Coating processes – Nonuniform coating – Applying superposed diverse coatings or coating a coated base
Patent
1992-04-20
1999-06-08
Tran, Hien
Coating processes
Nonuniform coating
Applying superposed diverse coatings or coating a coated base
427258, 427282, 427286, 4274071, B05D 132, B05D 500
Patent
active
059103370
ABSTRACT:
A method is described for reducing linewidth variations in the patterning of photoresists having non-uniform film thickness, comprising overcoating the photoresist with sufficient thickness of a nonreactive coating composition having a refractive index which within .+-.15 percent of that of the refractive index of the photoreist composition; said overcoating being of sufficient thickness such that it will result in about a one wave length phase lag between the oblique rays and the normal incident rays reflecting back from the substrate, upon arriving back at the resist surface. The effective thickness of the overcoating is a function of the exposure wavelength and the size of the numerical aperture of the objective lens used for expose. The overcoating compositions capable of providing the so defined refractive indices ranges, are described. For example, a polyacrylic acid coating composition having a refractive index of 1.5 at a thickness of 2.0 .mu.m, provides a workable overcoating to reduce linewidth variations for a resist having a refractive index of 1.7 and a film thickness of 0.9-1.0 .mu.m.
REFERENCES:
patent: 4308586 (1981-12-01), Coates
patent: 4405710 (1983-09-01), Balasubramanyam
patent: 4465767 (1984-08-01), Oba et al.
patent: 4971893 (1990-11-01), Taylor, Jr. et al.
patent: 4987048 (1991-01-01), Shinozaki et al.
Lyons Christopher Francis
Spinillo Gary Thomas
Wood Robert Lavin
Capella Steven
Crockatt Dale M.
International Business Machines - Corporation
Tran Hien
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