wet etching of SiO2

Kevin Huang kevhuang at stanford.edu
Mon Apr 4 13:31:44 PDT 2005


Hi,
     I would like to release some structure in the device layer of SOI
wafers (10 um/ 2 um/ 450 um SOI wafer).  The size of the structure will be
about 2 mm by 2 mm.  And I will etch the oxide on the whole 4" wafer.  I
read on the website about the etching rate.  Even if I use 49% concentrated
HF to etch, it will take about 20 hours to etch.  My questions are:
1) Is this a reasonable time to be expected when doing the etching?
2) Since the 49% HF is not buffered, will the acid work well for up to 20
hours or do I need to refresh the acid constantly?

Thank you for your time.

Kevin



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