Ex Parte Johnson et al

Patent Trial and Appeal Board

Sep 20, 2018

13446353 (P.T.A.B. Sep. 20, 2018)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
13/446,353 04/13/2012
127660 7590 09/24/2018
PARKER IBRAHIM & BERG LLP
One Financial Center
Boston, MA 02111
FIRST NAMED INVENTOR
Bayard K. Johnson
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
ATTORNEY DOCKET NO. CONFIRMATION NO.
0150020.U 7579
EXAMINER
QI,HUA
ART UNIT PAPER NUMBER
1714
NOTIFICATION DATE DELIVERY MODE
09/24/2018 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, JOHN P. DeLUCA,
and WILLIAM L. LUTER
Appeal2017-009411
Application 13/446,353
Technology Center 1700
Before LINDA M. GAUDETTE, MARK NAGUMO, and
DEBRA L. DENNETT, Administrative Patent Judges.
DENNETT, Administrative Patent Judge.
DECISION ON APPEAL 1
STATEMENT OF THE CASE
Appellants2 appeal under 35 U.S.C. § 134(a) from a rejection of
claims 12 and 14--22. We have jurisdiction under 35 U.S.C. § 6(b ).
We REVERSE.
1 In our Opinion, we refer to the Specification filed April 13, 2012 ("Spec.");
the Final Office Action mailed May 5, 2015 ("Final Act."); the Appeal Brief
filed November 7, 2016 ("Br."); and the Examiner's Answer mailed
February 21, 2017 ("Ans."). Appellants did not file a Reply Brief.
2 Appellants identify GTAT IP HOLDING LLC as the real party in interest.
Br. 1.
Appeal 2017-009411
Application 13/446,353
The claims are directed to methods of growing silicon ingots having
one or more dopants that are evenly distributed throughout the ingot. Sole
independent claim 12, reproduced below with disputed limitations italicized,
is illustrative of the claimed subject matter:
12. A method of Czochralski growth of a silicon ingot
comprising a dopant material in a concentration C and having a
segregation coefficient of k, the method comprising the steps
of:
i) providing a crucible having an inner growth zone in
fluid communication with an outer feed zone;
ii) pre-charging the inner growth zone with silicon and
the dopant material to form a mixture, wherein the mixture,
when melted, has a concentration of the dopant material of C/k,
where k is less than 1, and pre-charging the outer feed zone
with silicon and the dopant material in a concentration C, when
melted;
iii) melting the mixture in the inner growth zone and the
silicon and the dopant material in the outer feed zone;
iv) initiating growth of the silicon ingot from the inner
growth zone;
v) delivering a feed of silicon and the dopant material
into the outer feed zone while growing the silicon ingot, the
feed having an average concentration of the dopant material C
when melted; and
vi) removing the silicon ingot comprising the dopant
material in concentration C.
Br. 15 (Claims App'x).
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Application 13/446,353
REFERENCES
The Examiner relies on the following prior art in rejecting the claims
on appeal:
Yamashita et al. us 5,021,225 June 4, 1991
("Yamashita")
Holder us 5,288,366 Feb.22, 1994
Nagai et al. us 5,900,055 May4, 1999
("Nagai")
Kraiem et al. US 2011/0030793 Al Feb. 10,2011
("Kraiem")
Kazama et al. JP 02-083292 A Mar. 22, 1990
("Kazama") 3
REJECTIONS
The Examiner maintains and Appellants seek review of the following
rejections under 35 U.S.C. § I03(a): (1) claims 12, 14, 18, and 20-22 over
Nagai, alternatively in view of Holder, and as evidenced by Yamashita, and
alternatively further in view ofKazama; and (2) claims 15-17 and 19 over
Nagai in view of Holder as evidenced by Yamashita and Kazama, and
further in view of Kraiem. Final Act. 3-8; Br. 5-11.
OPINION
Appellants indicate in the Specification that controlled doping and,
particularly, counter-doping, in the Czocharalski method4 is complicated by
3 The Examiner uses EP 35305 A as an English language equivalent of this
reference.
