Kenji Sakamoto et al.

Patent Trials and Appeals Board

Feb 25, 2020

13395677 - (D) (P.T.A.B. Feb. 25, 2020)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
13/395,677 03/13/2012 Kenji Sakamoto 140709.02201 2979
136404 7590 02/25/2020
Pepper Hamilton LLP/Boston
Attn: Boston IP Docketing Department
125 High Street
19th Floor
Boston, MA 02110-2736
EXAMINER
QI, HUA
ART UNIT PAPER NUMBER
1714
NOTIFICATION DATE DELIVERY MODE
02/25/2020 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
docketingbn@pepperlaw.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte KENJI SAKAMOTO and MASAYUKI TSUJI

Appeal 2019-002707
Application 13/395,677
Technology Center 1700
____________

Before JEFFREY T. SMITH, JAMES C. HOUSEL, and
GEORGE C. BEST, Administrative Patent Judges.

SMITH Administrative Patent Judge.
DECISION ON APPEAL
Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the
Examiner’s decision to reject claims 1–3, 5, 7–9, and 17–20. We have
jurisdiction under 35 U.S.C. § 6(b).
We REVERSE.
STATEMENT OF THE CASE
Appellant’s invention is generally directed to a method and apparatus
for successively producing epitaxial wafers in which an epitaxial growth

1 We use the word “Appellant” to refer to “applicant” as defined in 37
C.F.R. § 1.42. Appellant identifies the real party in interest as SUMCO
Corporation. Appeal Br. 1.
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layer is formed on a surface of a semiconductor wafer using a single wafer
processing growth furnace. (Spec. ¶ 2.)
Claim 1 illustrates the subject matter on appeal and is reproduced
below:
1. A method for producing epitaxial wafers using a single wafer
processing epitaxial growth furnace, comprising the steps of:
cleaning for removing deposit on a susceptor in the
epitaxial growth furnace, wherein the epitaxial growth furnace
includes a layer formation chamber which is substantially
partitioned into an upper space and a lower space by the
susceptor;
after the step of cleaning, performing first wafer
processing for obtaining a first epitaxial wafer by mounting a
first wafer on the susceptor and growing an epitaxial layer on
the first wafer based on first control parameters;
without a step of cleaning for removing deposit on the
susceptor in the epitaxial growth furnace after the first wafer
processing, performing second wafer processing after
transferring the first epitaxial wafer from the susceptor, for
obtaining a second epitaxial wafer by mounting a second wafer
on the susceptor and growing an epitaxial layer on the second
wafer based on second control parameters set such that the
second epitaxial wafer has approximately the same film
thickness profile as the first epitaxial wafer;
without a step of cleaning for removing deposit on the
susceptor in the epitaxial growth furnace after the second wafer
processing, performing at least third wafer processing after
transferring the second epitaxial wafer from the susceptor, for
obtaining a third epitaxial wafer by mounting a third wafer on
the susceptor and growing an epitaxial layer on the third wafer
based on the second control parameters set such that the third
epitaxial wafer has approximately the same film thickness
profile as the first and second epitaxial wafers; and
wherein the first control parameters and the second
control parameters each include a flow rate of reactive gas
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supplied to the upper space of the layer formation chamber and
a flow rate of inert gas supplied to the lower space of the layer
formation chamber, and the flow rate of the inert gas supplied
to the lower space in the second control parameters is lower
than the flow rate of the inert gas supplied to the lower space in
the first control parameters, and
wherein the first and the second control parameters are
set such that a difference in epitaxial layer film thickness
between the first wafer and the second wafer at a position 2 mm
from each respective wafer's edge toward a center of the wafer
(ROA2 difference) is 5 nm or less over the peripheries of the
first and second wafers.
Appeal Br. 22–23, Claims Appendix.
The following rejections are presented for our review:2
I. Claims 1–3, 5, 7–9, and 17–19 are rejected under 35 U.S.C.
§ 103(a) as unpatentable over Zojaji (US 2006/0169669 A1; published Aug.
3, 2006), and further in view of Miyashita (US 2010/0029066 A1; published
Feb. 4, 2010) and Takizawa (US 7,340,320 B2; issued Mar. 4, 2008).
II. Claim 20 rejected under 35 U.S.C. § 103(a) as unpatentable over
Zojaji, Miyashita, Takizawa and further in view of Arai (US 2001/0001384
A1; published May 24, 2001).
OPINION
After review of the respective positions provided by Appellant and the
Examiner, we REVERSE the Examiner’s rejections under 35 U.S.C.
§ 103(a). The Examiner has reproduced the rejections on appeal in the
Examiner’s Answer. (Ans. 3–19.)

