Hi, MEMS folks:

     This is David Tang, a graduate student in Louisiana Tech University. I'm
doing (100) Silicon deep etching (500mm). The Si wafer is coated with 0.6mm
SiO2 layer and 0.2mm Silicon Nitrate layer is coated on SiO2 layer(Silicon
Quest company). The etchant is KOH, temp 800C, stirring 220RPM and Silicon
Nitrate layer is used for masking. During the etching, I found Silicon Nitrate
stripped at some edge area, leading to the severe distortion of expected
pattern. Was it because 0.2mm Silicon Nitrate isn't sufficient to mask against
KOH etchant? Could you help me to improve process to obtain best pattern? Did
someone ever deposit Au/Cr layer on Silicon Nitrate layer to help mask against
KOH etchant? Thank you for any help.




Best regards

Yanjun(David) Tang

Graduate student
Institute for Micromanufacturing
Louisiana Tech University

1401 Tech Farm Rd. Apt. #238, Ruston, LA 71270, USA
Email: yta001@coes.latech.edu
          tang_yanjun@yahoo.com
Homepage: http://www.latech.edu/~yta001/index.htm
Tel: 1-318-255-5133