Apparatus and method for uniformly coating a substrate in an evacuable chamber
Donovan, RP., Periasamy, R., Clayton, A., & Ensor, D. (1993). Apparatus and method for uniformly coating a substrate in an evacuable chamber. (U.S. Patent No. 5229171). http://patft.uspto.gov/netacgi/nph-Parser?patentnumber=5229171
Abstract
An apparatus and method including a droplet coating generator for generating a stream of electrically charged coating droplets within an evacuable chamber towards a substrate positioned within the evacuable chamber. A piezoelectric vibrator and orifice plate coupled thereto generate the stream of coating droplets. The coating droplets are urged to move in a sweeping motion across the substrate by at least one pair of opposing spaced apart electrodes powered by an electrical power supply. A uniform coating is thus produced while the evacuable chamber is maintained at subatmospheric pressure as required during typical semiconductor processing. Multiple applications of a photoresist coating may be applied by the coating apparatus without requiring that the evacuable chamber be repeatedly vented and pumped down to subatmospheric pressure.
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