4 In the Czocharalski method, a seed crystal held at the end of a cable
contacts the melt. The seed crystal is pulled upwards slowly as
crystallization proceeds resulting in a cylinder a meter or more long,
Spec. ,r 3, and many hundreds of millimeters in diameter. Wafers may be
cut from the crystal cylinder.
3
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Application 13/446,353
segregation effects. Spec. ,r 6. "Segregation," according to Appellants, "is
the tendency of an impurity or dopant to remain in the melt during
solidification, with the effect that the concentration of a dopant on the liquid
side of the solid-liquid interface is different, usually greater, than that on the
solid side." Id. This phenomenon is characterized by a "segregation
coefficient," "k," the ratio of the concentration of dopant on the solid side of
the solidification interface to the concentration of the same dopant on the
liquid side of the solidification interface. Id. As a result, according to the
Specification, the concentration of dopant increases in the melt as a crystal is
formed and withdrawn from the melt. Accordingly, the amount of dopant is
not uniform along the length of the crystal. Id. ,r 7. Appellants assert that
there is a need in the industry for a method of producing silicon ingots
having at least one dopant in which each ingot has substantially constant
dopant concentrations. Id. ,r 9.
Appellants do not argue the claims separately. Br., generally. We
decide the appeal as to both grounds of rejection based on arguments made
in support of patentability of claim 12.
With respect to claim 12, the Examiner finds that Nagai teaches a
method of Czochralski growth of a silicon ingot, including use of an inner
and outer crucible that communicate through pores, and charging silicon
material and dopant material into the outer crucible while growing the
silicon mono-crystal from the crucible. Final Act. 3. The Examiner finds
that, although Nagai is silent about removing the silicon ingot, it would have
been obvious to one of ordinary skill in the art that removing the ingot was
necessarily a step in processing and use of the ingot. Id. at 3--4. The
Examiner also finds that Holder discloses removing the ingot. Id. at 4. The
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Application 13/446,353
Examiner further finds that the segregation coefficient k is an inherent
property for a specific dopant. Id.
The Examiner finds that Nagai in combination with Holder is silent as
to the ratio of dopant-to-silica concentrations in the inner and outer crucibles
as claimed. Id. However, the Examiner finds that Nagai teaches that the
concentration of dopant in the crystal growth system greatly affects the
resistivity of the resulting silicon crystal ingot, and the concentration is
variable due to segregation of dopant, thus the dopant concentration is a
result effective variable. Id. at 4--5. The Examiner determines that it would
have been obvious to one of ordinary skill in the art at the time of the
invention to have modified and optimized the dopant concentration in Nagai
by routine experimentation. Id. at 5 (citing In re Aller, 220 F.2d 454,456
(CCPA 1955)).
Appellants argue that both Nagai and Kazama teach initial (pre-
charging) conditions that are opposite to those claimed. Br. 7. Appellants
contend that Nagai teaches a process in which the ratio of dopant
concentration in the outer crucible (Cautz(W)) to that in the inner crucible
(Cintz(W)) is greater than the effective segregation coefficient of dopant (keff),
i.e., Cautz(W)/Cintz(W) > keff· Id. Appellants point to the sole example in
Nagai, which teaches that the concentration of dopant in the outer crucible is
twice the concentration of dopant in the inner crucible before
commencement of pulling of a silicon monocrystal. Id. at 8.
