreased
or eliminated. A notch area of the notched portions 52 is
especially preferably set at 30% or more the area of the surface on
which the silicon wafer 101 is place as described above. In this
case, although a pattern having a shape gradually curved from a
notch start position in the circumferential direction is used, the
pattern is not limited to this shape. The pattern may be sharply
bent from a straight line. Any shape which decreases or eliminates
portions to which heat is not directly conducted at all in the
radial direction may be used. In this case as well, the first
holder 118 and the second holder 114 are preferably connected to
each other to decrease a contact area as described in FIGS. 5 and
6.
[0085] In this manner, notches are formed on a counterbore surface
of the holder 110 on which the silicon wafer 101 is placed, so that
radiant heat from a heater is easily received by the edge of the
silicon wafer 101. Therefore, the silicon wafer 101 can be directly
heated by the heat source. As a result, the temperature of the
wafer edge can be increased. Furthermore, since a contact area
between the holder 110 and the silicon wafer 101 decreases, heat
radiated from the silicon wafer 101 can be suppressed.
[0086] As described above, heat received by the holder 110 from the
heater can be easily conducted to the silicon wafer 101. In
contrast to this, heat radiated from the silicon wafer 101 can be
prevented from being externally escaped. Furthermore, in addition
to the effect, the notches are formed on the counterbore surface of
the holder 110 on which the silicon wafer 101 is placed to make it
easy to receive radiant heat from the heater by the edge of the
silicon wafer 101, so that the temperature of the wafer edge can be
further increased. As a result, a temperature distribution near the
edge of the silicon wafer 101 can be kept uniform. Therefore, the
film thickness uniformity of the edge portion of the silicon wafer
101 can be improved.
Fourth Embodiment
[0087] In the first embodiment, the holder is divided into two
members, a member made of a material having a low heat conductivity
is arranged outside to suppress heat radiation. However, a method
of suppressing heat radiation is not limited to the method
described in the first embodiment. In a fourth embodiment, a method
of suppressing heat radiation by decreasing a heat transfer area of
a holder will be described.
[0088] FIG. 17 is a conceptual view showing a sectional
configuration of an example of a holder according to the fourth
embodiment. The other configurations are the same as those in the
first embodiment. A penetrating opening having a predetermined
inner diameter is formed in a holder 310. On a bottom surface of a
depressed portion (opening) dug from the upper surface side in a
predetermined depth at a right angle or a predetermined angle, the
silicon wafer 101 is supported to be in contact with the back side
surface of the silicon wafer 101. On the holder 310, an annular
groove G (second opening) is formed at a position which is located
outside the depressed portion on which the silicon wafer 101 is
placed and inside the outer peripheral end. When the groove G is
dug in the central portion of the holder 310 throughout the
circumference, whereby it becomes possible to make a thickness d of
the portion where the groove G is formed smaller than the thickness
of the internal portion of the groove G. Therefore, a sectional
area in the circumferential direction can be decreased. As a
result, a heat transfer area can be decreased. Therefore, heat
radiation from the silicon wafer 101 side to the outside (on the
rotating member 170 side) can be suppressed.
Fifth Embodiment
[0089] FIG. 18 is a conceptual view showing a sectional
configuration of an example of a holder according to a fifth
embodiment. The other configurations are the same as those in the
first embodiment. A holder 320 has a first holder 232 being in
contact with a silicon wafer 101 and arranged on the inside and a
second holder 234 connected to the first holder 232 and arranged on
the outside. The first holder 232 serves as an example of a first
support unit. The second holder 234 serves as an example of a
second support unit. A penetrating opening having a predetermined
inner diameter is formed in the first holder 232. On a bottom
surface of a depressed portion dug from the upper surface side in a
predetermined depth at a right angle or a predetermined angle, the
silicon wafer 101 is supported to be in contact with the back side
surface of the silicon wafer 101. The first holder 232 has an
annular projecting portion 233 extending to the back side (back
surface side of the silicon wafer 101) on the outer peripheral
portion. In the second holder 234, an opening which does not
penetrate is formed on the inner peripheral side. In this manner, a
projecting portion 235 extending to the inner peripheral side is
formed on a lower portion of an inner peripheral end. The first
holder 232 is supported to be in contact with a distal end portion
of the projecting portion 233 on the bottom surface of the opening
serving as an upper surface of the projecting portion 235.
