Appeal 2007-3372
Application 10/651,351
projection of the reticle pattern alters the resist image
dimension for a given amount of defocus. The difference in the
two images in the graph of Figure 2 of Takahashi result from
differences in the spherical aberration applied to a projection
rather than to the focus position of a projection. Thus,
Takahashi does not recognize an amount of defocus, or focal
depth, as a result-effective variable which affects spherical
aberration of a projected image. The lack of such recognition
precludes a prima facie obviousness rejection because the
determination of an optimum working range for a variable is
not within one of ordinary skill in the art if the variable is not
recognized as a result-effective variable.
The combination of Takahashi with [Yasuzato] also fails
to make obvious claim 3 because [Yasuzato] does not teach or
suggest the equation recited in claim 3. See, In re Vaeck, 947
F.2d 488, 20 USPQ2d 1438 (Fed. Cir. 1991).
Br. 11 and 12 (emphasis omitted).
This argument is not persuasive of any reversible error. In particular,
Takahashi’s Figure 2 “is a graph showing a relationship between a line
width of the resist image and the focus position…” for a particular
photoresist (Takahashi; col. 3, ll. 44-52). The line width change (resist
image dimension change) at differing focus positions with a spherical
aberration of zero (solid line of Figure 2) is greater than the line width
change when a predetermined spherical aberration is applied (Takahashi;
col. 3, ll. 53-65; Fig. 2, broken line).
However, we note that the incident light would be expected to defocus
or experience differing refractions while traveling through the resist material
to a focal location or point therein as evidenced by the differing angles that
the incident light would be expected to arrive with (Admitted Prior Art, Fig.
2). Thus, the focal distance into the resist would have been recognized by
one of ordinary skill in the art as a result effective variable for determining a
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