Hello David,

Is the nitride layer PECVD or stoichiometric?  I assume you actually have
2000A nitride and are etching at 80C.  If so we have also etched through
2000A of PECVD nitride mask in about the same time as is took to etch
through the wafer (this was at 55C) You may have better luck with EDP
instead of KOH if you have access to the necessary chemicals.

Regards,

Alexander K. Smith
Engineer, Microfabrication Laboratory
Case Western Reserve University

10900 Euclid Ave.
Cleveland, OH 44106
Bingham Building 342

Phone: (216)368-0265
Fax:   (216)368-0606


-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Yanjun(David) Tang
Sent: 03 June 2002 07:22
To: [email protected]
Subject: [mems-talk] (100) Si deep etching


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: [email protected]
          [email protected]
Homepage: http://www.latech.edu/~yta001/index.htm
Tel: 1-318-255-5133