Ex Parte Armacost et al

Board of Patent Appeals and Interferences

Nov 7, 2002

09014806 (B.P.A.I. Nov. 7, 2002)

The opinion in support of the decision being entered today was not written
for publication and is not binding precedent of the Board.
Paper No. 11
UNITED STATES PATENT AND TRADEMARK OFFICE
____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________
Ex parte
MICHAEL D. ARMACOST, DAVID M. DOBUZINSKY,
JOHN C. MALINOWSKI, HUNG Y. NG,
RICHARD S. WISE, and CHIENFAN YU

Appeal No. 2001-1133
Application No. 09/014,806
ON BRIEF

Before WALTZ, LIEBERMAN and KRATZ, Administrative Patent Judges.
LIEBERMAN, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 from the decision of the examiner
refusing to allow claims 1 through 3, 5 through 10, 12, 13, and 15 through 18, which
are all the claims pending in this application.
Appeal No. 2001-1133
Application No. 09/014,806
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THE INVENTION
The invention is directed to an anisotropic etching process wherein the etchant gas
comprises fluorohydrocarbon, diatomic oxygen and a carbon source. Each of the
components is present in a specific volume. Additional limitations are described in the
following illustrative claim.

THE CLAIMS
Claim 1 is illustrative of appellants’ invention and is reproduced below.
1. An anisotropic etching process for a nitride layer on a substrate, the process comprising
etching with an etchant gas comprised of a hydrogen-rich fluorohydrocarbon, diatomic
oxygen, and a carbon source, wherein the fluorohydrocarbon is present in the gas at 7% -
35% by volume, the diatomic oxygen is present in the gas at 1% - 35% by volume, and
the carbon source is present in the gas at 30% - 92% by volume.
THE REFERENCES OF RECORD
As evidence of obviousness, the examiner relies upon the following reference:
Kadomura 4,654,114 Mar. 31, 1987

