Appeal No. 95-1487
Application 07/813,387
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, as
s3
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
-5-
Page: Previous 1 2 3 4 5 6 7 Next
Last modified: November 3, 2007