Ex Parte Johnson

Patent Trial and Appeal Board

Feb 26, 2018

13464203 (P.T.A.B. Feb. 26, 2018)

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.
13/464,203 05/04/2012 Bayard K. Johnson 0150023 .U 4864
127660 7590 02/28/2018
PARKER IBRAHIM & BERG LLC
One Financial Center
Boston, MA 02111
EXAMINER
QI, HUA
ART UNIT PAPER NUMBER
1714
NOTIFICATION DATE DELIVERY MODE
02/28/2018 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):
patent@piblaw.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte BAYARD K. JOHNSON
Appeal 2017-005840
Application 13/464,2031
Technology Center 1700
Before LINDA M. GAUDETTE, JENNIFER R. GUPTA, and
SHELDON M. McGEE, Administrative Patent Judges.
McGEE, Administrative Patent Judge.
DECISION ON APPEAL
Pursuant to35U.S.C. § 134, Appellant seeks our review of the
Examiner’s rejections adverse to the patentability of claims 1—6 under
35 U.S.C. § 103(a).
We have jurisdiction under 35 U.S.C. § 6.
We affirm.
1 Appellant identifies GTAT IP Holding LLC as the real party in interest.
Br. 2.
Appeal 2017-005840
Application 13/464,203
SUBJECT MATTER
The appealed subject matter concerns methods of growing a silicon
ingot comprising a dopant via a continuous Czochralski growth method.
Spec. H2, 25; Fig. 6. Figure 6 of the application is reproduced below:
Figure 6 depicts a cross-sectional view of the Czochralski growth
system. Spec. 114.
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Appeal 2017-005840
Application 13/464,203
The growth method of claim 1 is illustrative, and is copied below with
key limitations at issue in this appeal italicized:
1. A method of growing a silicon ingot comprising a dopant
material having a segregation coefficient of k, the method
comprising the steps of:
i) providing a crucible [16] having an inner growth zone
[22] in fluid communication with [28] an outer feed zone [26];
ii) providing an initial charge in the inner growth zone and
the outer feed zone, the initial charge in the inner growth zone
comprising silicon and the dopant material and the initial charge
in the outer feed zone comprising silicon and no dopant material;
iii) melting the silicon and dopant material in the inner
growth zone to form a melted mixture and the silicon in the outer
feed zone to form a silicon melt, the melted mixture and the
silicon melt having upper melt surfaces at substantially similar
heights, wherein the inner growth zone has a cross-sectional
surface area As at the upper melt surface of the melted mixture
and the crucible has a total cross-sectional surface area At at the
upper melt surface area of the melted mixture and the silicon
melt;
iv) growing the silicon ingot from the inner growth zone;
and
v) removing the grown silicon ingot comprising the dopant
material in an axially substantially constant concentration,
wherein the method is a continuous Czochralski growth
method comprising the step of delivering a feed comprising
silicon and no dopant material into the silicon melt in the outer
feed zone in an amount MF, while growing the silicon ingot to an
amount Mx, and wherein
(dMihlM,) = 1 — k(AJAs)
wherein the continuous Czochralski growth method is
performed without supplying additional dopant material while
growing the silicon ingot to an amount Mx.
App. Br. 12—13 (emphasis added).
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Appeal 2017-005840
Application 13/464,203
OPINION
In rejecting claims 1—6 under 35 U.S.C. § 103(a) over the combined
teachings of Furukawa2 and Yamashita,3 the Examiner finds that Furukawa
discloses a method of growing a silicon ingot in accordance with every
element recited in claim 1, but does not explicitly disclose the initial
compositions of the charges in the claimed inner growth and outer feed
zones. Final Act. 2—5. To address this deficiency, the Examiner finds that
Yamashita’s method of growing a silicon semiconductor crystal uses a
multi-chamber crucible containing an initial charge of doped silicon material
in its inner chamber and an initial charge of un-doped silicon in its outer
chamber. Id. at 3. In view of Yamashita’s stated object to grow a
semiconductor crystal with a controlled and/or relatively constant resistivity,
the Examiner concludes that it would have been obvious to modify
Furukawa’s method to include Yamashita’s initial charge compositions in
