U.S. patent application number 12/512283 was filed with the patent office on 2010-02-04 for susceptor, vapor phase growth apparatus, and method of manufacturing epitaxial wafer.
This patent application is currently assigned to SUMCO CORPORATION. Invention is credited to Junji MIYASHITA.
Application Number | 20100029066 12/512283 |
Document ID | / |
Family ID | 41608784 |
Filed Date | 2010-02-04 |
United States Patent
Application |
20100029066 |
Kind Code |
A1 |
MIYASHITA; Junji |
February 4, 2010 |
SUSCEPTOR, VAPOR PHASE GROWTH APPARATUS, AND METHOD OF
MANUFACTURING EPITAXIAL WAFER
Abstract
An aspect of the present invention relates to a susceptor
comprising a counterbored groove receiving a semiconductor wafer in
the course of manufacturing an epitaxial wafer by vapor phase
growing an epitaxial layer on a surface of the semiconductor wafer,
wherein a lateral wall of the counterbored groove is comprised of
at least one flat portion and at least one protruding portion being
higher than the flat portion, and a height of the flat portion is
equal to or greater than a thickness of the semiconductor
wafer.
Inventors: |
MIYASHITA; Junji; (Saga,
JP) |
Correspondence
Address: |
GREENBLUM & BERNSTEIN, P.L.C.
1950 ROLAND CLARKE PLACE
RESTON
VA
20191
US
|
Assignee: |
SUMCO CORPORATION
Tokyo
JP
|
Family ID: |
41608784 |
Appl. No.: |
12/512283 |
Filed: |
July 30, 2009 |
Current U.S.
Class: |
438/478 ;
118/728; 257/E21.461 |
Current CPC
Class: |
C23C 16/4584 20130101;
C30B 29/06 20130101; H01L 21/0262 20130101; H01L 21/67386 20130101;
H01L 21/02532 20130101; C23C 16/4585 20130101; C30B 25/12
20130101 |
Class at
Publication: |
438/478 ;
118/728; 257/E21.461 |
International
Class: |
H01L 21/36 20060101
H01L021/36; C23C 16/458 20060101 C23C016/458 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 31, 2008 |
JP |
2008-197880 |
Claims
1. A susceptor comprising: a counterbored groove receiving a
semiconductor wafer in the course of manufacturing an epitaxial
wafer by vapor phase growing an epitaxial layer on a surface of the
semiconductor wafer, wherein a lateral wall of the counterbored
groove is comprised of at least one flat portion and at least one
protruding portion being higher than the flat portion, and a height
of the flat portion is equal to or greater than a thickness of the
semiconductor wafer.
2. The susceptor according to claim 1, wherein the height of the
flat portion is about 1.0 to 2.0 times greater than the thickness
of the semiconductor wafer.
3. The susceptor according to claim 1, wherein a difference in
height between the highest portion of the protruding portion and an
upper surface of the flat portion ranges from about 0.1 to 5
mm.
4. A vapor phase growth apparatus comprising: the susceptor
according to claim 1; and a reaction chamber housing the
susceptor.
5. A method of manufacturing an epitaxial wafer by vapor phase
growing an epitaxial layer on a surface of a semiconductor wafer,
comprising: conducting the vapor phase growing in a state where the
semiconductor wafer is received in the counterbored groove of the
susceptor according to claim 1.
6. The method of manufacturing an epitaxial wafer according to
claim 5, wherein the semiconductor wafer is received in the
counterbored groove such that, on the surface of the semiconductor
wafer, an edge surface in a direction where close {111} planes are
present is positioned opposite the protruding portion.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority under 35 USC
119 to Japanese Patent Application No. 2008-197880, filed on Jul.
31, 2008, which is expressly incorporated herein by reference in
its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a susceptor and a vapor
phase growth apparatus, and more particularly, to a susceptor
permitting the manufacturing of an epitaxial wafer comprising an
epitaxial layer of uniform thickness, and to a vapor phase growth
apparatus comprising the susceptor.
[0004] The present invention further relates to a method of
manufacturing an epitaxial wafer employing the above susceptor.
[0005] 2. Discussion of the Background of the Invention
[0006] The reduction of crystal defects in semiconductors,
particularly crystal defects on or near the surface, has been
gaining importance in recent years with the high level of
integration of semiconductor devices. Thus, the demand is
increasing for epitaxial wafers obtained by vapor phase growth of
epitaxial films of good crystallinity on the surfaces of substrate
wafers.
