Ex Parte Prokes et al

Patent Trial and Appeal Board

Jul 9, 2018

14192935 (P.T.A.B. Jul. 9, 2018)

UNITED STA TES p A TENT AND TRADEMARK OFFICE
APPLICATION NO. FILING DATE
14/192,935 02/28/2014
26384 7590 07/10/2018
NAVAL RESEARCH LABORATORY
AS SOCIA TE COUNSEL (PA TENTS)
CODE 1008.2
4555 OVERLOOK A VENUE, S.W.
WASHINGTON, DC 20375-5320
FIRST NAMED INVENTOR
Sharka M. Prokes
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.
102323-US2 5110
EXAMINER
KEBEDE, BROOK
ART UNIT PAPER NUMBER
2894
MAIL DATE DELIVERY MODE
07/10/2018 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 SHARKA M. PROKES, ERIN CLEVELAND,
and LAURA RUPPALT
Appeal2017-008708
Application 14/192,935
Technology Center 2800
Before ROMULO H. DELMENDO, CHRISTOPHER C. KENNEDY, and
BRIAND. RANGE, Administrative Patent Judges.
DELMENDO, Administrative Patent Judge.
DECISION ON APPEAL
The Applicants (hereinafter "Appellants") 1 appeal under 35 U.S.C.
§ 134(a) from the Primary Examiner's final decision to reject claims 1-16.2
We have jurisdiction under 35 U.S.C. § 6(b ).
We affirm.
1 The Appellants identify the real party in interest as the United States of
America, as represented by the Secretary of the Navy (Appeal Brief filed
July 20, 2016, hereinafter "Br.," 2).
2 Br. 3-5; Final Office Action entered July 20, 2015, hereinafter "Final
Act.," 2-7; Examiner's Answer entered November 23, 2016, hereinafter
"Ans.," 2-11.
Appeal2017-008708
Application 14/192,935
I. BACKGROUND
The subject matter on appeal relates to a semiconductor material and
to a method for its manufacture (Specification filed February 28, 2014,
hereinafter "Spec.," ,r 1 O; Br. 7-8 (Claims Appendix)). According to the
Appellants, pre-treating a semiconductor substrate surface-i.e., removing
or modifying semiconductor substrate surface oxides-"in situ, immediately
prior to dielectric deposition, reduc[ es] the likelihood of contamination or
reoxidation of [the] surface possible with ex situ methods" (id. ,r 12).
Representative claim 1 is reproduced from the Claims Appendix to the
Appeal Brief (Br. 7), with key limitations emphasized, as follows:
1. A method of forming a semiconductor/dielectric material,
compnsmg:
loading a III-V compound semiconductor substrate into an
atomic layer deposition [ ALD] reactor and applying an ultra-
high vacuum, wherein the substrate may contain a native oxide
on a surface of the substrate;
exposing the substrate to a hydrogen plasma, wherein the
hydrogen plasma removes, modifies, or removes and modifies
the native oxide; and
after plasma exposure, in-situ depositing a high-k
dielectric onto the substrate using atomic layer deposition,
wherein there is no break in the vacuum between the plasma
exposure and the atomic layer deposition.
II. REJECTION ON APPEAL
On appeal, the Examiner maintains a rejection under pre-AIA
35 U.S.C. § I03(a) of claims 1-16 as unpatentable over Doan et al. 3
3 US 2006/0057800 Al, published March 16, 2006.
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Application 14/192,935
(hereinafter "Doan"), Chiang et al. 4 (hereinafter "Chiang"), and Hong et al. 5
(hereinafter "Hong") (Ans. 2-11; Final Act. 2-7).
III. DISCUSSION
The Appellants rely on the same arguments for all claims on appeal
(Br. 3-5). Therefore, we confine our discussion to claim 1, which we select
as representative pursuant to 37 C.F.R. § 4I.37(c)(l)(iv). As provided by
this rule, claims 2-16 stand or fall with claim 1.
