Experimental Research on Fabrication of Interdigital Transducers for Acoustic Surface Waves.

Abstract : The objective of the program was to fabricate a variety of surface wave transducers on various substrates, using a digitally-controlled electron beam to expose the transducer patterns. Transducers were fabrication on lithium tanta late and lithium niobate substrates with finger and space widths varying from 1.6 to 0.6 micrometers, finger lengths from 240 to 400 micrometers, and number of fingers from 8 to 27 per transducer. An overlapping line segment technique was used along with multi-exposures to obtain line smoothness better than 0.04 micrometers. An exposure control with uniform 2.2% gradations was designed and used to obtain specified line widths. Vibration isolation and ambient magnetic noise cancellation permitted electron beam exposures of device patterns to be made in a relatively noisy environment.