[0007] An epitaxial wafer is normally manufactured by feeding a
starting material gas onto the surface of a substrate wafer while
the substrate wafer is being supported by a susceptor to induce
vapor phase growth of an epitaxial layer. A susceptor having a
counterbored groove receiving the wafer is generally employed. Such
susceptor is disclosed in, for example, Japanese Unexamined Patent
Publication (KOKAI) No. 2003-12397, which is expressly incorporated
herein by reference in its entirety.
[0008] The use rate in the surface when manufacturing semiconductor
devices from epitaxial wafers has tended to increase with the level
of integration in recent years. However, when a conventional
susceptor such as the susceptor described in Japanese Unexamined
Patent Publication (KOKAI) No. 2003-12397 is employed to vapor
phase grow an epitaxial film on a substrate wafer, depending on the
orientation of the crystal axis, a phenomenon has tended to occur
whereby the thickness along the perimeter portion of the epitaxial
film has differed from the thickness at the center portion thereof.
The perimeter portions of such epitaxial wafers cannot be used to
fabricate devices, making it difficult to raise the use rate in the
surface.
SUMMARY OF THE INVENTION
[0009] Accordingly, a non-limiting aspect of the present invention
provides for means for manufacturing an epitaxial wafer having an
epitaxial layer of uniform thickness.
[0010] A first non-limiting aspect of the present invention relates
to a susceptor comprising:
[0011] a counterbored groove receiving a semiconductor wafer in the
course of manufacturing an epitaxial wafer by vapor phase growing
an epitaxial layer on a surface of the semiconductor wafer, wherein
a lateral wall of the counterbored groove is comprised of at least
one flat portion and at least one protruding portion being higher
than the flat portion, and a height of the flat portion is equal to
or greater than a thickness of the semiconductor wafer.
[0012] The height of the flat portion may be about 1.0 to 2.0 times
greater than the thickness of the semiconductor wafer.
[0013] The difference in height between the highest portion of the
protruding portion and an upper surface of the flat portion may
range from about 0.1 to 5 mm.
[0014] A second non-limiting aspect of the present invention
relates to a vapor phase growth apparatus comprising:
[0015] the above susceptor; and
[0016] a reaction chamber housing the susceptor.
[0017] A third non-limiting aspect of the present invention relates
to a method of manufacturing an epitaxial wafer by vapor phase
growing an epitaxial layer on a surface of a semiconductor wafer,
comprising:
[0018] conducting the vapor phase growing in a state where the
semiconductor wafer is received in the counterbored groove of the
above susceptor.
[0019] The semiconductor wafer may be received in the counterbored
groove such that, on the surface of the semiconductor wafer, an
edge surface in a direction where close {111} planes are present is
positioned opposite the protruding portion.
[0020] According to a non-limiting feature of the present
invention, an epitaxial wafer having an epitaxial layer of uniform
film thickness over the entire surface can be provided.
[0021] Since a non-limiting feature of the present invention
permits the formation of an epitaxial layer of good crystallinity
on a semiconductor wafer, it is possible to reduce the crystal
defects in a semiconductor element based on the crystal orientation
of a semiconductor wafer, particularly crystal defects on or near
the surface.
[0022] Other exemplary embodiments and advantages of the present
invention may be ascertained by reviewing the present disclosure
and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] The present invention will be described in the following
text by the exemplary, non-limiting embodiments shown in the
figures, wherein:
[0024] FIG. 1 is a partially enlarged view of the susceptor of a
non-limiting aspect of the present invention;
[0025] FIG. 2 is a descriptive drawing of the shape of the
protruding portion in the susceptor of a non-limiting aspect of the
present invention;
[0026] FIG. 3 is a schematic sectional view of an example of the
vapor phase growth apparatus of a non-limiting aspect of the
present invention; and
[0027] FIG. 4 shows the distribution of the film thickness along
the perimeter of the epitaxial wafers manufactured in Example 1 and
Comparative Example 1.
