Ex parte HANYU et al.

Board of Patent Appeals and Interferences

Jan 30, 1998

07813387 (B.P.A.I. Jan. 30, 1998)

Application for patent filed December 27, 1991.1
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THIS OPINION WAS NOT WRITTEN FOR PUBLICATION
The opinion in support of the decision being entered
today (1) was not written for publication in a law
journal and (2) is not binding precedent of the Board.
Paper No. 30
UNITED STATES PATENT AND TRADEMARK OFFICE
________________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
________________
Ex parte ISAMU HANYU, MITSUJI NUNOKAWA
and SATORU ASAI
________________
Appeal No. 95-1487
Application 07/813,3871
________________
HEARD: January 16, 1998
________________
Before KIMLIN, PAK and WALTZ, Administrative Patent Judges.
WALTZ, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134 from the examiner’s
final rejection of claims 1, 2 and 4-16, which are the only
claims remaining in this application.
According to appellants, the invention is directed to an
optical exposure mask for patterning an optical beam and a method
Appeal No. 95-1487
Application 07/813,387
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for forming a phase shift mask and pattern. The invention
basically centers around use of MgO or a compound formed from MgO
and Al O as an etching stop layer for phase shift masks (main2 3
brief, page 2). Claim 1 is illustrative of the subject matter on
appeal and is reproduced below:
1. An optical exposure mask for patterning an optical beam,
comprising:
an etching stop layer of a material containing MgO or a
compound formed from MgO and A1 O , said etching stop layer2 3
having upper and lower major surfaces and said material being
substantially transparent to the optical beam used for the
exposure;
a transparent pattern of a material provided on one of said
upper and lower major surfaces of said etching stop layer, said
transparent pattern passing the optical beam freely; and
an opaque pattern provided on one of said upper and lower
major surfaces of said etching stop layer for patterning the
optical beam, said opaque pattern being defined be [sic, by] an
edge,
said etching stop layer having an etching rate substantially
smaller than an etching rate of the material that forms the
transparent pattern for any of dry and wet etching processes, and
said transparent pattern being provided along said edge of
said opaque pattern and having a thickness set to cancel a
diffraction of the optical beam at said edge of said opaque
pattern.
The references relied upon by the examiner as evidence of
obviousness are as follows:
Nakagawa et al. (Nakagawa) 61-278179 Dec. 9, 1986
(Japanese Kokai)
Kawabata et al. (Kawabata) 0 395 425 Oct. 31, 1990
Appeal No. 95-1487
Application 07/813,387
A new ground of rejection was made in the main examiner’s2
answer (page 4), rejecting claims 1, 2 and 4-16 under § 103 as
unpatentable over Kim et al. (U.S. Patent No. 4,767,724) in view
of Smoot et al. (U.S. Patent No. 5,114,813). Appellants
submitted a reply brief dated Dec. 7, 1994 (Paper No. 22) in
response to the new ground of rejection. The examiner responded
with a supplemental examiner’s answer dated Dec. 30, 1994 (Paper
No. 23). However, according to the letter dated April 8, 1997
(Paper No. 25), the new ground of rejection has been withdrawn.
Accordingly, the only rejection on appeal before this merits
panel is the rejection of claims 1,2 and 4-16 under § 103 over
Kawabata in view of Nakagawa.
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(European Patent Application)
Claims 1, 2 and 4-16 stand rejected under 35 U.S.C. § 103 as
unpatentable over Kawabata in view of Nakagawa. We reverse this2
rejection for reasons which follow.
OPINION
The examiner has made the finding that Kawabata discloses a
phase shift mask and a method of preparing this mask which
includes (a) patterning a light shielding opaque layer (e.g.,
chrome) on a transparent substrate; (b) depositing on the entire
surface an etch stop layer of aluminum oxide (Al O ); 2 3
(c) depositing a phase shift layer of silicon dioxide on the
entire surface to a desired thickness; and (d) then depositing
and patterning a resist layer with subsequent etching of the
silicon dioxide layer to form the 90 phase shifter (seeo
Kawabata, page 15, lines 8-20, Figures 45A-E, and the main
answer, page 3). The examiner states that the "construction of
Appeal No. 95-1487
Application 07/813,387
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the mask and method of making it" as disclosed by Kawabata
differs from the claimed construction and method only by the use
of MgO as an etch stop layer instead of the aluminum oxide etch
stop layer of Kawabata (main answer, page 3). Appellants do not
contest these findings (main brief, page 3).
The examiner states that Nakagawa "teaches the use of
magnesium oxide as an etching stop layer arranged between the
layer to be subjected to etching" (main answer, page 4). The
examiner alleges that magnesium oxide and aluminum oxide are used
"interchangeably" as is well known in the art and, "because the
transmittance properties of the materials used for the etch stop
layers is [sic, are] known," it would have been obvious to adjust
the material composition to achieve the desired result of
transmittance in a known region (main answer, page 4).
Appellants contend that Nakagawa is not related to optical
devices and provides no description or suggestion regarding the
optical properties of the MgO etching stopper (main brief, page
3). As appellants argue, it is essential that the material
forming the mask be substantially transparent to the optical
beam. Appellants further argue that, in the absence of the
knowledge that MgO has a high transparency for ultraviolet
radiation, one of ordinary skill in the art would never be led to
Appeal No. 95-1487
Application 07/813,387
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the use of MgO as an etching stopper in a phase shift mask (main
brief, page 4).
The fact that Nakagawa teaches the use of MgO as an etch stop
layer is not controverted. However, there is no teaching or
suggestion in the applied prior art to use MgO as an etch stop
layer in a phase shift mask or that MgO has optical properties
similar to the aluminum oxide etch stop layer of Kawabata. See
Pro-Mold and Tool Co. v. Great Lakes Plastics Inc., 75 F.3d 1568,
1573, 37 USPQ2d 1626, 1629 (Fed. Cir. 1996) ("It is well estab-
lished that before a conclusion of obviousness may be made based on
a combination of references, there must have been a reason,
suggestion, or motivation to lead an inventor to combine those
references."). The examiner’s allegations that the "use of MgO and
Al2O3 [sic, A1 O ] interchangeably is well known in the art, ass 3
these materials have similar physical, chemical and etch resistant
properties" and "the transmittance properties of the materials
used for the etch stop layers is [sic, are] known" are not
supported by the facts on the record before us. Where the legal
Appeal No. 95-1487
Application 07/813,387
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conclusion of obviousness is not supported by facts, it cannot
stand. In re Warner, 379 F.2d 1011, 1016-17, 154 USPQ 173,
177-78 (CCPA 1967), cert. denied, 389 U.S. 1057 (1968).
For the foregoing reasons, the rejection of claims 1, 2 and
4-16 under 35 U.S.C. § 103 as unpatentable over Kawabata in view
of Nakagawa is reversed.
REVERSED
EDWARD C. KIMLIN )
Administrative Patent Judge )
)
)
)
CHUNG K. PAK ) BOARD OF PATENT
Administrative Patent Judge ) APPEALS AND
) INTERFERENCES
)
)
THOMAS A. WALTZ )
Administrative Patent Judge )
Appeal No. 95-1487
Application 07/813,387
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