Appeal No. 95-2579
Application 08/134,707
Opinion
We have carefully considered the respective positions advanced by appellant and the examiner.
For the reasons set forth below, we will not sustain any of the examiner's rejections.
According to appellant, “in the method of this invention the solutions of polyamic acids are partially
imidized before they are applied to the substrate” (p. 3, lines 14-16). Independent claims 1 and 13 require
partially imidizing the polyamic acid [step (C) of the claimed method] and forming a second solution of
partially imidized polyamic acid which is more concentrated than the first solution [step (D) of the claimed
method] before applying the second solution to a substrate. On page 11, lines 18-27 of the specification,
appellant discloses the concentration step as follows:
Concentration can be accomplished by gently heating under vacuum at about 80 to about
130E C. Concentration is preferably achieved by precipitating the partially imidized
polyamic acid from the first solution, preferably by the addition of water. The precipitated
partially imidized polyamic acid is collected, usually by filtration, and can be washed (e.g.,
in methanol), and dried, if desired. It is then dissolved in a second organic solvent ... to
form the second solution of about 20 to about 50 wt% solids.
Chion, the examiner’s principle reference, teaches on page 5, lines 20-24 that
[p]artial imidization preferably to a level of about 10 to about 30 percent of the polyamic
acid may be accomplished during the coating process wherein the polyamic acid based
photoresist solution is deposited on the semiconductor substrate. Thus after the polyamic
acid based photoresist solution is coated on the semiconductor substrate, the substrate is
heated at a temperature of about 85-95EC for about 15 to about 30 minutes to effect
about 10 to about 20% imidization of the polyamic acid.
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