[0028] Explanations of symbols in the drawings are as follows:
[0029] 1 Vapor phase growth apparatus [0030] 2 Reaction chamber
[0031] 3 Upper dome [0032] 4 Lower dome [0033] 5 Dome mounting
member [0034] 6 Halogen lamp [0035] 7 Susceptor rotating shaft
[0036] 8 Support arm [0037] 9 Lift pin [0038] 10 Susceptor [0039]
11 Lift arm [0040] 12 Gas feed inlet [0041] 13 Gas exhaust outlet
[0042] 14 Gas feed inlet [0043] 15 Gas exhaust outlet
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0044] Unless otherwise stated, a reference to a compound or
component includes the compound or component by itself, as well as
in combination with other compounds or components, such as mixtures
of compounds.
[0045] As used herein, the singular forms "a," "an," and "the"
include the plural reference unless the context clearly dictates
otherwise.
[0046] Except where otherwise indicated, all numbers expressing
quantities of ingredients, reaction conditions, and so forth used
in the specification and claims are to be understood as being
modified in all instances by the term "about." Accordingly, unless
indicated to the contrary, the numerical parameters set forth in
the following specification and attached claims are approximations
that may vary depending upon the desired properties sought to be
obtained by the present invention. At the very least, and not to be
considered as an attempt to limit the application of the doctrine
of equivalents to the scope of the claims, each numerical parameter
should be construed in light of the number of significant digits
and ordinary rounding conventions.
[0047] Additionally, the recitation of numerical ranges within this
specification is considered to be a disclosure of all numerical
values and ranges within that range. For example, if a range is
from about 1 to about 50, it is deemed to include, for example, 1,
7, 34, 46.1, 23.7, or any other value or range within the
range.
[0048] The following preferred specific embodiments are, therefore,
to be construed as merely illustrative, and non-limiting to the
remainder of the disclosure in any way whatsoever. In this regard,
no attempt is made to show structural details of the present
invention in more detail than is necessary for fundamental
understanding of the present invention; the description taken with
the drawings making apparent to those skilled in the art how
several forms of the present invention may be embodied in
practice.
[0049] The first non-limiting aspect of the present invention
relates to a susceptor comprising a counterbored groove receiving a
semiconductor wafer in the course of manufacturing an epitaxial
wafer by vapor phase growing an epitaxial layer on a surface of the
semiconductor wafer. In the susceptor, a lateral wall of the
counterbored groove is comprised of at least one flat portion and
at least one protruding portion being higher than the flat portion,
and a height of the flat portion is equal to or greater than a
thickness of the semiconductor wafer.
[0050] For example, a phenomenon whereby the perimeter film
thickness increases locally in the <110> orientation is
observed when vapor phase growing an epitaxial layer on the (100)
plane of a semiconductor wafer. In this context, the "perimeter"
refers to the area from the outer rim of the wafer to 5 mm from the
outer rim, for example. However, depending on the diameter of the
semiconductor wafer, there may also be cases where it comprises the
area to 1 mm from the outer rim, or to 7 mm from the rim, for
example. The above phenomenon is thought to occur because the rate
of vapor phase growth in the <100> orientation at the
perimeter is greater than that in the <111> orientation at
the perimeter. That is, the phenomenon whereby the thickness at the
perimeter of the epitaxial layer differs greatly from the thickness
in the center portion is thought to occur because there are
orientations with rapid vapor phase growth rates and orientations
with slow vapor phase growth rates in the wafer surface at the
perimeter. That is, since the silicon growth rate on the {111}
planes is slow, the growth rate on main surfaces adjacent thereto
becomes relatively fast, and the epitaxial layer becomes locally
thicker. In the susceptor of a non-limiting aspect of the present
invention, since portions (the protruding portions) of the lateral
wall of the counterbored groove are high, as set forth above, by
receiving the semiconductor wafer in the counterbored groove so
that the protruding portions face the edge surface in the
orientations of rapid vapor phase growth rate, the amount of
starting material gas that is fed to the perimeter can be reduced
in the orientations of rapid vapor phase growth rate to inhibit
vapor phase growth along the perimeter. Thus, the differences in
vapor phase growth rate due to crystal orientation along the
perimeter of the semiconductor wafer can be inhibited, and thus an
epitaxial layer of uniform film thickness can be formed over the
entire surface.
[0051] Further, by providing a counterbored groove the lateral wall
of which is of a height that is greater than the thickness of the
wafer, and positioning the wafer therein, wraparound of silicon
onto the rim portion (particularly the rear surface), including the
chamfer of the wafer, can be suppressed. Providing protruding
portions on the lateral wall can prevent local silicon growth in
the rim portion in orientations with rapid vapor phase growth
rates, stabilize the vapor phase growth rate at the perimeter, and
prevent variation, thereby making it possible to stably obtain an
epitaxial layer of uniform thickness.
