A number of dry etching techniques have been developed and their ability to produce anisotropic etch profiles has been demonstrated. In addition to etch anisotropy, an important consideration for device and circuit fabrication is whether a sample suffers radiation damage by exposure to ions, electrons, or ultraviolet light during etching. In this study we evaluate the degree of radiation damage induced in GaAs by ion-beam etching with Ar, reactive-ion etching with CF4 and CHF3, and ion-beam-assisted etching with Ar and Cl2. In addition, we propose and demonstrate processing techniques which can be used after dry etching to reduce the effects of radiation damage. GaAs samples were etched under a variety of etching conditions. The degree of radiation damage caused by etching was determined by evaluating Schottky diodes fabricated on the etched surfaces and by using deep level transient spectroscopy to characterize trapping centers. It was found that the barrier heights and breakdown voltages of Schottky diodes were changed after etching. Also, an increase in the density of traps was observed. Variations in the etching conditions had a strong effect on the measured characteristics of the samples.
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Pang et al. (1983) studied this question.