8 - Wet and Dry Etching of Compound Semiconductors

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Control of etch rates, etch selectivity, and sidewall profile are becoming increasingly important, as processing of compound semiconductor devices is ever more exacting. The fabrication of a typical III–V semiconductor device involves a sequence of patterning, etch, and deposition steps. This chapter discusses the use of wet chemical solutions or plasmas for the etch steps. Most processing sequences involve a combination of both wet chemical and dry etching, although the trend is clearly toward the use of plasmas because of the more anisotropic features and better dimensional control that can be obtained. Plasma etching has a number of variants, but this chapter concentrates on the use of reactive ion etching (RIE), which is the most common dry etching method used in III–V technology. The chapter lists the typical wet and dry etch mixtures for the most common III–V semiconductors and explains the application of these mixtures for fabrication of several types of devices.