Appeal No. 94-3399
Application 07/871,374
examiner under 37 CFR § 1.142(b) as being drawn to a non-
elected invention.
Claims 1 and 2 are representative of the subject matter
on appeal and read as follows:
1. A method of reducing linewidth variations in the
patterning of a photoresist layer having a non-uniform
thickness in a photolithographic process using light from a
partially coherent lens, said method comprising: overcoating a
first layer comprising a photoresist composition with a second
layer comprising a non-reactive, transparent, water soluble
material with a refractive index within ± 15% of the
refractive index of the photoresist, the second, overcoating,
layer of water soluble material being of sufficient thickness
to cause about a one wave length phase delay to accumulate in
that portion of the exposing light having an incident angle to
the second layer upper surface equal to about the arccos of
the numerical lens aperture value, said phase delay being in
comparison to that portion of the exposing light having an
incident angle normal to the second layer upper surface,
wherein said phase delay accumulates upon traversing an
optical path from the photoresist layer upper surface to the
photoresist layer lower surface and reflecting back to the
photoresist layer upper surface.
2. The method of claim 1 where the thickness of said
second, overcoating, layer of water soluble material is define
by the formula
T2 = L/2N{cos IN / (1 - cos I)} - T1
where T2 is the thickness of the overcoating water soluble
material layer, T1 is the thickness of the photoresist layer,
L is the wavelength of the exposing light, N is the numerical
lens aperture value, I is equal to arcsin (N), and I’ is equal
to arcsin (I / N).
The appealed claims stand rejected as follows:
2
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