2 The complete statement of the rejection on appeal appears in the Final
Office Action. (Final Act. 4–12.)
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The Examiner finds Zojaji teaches a method of producing epitaxial
wafers using a single wafer processing epitaxial growth furnace. (Final Act.
4.) The Examiner finds Zojaji discloses a step of cleaning for removing
deposit from the furnace that is repeated after processing of multiple
epitaxial substrates. (Final Act. 4; Zojaji ¶ 60.) The Examiner recognizes
Zojaji does not suggest that the susceptor disposed within the furnace
chamber partitions the furnace’s layer formation chamber into an upper
space and a lower space. (Final Act. 4.) The Examiner finds Miyashita
teaches a process of manufacturing epitaxial wafers, wherein a reaction
chamber is divided into an upper space and a lower space by a susceptor.
(Final Act. 4; Miyashita Fig. 3, ¶¶ 65–66.)
The Examiner recognizes Zojaji and Miyashita do not disclose
successively growing an epitaxial layer on the second and third wafers based
on a second control parameters, which are different than the control
parameters for a first wafer, such that the second and third wafers have
approximately the same thickness profiles as the first epitaxial wafer. (Final
Act. 5.) The Examiner finds Takizawa teaches a method of producing
epitaxial multiple wafers using processing control parameters, including gas
flow rate, controlled and adjusted in order to eliminate inconsistency, e.g.,
thickness inconsistency, that occurs as the number of process wafers
changes. (Final Act. 5–6; Takizawa cols. 2 and 10.) The Examiner finds
Zojaji, Miyashita, and Takizawa teach flowing reactive gas and inert gas into
the processing chamber having the upper space and the lower space for film
deposition meeting the limitations recited in claim 1. (Final Act. 6–7.) The
Examiner concludes:
Based on the factual teachings of Zojaji/Miyashita/Takizawa, it
would have been obvious to one ordinary skill in the art that the
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control parameters of the deposition recipe comprising the flow
rate of reactive gas and the flow rate of the inert gas for
epitaxial layer growth for each wafer of the multiple wafer[s]
affect the properties or qualities of the resulting epitaxial
wafers. Thus it would have been obvious that one of ordinary
skill in the art at the time of invention would have
modified/optimized the flow rates of the inert gas supplied to
the lower space and the flow rate of the reactive gas for
epitaxial layer growth for each wafer in the process of
Zojaji/Miyashita/Takizawa, and obtained various gas flow rates
including the instantly claimed “the flow rate of the inert gas
supplied to the lower space in the second control parameter is
lower than the flow rate of the inert gas supplied to the lower
space in the first control parameter” as recited in claim 1.
(Final Act. 7.)
The Examiner further determines:
[I]t would have been obvious that one of ordinary skill in the art
at the time of invention would have modified and/or optimized
the flow rates of the inert gas and the reactive gas (the first and
the second control parameters) in the process of
Zojaji/Miyashita/Takizawa, and obtained wafers having a
difference in epitaxial layer film thickness between the first
wafer and the second as less as possible, including “a difference
in epitaxial layer film thickness between the first wafer and the
second wafer at a position 2 mm from each respective wafer's
edge toward a center of the wafer (ROA2 difference) is 5 nm or
less over the peripheries of the first and second wafers” as
recited in claim 1, in order to control the thicknesses
consistency of the resulting epitaxial film on the wafers and get
epitaxial wafers as uniform as possible as suggested by
Takizawa, by conducting routine experimentation of a result
effective variable. See MPEP 2144.05 II A-B.
(Final Act. 8–9.)
The dispositive issue on appeal is:
Did the Examiner err in determining that the combination of Zojaji,
Miyashita, and Takizawa teach or suggest controlling the flow rate of inert
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gas in the lower chamber was known to effect epitaxial layer uniformity and
for the purpose of ensuring that the ROA2 difference is 5 nm or less as
recited in the method of independent claim 1?
We answer this question in the affirmative.
Appellant argues that one of ordinary skill in the art would not have
been led by the teachings of Zojaji, Miyashita, and Takizawa to control the
flow rate of inert gas in the lower chamber to effect epitaxial layer
uniformity and for the purpose of ensuring that the ROA2 difference is 5 nm
or less as recited in the method of independent claim 1. (Appeal Br. 18–20.)
The Examiner has not demonstrated that Zojaji, Miyashita, and
Takizawa teach or suggest a relationship between the flow rate of inert gas
supplied to the lower chamber of the furnace and the uniformity of film
thickness at a position 2 mm from each respective wafer’s edge toward a
center of the wafer (ROA2 difference). Neither Zojaji nor Takizawa
disclose a susceptor that partitions the reaction chamber into an upper and
lower space wherein inert gas is flowed into the lower space. Takizawa
discloses controlling the pressure, temperature and gas flow rate in the
reactor chamber for the purpose of controlling the film is deposited on a
wafer. (Takizawa col. 8.) Miyashita discloses the purpose of supplying the
inert gas to the lower space is to keep the circumference of the wafer clean.
(Miyashita ¶¶ 50, 66.) Miyashita does not teach the effect of the flow, or
adjustments to the flow rate, on film thickness at the wafer periphery (ROA2
difference) as required by independent claim 1.
The Examiner’s explanation that one having ordinary skill in the art
would have arrived at the claimed ROA2 difference through routine
experimentation (Final Act. 8–9) does not provide the requisite rational
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underpinning explaining why a person of ordinary skill in the art would have
arrived at the claimed invention through routine optimization of the flow rate
to the lower space of the chamber. See In re Stepan Co., 868 F.3d 1342,
1346 (Fed. Cir. 2017) (reversing a rejection based on a rationale of routine
optimization because the rejection failed to explain why it would have been
routine optimization to arrive at the claimed invention.) Miyashita does not
teach the effect of the flow, or adjustments to the flow rate, on film thickness
at the wafer periphery.
Accordingly, we do not sustain the rejection of claims 1–3, 5, 7–9,
17–19 (Rejection I) for the reasons presented by Appellant (Appeal Br. 18–
20) and those given above.
Appealed Rejection II relies on the combination of Zojaji, Miyashita,
and Takizawa to reject claim 20, in combination with the additional prior art
reference Arai. The Examiner cited Arai to address limitations not included
in the dispositive issue. Accordingly, because all rejections are based on the
combined teachings of Zojaji, Miyashita, and Takizawa, we also do not
sustain this rejection for the reasons presented by Appellant and given
above.
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CONCLUSION
In summary:
Claims
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1–3, 5, 7–9,
17–19
103 Zojaji, Miyashita,
Takizawa
1–3, 5, 7–
9, 17–19
20 103 Zojaji, Miyashita,
Takizawa, Arai
20
Overall
Outcome
1–3, 5, 7–
9, 17–20
REVERSED