Dear Xiaoyong,

 you can try metal: Tungsten,but there are more others. I have tried the
mentioned one, thus I suggest to try this one, especially as it is
relatively easy to remove in hydrogen peroxide (H2O2). I recommend you the
papers of Kirt R. Williams, J. of MEMS vol. 5 no. 4 (1996) and vol 12 no.6
(2003).

 Best Regards.

  Karolina


---------- Wiadomość przekazana dalej ----------
From: Xiaoyong Liu 
To: 
Date: Thu, 7 Jan 2010 20:08:24 +0000
Subject: [mems-talk] protecting layer/material during KOH Si etching for SiN
membrane formation
Hi All,

     I am in a processing of making SiN membrane by using KOH chemical
etching on SiN(~50nm) coated Si wafers. There are some patterns on one side
of wafer, and I want them intact during KOH etching. The total etching time
will be about 5-6 hours.  I am wondering if there is any material/film I can
put on to protect that side of wafer, and can be readily removed afterwards..

Thanks a lot

Xiaoyong