Ex Parte Hsu et al

Board of Patent Appeals and Interferences

Dec 15, 2010

11450204 (B.P.A.I. Dec. 15, 2010)

UNITED STATES PATENT AND TRADEMARK OFFICE
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BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
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Ex parte PENG-FU HSU, JIN YING, and HUN-JAN TAO
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Appeal 2009-010910
Application 11/450,204
Technology Center 2800
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Before CARLA M. KRIVAK, CARL W. WHITEHEAD, JR., and
BRADLEY W. BAUMEISTER, Administrative Patent Judges.

BAUMEISTER, Administrative Patent Judge.

DECISION ON APPEAL1

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. § 1.304, or for filing a request for rehearing,
as recited in 37 C.F.R. § 41.52, begins to run from the “MAIL DATE”
(paper delivery mode) or the “NOTIFICATION DATE” (electronic delivery
mode) shown on the PTOL-90A cover letter attached to this decision.
Appeal 2009-010910
Application 11/450,204

2
STATEMENT OF CASE
Summary
Claims 1, 3,2 7, 12, and 13 stand rejected as anticipated under 35
U.S.C. § 102(b) as anticipated by Ohmi (US 2004/0108575 A1; published
June 10, 2004). Claims 4-6, 8-10, and 14-21 stand rejected as obvious under
35 U.S.C. § 103(a) over Ohmi in view of Hayakawa (US 2004/0089902 A1;
published May 13, 2004); Claims 11 stands rejected as obvious under 35
U.S.C. § 103(a) over Ohmi in view of Ahn (US 2007/0049051 A1;
published March 1, 2007). Appellants appeal under 35 U.S.C. § 134(a) from
these rejections.
We reverse.
Background
Appellants’ invention relates to a method of forming a gate dielectric
stack for metal-oxide-semiconductor (MOS) devices (Spec. 1). The method
steps include forming a base oxide layer on a semiconductor substrate and
forming a high-k dielectric layer on the base oxide layer (Abstract).
Independent claims 1 and 14 both set forth that the base oxide layer is
formed on the substrate “by submerging the semiconductor substrate in a
solution comprising de-ionized water and ozone.”
Appellants argue that Ohmi does not render the appealed claims
unpatentable because Ohmi does not disclose forming a gate dielectric base
oxide layer by this submersion technique (App. Br. 7-16). Specifically,
Appellants acknowledge that Ohmi discloses a substrate flattening step that
entails oxidizing a semiconductor substrate with de-ionized water and ozone
(id.). However, Appellants contend that when this method of oxide layer

2 Claim 3 improperly depends from canceled claim 2 (App. Br. 17).
Appeal 2009-010910
Application 11/450,204

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formation is employed for flattening, the oxide layer is subsequently
removed, and that Ohmi never discloses that an oxide layer formed by this
method may be left intact for subsequent use as the base oxide of the gate
dielectric stack (id.).

ANALYSIS
Appellants’ arguments are persuasive. Ohmi discloses a method of
forming a MOS transistor gate dielectric stack that includes flattening the
silicon substrate to a prescribed surface smoothness and, then, “forming an
oxide film on the cleaned surface by oxidizing the cleaned silicon surface in
an atmosphere containing oxygen radicals” (Abstract; ¶¶ [0050]-[0051]).
Ohmi states that one alternative for performing the flattening step is to
oxidize the semiconductor substrate in de-ionized water and ozone
(¶¶ [0052]-[0056]), but nowhere discloses that this oxidation method may be
used for subsequently forming the base oxide that is to be retained. To the
contrary, Ohmi expressly states that when de-ionized water and ozone is
used to form oxide layers, the layers are subsequently removed. See, e.g.,
¶ [0181] (disclosing a cleaning method that entails using de-ionized water
and ozone to form oxide layers in the first and third steps, but that these two
oxide layers are respectively removed in the process’s second and fourth
steps). The silicon oxide layer that forms the permanent base oxide layer is
disclosed as being alternatively formed by oxidation in an oxygen radical
atmosphere (¶ [0140]).
For the foregoing reasons, Appellants have persuaded us of error in
the Examiner’s anticipation rejection of claims 1, 3, 7, 12, and 13.
Accordingly, we will not sustain the Examiner’s rejection of those claims.
Appeal 2009-010910
Application 11/450,204

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With respect to the remaining, obviousness rejections of dependent claims 4-
6, 8-11, and 14-21, the Examiner has not alleged that either Hayakawa or
Ahn cures the deficiency of the rejection explained above. Likewise, for the
reasons discussed above, we will not sustain the rejections of those claims.

DECISION
The Examiner’s decision rejecting claims 1 and 3-21 is reversed.

REVERSED

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