Ex Parte Smith et al

Patent Trial and Appeal Board

Nov 30, 2016

12940821 (P.T.A.B. Nov. 30, 2016)

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.
10031.007310 8345
EXAMINER
TRINH, THANH TRUC
ART UNIT PAPER NUMBER
1756
MAIL DATE DELIVERY MODE
12/940,821 11/05/2010
74254 7590 11/30/2016
Okamoto & Benedicto LLP
P.O. Box 641330
San Jose, CA 95164-1330
David D. SMITH
11/30/2016 PAPER
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.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
BEFORE THE PATENT TRIAL AND APPEAL BOARD
Ex parte DAVID D. SMITH and TAESEOK KIM
Appeal 2015-005090
Application 12/940,821
Technology Center 1700
Before ADRIENE LEPIANE HANLON, MICHAEL P. COLAIANNI, and
JEFFREY R. SNAY, Administrative Patent Judges.
COLAIANNI, Administrative Patent Judge.
DECISION ON APPEAL
Appeal 2015-005090
Application 12/940,821
Appellants appeal under 35 U.S.C. § 134 the final rejection of claims
1—10. We have jurisdiction over the appeal pursuant to 35 U.S.C. § 6(b).
We AFFIRM.
Appellants’ invention is directed to solar cell fabrication processes
and structures (Spec. 12). The claimed process allegedly lowers fabrication
costs associated with forming solar cell diffusion regions (i.e. N-type and P-
type regions) (Spec. Tflf 3, 4).
Claims 1,8, and 9 are illustrative:
1. A method of fabricating a solar cell structure, the method comprising:
forming a thin dielectric layer on a solar cell substrate;
forming first silicon nano-particle diffusion regions of the solar cell
structure by printing P-type doped silicon nano-particles over the thin
dielectric layer;
forming second silicon nano-particle diffusion regions of the solar cell
structure by printing N-type doped silicon nano-particles over the thin
dielectric layer; and
forming a continuous nano-particle film at least at an interface with the
thin dielectric layer by heating the N-type and P-type doped silicon nano­
particles at a sintering temperature less than a melting point of the N-type
and P-type doped silicon nano-particles for an amount of time sufficient to
form the continuous nano-particle film.
(emphasis added)
8. The method of claim 1 further comprising:
forming a wetting agent on the thin dielectric prior to printing the N-type
and P-type doped silicon nano-particles.
9. The method of claim 8 wherein the wetting agent comprises
amorphous silicon.
Appellants appeal the following rejections:
1. Claims 1, 2, 4—6, and 10 are rejected under 35 U.S.C. § 103(a) as
unpatentable over Swanson (US 2008/0121279 Al, published May
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Application 12/940,821
29, 2008) in view of Yasutomi et al. (US 5,271,871, issued Dec. 21,
1993) (“Yasutomi”).
2. Claim 3 is rejected under 35 U.S.C. § 103(a) as unpatentable over
Swanson in view of Yasutomi and Shah et al. (US 7,615,393 Bl,
issued Nov. 10, 2009) (“Shah”).
3. Claim 7 is rejected under 35 U.S.C. § 103(a) as unpatentable over
Swanson in view of Yasutomi and Anthony et al. (US 3,936,319,
issued Feb. 3, 1976) (“Anthony”).
4. Claims 8 and 9 are rejected under 35 U.S.C. § 103(a) as unpatentable
over Swanson in view of Yasutomi and Fu et al. (US 2008/0236665
Al, published Oct. 2, 2008) (“Fu”).
Appellants argue the subject matter of claims 1,8, and 9 only (App.
Br. 2—9). Claims 2—7 and 10 will stand or fall with our analysis of the
rejection of the sole independent claim 1.
FINDINGS OF FACT & ANALYSIS
REJECTIONS (1), (2), AND (3): Claim 1
The Examiner finds that Swanson teaches the subject matter of claim
1, except for forming a continuous nano-particle film at least at an interface
with the thin dielectric layer by heating the N-type and P-type doped silicon
nano-particles at a sintering temperature less than a melting point of the N-
type and P-type doped silicon nano-particles for an amount of time sufficient
to form the continuous nano-particle film (Final Act. 3—4). The Examiner
finds that Yasutomi teaches heating or sintering a mixture of particles to a
temperature of less than the melting point of the particles to link the particles
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together and to reduce voids and prevent a reduction of strength (Final Act.