[0052] Further, it becomes difficult to achieve uniform film
thickness over the entire surface in orientations other than the
orientation in which it is desirable to inhibit the vapor phase
growth rate at the perimeter when the height of the lateral wall of
the counterbored groove is changed, as set forth above. Thus, the
lateral wall is made flat everywhere except for the protruding
portions in the susceptor.
[0053] The susceptor of a non-limiting aspect of the present
invention will be described in further detail below.
[0054] FIG. 1 shows a partially enlarged view (a view of the
lateral wall from within the susceptor groove) of the susceptor of
a non-limiting aspect of the present invention. The protruding
portions need only be higher than the flat portions; the shape
thereof is not specifically limited. Specific examples of the
sectional shape of the protrusions are trapezoidal (FIG. 1(a)),
triangular (FIG. 1(b)), and rectangular (FIG. 1(c)).
[0055] The shape of the protruding portions will be further
described with reference to FIG. 2.
[0056] In FIG. 2, straight line (a) denotes an imaginary straight
line that begins at the center of the wafer surface, runs in an
orientation (for example, in <110> orientations parallel to
{100} planes, or in an orientation equivalent to [011] orientation
parallel to (100) plane) with a greater rate of perimeter vapor
phase growth than the other orientations, and passes through the
center of the upper surface (flat surface) of the protruding
portion. Straight line (b) denotes an imaginary straight line that
begins at the center of the wafer surface and runs through the edge
of the upper surface of the protruding portion. Straight line (c)
denotes an imaginary straight line that begins at the center of the
wafer surface and runs through the lower edge of the protruding
portion. The angle .theta..sub.1 formed by straight line (a) and
straight line (b) can be about 0 to 15.degree., for example, and is
desirably about 0 to 10.degree.. When .theta..sub.1 is 0.degree.,
the sectional shape of the protruding portion becomes triangular.
The angle .theta..sub.2 formed by straight line (a) and straight
line (c) is desirably about 5 to 20.degree., for example.
[0057] The number of such protruding portions in the susceptor is
desirably equal to the number of orientations of rapid perimeter
vapor phase growth rate. For example, when the surface on which the
epitaxial layer is formed is (100) plane, the orientations in which
perimeter vapor phase growth should be suppressed is <110>
orientations. Thus, the number of protruding portions equal to the
number of orientations (4) is desirably provided. When the wafer
notch of the lateral wall of the counterbored groove is made in
<110> orientations and the opposing position (notch-opposing
part) is made 0.degree., it is preferable to provide protruding
portions in the 85.degree. to 95.degree., 175.degree. to
185.degree., 265.degree. to 275.degree., and 355.degree. to
5.degree. portions.
[0058] The "flat portion" in the susceptor of a non-limiting aspect
of the present invention refers to a portion of which upper surface
is flat, as shown in FIG. 1. The height thereof is made equal to or
greater than the thickness of the semiconductor wafer positioned
within the counterbored groove to prevent wraparound of starting
material gas onto the rear surface of the wafer, as set forth
above. From the perspective of achieving good vapor phase growth on
the surface of the wafer while preventing wraparound of starting
material gas onto the rear surface of the wafer, the height of the
flat portions is desirably about 1.0 to 2.0-fold, preferably 1.0 to
1.3-fold, the height of the positioned wafer. Specifically, it can
be about 0.6 to 1.0 mm.
[0059] The difference in height between the highest portion of the
protruding portion and the upper surface of the flat portion is
desirably about 0.1 to 5 mm, preferably about 0.1 to 0.5 mm. Within
the above range, vapor phase growth of the perimeter can be
inhibited without significantly inhibiting vapor phase growth in
the area other than the perimeter in orientations of rapid vapor
phase growth, achieving the uniformity of the film thickness in the
surface.
[0060] The counterbored groove is comprised of, for example, a
lateral wall of the shape set forth above and an approximately
round bottom. When the distance from the outermost edge of the
semiconductor wafer positioned in the counterbored groove to the
lateral wall is excessive, it may become difficult to achieve an
effect by providing protruding portions. From that perspective, the
shape of the bottom of the counterbored groove is desirably
determined based on the size of the positioned semiconductor wafer
so that the distance from the outermost edge of the semiconductor
wafer to the lateral wall will be about 0.5 to 2.0 mm.