THE REJECTIONS
Claims 1 through 3, 5 through 10, 12, 13, and 15 through 18 stand rejected
under 35 U.S.C. §103(a) as being unpatentable over Kadomura.
Claims 1 through 3, 5 through 10, 12, 13, and 15 through 18 stand rejected
Appeal No. 2001-1133
Application No. 09/014,806
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under 35 U.S.C. § 112, first paragraph, for failing to enable any person skilled in the art
to make and use the invention.
OPINION
We have carefully considered all of the arguments advanced by the appellants and
the examiner and agree with the appellants that the rejections of the claims under §§ 112
and 103(a) are not well founded. Accordingly, we reverse these rejections.
The Rejection under § 112
We turn first to the examiner’s rejection under the first paragraph of 35 U.S.C.
§ 112, first paragraph, on the grounds of lack of enablement. When rejecting a claim
under the enablement requirement of section 112, the PTO bears the initial burden of
setting forth a reasonable explanation as to why it believes the scope of protection provided
by the claimed subject matter is not adequately enabled by the description of the invention
provided in the specification of the application. This includes providing sufficient reasons
for doubting any assertions in the specification as to the scope of enablement. If this
burden is met, the burden then shifts to the appellants to provide suitable proofs that the
specification is enabling. In re Wright, 999 F.2d 1557, 1561-62, 27 USPQ2d 1510,
1513 (Fed. Cir. 1993); In re Marzocchi, 439 F.2d 220, 223-24, 169 USPQ 367,
369-70 (CCPA 1971).
The examiner’s position is that the claimed subject matter is not enabled in the
specification, because the original specification provided that the only concentrations given
Appeal No. 2001-1133
Application No. 09/014,806
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relate specifically to CH3F. See Answer, page 4. Furthermore, the only examples found in
the specification are likewise directed to CH3F. Id. When the disclosure is coupled with
appellants statement that as the, “mechanism for nitride: oxide selectivity in their chemistry
is not well understood,” it follows that the invention as claimed is not enabled. Id. We
disagree.
As we stated above, the burden of proof of finding that the invention is not enabled
rests with the Office. The specification provides specific volume ratios for CH3F, diatomic
oxygen and carbon dioxide. See specification, pages 4 and 5. In addition, the
specification as originally filed, provides for an etchant gas comprising a hydrogen rich
fluorohydrocarbon, an oxidant and a carbon source. See original claim1. Furthermore,
original claim 4 specifically provides for a fluorohydrocarbon gas present at approximately
7% - 35% by volume. Based upon these findings, we conclude that appellants specifically
intended that the volume of fluorohydrocarbon gas apply to all fluorohydrocarbons and not
just the CH3F as argued by the examiner. Accordingly, we cannot agree with the
examiner’s conclusion that the ratios apply only to the sole aforesaid fluorohydrocarbon,
CH3F. Furthermore, the argument presented in the Answer, pages 4 and 5, based upon
the statement that since the, “mechanism for nitride: oxide selectivity in their chemistry is
not well understood,” it would not apply to other fluorohydrocarbons, is speculative in
nature and insufficient to support a rejection on the grounds of lack of enablement.
Accordingly, we cannot sustain the rejection under § 112.
Appeal No. 2001-1133
Application No. 09/014,806
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The Rejection under § 103
"[T]he examiner bears the initial burden, on review of the prior art or on any other
ground, of presenting a prima facie case of unpatentability." See In re Oetiker, 977 F.2d
1443, 1445, 24 USPQ2d 1443, 1444 (Fed. Cir. 1992). The examiner relies upon a
single reference to reject the claimed subject matter and establish a prima facie case of
obviousness. It is the examiner’s position that, although, “Kadomura is silent as to using
diatomic oxygen,” nonetheless, “it would have been obvious to those of ordinary skill in
the art to include O2 in the etchant gas mixture because it is well known as oxidizing gas
and because combining materials or additives for their art recognized function and said
additives do perform their art recognized function is obvious.” See Answer, pages 6 and
7. We disagree.
Kadomura is directed to a dry etching method wherein silicon nitride existing on a
substrate of silicon dioxide can be etched at a sufficiently high selective ratio between the
nitride and the oxide without providing deposition of polymeric film. See column 2, lines
47-53. Furthermore, we agree with the examiner’s finding that, “Kadomura is silent as to
using diatomic oxygen.” See Answer, page 6. The entire issue of a teaching or suggestion
for the utilization of oxygen is a result of the background disclosure present in the
Kadomura patent. We find that Kadomura states in the background of the invention that,
the etch rate of Si3N4 becomes higher when the etching gas
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contains a small amount of O2 or CO2. However, when using such a mixed
gas for etching of Si3N4 on top of SiO2, the etch rate of the underlying SiO2
also increases because of the suppression of the formation of the polymers
which are effective to prevent etching of SiO2. Consequently, the selective
ratio of etching between Si3N4 and SiO2 becomes very much lower than the
desired or tolerable level. This deficiency is not fundamentally removed even
when CO2 is added to the etching gas instead of O2.
See column 2, lines 33-44. See also column 1, lines 45-61, and column 3, lines
34-42. We determine that the entire disclosure present in Kadomura supports the
proposition that the utilization of oxygen lowers the selectivity ratio of etching between
silicon nitride on a silicon dioxide substrate. Accordingly, we conclude that Kadomura
expressly teaches away from the utilization of oxygen in etching a silicon nitride on a silicon
dioxide substrate. It follows that the examiner’s conclusion that oxygen be present in an
etching process because it is a well known oxidizing gas is untenable. Accordingly, the
rejection of the examiner cannot be sustained.
DECISION
The rejection of claims 1 through 3, 5 through 10, 12, 13, and 15 through 18
under 35 U.S.C. §103(a) as being unpatentable over Kadomura is reversed.
The rejection of claims 1 through 3, 5 through 10, 12, 13, and 15 through 18
under 35 U.S.C. § 112, first paragraph, for failing to enable any person skilled in the art
to make and use the invention is reversed.
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The decision of the examiner is reversed.

REVERSED
THOMAS A. WALTZ )
Administrative Patent Judge )
)
)
)
)
) BOARD OF PATENT
PAUL LIEBERMAN ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
)
PETER F. KRATZ )
Administrative Patent Judge )
Appeal No. 2001-1133
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