Ex Parte Ohuchi

Board of Patent Appeals and Interferences

Jan 19, 2005

09348654 (B.P.A.I. Jan. 19, 2005)

Paper No. 32
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is not binding precedent of the Board.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
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Ex parte MASAHIKO OHUCHI
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Appeal No. 2005-0202
Application No. 09/348,654
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ON BRIEF
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Before KIMLIN, TIMM, and PAWLIKOWSKI, Administrative Patent Judges.
TIMM, Administrative Patent Judge.
DECISION ON APPEAL
This appeal involves claims 1-7 and 9 which are all the claims pending in the application.
We have jurisdiction over the appeal pursuant to 35 U.S.C. § 134.
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1As prior art of record, the Examiner also lists U.S. Patent 5,763,328 issued to Yoshihara. Yoshihara is
discussed in the first ground of rejection (Answer, p. 3 and p. 5), but Yoshihara is not listed in the statement of any
rejection. “Where a reference is relied on to support a rejection, whether or not in a ‘minor capacity,’ there would
appear to be no excuse for not positively including the reference in the statement of rejection.” In re Hoch, 428 F.2d
1341, 1342 n.3, 166 USPQ 406, 407 n.3 (CCPA 1970). We do not consider Yoshihara.
2The Examiner has withdrawn a rejection under 35 U.S.C. § 112, ¶ 1 (Answer, p. 3).
INTRODUCTION
The Examiner maintains rejections under 35 U.S.C. § 103(a). As evidence of
unpatentability, the Examiner relies upon the following prior art references:1
Landau et al. (Landau) 4,592,800 Jun. 3, 1986
Konno et al. (Konno) 5,397,432 Mar. 14, 1995
Yachi 5,578,163 Nov. 26, 1996
Admitted Prior Art, specification, page 3, last paragraph and page 4.
The claims are rejected by the Examiner as follows:2
1. Claims 1-6 and 9 stand rejected under 35 U.S.C. § 103(a) as being unpatentable over
Konno, Admitted Prior Art, and Yachi.
2. Claim 7 stands rejected under 35 U.S.C. § 103(a) as being unpatentable over Konno,
Admitted Prior Art, and Yachi and further in view of Landau.
As the Appellant states that all the claims stand or fall together(Brief, p. 6), we select
claims 1 and 7 to represent the issues on appeal. Claims 1 and 7 read as follows:
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1. A process for patterning a target layer, comprising the steps in sequence of:
a) preparing a semiconductor structure having said target layer covered with an etching
mask formed of photo-resist;
b) heating said semiconductor structure from step a) to an initial temperature of between
50 degrees centigrade and 100 degrees centigrade and exposing said semiconductor structure to
an etchant containing halogen so as to form said target layer into a pattern partially covered with
unintentional layers of etching residue containing pieces of said photo-resist and halide;
c) heating the resultant structure of step b), over a time period of 30 to 70 seconds, from
said initial temperature to a second temperature of between 100 degrees centigrade and 200
degrees centigrade and exposing the resultant structure of step b) to a gaseous mixture containing
ionic water vapor where at least one of H+ and OH exists so that said halide reacts with said at
least one H+ and OH; and
d) heating the resultant structure of step c) from said second temperature to a target
ashing temperature of between 200 degrees centigrade and 250 degrees centigrade and ashing
said photo-resist so as to remove said etching mask from the resultant structure of step c).
7. The process as set forth in claim 6, in which said etching gas further contains
hydrofluorocarbon expressed as CH4-xFx.
Appellant has not convinced us of reversible error on the part of the Examiner. We,
therefore, affirm. Our reasons follow.
OPINION
Claim 1
Claim 1 is directed to a process for patterning a target layer residing on a semiconductor
substrate. In this process, the target layer is masked with photo-resist (step a) and subjected to
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3Appellant does not contest the finding of the Examiner that the discussion in the last paragraph of page 3
and on page 4 of the specification is admitted prior art. We, therefore, accept the finding as true.
dry etching (step b) to pattern the target layer. After etching, an anti-after-corrosion treatment is
conducted to remove etching residue (step c) and then the photo-resist is removed by ashing
(step d).
