I am having difficulty with HNA silicon etching and wondered if anyone has
insight on how to resolve it. Currently, I am using 15%HF, 78%Nitric and 7%
Acetic with the etch rate of >3um/minute, with no agitation and excellent
surface finish/uniformity. The problem I am having is the etch rate
diminishes over time <2um. The interesting thing is; if I let the solution
set for a period of time it returns to the original >3um/minute. How do I
stabilize this? 150mm wafer w/8 liter solution.

David Foehl
Development Engineer
Innovative Micro Technology
805-681-2826