The Examiner finds that Doan describes a method for forming a
semiconductor/ dielectric material that includes most of the limitations
recited in claim 1 but acknowledges that Doan does "not disclose the
[semiconductor] substrate being a Group III-V substrate and applying of
ultra-high vacuum" (Ans. 2). The Examiner finds, however, that Chiang
describes a method including an in-situ substrate cleaning process using
hydrogen plasma in an ALD reactor under vacuum conditions and then
performing a dielectric film deposition (ALD) process without breaking the
vacuum to avoid substrate contamination (id. at 3). The Examiner concludes
from these findings that a person having ordinary skill in the art would have
been prompted to implement Chiang's technique (i.e., in-situ cleaning and
ALD deposition without breaking the vacuum) in Doan to avoid substrate
contamination (id.).
The Examiner states further that the combined teachings of Doan and
Chiang "do not disclose the substrate being a Group III-V substrate and
4 US 2002/0068458 Al, published June 6, 2002.
5 US 2013/0267077 Al, published October 10, 2013.
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Application 14/192,935
applying of ultra-high vacuum" (id.). 6 Relying on Hong's disclosure of a
method in which a Group III-V semiconductor substrate is loaded into an
ALD reactor through a chamber held under ultra-high vacuum, the Examiner
reasons that a person having ordinary skill in the art would have carried out
the method suggested by the combined teachings of Doan and Chiang in a
ultra-high vacuum as shown in Hong to eliminate native oxides completely
(id.).
The Appellants contend that the Examiner failed to establish a prima
facie case of obviousness because "there is no rationale supporting the
conclusion of obviousness" (Br. 4). The Appellants argue that although
"Chiang discloses a method for in-situ cleaning and subsequent atomic layer
deposition within a single processing chamber" (id.), Chiang teaches feeding
both argon and hydrogen to generate plasma for removing contaminants at a
pressure that can be maintained in the range of 102-10-7 torr, more
preferably 101-10-4 torr (id.). The Appellants also argue that although
Chiang teaches that the method can be performed without argon, such a
method "would result in decreased contaminant removal" (id.). The
Appellants argue that, by contrast, Hong teaches that the substrate-forming
chamber cannot be filled with any inert gas under any circumstance (id.),
and, therefore, "Hong specifically teaches away from using any inert gas"
(id. at 5). Furthermore, the Appellants contend that Hong's further
processing is for surface-reconstruction-not for removing a native oxide
6 The Appellants assert that "[ u ]ltra-high vacuum is understood by one
having ordinary skill in the art as being less than 10-9 torr" (Br. 5). Although
the Appellants do not direct us to any supporting evidence, the Examiner
does not appear to contest the Appellants' assertion.
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Application 14/192,935
layer, and, thus, "Hong never discloses that the ultra-high vacuum allows for
complete elimination of native oxide" (id.).
The Appellants' arguments fail to identify any reversible error in the
Examiner's rejection. In re Jung, 637 F.3d 1356, 1365 (Fed. Cir. 2011).
The only difference between Chiang's method and the method recited
in claim 1 is that, although Chiang teaches vacuum conditions and
exemplary vacuum pressures (Chiang ,r,r 13 ("The method is in-situ, without
air break, without substrate transfer under vacuum"), 26 ("pressure can be
maintained in the range of 102-10-7 torr")), it does not specifically mention
"ultra-high vacuum" as specified in claim 1. Specifically, Chiang teaches
that after a semiconductor's silicon 7 substrate surface is pre-cleaned to
remove oxides and other residues, "the substrate must not be exposed to any
oxygen or impurity-containing ambients (e.g., C, Cl, F, etc.)" (id. ,r,r 4, 8).
To meet this need, Chiang teaches that "it is highly desirable to have an in-
situ cleaning process within the same processing chamber as the subsequent
deposition step" and that "[ t ]his is especially important to low dielectric
constant ('low-k') insulator integration with copper metallization" (id. ,r 9;
emphasis added). According to Chiang, "[t]he method is in-situ, without air
break, without substrate transfer under vacuum" using an apparatus
designed for "Modulated Ion-Induced Atomic Layer Deposition (MII-
ALD)" (id. ,r 13; emphasis added).