4). The Examiner concludes that it would have been obvious to modify the
method of Swanson by applying the sintering steps of Yasutomi to the N-
type doped and P-type doped silicon nano-particles in order to link the
silicon nano-particles together, reduce voids and prevent a reduction in
strength as taught by Yasutomi. Id. The Examiner finds that the
combination of Yasutomi’s sintering step with Swanson’s method is nothing
more than the use of a known technique for its intended function in a known
environment to accomplish an entirely expected result (Final Act. 5).
Appellants argue that Yasutomi does not teach heating silicon nano­
particles as used by Swanson’s method (App. Br. 3). Appellants contend
that Yasutomi teaches not that sintering in general is beneficial, but rather
that sintering a particular mold composition may be beneficial. Id.
Appellants argue that Yasutomi teaches that it is important to use a binder in
the composition to reduce voids and increase packing density. Id.
Appellants contend that Yasutomi teaches heating metallic powder at a
temperature below the melting point of the metallic powder and then further
heating the metallic powder at high temperatures, which Appellants allege is
above the melting point of the metallic powder (App. Br. 4). Appellants
argue that Yasutomi does not consider the melting point of the silicon
portion of the powder mixture when setting the heating temperature of the
metallic powder. Id. Appellants argue that Yasutomi limits the amount of
silicon in the powder mixture and even claims the metallic powder as being
‘free of silicon.'1'’ Id.
Contrary to Appellants’ arguments, Yasutomi teaches that the particle
mixture includes metallic particles and may include silicon particles sized to
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Application 12/940,821
be less than 100 pm in order to control the resistivity of the layer (Yasutomi
col. 3,11. 12—38, 42-44). Yasutomi’s claim 1 does not recite that the particle
mixture is free of silicon as argued by Appellants. Rather, claim 1 recites
that the metallic powder is “free of Si” but the claim further recites that the
inorganic compound of the particle mixture includes silicide or oxide silicide
(Claims 1 and 3). Yasutomi’s claims comport with its disclosure that
includes having a mixture of metallic particles and silicide particles. Indeed,
Yasutomi’s Examples 10 and 11 in Table 2 in column 9 teaches that the ratio
of metallic powder to silicon powder may be such that the silicon portion is
the major component of the blend. We note that silicon has a melting point
of 1,420°C and titanium has a melting point of 1,800°C1. Therefore,
Yasutomi’s teaching to sinter the Ti:Si particle blend at a temperature below
the melting point followed by raising the temperature to a value within the
range of 600 to 1350°C would constitute heating the silicon particles to a
temperature below its melting point. In other words, Yasutomi teaches
sintering a particle blend with 90% silicon at a temperature below the silicon
portion’s melting point (Example 11, Table 2, column 9).
Although Yasutomi teaches that by adding binder to the particle
mixture the packing density of the particles and strength of the product can
be increased (Yasutomi, col. 7,11. 28—35), we note that Swanson also uses a
surfactant on the silicon particles to aid in their deposition (Swanson 115).
Also, the claim is open-ended and does not exclude the use of binder along
with the silicon particles. Yasutomi further teaches that the particle blend
can be made into a thin substrate by using a doctor blade method (col. 6,11.
39, 47-48). Yasutomi further discloses that the sintering method expands
1 Perry’s Chemical Engineers’ Handbook, 6th Ed. pp. 3-20, 3-23.
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the scope of use of the ceramics to include electronic parts such as, but not
limited to, electrode materials, current collectors, commutators, etc. (col. 8,
11. 1—9). Yasutomi thus teaches how to provide a thin layer that may be
made of silicon particles with improved strength and durability.
Appellants further argue that Swanson, directed to solar cells, and
Yasutomi, directed to ceramic parts, are directed to different fields of
endeavor (App. Br. 5). Appellants contend that Swanson is directed to
electrical arts and Yasutomi is directed to mechanical arts. Id. Appellants
contend that Yasutomi uses non-silicon containing metallic particles and
Swanson uses silicon nano-particles. Id.
