Dear All,

I describe my requirements about KOH anisotropic etching as below.

Target:
To get surface roughness < 50nm of Si (111) surface on Si wafer by using KOH
etching.

Current experimental recipe:
We have tried several KOH solutions (concentration: from 30% to 50%,
temperature: from 60C-90C). Besides, we have also tried to add some IPA into
KOH solution. And now, we are trying electro-polish with HF solution.

Current results:
The surface roughness are all larger than 50nm under methods mentioned above.

Requirements:
1. After going through methods above, our results are still not good enough to
be mirrors and v-grooves. We think the roughness may due to the substrates (Si
wafer), there may be some defects inside. Therefore, please recommand me some
wafer suplliers who can provide low defect wafers for MEMS bulk micromachinig
purpose!!
2. The best answer, I hope and a lot of people hope, is the one who have
succeed  in getting nice roughness of (111) surface can share experience with
me and us.

Thank you!!

Wing Wu

Industrial Technology Research Institute
Opto-Electronics & Systems Laboratories
Chutung, Hsinchu 310, Taiwan, R.O.C.
E-mail:wuwing@itri.org.tw
Http://www.oes.itri.org.tw