> What are typical etch rates for borosilicate glass in HF?
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There are many formulations of borosilicate glass.
One common one in MEMS is Pyrex 7740,
which is 81% SiO2, 13% B2O3, 4% Na2O, and 2% Al2O3.
For Pyrex 7740, our measured etch rate in 5:1 BHF is 43 nm/min.
Curiously, this is much slower than the ER for fused quartz (pure SiO2), at
130 nm/min.
    --Kirt Williams, Ph.D.   consultant