Ex Parte Ko et al

Board of Patent Appeals and Interferences

Jun 23, 2006

09585682 (B.P.A.I. Jun. 23, 2006)

The opinion in support of the decision being entered today was not written for publication and
is not binding precedent of the Board.

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte KEI-YU KO, LI LI,
and GUY T. BLALOCK
____________

Appeal No. 2006-0114
Application No. 09/585,682
____________

ON BRIEF
____________

Before WALTZ, KRATZ, and JEFFREY T. SMITH, Administrative Patent Judges.
JEFFREY T. SMITH, Administrative Patent Judge.

DECISION ON APPEAL
Applicants appeal the decision of the Primary Examiner finally rejecting
claims 1 to 13, all of the pending claims in the application. We have jurisdiction
under 35 U.S.C. § 134.

Comment [s1]: Indent five spaces
only.
Appeal No. 2006-0114
Application No. 09/585,682

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BACKGROUND
Appellants’ invention relates to semiconductor devices that include
passivation structures with one or more sidewalls that are oriented substantially
perpendicular to a plane of a substrate and that terminate at undoped silicon oxide
structures. (Brief, p. 5) Claims 1 and 6, as presented in the Brief, are reproduced
below:
1. A semiconductor device, comprising:
a semiconductor substrate including an active surface;
at least one conductive line disposed upon the active surface, the at least
one conductive line being flanked by sidewall spacers;
an undoped silicon dioxide cap disposed over and in contact with the at
least one conductive line;
a passivation layer over the undoped silicon dioxide cap; and
at least one contact aperture defined through the passivation layer and
including at least one sidewall extending substantially perpendicularly
relative to the semiconductor substrate, at least a portion of the at least one
sidewall terminating at an interface between the passivation layer and the
undoped silicon dioxide cap.

6. A semiconductor device, comprising:
a semiconductor substrate;
at least one undoped silicon oxide structure; and
at least one doped silicon oxide structure over the at least one undoped
silicon oxide structure and having at least one sidewall substantially
perpendicular to a plane of the semiconductor substrate, at least a portion of
the at least one sidewall terminating at an interface between the at least one
doped silicon dioxide structure and the at least one undoped silicon oxide
structure.

Appeal No. 2006-0114
Application No. 09/585,682

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CITED PRIOR ART
As evidence of unpatentability, the Examiner relies on the following references:
Blalock et al. (Blalock) 5,286,344 Feb. 15, 1994

Lur 5,428,240 Jun. 27, 1995

Claims 1-13 stand rejected under 35 U.S.C. § 103(a) as obvious over Blalock in
view of Lur. (Answer, pp. 4-10).
DISCUSSION
We have carefully reviewed the claims, specification and applied prior art,
including all of the arguments advanced by both the Examiner and Appellants in support
of their respective positions. This review leads us to conclude that the rejection of claims
1 to 13 is not well founded. Our reasons appear below.
Blalock discloses multi-layered semiconductor structures that may be composed of
a doped silicon dioxide outer (passivation) layer on a silicon nitride stop layer. The
Examiner recognizes that Blalock does not disclose that the material of the cap (stop)
layer may be undoped silicon dioxide. The Examiner asserts that Lur teaches the
equivalence of forming an etch cap (stop) layer from undoped silicon dioxide and silicon
nitride. Thus, the Examiner concluded that it would have been obvious to one of ordinary
skill in the art to modify the stop layer of Blalock by using the undoped silicon dioxide in
place of silicon nitride. (Answer, pp. 3-6).
Appeal No. 2006-0114
Application No. 09/585,682

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We recognize that based on the teaching of Lur persons of ordinary skill in the art
would have recognized that various materials are suitable for use as etch stop layers.
(Col. 5, ll. 29-35). This includes undoped silicon dioxide and silicon nitride as
recognized by the Examiner. It is not disputed that Blalock discloses a process for
producing semiconductor devices that comprise a cap (stop) layer composed of silicon
nitride. Blalock’s invention is a process that uses a fluorinated chemical etchant that has
a high selectivity of SiO2 etch rate with respect to Si3N4 etch rate. Thus, Blalock
discloses it is essential that the stop layer of the formed semiconductor device be silicon
nitride. (Cols. 3-4). If the stop layer were replaced with a non nitride containing stop
layer, as suggested by the Examiner, the process of Blalock would not function to form a
semiconductor device comprising a nitride containing layer. Consequently, we agree
with Appellants, Brief, page 10, that,
one of ordinary skill in the art would have had no reason to expect that the
asserted combination of teachings from Blalock and Lur would have
resulted in the structures recited in claims 1 - 13 . . . If the undoped silicon
oxide etch stop were merely substituted for the silicon nitride layer of
Blalock, due to lack of selectivity for the disclosed etchant between doped
and undoped silicon oxides, etching of the overlying doped silicon dioxide
layer would continue on into the undoped silicon dioxide film. Lur also fails
to teach or suggest any specific etchants that could be used to form
sidewalls having the characteristics that are recited in independent claims 1
and 6. Therefore, one of ordinary skill in the art would have no reason to
expect the asserted combination of teachings from Blalock and Lur to be
successful.

Comment [s2]: This new paragraph
should be indented five spaces.
Comment [s3]: Quotations fifty
words or more should be indented left
and right without quotation marks within
block. See page 43 of Blue Book 5.1.
Appeal No. 2006-0114
Application No. 09/585,682

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Thus, the Examiner has failed to establish a prima facie case of obviousness to
support the stated rejection. Accordingly, we reverse the Examiner’s rejection under
35 U.S.C. § 103(a) of claims 1 to 13 over the combination of Blalock and Lur.

REVERSED

)
)
THOMAS A. WALTZ )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
PETER F. KRATZ ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
JEFFREY T. SMITH )
Administrative Patent Judge )

JTS/sld
Appeal No. 2006-0114
Application No. 09/585,682

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BRICK G. POWER
TRASK BRITT
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