Hi David,
this could be a problem with the photolithography stage, if your hard mask
is patterned. Typically during the process the edge bead of resist is
removed, which means that at the wafer edges the nitride and oxide will be
removed exposing silicon to the KOH etchant. If you do not remove the bead
of resist at the wafer edges, then the nitride and oxide will remain,
protecting during the etch.
Hope this helps,
Helen.
Dr Helen Berney, MIEEE, MEBF
National Microelectronics Research Centre, Prospect Row, Cork, Ireland
Tel +353-21-4904010 Fax +353-21-4270271 Email hberney@nmrc.ie
http://www.nmrc.ie/research/transducers-group/index.html
-----Original Message-----
From: mems-talk-admin@memsnet.org [mailto:mems-talk-admin@memsnet.org]On
Behalf Of Yanjun(David) Tang
Sent: 03 June 2002 07:22
To: mems-talk@memsnet.org
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: yta001@coes.latech.edu
tang_yanjun@yahoo.com
Homepage: http://www.latech.edu/~yta001/index.htm
Tel: 1-318-255-5133
_______________________________________________
mems-talk@memsnet.org mailing list: to unsubscribe or change your list
options, visit http://mail.mems-exchange.org/mailman/listinfo/mems-talk
Hosted by the MEMS Exchange, providers of MEMS processing services.
Visit us at http://www.mems-exchange.org/