Appellants’ argument only addresses whether Swanson and Yasutomi
are in the same field of endeavor; the first prong of the analogous art test set-
forth in In re Clay, 966 F.2d 656, 659 (Fed. Cir. 1992). However, the court
in Clay also stated that the art may be analogous if it is reasonably pertinent
to Appellants’ problem. Clay, 966 F.2d at 659.
The Examiner finds that Yasutomi is reasonably pertinent to
Appellants’ problem of processing particles so that the particles link together
to form a continuous material (Ans. 8). Appellants do not meaningfully
respond to this finding by the Examiner (Reply Br. 4). Rather, Appellants
focus on the methods of molding in Yasutomi differing from the method of
forming the silicon nano-particle layer in Swanson. Id. Appellants have not
shown that Yasutomi’s doctor blade method would have been detrimental to
Swanson’s device. Appellants’ citation to Yasutomi on page 4 of the Reply
Brief is taken out of context. Yasutomi teaches that doctor blade method
may be used to form thin substrates. However, the sentence preceding that
sentence is directed to molding using a mechanical press, a different method
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from the doctor blade method (Yasutomi col. 6,11. 35—48). No evidence has
been provided by Appellants to show that Yasutomi’s doctor blade method
of forming thin film would destroy Swanson’s solar cell. Nevertheless,
Appellants’ response fails to address why Yasutomi’s method of sintering
particles is not pertinent to Appellants’ problem, which is found by the
Examiner to be processing particles to link them together.
Appellants’ argument that Yasutomi uses non-silicon containing
particles is not accurate. Rather, Yasutomi teaches using non-silicon
containing metallic particles as part of the particle blend that is used to form
the molded article. The other portion of Yasutomi’s blend of particles may
include silicon containing particles to aid in controlling the resistivity of the
layer (col. 3,11. 20—24). Swanson teaches depositing silicon nano-particles
on a substrate to form N-type doped and P-type doped regions (Swanson |
15). The Examiner relies on Yasutomi to teach that is known to sinter 1 pm
or less sized particles of silicon at a temperature below the particulate
silicon’s melting point (Final Act. 4; Ans. 5).
Appellants contend that there is no support for the conclusion that
Yasutomi’s process would yield a predictable result when applied to silicon
nano-particle films in the manufacture of solar cells (App. Br. 6).
Appellants argue that Yasutomi’s high temperature sintering may melt or
change the electrical characteristics of silicon nano-particles and other films
of the solar cell. Id.
Appellants’ argument provides no evidence to substantiate the mere
attorney argument that forming Swanson’s silicon nano-particle layer using
Yasutomi’s process would necessarily affect the electrical characteristics of
the nano-particles or the other films of the solar cell. Rather, the Examiner
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Application 12/940,821
finds that Yasutomi’s sintering temperature range (i.e., 600 to 1350°C)
includes the same heat treatment temperature used by Appellants (i.e.,
900°C) (Ans. 10). Accordingly, it appears that Yasutomi includes values
within Appellants’ claimed range. Moreover, Appellants’ argument fails to
appreciate that a person of ordinary skill is also a person of ordinary
creativity not an automaton. KSR Int 7 Co. v. Teleflex Inc., 550 US 398, 421
(2007). A person of ordinary skill would appreciate that the process would
be modified so as to avoid damage to sensitive layers of the solar cell layers.
Appellants have not shown that making such a modification would have
been beyond the ordinary skill in the art.
For the above reasons, the preponderance of the evidence favors the
Examiner’s conclusion that it would have been obvious to use Yasutomi’s
sintering method to sinter the N-type and P-type regions formed of silicon
nano-particles on Swanson’s substrate. We affirm the Examiner’s § 103(a)
rejections (1), (2) and (3) listed supra.
REJECTION (4): Claims 8 and 9
Claim 8 depends from claim 1 and recites “forming a wetting agent on
the thin dielectric prior to printing the N-type and P-type doped silicon nano­
particles.”
Claim 9 depends from claim 8 and recites “wherein the wetting agent
comprises amorphous silicon.”
