Hans-Joachim Schulze et al.

Patent Trials and Appeals Board

Aug 7, 2019

15187971 - (D) (P.T.A.B. Aug. 7, 2019)

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.
15/187,971 06/21/2016 Hans-Joachim Schulze 1012-1602/2011P51069
US03
8310
57579 7590 08/07/2019
MURPHY, BILAK & HOMILLER/INFINEON TECHNOLOGIES
1255 Crescent Green
Suite 200
CARY, NC 27518
EXAMINER
GREEN, TELLY D
ART UNIT PAPER NUMBER
2822
NOTIFICATION DATE DELIVERY MODE
08/07/2019 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):
official@mbhiplaw.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte HANS-JOACHIM SCHULZE, ALEXANDER SUSITI,
MARKUS ZUNDEL, and REINHARD PLOSS
____________

Appeal 2018-008593
Application 15/187,971
Technology Center 2800
____________

Before ROMULO H. DELMENDO, MONTÉ T. SQUIRE, and
MERRELL C. CASHION, JR., Administrative Patent Judges.

DELMENDO, Administrative Patent Judge.

DECISION ON APPEAL
The Applicant1 (“Appellant”) appeals under 35 U.S.C. § 134(a) from
the Primary Examiner’s final decision to reject claims 1, 3–9, 11, and 13.2, 3
We have jurisdiction over the appeal under 35 U.S.C. § 6(b).
We affirm.

1 The Applicant is “Infineon Technologies AG” (Application Data Sheet
filed June 21, 2016), which is also identified as the real party in interest
(Appeal Brief filed March 6, 2018 (“Appeal Br.”), 2).
2 Appeal Br. 3–16; Reply Brief filed August 28, 2018 (“Reply Br.”), 2–5;
Final Office Action entered August 11, 2017 (“Final Act.”), 2–7; Examiner’s
Answer entered June 28, 2018 (“Ans.”), 3–10.
3 Claims 10 and 12 are also pending, but these claims are no longer on
appeal as the rejection as to these claims has been withdrawn (Ans. 3).
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I. BACKGROUND
The subject matter on appeal relates to a method for manufacturing a
semiconductor device (Specification filed June 21, 2016 (“Spec.”),
Abstract). Representative claim 1 is reproduced from the Claims Appendix
to the Appeal Brief, as follows:
1. A method of manufacturing a semiconductor device, the
method comprising:
forming a trench in a semiconductor body at a first surface
of the semiconductor body;
forming a polysilicon material in the trench; and thereafter
introducing dopants into the polysilicon material by a high
dose and low energy process, wherein the high dose and
low energy process is an ion shower implantation or a
plasma deposition; and
performing a thermal treatment configured to drive-in the
dopants into the polysilicon material.
(Appeal Br. 17 (emphasis added)).
II. REJECTION ON APPEAL
Claims 1, 3–9, 11, and 13 stand rejected under 35 U.S.C. § 103(a) as
unpatentable over Williams et al.4 (“Williams”), Gardner et al.5 (“Gardner”),
and Henley et al.6 (“Henley”) (Ans. 3–10; Final Act. 2–7).

