Ex Parte Hui et al

Board of Patent Appeals and Interferences

Oct 31, 2006

10799413 (B.P.A.I. Oct. 31, 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publication and is not binding precedent of the Board.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 ANGELA T. HUI, JUSUKE OGURA, and YIDER WU
_______________

Appeal No. 2006-2728
Application No. 10/799,413
_______________

ON BRIEF
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Before HAIRSTON, KRASS and HOMERE, Administrative Patent Judges.

HAIRSTON, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal from the final rejection of claims 1 through 5 and 10 through 15.
The disclosed invention relates to a method for avoiding oxide gouging in shallow
trench isolation (STI) regions of a semiconductor device.
Claim 10 is illustrative of the claimed invention, and it reads as follows:
10. A method for avoiding oxide gouging in shallow trench isolation (STI) regions of
a semiconductor device comprising the steps of:

etching a trench in an STI region;

filling said trench with an insulating material;

depositing an anti-reflective coating layer over said STI region and extending beyond
the boundaries of said STI region;

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etching a portion of said anti-reflective coating layer over said STI region leaving a
remaining portion of said anti-reflective coating layer over said STI region and extending
beyond the boundaries of said STI region; and

depositing a protective cap covering said STI region and extending beyond the
boundaries of said STI region, wherein said protective cap covers said remaining portion of
said anti-reflective coating layer and said insulating material over said STI region.

The references relied on by the examiner are:
Tripsas et al. (Tripsas) 6,034,395 Mar. 07, 2000
Yang et al. (Yang) 6,110,779 Aug. 29, 2000
Hsu et al. (Hsu) 6,197,637 Mar. 06, 2001

Claims 1 through 5 and 10 through 15 stand rejected under the second paragraph of
35 U.S.C. § 112 as being indefinite for failing to particularly point out and distinctly claim
the subject matter which applicants regard as the invention.
Claims 10, 11, 14 and 15 stand rejected under 35 U.S.C. § 103(a) as being
unpatentable over Hsu in view of Yang.
Claims 12 and 13 stand rejected under 35 U.S.C. § 103(a) as being unpatentable over
Hsu in view of Yang and Tripsas.
Reference is made to the briefs and the answer for the respective positions of the
appellants and the examiner.
OPINION
We have carefully considered the entire record before us, and we will reverse the
indefiniteness rejection of claims 1 through 5 and 10 through 15, sustain the obviousness
rejections of claims 10 and 15 and reverse the obviousness rejections of claims 11 through
14.
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Turning first to the indefiniteness rejection, the examiner is of the opinion (answer,
pages 3 through 5) that etching of the anti-reflective coating layer, the polysilicon layer and
the gate oxide layer would remove the layers as a whole, and that none of the layers would
remain “leaving a remaining portion . . . over said STI region and extending beyond the
boundaries of said STI region.”
According to the appellants (brief, pages 5 through 10), Figures 3B and 3C and page
8, lines 1 through 7 of the disclosure illustrate and describe how each of the noted layers is
etched “leaving a remaining portion . . . over said STI region and extending beyond the
boundaries of said STI region.”
We agree with the appellants’ arguments. The referenced portion of the disclosure
indicates that the anti-reflective coating layer 34, the polysilicon layer 32 and the gate oxide
layer 30 are etched “over a portion of the STI region,” and the referenced figures of the
drawing clearly show that a portion of each layer remains “over” the STI region (i.e., trench
14), and that each layer extends “beyond” the boundaries of the STI region. None of the
disclosed etching steps removes a layer as a whole.
The examiner’s contention that the claim 1 phrase “etching an exposed portion of
said polysilicon layer and said gate oxide layer over said STI region” lacks antecedent basis
because “[n]either the polysilicon nor the gate oxide have been exposed, because the anti-
reflective coating layer is still remaining over the STI region and extending beyond the
boundaries of the STI region” is without merit in view of the referenced portion of the
disclosure and the referenced figures of the drawing noted supra. Figure 3B of the drawing
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clearly shows the polysilicon layer 32 exposed through the hole in the mask layer 36.
In summary, the indefiniteness rejection of claims 1 through 5 and 10 through 15 is
reversed because the claims on appeal do, in fact, set out and circumscribe a particular area
with a reasonable degree of precision and particularity when read in light of the application
disclosure as they would be by one possessing ordinary skill in the art. In re Moore, 439
F.2d 1232, 1235, 169 USPQ 236, 238 (CCPA 1971).
Turning next to the obviousness rejection of claims 10 and 15, we agree with the
examiner’s findings (answer, pages 5 through 7) that Hsu teaches a method that avoids oxide
gouging in isolation regions of a semiconductor device. Hsu teaches that the isolation
regions 230 can be formed either as the isolation regions or as shallow trench isolation (STI)
regions (column 3, lines 31 through 35). Accordingly, Hsu teaches an alternative
embodiment that avoids oxide gouging in shallow trench isolation (STI)1 regions 230 as
claimed. The shallow trench isolation regions are filled with an insulating material (e.g.,
thermal oxide2) (column 3, lines 31 through 35). We additionally agree with the examiner’s
findings that an anti-reflective coating (ARC) 241a is deposited over the trench regions, and
that the ARC 241a extends beyond the boundaries of the trench regions (Figure 5B; column
3, lines 42 through 48). Thereafter, Hsu etches portions 242 of the ARC 241a over each of
the trench regions (Figure 5B; column 3, lines 42 through 51 “leaving a remaining portion of
said anti-reflective coating layer over said STI region and extending beyond the boundaries