[0061] The susceptor of a non-limiting aspect of the present
invention can be manufactured using the materials used in
conventional susceptors. For example, the susceptor can be
manufactured by coating SiC on the surface of a carbon base
material. Wafer contamination by the base material can be prevented
by coating SiC on the surface of the base material.
[0062] The vapor phase growth apparatus of the second non-limiting
aspect of the present invention comprises the above susceptor and a
reaction chamber housing the susceptor. A configuration that is
identical to that of known vapor phase growth apparatuses normally
employed in the manufacturing of epitaxial wafers, with the
exception of containing the susceptor of a non-limiting aspect of
the present invention, may be employed. Configurations of vapor
phase growth apparatuses are described in detail in Japanese
Unexamined Patent Publication (KOKAI) Nos. 2004-63865, 2005-197380,
and 2007-189222 or English language family member US 2007/0160507
A1, and Japanese Patent No. 3,931,578 or English language family
member US 2003/0075109 A1, for example. The contents of the above
applications are expressly incorporated herein by reference in
their entirety.
[0063] The third non-limiting aspect of the present invention
relates to a method of manufacturing an epitaxial wafer by vapor
phase growing an epitaxial layer on a surface of a semiconductor
wafer. In the above method, the vapor phase growing is conducted in
a state where the semiconductor wafer is received in the
counterbored groove of the susceptor of a non-limiting aspect of
the present invention.
[0064] FIG. 3 shows an example (schematic sectional view) of the
vapor phase growth apparatus of a non-limiting aspect of the
present invention. The vapor phase growth apparatus of a
non-limiting aspect of the present invention and the method of
manufacturing an epitaxial wafer of a non-limiting aspect of the
present invention will be described below based on FIG. 3. However,
the present invention is not limited to the form shown in FIG.
3.
[0065] In FIG. 3, a vapor phase growth apparatus ("apparatus"
hereinafter) 1 comprises in the interior thereof a chamber
("reaction chamber" hereinafter) 2 forming an epitaxial film.
Reaction chamber 2 is equipped with an upper dome 3, a lower dome
4, and a dome mounting member 5. Upper dome 3 and lower dome 4 are
comprised of a transparent material such as quartz. Multiple
halogen lamps 6 are disposed above and below apparatus 1, heat
susceptor 10 and semiconductor wafer W. Susceptor 10 is rotated by
support arms 8, connected to a susceptor rotating shaft 7, that
insert into the perimeter of the lower surface thereof. Susceptor
10 has a counterbored groove in which is positioned a wafer, as
described above. The counterbored groove is comprised of an
approximately round bottom receiving semiconductor wafer W, and a
lateral wall surrounding the bottom. As shown in FIG. 3, a total of
three throughholes (for inserting lift pins) 10b can be formed at
intervals of about 120.degree. each, for example, in a
circumferential direction in the perimeter of susceptor 10. A lift
pin 9, lifting and lowering semiconductor wafer W, is freely
inserted in each lift pin insertion hole 10b. Lift pins 9 are
lifted and lowered by lift arms 11.
[0066] In dome mounting member 5, at a height position opposite
susceptor 10, a gas supply inlet 12 and a gas exhaust outlet 13 are
arranged in opposing fashion. Through gas supply inlet 12, a
reaction gas, in the form of a Si source gas (starting material
gas) such as SiHCl.sub.3 that has been diluted with hydrogen gas
(carrier gas) and into which has been mixed a trace quantity of
dopant, is fed into the interior of the reaction chamber 2 in a
direction (horizontal) parallel to the surface of semiconductor
wafer W. The reaction gas that is fed in passes over the surface of
semiconductor wafer W, and following epitaxial film growth, is
exhausted to the exterior of apparatus 1 through gas exhaust outlet
13. Carrier gas is normally fed through a gas supply inlet 14 on
the lower surface of the susceptor to keep the circumference of the
wafer clean. Using the susceptor of a non-limiting aspect of the
present invention can make it possible to reduce the amount of
starting material gas fed to the perimeter in orientations where
the rate of vapor phase growth of the perimeter is rapid.
Differences in the rate of perimeter vapor phase growth depending
on the orientation of the crystals can be thus reduced, making it
possible to obtain an epitaxial wafer of uniform film thickness
over the entire surface.