Centering (alignment of a center position) of the first holder 232
is performed on the side surface of the opening. When the first
holder 232 substantially moves in a horizontal direction, a part of
the side surface is brought into contact with the side surface of
the opening of the second holder 234. Therefore, since the contact
portion between the first holder 232 and the second holder 234
corresponds to the bottom surface of the opening and the distal end
portion of the projecting portion 233, a heat transfer area can be
decreased. The area of the distal end surface of the projecting
portion 233 is preferably minimized. The area is more decreased to
make it possible to further decrease the heat transfer area. Even
if the first holder 232 and the second holder 234 are in contact
with each other, the heat transfer further decreases when a simple
combination is designed such that respective parts physically
support the other parts. More specifically, when the first holder
232 is merely placed on a predetermined portion of the second
holder 234, the heat transfer further decreases. Even though two
essentially separated parts are combined to each other, some gap is
generated between the contact surfaces of the parts. This physical
gap (distance) may be about 10 to 30 .mu.m. For example, it is
assumed that the heat conductivities of the materials of the first
holder 232 and the second holder 234 are given by 0.25 W/mmK. When
a gas entering the gap is an H.sub.2 gas, the heat conductivity of
the H.sub.2 gas is about 0.0007 W/mmK. In addition, when the
atmosphere becomes almost vacuum, the heat conductivity further
decreases with the decrease in pressure. In this manner, when the
contact portion has a gap, the specific heat conductivity of the
part serving as a solid state is considerably smaller than the heat
conductivity of the actual contact portion. Therefore, heat
transfer between the first holder 232 and the second holder 234 is
considerably suppressed. For this reason, heat radiation from the
silicon wafer 101 side to the outside (on the rotating member 170
side) can be considerably suppressed.
[0090] In this case, the upper surface level of the second holder
234 is desirably equal to the upper surface level of the first
holder 232 or lower than the upper surface level of the first
holder 232. More specifically, an offset t is desirably set at 0 or
more. In this manner, a gas supplied from the upper portion of the
silicon wafer 101 can be smoothly flowed to the outer peripheral
side of the silicon wafer 101 without being delayed.
[0091] As in the first embodiment, as the material used in the
first holder 232, a material having a heat conductivity higher than
that of the material used in the second holder 234 is more
preferably used.
Sixth Embodiment
[0092] FIG. 19 is a conceptual view showing another example of a
holder according to a sixth embodiment when the holder is viewed
from the above.
[0093] FIG. 20 is a conceptual view showing a sectional structure
of the holder shown in FIG. 19. The other configurations are the
same as those in the first embodiment. A holder 330 has a first
holder 242 (example of a first support unit) being in contact with
a silicon wafer 101 and arranged on the inside and a second holder
244 (example of a second support unit) connected to the first
holder 242 and arranged on the outside. A penetrating opening
having a predetermined inner diameter is formed in the first holder
242. On a bottom surface of a depressed portion dug from the upper
surface side in a predetermined depth at a right angle or a
predetermined angle, the silicon wafer 101 is supported to be in
contact with the back side surface of the silicon wafer 101. The
first holder 242 has a plurality of projecting portions 248. The
projecting portions 248 are preferably formed at three or more
positions. The projecting portions 248 are preferably arranged at
equal angles about an axis of rotation in such a manner as to
surround the silicon wafer 101 when viewed from the above. An
opening is formed in the second holder 244 on an inner peripheral
side, and the first holder 242 is supported to be in contact with a
distal end portion of the projecting portion 248 on a bottom
surface of the opening. The first holder 242 further has a
plurality of projecting portions 246 extending to the outer
peripheral side. The projecting portions 246 are preferably formed
at three or more positions. The projecting portions 246 are
preferably arranged at equal angles about an axis of rotation when
viewed from the above. When the first holder 242 substantially
moves in a horizontal direction, some of the projecting portions
246 are brought into contact with the side surface of the opening
of the second holder 244. In this manner, centering (alignment of a
center position) of the first holder 242 is performed. As described
above, the distal end portion of the projecting portions 248 is in
contact with the second holder 244 to make it possible to decrease
a heat transfer area. Therefore, heat radiation from the silicon
wafer 101 side to the outside (on the rotating member 170 side) can
be suppressed.
