Dear all
I would like to ask if anyone have experiences with  etching by KOH+IPA.
I need to use KOH with IPA to get appropriate ratio of etching rate <100> to
other higher surface, but it results in some problems.

<1>  The etching rate seems not stable. I try the same parameter (the
concentration of KOH I use is below 30%, temp. is aournd 75~65 centigrade)
but often get different results. Etching rate and ratio of different surface in
first 1 hr seems different from following several hours.
It means that I need to check etching rate and change the KOH everytime I etch.
Could someone has the same experience or help me explain it?
<2> When I use KOH below 30% with IPA, the hillock problem become very serious,
do anyone have some ways to solve this ?

Regards,

Kuang H.