Argon and reactive ion beam etching for SAW devices

Abstract

Ion Beam Etching has played a prominent part in the development of surface accoustic wave (SAW) devices. Two modes have been developed: (1) argon ion beam etching is used for the precision manufacture of grooves in lithium niobate for reflective array pulse compression filters (RAC); (2) reactive ion beam etching in CHF 3 is used for etching grooves in quartz for SAW resonators and surface skimming bulk wave transducers. The etch rate of quartz in CHF 3 increases with the beam current density and is substantially independent of the ion beam incidence angle. Predictable groove profile shaping is demonstrated. Polymerization of the CHF 3 etching gas is shown to be a function of the charge conditions existing on the surface of the substrate. Plasma developable resists of good reactive ion beam etching resistance are shown to have a sub micron line resolution capability.