The Examiner rejects claims 8 and 9 over the combined teachings of
Swanson in view of Yasutomi and Fu. The Examiner’s findings regarding
Swanson and Yasutomi are as indicated with regard to claim 1. The
Examiner finds that Swanson and Yasutomi do not teach forming a wetting
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Application 12/940,821
agent on the thin dielectric prior to printing the N-type and P-type doped
silicon nano-particles (claim 8), wherein the wetting agent comprises
amorphous silicon (claim 9) (Final Act. 7).
The Examiner finds that Fu’s 134 teaches pre-coating a substrate with
molten silicon to alter the surface wettability and adhesion of the substrate
(Final Act. 7). The Examiner finds that Fu’s 140 and as shown in Figure 6
teaches using amorphous silicon as a wetting agent layer (Ans. 11). The
Examiner concludes that it would have been obvious to modify the method
of Swanson by forming a wetting agent of amorphous silicon as taught by Fu
on the thin dielectric prior to printing the N-type or P-type doped silicon
nano-particles in order to alter the surface wettability and adhesion as taught
by Fu (Final Act. 7—8).
With regard to claim 8, Appellants argue that Fu’s wetting agent is
applied to glass substrate for altering the wettability and adhesion of molten
silicon not printed silicon nano-particles (App. Br. 7). Appellants contend
that there is no disclosure regarding why altering the surface wettability and
adhesion would be beneficial to the modified Swanson (App. Br. 7).
Appellants contend that the Examiner has not explained the extent of the
proposed alteration to Swanson in light of Fu’s teaching to stop the further
wetting of silicon at a position on the substrate (App. Br. 7—8).
Appellants’ arguments are not persuasive. Swanson teaches that
surfactant (i.e., a wetting agent) may be applied to either the silicon nano­
particles or the substrate (115). Therefore, Swanson, alone, recognizes that
a wetting agent within the meaning of claim 8 may be used prior to silicon
nano-particle deposition.
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Regarding claim 9 Appellants argue that Fu’s molten silicon is not a
wetting agent and when the layer of silicon cools it is not amorphous silicon
(App. Br. 8—9). The Examiner, however, finds that Fu’s layer 44 constitutes
an amorphous silicon wetting layer (Ans. 11). Appellants respond that Fu’s
layer 44 is between the silicon dioxide layer 43 and the silicon thin film base
45 (Reply Br. 6). Appellants contend that thin film base 45 is not a printed
N-type and P-type doped silicon nano-particle layer and Fu fails to teach that
the wetting agent will improve the adhesion of printed N-type and P-type
doped silicon nano-particles to a thin dielectric. Id. Appellants contend that
the Examiner has not provided articulated reasoning why one of ordinary
skill in the art would form a wetting agent on the thin dielectric as modified
by Swanson. Id.
Appellants’ arguments in the Reply Brief fail to recognize that claim 9
as it ultimately depends on claim 1 is open-ended and does not preclude
various additional layers between the dielectric layer and the N-type and P-
type doped silicon nano-particles. Claim 1 recites “forming [first and
second] silicon nano-particle diffusion regions [over] the solar cell structure”
and “forming [] silicon nano-particle diffusion regions . . . over the thin
dielectric layer” (emphasis added). Claim 8 recites “forming a wetting agent
on the thin dielectric prior to printing” (emphasis added). Claims 1 and 8
does not require that the wetting agent be formed directly on the dielectric
with no intervening layers. The claim does not recite that the wetting agent
layer improves adhesion between the dielectric layer and the silicon nano­
particle regions. Appellants’ arguments are not commensurate in scope with
the claimed subject matter.
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Moreover, Swanson teaches to use a surfactant (i.e., wetting agent) on
the surface along with the nano-particles (Swanson 115). Fu teaches that
amorphous silicon is a known wetting agent (Fu 140). Therefore, it would
have been obvious to use Fu’s amorphous silicon wetting agent as the
wetting agent in Swanson because such a combination is nothing more than
the predictable use of prior art elements for their intended function (i.e.,
wetting agents). To that end, we note Appellants do not direct us to any
evidence or present any technical reasoning showing that the wetting agent
disclosed in Fu would not have been suitable in Swanson.
On this record, we affirm the Examiner’s § 103(a) rejection of claims
8 and 9 over Swanson in view of Yasutomi and Fu.
DECISION
The Examiner’s decision 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).
ORDER
AFFIRMED
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