7 Silicon is a Group IV element.
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Application 14/192,935
Chiang's Figure 1 is reproduced below:
160
11
125
vulu,ge, Control
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o.uty cycle~......-~
Power Level
190
Chiang's Figure 1 "illustrates an apparatus suitable for in-situ
preclean/surface treatment followed by MII-ALD deposition" (id. ,r 23),
wherein the apparatus includes a plasma generating chamber 170 and a
deposition chamber 180 where substrate 181 is disposed for cleaning (using,
e.g., hydrogen 110 and/or argon 130 to remove oxides on the substrate 181 's
surface and resulting gaseous byproducts are pumped 184 away) and
deposition ( reacting a first precursor 100 and a second precursor to effect
film deposition) (id. ,r,r 23-29).
Although Chiang does not describe "ultra-high vacuum" conditions
explicitly, we agree with the Examiner's position that a person having
ordinary skill in the art would have appreciated that operation at the highest
possible vacuum level would ensure the lowest possible contamination level.
In this regard, Chang emphasizes the importance of minimizing
contamination, and a person having ordinary skill in the art would have
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Application 14/192,935
drawn a reasonable inference that vacuum facilitates minimizing
contamination ( e.g., Chang ,r 11 ("the integrated in-situ cleaning method
should be able to clean and treat the bottoms and sidewalls of high aspect
ratio vias and trenches without redeposition or significant change in feature
profiles"); ,r 13 ("the present invention employs a halogen containing, or
preferably hydrogen containing, radical and argon ions to clean and treat the
bottoms and sidewalls of high aspect ratio features without redeposition of
the removed contaminants"); id. ("The method is in-situ, without air break,
without substrate transfer under vacuum .... ")).
Hong confirms that pumping down a chamber, which is used to
process a semiconductor device manufactured from silicon, compound HI-
V, or II-VI materials, to ultra-high vacuum conditions avoids contamination
(Hong ,r,r 22, 23 ("Since ... the pressure in the ALD chamber 14 just could
be pumped down to 5x10-9 Torr, the configuration of the buffer chamber 16
and the valves 22, 23 could not only avoid chemical agents or water vapor
used during the ALD process entering the modular track 10, but also
maintain the ultrahigh vacuum (about 5x10-10 torr) in the modular track
10.")). Hence, a person having ordinary skill in the art would have
understood that the vacuum pressure is a result-effective variable that can be
optimized by routine experimentation. In re Aller, 220 F.2d 454, 456
(CCPA 1955).
In view of these findings, we discern no reversible error in the
Examiner's conclusion that a person having ordinary skill in the art would
have used ultra-high vacuum pressures, as shown in Hong, in Chiang's
method in order to effect complete or substantially complete surface native
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Application 14/192,935
oxide removal. Here, the Appellants do not assert, much less prove, that
ultra-high vacuum pressures provide some unexpected result.
The Appellants argue that Hong describes surface reconstruction
rather than native oxide removal (Br. 5). That argument fails because Hong
actually teaches a substrate forming step 21 that includes native oxide
removal as a sub-step (Hong Fig. 2; ,r 25). Moreover, the Examiner relies on
Hong primarily for the ultra-high vacuum conditions for avoiding
contamination (Ans. 3), which is not affected by the presence or absence of a
native oxide removal step.
Finally, the Appellants' argument (Br. 5) that Hong's teaching that an
inert gas should not be used is contradictory to Chiang's teaching that argon
should be used is misplaced. First, claim 1 does not preclude the use of
argon as described in Chiang. Second, Chiang teaches that cleaning may be
conducted in the absence of argon, although "this may result in a lower
dissociation fraction and hence reduced efficiency of atomic hydrogen 176
generation" (Chiang ,r 28; italics added). But in no way does Chiang suggest
that the absence of argon would result in an inoperable method. Third, and
most important, the presence or absence of argon is irrelevant to the concept
of evacuating the chamber to avoid contamination to the greatest extent
possible, which a person having ordinary skill in the art would have gleaned
from the collective teachings found in the prior art.
For these reasons, and those given by the Examiner, we sustain the
Examiner's rejection.
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IV. SUMMARY
The Examiner's rejection under 35 U.S.C. § 103(a) of claims 1-16 is
sustained. Therefore, the Examiner's final decision to reject claims 1-16 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
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