[0094] In this case, the projecting portions 246 and the projecting
portions 248 may be formed integrally with the first holder 242 or
separately formed as different parts. In particular, when the
projecting portions 246 and the projecting portions 248 are
different parts, only openings may be formed to fix the projecting
portions to the first holder 242. For this reason, processing for
the first holder 242 is preferably simple.
[0095] FIG. 21 is a conceptual view showing still another example
of the holder according to the sixth embodiment when the holder is
viewed from the above.
[0096] FIG. 22 is a conceptual view showing a sectional
configuration of the holder shown in FIG. 21.
[0097] The second holder 244 has an opening on an inner peripheral
side and a plurality of projecting portions 258 formed in the
bottom surface of the opening. The second holder 244 supports the
first holder 242 such that the distal end portion of the projecting
portions 258 is brought into contact with the back surface of the
first holder 242. In the second holder 244, a plurality of
projecting portions 256 extending to the inner peripheral side are
formed on the side surface of the opening. When the first holder
242 substantially moves in a horizontal direction, the projecting
portions 256 are brought into contact with the side surface of the
first holder 242. More specifically, centering (alignment of a
center position) of the first holder 242 is performed by the
projecting portions 256. In this case, the projecting portions are
arranged on the second holder 244 side. With this configuration,
the same effect as described above can be obtained. The projecting
portions 256 and the projecting portions 258 may be formed
integrally with the second holder 244 or formed as different parts.
In particular, the projecting portions 256 and the projecting
portions 258 are formed different parts, only openings may be
formed to fix the projecting portions to the second holder 244. For
this reason, processing for the second holder 244 is preferably
simple. In FIG. 23, the projecting portions 248 may be formed on
the first holder 242 and the projecting portions 256 may be formed
on the second holder 244. Or, In FIG. 24, the projecting portions
258 may be formed on the first holder 242 and the projecting
portions 246 may be formed on the second holder 244.
[0098] In the sixth embodiment, the two types of holders are
explained. In any type, the holder is divided into two different
parts called first and second holders, and the first and second
holders are combined to each other. For this reason, as described
above, a gap may be generated at the contact portion in a precise
sense. Therefore, the specific heat conductivity of the part is
considerably higher than the heat conductivity of the actual
contact portion. Furthermore, in the sixth embodiment, heat
transfer can be considerably suppressed since a target is brought
into contact with several projecting portions.
[0099] According to the embodiments described above, heat can be
made difficult to be transferred to a substrate, or/and heat from
the substrate can be made difficult to be escaped. As a result, the
temperature of the substrate can be secured. Therefore, a
temperature distribution of the substrate edge can be made
preferable, and the film uniformity can be improved.
[0100] With this configuration, a temperature distribution near the
edge can be kept uniform, and epitaxial growth having a size of 60
.mu.m or more which is equal to the thickness of an n-type base
having excellent film uniformity can be achieved.
[0101] As a matter of cause, the present invention can be applied
to formation of epitaxial layers of thick bases of not only an
IGBT, but also a power MOS which is a power semiconductor and
requires a high withstand voltage or a GTO (gate turn-off
thyristor) used as a switching element for an electric train or a
general thyristor (SCR).
[0102] The embodiments are described with reference to the concrete
examples. However, the present invention is not limited to the
concrete examples. For example, an epitaxial growth apparatus is
described as an example of a vapor phase deposition apparatus.
However, the vapor phase deposition apparatus is not limited to the
epitaxial growth apparatus. Any apparatus to perform vapor phase
deposition of a predetermined film on a sample surface may be used.
For example, an apparatus which grows, e.g., a polysilicon film may
be used.
[0103] Parts such as apparatus configurations and control methods
which are not directly required to explain the invention are
omitted. However, required apparatus configurations or required
control methods can be appropriately selected and used. For
example, although the configuration of the control unit for
controlling the epitaxial growth apparatus 100 is omitted, a
required control unit configuration may be appropriately selected
and used as a matter of course.
[0104] All vapor phase deposition apparatuses and all shapes of
support members which include the elements of the present invention
and can be appropriately changed in design by a person skilled in
the art are included in the spirit and scope of the invention
[0105] Additional advantages and modification will readily occur to
those skilled in the art. Therefore, the invention in its broader
aspects is not limited to the specific details and representative
embodiments shown and described herein. Accordingly, various
modifications may be made without departing from the spirit or
scope of the general inventive concept as defined by the appended
claims and their equivalents.
* * * * *