[0067] One example of the semiconductor wafer is a silicon wafer.
However, other semiconductor wafers such as compound semiconductor
wafers are also acceptable; there is no specific limitation. The
surface on which the epitaxial layer is formed is not specifically
limited. Examples are the {100} planes and the {110} planes. In the
formation of an epitaxial layer with a conventional susceptor, the
epitaxial layer becomes thick along the outer rim in axial
directions parallel to the main surface in directions in which the
{111} planes are present, on the main surface adjacent to the {111}
planes. For example, since the rate of vapor phase growth at the
perimeter in the <100> orientations is greater than the rate
of vapor phase growth at the perimeter in the <111>
orientations, when an epitaxial layer is grown on the (100) plane,
the perimeter film thickness locally increases on the (100) plane
in the <110> orientations, as set forth above. By contrast,
according to the susceptor of a non-limiting aspect of the present
invention, an epitaxial layer of uniform film thickness can be
obtained over the entire surface by positioning a semiconductor
wafer in the counterbored groove such that the edge surface in an
orientation where the rate of vapor phase growth is rapid at the
perimeter, specifically, in an orientation where close {111} planes
are present, is positioned opposite the protruding portion.
[0068] The thickness of the semiconductor wafer is, for example
about 600 to 1,000 micrometers. As set forth above, the height of
the lateral wall of the counterbored groove of the susceptor is
determined based on the thickness of the semiconductor wafer.
[0069] The semiconductor wafer can be positioned, for example, by
first conveying the semiconductor wafer into the reaction chamber
from an external conveyor device, lifting the semiconductor wafer
upward through the throughholes by means of the lift pins,
receiving the semiconductor wafer, and then lowering the
semiconductor wafer down onto the susceptor. Subsequently, starting
material gas can be fed to the upper surface side of the susceptor
in the reaction chamber to bring the surface of the semiconductor
wafer into contact with the starting material gas and conduct a
vapor phase reaction (epitaxial growth). Examples of starting
material gases that can be employed are: SiH.sub.4,
SiH.sub.2Cl.sub.2, SiHCl.sub.3, and SiCl.sub.4. The starting
material gas is normally fed in after being mixed with a carrier
gas. Examples of carrier gases that can be employed are hydrogen
gas and inert gases. It suffices to suitably set the blending ratio
of the starting material gas and the carrier gas.
[0070] It suffices to determine the flow rate of the gas supplied
to the upper surface side of the susceptor based on the temperature
conditions within the reaction chamber, the desired epitaxial layer
thickness, and the like. It is normally about 50 to 100
liters/minute.
[0071] When feeding carrier gas to the lower surface side of the
susceptor, a carrier gas such as hydrogen or an inert gas can be
employed. The flow rate of the carrier gas fed to the lower surface
side of the susceptor is desirably set to about 1/3 to 1/4 the flow
rate of the gas fed to the upper surface side.
[0072] When feeding the gas, the semiconductor wafer is normally
heated. As shown in FIG. 3, a heating means in the form of heating
lamps provided above and/or below the susceptor can be employed. An
annular preheating plate (preheating ring) can also be provided
around the susceptor. The heating temperature of the wafer and
susceptor can be suitably set.
[0073] Once the vapor phase growth process has been completed and
an epitaxial layer has been formed on the surface, the wafer can be
lifted upward through the throughholes by the lift pins and picked
up. The wafer that has been picked up can be moved to a conveyor
device by a robot arm or the like and discharged to the exterior of
the reaction chamber. Epitaxial wafers can be produced in large
numbers by repeating the above series of steps.
EXAMPLES
[0074] The present invention will be described in detail below
based on examples. However, the present invention is not limited to
the examples.
Example 1
[0075] A 300 mm semiconductor wafer on which an epitaxial layer is
to be formed on the (100) face thereof was placed on a susceptor
that had been disposed within the reaction chamber of a vapor phase
growth apparatus and that was equipped with protruding portions in
the 85.degree. to 95.degree., 175.degree. to 185.degree.,
265.degree. to 275.degree., and 355.degree. to 5.degree. portions
thereof when the position opposite the wafer notch (notch-opposing
part) of the lateral wall of the counterbored groove was aligned
with 0.degree..
[0076] An epitaxial film was grown by vapor phase epitaxy on the
surface of the semiconductor wafer placed on the susceptor. The
epitaxial growth process will be described in detail below.