1 The STI teachings of Yang (Figure 4; column 6, lines 24 through 26) are merely cumulative to the teachings of
Hsu.
2 Appellants acknowledge (specification, page 1) that thermal silicon oxide is used to fill the trenches.
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of said STI region” as claimed. Finally, Hsu deposits a protective cap 246 (Figure 5C;
column 3, lines 59 through 61) “covering said STI region and extending beyond the
boundaries of said STI region, wherein said protective cap covers said remaining portion of
said anti-reflective coating layer and said insulating material over said STI region” as
claimed. Thus, the obviousness rejection of claims 10 and 15 is sustained because Hsu
teaches all of the method steps of claims 10 and 15. In sustaining a multiple reference
rejection under 35 U.S.C. § 103, the Board may rely on one reference alone without
designating it as a new ground of rejection. In re Bush, 296 F.2d 491, 496, 131 USPQ 263,
266-67 (CCPA 1961); In re Boyer, 363 F.2d 455, 458, n.2, 150 USPQ 441, 444, n.2 (CCPA
1966).
The obviousness rejection of claims 11 and 14 is reversed because neither Hsu nor
Yang teaches or would have suggested to the skilled artisan to use an etching step in lieu of
the chemical mechanical polishing planarization of the protective cap layer 246 (column 4,
lines 5 through 12).
The obviousness rejection of claims 12 and 13 is reversed because the applied
references neither teach nor would have suggested to the skilled artisan to use a photoresist
material in lieu of the oxide protective cap layer 246 (column 5, lines 3 and 4).
DECISION
The decision of the examiner rejecting claims 1 through 5 and 10 through 15 under
the second paragraph of 35 U.S.C. § 112 is reversed, and the decision of the examiner

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rejecting claims 10 through 15 under 35 U.S.C. § 103(a) is affirmed as to claims 10 and 15,
and is reversed as to claims 11 through 14.
No time period for taking any subsequent action in connection with this appeal may
be extended under 37 CFR § 1.136(a)(1)(iv).
AFFIRMED-IN-PART

)
KENNETH W. HAIRSTON )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
ERROL A. KRASS ) APPEALS AND
Administrative Patent Judge ) INTERFERENCES
)
)
)
JEAN R. HOMERE )
Administrative Patent Judge )

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