The process of the claims is used in the formation of conductive lines in semiconductor
devices. Konno describes such a process with steps of masking, etching, anti-after-corrosion
treatment and ashing. As acknowledged by the Examiner, Konno does not describe performing
the anti-after-corrosion treatment prior to the ashing step. In Konno, the anti-after-corrosion
treatment is performed either concurrently with ashing or after ashing (Konno, abstract; col. 3, l.
51 to col. 4, l. 10). But, as found by the Examiner, not only were concurrent anti-after-corrosion
treatment and after anti-after-corrosion treatment known in the prior art, but anti-after-corrosion
treatment before ashing was also known to those of ordinary skill in the art (Answer, p. 4
referring to Admitted Prior Art, specification, p. 4).3 We agree with the Examiner that the
evidence indicates that those of ordinary skill in the art understood that the steps could be
conducted in any of the known sequences.
In the arguments, Appellant focuses on a portion of the rejection in which Ex parte Rubin
was cited for the proposition that “in general, the transposition of process steps or the splitting of
one step into two, where the processes are substantially identical or equivalent in terms of
function, manner and result, was held to [] not patentably distinguish the processes.” (Brief, p. 7
quoting Final Rejection, p. 3). Appellant argues that “[i]n reaching this conclusion, the
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Examiner has ignored the express teachings of Appellant’s sworn specification that the order in
which conventional ashing and etching residue removing steps are performed is in fact critical.”
(Id.).
The problem with Appellant’s argument is that there is no foundation of evidence relied
upon to support the asserted criticality. Such evidence is required because the evidence relied
upon by the Examiner is sufficient to support a prima facie case of obviousness. See In re
Fortess, 369 F.2d 1009, 1017, 152 USPQ 13, 19-20 (CCPA 1966). This is because, according to
the Admitted Prior Art, processes including both an etching residue removing step (anti-after-
corrosion step; claim 1, step c), and an ashing step (claim 1, step d) were known in the prior art,
each step known to produce a particular effect. Moreover, the evidence shows that performance
of the steps in any of the three possible sequences, one before the other in either order or
concurrently, was known (Admitted Prior Art, specification, p. 4). The evidence indicates that
those of ordinary skill in the art would have understood that a workable result would occur with
each: the anti-after-corrosion step would remove etching residue and the ashing step would
remove photo-resist. That is enough to establish a prima facie case and shift the burden to
Appellant to demonstrate patentability through secondary considerations such as unexpected
results. Fortess, 369 F.2d at 1017, 152 USPQ at 19-20; In re Piasecki, 745 F.2d 1468, 1472,
223 USPQ 785, 788 (Fed. Cir. 1984). “[I]t is well settled that unexpected results must be
established by factual evidence.” In re Geisler, 116 F.3d 1465, 1470, 43 USPQ2d 1362, 1365
(Fed. Cir. 1997). Appellant has not provided the level of factual evidence required.
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We are cognizant of the fact that the specification indicates that the different sequences
of steps result in somewhat different results and that there are trade-offs for each sequence
(specification, pp. 4-5; see Reply Brief, pp. 2-3). However, the fact that there are some
differences does not negate the teaching that all three sequences were known by those of
ordinary skill in the art. Nor do the discussed differences provide the requisite level of evidence
needed to show criticality for the claimed sequence of steps. See In re Klosak, 455 F.2d 1077,
1080, 173 USPQ 14, 16 (CCPA 1972)(“[I]t is not enough to show that results are obtained which
differ from those obtained in the prior art: that difference must be shown to be an unexpected
difference”).
Appellant also argues that there are other differences between the claimed invention and
the prior art (Brief, pp. 8-9). These differences, however, are in the nature of temperature and
time adjustments; adjustments which one of ordinary skill in the art would have routinely made
to optimize the results of the process. It is well settled that where patentability is predicated
upon a change in condition of a prior art process, such as a change in temperature, the burden is
on the applicant to establish the nonobviousness of the process through unexpected results or
other evidence of secondary considerations. See In re Woodruff, 919 F.2d 1575, 1578, 16
USPQ2d 1934, 1936 (Fed. Cir. 1990); In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235
(CCPA 1955).
