[mems-talk] a question about KOH etch back

[Chin-Jen Chiang]

Shay,
   
  Thanks so much for your input.
   
  Can I ask you a few more question?
   
  Someone told me in the process of koh etch, if you take your etched wafer out and in from the heated koh etchant to measure the remaining thickness for etching control, the thermal stress due to temperature difference will easily break the thin Si membrance as it is etehed to the on range of a few tens of micrometer. Do you have any adivce about this?
   
  Regards
  Lawrence 
  

"shay at mizur.com" <shay at mizur.com> 說：
  Hi
can be done. you have to get good control over the rate so you know when to
stop. if you do a whole wafer, have ready something to 'fish' it with from
the koh and transfter to DI water for rinsing. also, you should float it on
IPA after rinsing so it wouldn't stick and let dry over a piece of paper.
id you do only 1mm islands in a wafer there is no problem. you can go down
to 0.5u for this size.