An apparatus and method including a droplet coating generatorfor generating a stream of electrically charged coating dropletswithin an evacuable chamber towards a substrate positioned withinthe evacuable chamber. A piezoelectric vibrator and orifice platecoupled thereto generate the stream of coating droplets. Thecoating droplets are urged to move in a sweeping motion across thesubstrate by at least one pair of opposing spaced apart electrodespowered by an electrical power supply. A uniform coating is thusproduced while the evacuable chamber is maintained atsubatmospheric pressure as required during typical semiconductorprocessing. Multiple applications of a photoresist coating may beapplied by the coating apparatus without requiring that theevacuable chamber be repeatedly vented and pumped down tosubatmospheric pressure.
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