Appellant asserts that neither the cited art nor the Admitted Prior Art teaches that the
ashing temperature is a result-effective variable, i.e., the ashing rate is dependent on temperature
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(Reply Brief, p. 4). That the ashing temperature was understood to affect the results of ashing
can hardly be questioned. Such is evidenced by language in Konno such as: “[t]hen, the
substrate 1 is heated, for example, to 100° to 200° C.” (Konno, col. 6, ll. 12-13). One of
ordinary skill in the art is clearly expected to perform routine experimentation to determine the
workable or optimal temperature for ashing.
Appellant also argues that Konno teaches against the introduction of water vapor prior to
ashing (Brief, p. 9 referring to column 10, lines 5-16 of Konno). First, the Admitted Prior Art
indicates that performance of the anti-after-corrosion treatment before ashing was known in the
art. Second, we agree with the Examiner that Konno does not teach against the introduction of
water vapor for the anti-after-corrosion treatment prior to ashing (Answer, p. 7). The portion of
Konno referenced by Appellant discusses the performance of the anti-after-corrosion and ashing
steps separately but in the same apparatus. Konno then discusses a way to overcome the
problem of water vapor removal by using an apparatus with separate stations for the anti-after-
corrosion treatment and ashing steps (Konno, col. 10, ll. 9-17). One would simply use separate
stations to overcome the problem. There is no teaching away from performing anti-after-
corrosion treatment prior to ashing in Konno.
Claim 7
To reject claim 7, the Examiner adds Landau. Claim 7 requires that the etching gas
contain hydrofluorocarbon expressed as CH4-xFx.
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Appellant argues that despite a rather extensive shopping list of halogen compounds,
Landau fails to specifically teach a CH4-xFx compound and teaches that compounds of bromine
and fluorine are undesirable (Brief, p. 11).
First of all, some of the “shopping list of halogen compounds” listed by Appellant are
disclosed in Landau not as etchants, but as substitute adsorbent gaseous species (Landau, col. 4,
ll. 31-34). What Landau discloses in terms of etchants is the use of SiCl4 and Cl2, SCl6, SiCl4,
BCl3 plus Cl2, BCl3, CCl4, CHCl3, and C2HCl3 and compounds of other halogens, e.g.,
compounds of bromine and fluorine (Landau, col. 4, ll. 12- 22). This disclosure suggests CH4-xFx
compounds such as CF4 and CHF3 as those are homologs to the chlorine compounds listed.
Second, Landau does not teach away from using compounds of fluorine. That Landau
indicates that the chlorine compounds are, as a practical matter, more extensively used does not
negate the fact that the use of fluorine compounds is also taught. A reference may be relied upon
for all that it would have reasonably suggested to one having ordinary skill in the art, including
non-preferred embodiments. Merck & Co v. Biocraft Labs., Inc., 874 F.2d 804, 807, 10 USPQ2d
1843, 1847 (Fed. Cir.), cert. denied, 493 U.S. 975 (1989). Disclosed examples and preferred
embodiments do not constitute a teaching away from a broader disclosure or non-preferred
embodiments. In re Susi, 440 F.2d 442, 446 n.3, 169 USPQ 423, 426 n.3 (CCPA 1971).
We conclude that the Examiner has established a prima facie case of obviousness with
respect to the subject matter of claims 1-7 and 9 which has not been sufficiently rebutted by
Appellant.
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CONCLUSION
To summarize, the decision of the Examiner to reject claims 1-7 and 9 under 35 U.S.C.
§ 103(a) is affirmed.
No time period for taking any subsequent action in connection with this appeal may be
extended under 37 CFR § 1.136(a).
AFFIRMED
EDWARD C. KIMLIN )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
CATHERINE TIMM ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
BEVERLY A. PAWLIKOWSKI )
Administrative Patent Judge )
CT/tdl
Appeal No. 2005-0202
Application No. 09/348,654
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Norman P. Soloway
Hayes Soloway Hennessey
Grossman & Page PC
175 Canal Street
Manchester, NH 03101