Reactive ion beam etching of lithium tantalate and its application for pyroelectric infrared detectors

The properties of reactive ion beam etching (RIBE) of single crystalline lithium tantalate (LiTaO3) and photoresist are reported, with particular attention given to the dependence on the gas flow, the ion beam current, the accelerating voltage as well as the angle of incidence. For the experiments a filamentless r.f. ion beam source and gas mixtures containing C2F6, CF4, Ar and O-2 were applied. Compared with Ar ion beam etching (IBE) the LiTaO3/photoresist etch rate selectivity was found to be three times higher. High selective RIBE of LiTaQ and photoresist is an efficient process for the production of one- and two-dimensional pyroelectric IR detectors: The thickness of a LiTaO3 wafer patterned with photoresist must be reduced by etching by about 10- 15 mu m.