Furukawa’s inner growth and outer feed zones. Id.
Appellant presents arguments against the rejection as a group. Br. 7—
10. We, therefore, select claim 1 and decide the appeal on the basis of this
claim alone. 37 C.F.R. § 41.37(c)(l)(iv).
Appellant contends that the combined references fail to teach a
continuous Czochralski growth method where a feed comprising silicon and
no dopant is delivered into the silicon melt in the outer feed zone which also
comprises silicon and no dopant. Br. 7—9. We are not persuaded by this
argument.
2 Jun Furukawa, et al., US 2006/0254499 Al, published Nov. 16, 2006.
3 Youji Yamashita, et al., US 5,021,225, issued June 4, 1991.
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Appeal 2017-005840
Application 13/464,203
Although claim 1 states that the initial charge in the outer feed zone
comprises silicon and no dopant, we agree with the Examiner (Final Act. 5—
6; Ans. 3) that, once melted, this “silicon melt” is not required by the claims
to always be dopant-free. Rather, claim 1 expressly recites that the inner
growth zone which contains silicon and a dopant material is “in fluid
communication with” the outer feed zone. This “fluid communication” is
achieved by means of an aperture, such as aperture 28 in Figure 6, which
allows the melted mixture in the inner growth zone and the silicon melt in
the outer feed zone to “have upper melt surfaces at substantially similar
heights” as recited in claim 1. Spec. H 36, 38. Thus, we agree with the
Examiner’s rationale (Final Act. 6), unchallenged by Appellant, that “the
[melted] mixture in the inner zone and the [silicon] melt in the out[er] zone
would communicate with each other through the at least one aperture [in the]
wall due to the inherent fluidity of the melt.” See also Ans. 4. Due to this
fluid communication between the inner and outer zones, it is reasonable to
expect that, once the melting step was carried out, some of the dopant from
the initial charge in the inner growth zone’s “melted mixture” would travel
through the aperture into the “silicon melt” of the outer feed zone.
Therefore, because the claims do not require the silicon melt in the outer
feed zone to remain dopant-free, Appellant has identified no error in the
rejection by asserting that the references fail to teach such a feature. In re
Self, 671 F.2d 1344, 1348 (CCPA 1982) (“Appellant’s arguments fail from
the outset because . . . they are not based on limitations appearing in the
claims.”).
Appellant also contends that there would have been no motivation for
the skilled artisan to combine the teachings of Furukawa, which teaches a
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Appeal 2017-005840
Application 13/464,203
continuous process, with Yamashita, directed to a batch process, because
“the steps associated with the two processes are completely different.”
Br. 10. This argument fails to persuade us of error in the rejection. As
correctly noted by the Examiner (Ans. 6), the rejection relies on the
teachings of Yamashita merely for the initial charge compositions for both
the inner and outer crucible zones. Final Act. 3. Yamashita discloses that
using “doped melt and undoped melt... in the inner and outer chambers” of
a crucible, respectively, is part of a process which enables the resistivity of
the crystal to “be controlled to be within a desired range.” Yamashita 4:5—
19. Even though Yamashita’s Czochralski technique for preparing semi­
conductor crystals is carried out in batches, the skilled artisan would have
recognized that utilizing Yamashita’s initial charge compositions in other
Czochralski processes, such as Furukawa’s continuous Czochralski process,
may predictably yield similar improvements in the resultant crystal’s
resistivity. “[I]f a technique has been used to improve one device, and a
person of ordinary skill in the art would recognize that it would improve
similar devices in the same way, using the technique is obvious unless its
actual application is beyond his or her skill.” KSR Int 7 Co. v. Teleflex Inc.,
550 U.S. 398,417 (2007).
DECISION
The Examiner’s final decision to reject claims 1—6 is affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1).
AFFIRMED
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