23.4. DRIE Advanced Issues and Challenges
Practical DRIE processes are optimized with respect to etch rate and uniformity, but other issues have to be tackled simultaneously: etch rate depends on etchable area, feature size, and shape, all of which become more prominent for high aspect ratio structures. Optimization of rate can have a negative effect on sidewall profile control and vice versa. This chapter discusses some of the issues of fine-tuning DRIE processes, and the non-idealities that may occur.
23.4.1. Vertical Sidewalls
DRIE and wet etching of < 110 > silicon both result in vertical walls. The availability of < 110 > silicon is limited, and only simple structures (grooves, ridges) are possible because of crystal plane effects in the ...
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