4 US 2005/0035398 A1, published February 17, 2005.
5 US 6,150,222, issued November 21, 2000.
6 US 6,083,324, issued July 4, 2000.
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III. DISCUSSION
Unless separately argued as indicated and addressed below, the
rejected claims stand or fall with claim 1, which we select as representative.
37 C.F.R. § 41.37(c)(1)(iv).
1. Claim 1
The Examiner finds that Williams describes a method that includes
most of the limitations recited in claim 1, including introducing dopants into
a polysilicon material in a trench by an ion shower implantation or plasma
deposition (Final Act. 3). The Examiner acknowledges that “Williams does
not specifically disclose depositing the polysilicon material first and
thereafter, introducing the dopants into the polysilicon material by a high
dose and low energy process” (id.). The Examiner finds further that Gardner
discloses depositing a polysilicon material and then introducing dopants into
the polysilicon material by a low energy process (ion shower implantation)
(id.). The Examiner concludes from these findings that “[i]t would have
been obvious to one of ordinary skill in the art . . . to modify the invention of
Williams with the teachings of Gardner for the purpose of introducing the
appropriate dopant atoms” (id.). According to the Examiner, the
determination of an appropriate implant voltage range (0.1 kV to 30 kV)
would have been obvious to a person having ordinary skill in the art as a
matter of discovering optimum values of a result-effective variable (id. at 4).
The Examiner further states that “Williams as modified by Gardner
does not specifically disclose introducing the dopants into the polysilicon
material by a high dose and low energy process” (id.). The Examiner finds
that Henley discloses introducing dopants into a silicon/polysilicon material
by a high dose and low energy process and then concludes that “[i]t would
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have been obvious to one of ordinary skill in the art . . . to modify the
invention of Williams with the teachings of Henley for the purpose of
introducing the appropriate dopant atoms and gettering layers” (id. at 4–5).
Furthermore, the Examiner concludes that the determination of the dopant
dosage amounts would have been obvious as a matter of design choice and
optimization of a result-effective variable (id. at 5).
The Appellant contends that the “combination of the cited references
fails to render obvious” the disputed claim limitations highlighted in
reproduced claim 1 above (Appeal Br. 3). Specifically, the Appellant argues
that Henley discloses forming a gettering layer beneath an active region on a
wafer for removing impurities from an active region of an integrated circuit
to be formed on the wafer (id. at 4). According to the Appellant, Henley
teaches implanting gas-forming or precipitate-forming particles, such as ions
or charged atoms or molecules (e.g., hydrogen ions or ions formed from
noble gases), which are not dopants as required by the claim (id. at 4–5). In
support, the Appellant relies on various documents marked as Exhibits A–D
(id. at 6–9). As for the “high dose” limitation, the Appellant argues that “ion
implantation at the level of 2-8x1012 ions/cm2 [disclosed in Gardner] is not
the same as introducing dopants by a high dose process” (id. at 10
(emphases omitted)).
Although we agree with the Appellant regarding Henley’s scope and
content, the Appellant’s arguments in totality fail to identify reversible error
in the Examiner’s rejection. In re Jung, 637 F.3d 1356, 1365 (Fed. Cir.
2011).
Before addressing the scope and content of the prior art, we point out
that the Appellant does not direct us to definitions in the Specification for
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the terms “high dose” and “low energy process” (Appeal Br. 3–10).
Although the Specification provides examples of suitable ranges for what
would be considered “high dose” and “low energy process” (see, e.g., Spec.
¶¶ 49 (exemplary implanted phosphor in a range between 5 x 1016/cm2 and
5 x 1017/cm2 and exemplary implant voltages in a range of 0.1 kV to 30 kV),
59 (same)), it does not delineate the full scope of what these terms
encompass. Therefore, we are obligated to give these terms their broadest
reasonable interpretations not inconsistent with the Specification. In re
ICON Health & Fitness, Inc., 496 F.3d 1374, 1379 (Fed. Cir. 2007) (“[W]e
look to the specification to see if it provides a definition for claim terms, but
otherwise apply a broad interpretation.”). Id. “As [our reviewing] court has
discussed, this methodology produces claims with only justifiable breadth.”
Id.
We next turn to the prior art teachings. Figures 15A–15C (partially
annotated) of Williams are reproduced as follows:

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Williams’s Figures 15A–15C above depict a process for fabricating a zener-
clamped TBOX (thick bottom oxide) trench gate device 850, wherein the
process includes, inter alia: forming a trench 955; oxidizing the trench 955;
and depositing a polysilicon layer 958 to a thickness roughly equal to the
trench depth, which “may [then] be doped in-situ or alternatively followed
by an ion implantation and 1 hour diffusion at 950° C. to 1000° C. to drive
the implanted dopant down into the trench polysilicon layer 958” (Williams,
¶¶ 159, 162–165). According to Williams, phosphorous is used as the
dopant for N-channel MOSFETs and boron for P-channel devices, some of
which may also use phosphorous-doped polysilicon or boron polysilicon
with a small amount of phosphorus (id. ¶ 165).
Although Williams does not explicitly teach the dopant dosages or
energy levels used for implantation for the process disclosed in Figures
15A–15C, we concur with the Examiner that the discovery of suitable
dosages and energy levels would have been obvious to a person having
ordinary skill as a matter of routine optimizations of result-effective
variables for the reasons discussed below. In re Applied Materials, Inc., 692
F.3d 1289, 1295 (Fed. Cir. 2012) (“‘[W]here the general conditions of a
claim are disclosed in the prior art, it is not inventive to discover the
optimum or workable ranges [of variables known to be result-effective] by
routine experimentation.’” (quoting In re Aller, 220 F.2d 454, 456 (CCPA
1955)).
Specifically, Gardner teaches that a boron dopant concentration of
approximately 2–8 x 1012 ions/cm2 and an energy level range of
approximately 5–20 keV are suitable when introducing the dopant into a
polysilicon layer 18 by ion implantation (Gardner, Fig. 5 and col. 4, ll. 50–
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62). Thus, Gardner’s energy level range appears to overlap the exemplary
energy level range disclosed in the current Specification (Spec. ¶¶ 49, 59).
Therefore, the determination of an optimum or suitable range of energy
levels depending on the dopant would have been a matter of routine
experimentation. Indeed, the Appellant’s own relied-upon evidence
supports the Examiner’s determination (Ex. C, 2–3 (“Doping a
semiconductor in a good crystal introduces allowed energy states within the
band gap, but very close to the energy band that corresponds to the dopant
type.”). In re Hedges, 783 F.2d 1038, 1039–40 (Fed. Cir. 1986).
Regarding the boron dopant concentration, Gardner’s range of
approximately 2–8 x 1012 ions/cm2 is significantly lower than, e.g., the
Inventors’ exemplary boron dosage of 5 x 1016 [ions]/cm2 (id.).
Nevertheless, Williams shows an example in which the boron dopant dosage
is somewhat higher and closer to the Inventors’ disclosed exemplary
range—i.e., 2 x 1015 to 4 x 1015/cm2 (Williams, ¶ 168). And, the Appellant
does not direct us to any specific description in the Specification that
delineates the lower boundaries of what would be considered “high dose”
nor objective evidence establishing that Gardner’s 2–8 x 1012 ions/cm2 or
Williams’s 2–4 x 1015/cm2 would not be considered as “high dose.”
Moreover, the Appellant’s proffered evidence (Exhibits A–D)
establish that dopant dosages and energy levels are result-effective variables.
Regarding dopants, Exhibit A defines “dopant” as “an impurity added
intentionally in a very small, controlled amount to a pure semiconductor to
change its electrical properties” (Ex. A, 1 (emphasis added)). Exhibit B
states that “[d]oping means the introduction of impurities into a
semiconductor crystal to the defined modification of conductivity” (Ex. B,
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1). Similarly, Exhibit C teaches that “doping is the intentional introduction
of impurities into an intrinsic semiconductor for the purpose of modulating
its electrical properties” (Ex. C, 1 (not paginated; bolding omitted)).
Significantly, Exhibit C teaches that “increased doping leads to increased
conductivity due to the higher concentration of carriers” (id. at 2 (emphasis
added)). Exhibit D also states that “[d]oping is the process of adding
impurities to intrinsic semiconductors to alter their properties” (Ex. D, 1).
Thus, these documents firmly establish that a person having ordinary skill in
the art would have reasonably understood that the amount or dosage of a
dopant would affect the electrical properties of the semiconductor into which
it is implanted (e.g., increase electrical conductivity). Therefore, we concur
with the Examiner (Final Act. 5) that a person having ordinary skill in the art
would have known that dopant dosage is a result-effective variable. Given
that dopant dosage would have been considered to be a result-effective
variable, a person having ordinary skill in the art would have determined the
range of optimum or workable dopant dosages, including “high dose[s]” as
recited in claim 1, through nothing more than routine experimentation.
For these reasons, we uphold the rejection as maintained against claim
1.
2. Claim 5
Claim 5, which depends from claim 1, recites: “wherein one or both
of phosphorus and boron are introduced as the dopants” (Appeal Br. 17).
The Appellant argues that the Examiner’s finding regarding Williams is
“clear error” (Appeal Br. 11 (emphasis omitted)).
The Appellant’s argument has no persuasive merit. As we found
above, and as the Examiner points out (Ans. 8), Williams explicitly teaches
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phosphorus and/or boron (Williams, ¶ 165). Consistent with the Examiner’s
position, the Appellant’s argument directed to Henley’s disclosure does not
negate Williams’s teaching in this regard.
Therefore, we uphold the rejection as maintained against claim 5.
3. Claim 3
Claim 3, which depends from claim 1, recites: “wherein the dopants
are introduced at a dose in a range between 5 x 1016 cm-2 and 5 x 1017 cm-2”
(Appeal Br. 17). The Appellant argues that Henley discloses implantation of
helium, which is not a dopant (id. at 12). But that fact does not alter our
conclusion that the dopant dosage is a result-effective variable that may be
optimized by routine experimentation, as we discussed above.
Therefore, we sustain the rejection as maintained against claim 3.
4. Claims 6 and 7
Claim 6, which depends from claim 1, recites: “further comprising
forming a gate dielectric in the trench prior to forming the polysilicon
material in the trench” (id. at 17). Claim 7 depends from claim 6 (id.). The
Appellant argues that the Examiner’s finding that Williams teaches a gate
oxide is “clear error” because Henley does not teach a gate or gate trench
(id. at 13 (emphasis omitted); see also id. at 13–14).
The Appellant’s argument lacks persuasive merit because Williams
teaches a gate oxide—i.e., a “gate dielectric” as required by claims 6 and 7
(Williams, ¶¶ 164–65).
5. Claim 9
Claim 9, which depends from claim 1, recites: “wherein the
polysilicon material is formed as a conformal polysilicon layer including a
sidewall part and a bottom part” (Appeal Br. 18). The Appellant argues that
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“[d]epositing polysilicon layer 958 to a thickness roughly equal to the
trench depth is not the same as forming ‘a conformal polysilicon layer
including a sidewall part and a bottom part’ as required by claim 9” (id.
at 14 (citing Exhibit E (defining “conformal” as “leaving the size of the
angle between corresponding curves unchanged”)).
The Appellant’s argument is not persuasive. Williams’s disclosure
that the “polysilicon layer 958 is deposited to a thickness roughly equal to
the trench depth” (Williams, ¶ 165) would result in a coating that is about
equal to the trench depth, which would meet the “conformal” limitation.
Therefore, we also sustain the rejection as maintained against claim 9.
IV. SUMMARY
The Examiner’s rejection under 35 U.S.C. § 103(a) is sustained.
Therefore, the Examiner’s final decision to reject claims 1, 3–9, 11, and 13
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).

AFFIRMED