Appellants are correct that, in the single example, Nagai teaches pre-
charging the outer crucible with a higher dopant concentration than is
charged in the inner crucible. Nagai col. 7, 1. 66-col. 8, 1. 4. However,
Nagai's disclosure is not limited to the single example. See In re Lamberti,
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Application 13/446,353
545 F.2d 747,750 (CCPA 1976) ("all disclosures of the prior art, including
unpreferred embodiments, must be considered"); see also In re Preda, 401
F.2d 825, 826 (CCPA 1968) ("[I]n considering the disclosure of a reference,
it is proper to take into account not only specific teachings of the reference
but also the inferences which one skilled in the art would reasonably be
expected to draw therefrom."). "[F]or purposes of§ 103, a reference is prior
art for all that it discloses." Symbol Techs., Inc. v. Opticon, Inc., 935 F.2d
1569, 1578 (Fed. Cir. 1991); see also ETVP Co,p. v. Reliance Universal Inc.,
755 F.2d 898, 907 (Fed. Cir. 1985) ("A reference must be considered for
everyihing it teaches by way of technology and is not limited to the
particular invention it is describing and attempting to protect.").
Nagai teaches that the dopant concentration ratio is larger than an
effective segregation coefficient as pulling of a silicon monocrystal is
commenced: Cautt(W)/Cintt(W) > keff- Nagai col. 3, 11. 3-8. The dopant
concentration ratio, however, does not require that the dopant concentration
in the outer crucible is greater than the dopant concentration in the inner
crucible, as Appellants argue. See Br. 8. For example, if the dopant is
boron, which has a keffOf 0.75 according to Nagai (col. 6, 1. 37), and Cautz(W)
= 1, then Cintz(W) may be any value below 1.33, meaning that Cintz(W) may
be greater than Cautz(W). In sum, contrary to Appellants' contention, Nagai
discloses pre-charging the inner crucible with silicon and a dopant wherein
the resulting mixture may have an initial dopant concentration that is greater
than the dopant concentration in the outer crucible, and meets the limitation
in claim 12.
The Examiner finds correctly that the segregation coefficient is an
inherent property of a specific dopant material. Final Act. 4. However, we
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Application 13/446,353
are unable to discern substantial evidence in the record supporting the
Examiner's determination that the concentration of dopant in melted, pre-
charged, silicon/dopant material is inherently taught by Nagai. See id.
Nagai discloses that a ratio of the concentration of dopant in silicon melt in
the outer crucible (Cautz(W)) to that in the inner crucible (Cintz(W)) is greater
than the effective segregation coefficient of dopant (keff). Nagai col. 2, 1. 64--
col. 3, 1. 8. That the ratio is greater than an inherent value when the
crucibles are pre-charged conveys nothing regarding the actual
concentrations of dopant in the inner and outer crucibles. "The mere fact
that a certain thing may result from a given set of circumstances is not
sufficient [to establish inherency]." In re R!jckaert, 9 F.3d 1531, 1533-34
(Fed. Cir. 1993).
We also fail to find substantial evidence in the record supporting the
Examiner's determination that Nagai inherently teaches that the feed has an
average concentration of dopant when melted. See Final Act. 4. Nagai
teaches pulling the silicon monocrystal while charging silicon material to the
silicon melt within the outer crucible while the dopant concentration ratio
decreases until it becomes equal to, then less than, the effective segregation
coefficient. Nagai col. 3, 11. 30-35. Nagai teaches recharging dopant to the
silicon melt stored in the outer crucible when the dopant concentration
becomes less than the effective segregation coefficient. Id. col. 3, 1. 36-37.
Thus, Nagai does not teach a feed with the same concentration of dopant as
is present in the mixture pre-charged to the outer crucible (as required by
claim 12). See Br. 15 (Claims App'x) (Claim 12 recites "delivering a feed
of silicon and the dopant material into the outer feed zone while growing the
silicon ingot, the feed having an average concentration of the dopant
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Application 13/446,353
material C when melted," and "C' is defined as the concentration of dopant
in both the silicon ingot and the mixture pre-charged into the outer
crucible.).
Appellants persuasively show that the Examiner reversibly erred in
determining that claim 12 is obvious over Nagai in view of Holder. The
Examiner does not cite other prior art as showing the elements missing from
Nagai and Holder. See generally, Final Act. and Ans. Therefore, we reverse
the rejection of claim 12 over the cited art. For the same reasons, we also
reverse the rejection of claims 14--22.
DECISION
The rejections of claims 12 and 14--22 are reversed.
REVERSED
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