Wet chemistry is still very important in semiconductor and micromachining technology, in spite of important progress being made by the dry (or plasma) etching processes. For example, wet chemistry is used in the majority of the process steps employed in the production of integrated circuits. This is primarily because the cleaning of Si-processed wafers by wet chemical means is more effective than plasma techniques. Nevertheless, the dry methods are often favored where submicron geometries and narrow grooves must be etched into dielectrics and Si for integrated circuits (ICs), for example, in the fabrication of trench capacitors. The lateral etching generally observed using wet chemistry is a severe limiting factor in producing submicron-width features.
This chapter is not a comprehensive review. Rather, we intend it as a guide for today's work and also to pose significant challenges for future research and development. We emphasize those areas where wet etching has a significant advantage over dry etching. This often falls into the rapidly growing area of micromachined sensors and other applications, but it is also still quite important in integrated circuit technology.
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