[0077] The vapor phase epitaxial growth apparatus employed
comprised a chamber above and below which heaters were disposed,
and in the center of which was horizontally disposed a susceptor
that was capable of holding a single wafer and that was round when
viewed from above.
[0078] An upper counterbored portion (annular difference in
height), receiving a semiconductor wafer in a lateral state in
which the top and bottom surfaces were horizontal, was formed in a
portion on the inner circumference side of the surface of the
susceptor. On one lateral part of the chamber, gas feed inlets were
formed through which a prescribed carrier gas (H.sub.2 gas) and a
prescribed source gas (SiHCl.sub.3 gas) flowed parallel to the
wafer surface in the upper space of the chamber. Exhaust outlets
for the two gases were provided on the other lateral part of the
chamber.
[0079] During epitaxial growth, the semiconductor wafer was first
placed on the susceptor. The details of how it was positioned were
as set forth above.
[0080] Next, an epitaxial film was then grown on the surface of the
heated semiconductor wafer. That is, the carrier gas and the source
gas passed through their corresponding gas feed inlets and were
introduced into the chamber. The pressure within the furnace was
adjusted to 100.+-.20 KPa. Silicon produced by the thermal
decomposition or reduction of source gas was precipitated at a
reaction rate of 1.5 to 4.5 micrometers/minute on the semiconductor
wafer that had been heated to 1,000 to 1,200.degree. C. An
epitaxial film comprised of single crystal silicon 2 to 20
micrometers in thickness was thus grown on the surface of the
semiconductor layer.
[0081] An epitaxial wafer was manufactured by the above
process.
Comparative Example 1
[0082] With the exception that a conventional susceptor (a
susceptor that had a counterbored groove of constant lateral wall
height and had no protruding portions) was employed, an epitaxial
wafer was manufactured by the same method as in Example 1.
Film Thickness Distribution Along the Perimeter of the Epitaxial
Wafer
[0083] The thickness of the epitaxial films formed on the surfaces
of the semiconductor wafers in Example 1 and Comparative Example 1
was measured by infrared interferometry; the results are given in
FIG. 4. The results shown in FIG. 4 are measurements of the film
thickness along a circle at a point 2 mm from the perimeter edge of
the semiconductor wafer. As shown in the lower drawing of FIG. 4,
in the epitaxial wafer manufactured in Comparative Example 1, a
phenomenon was observed whereby the film along the perimeter was
locally thicker in the <110> orientations.
Measurement of the Variation in Film Thickness
[0084] A comparison of the film thickness of the epitaxial wafer
manufactured in Example 1 to that of the epitaxial wafer
manufactured in Comparative Example 1 as measured in the
<100> orientations and the <110> orientations by an
epitaxial film thickness measuring device (FT-IR) revealed that the
film thickness in the <110> orientations was 1.85 percent
greater than the film thickness in the <100> orientations, in
the epitaxial layer manufactured in Comparative Example 1. By
contrast, there was an increase of 0.75 percent in the epitaxial
layer manufactured in Example 1, indicating suppression to about
half the level in Comparative Example 1.
[0085] From these results, it will be understood that it was
possible to form an epitaxial layer of uniform film thickness over
the entire surface according to the present invention.
[0086] Although the present invention has been described in
considerable detail with regard to certain versions thereof, other
versions are possible, and alterations, permutations and
equivalents of the version shown will become apparent to those
skilled in the art upon a reading of the specification and study of
the drawings. Also, the various features of the versions herein can
be combined in various ways to provide additional versions of the
present invention. Furthermore, certain terminology has been used
for the purposes of descriptive clarity, and not to limit the
present invention. Therefore, any appended claims should not be
limited to the description of the preferred versions contained
herein and should include all such alterations, permutations, and
equivalents as fall within the true spirit and scope of the present
invention.
[0087] Having now fully described this invention, it will be
understood to those of ordinary skill in the art that the methods
of the present invention can be carried out with a wide and
equivalent range of conditions, formulations, and other parameters
without departing from the scope of the invention or any
embodiments thereof.
[0088] All patents and publications cited herein are hereby fully
incorporated by reference in their entirety. The citation of any
publication is for its disclosure prior to the filing date and
should not be construed as an admission that such publication is
prior art or that the present invention is not entitled to antedate
such publication by virtue of prior invention.
* * * * *