Hi,

If the etch is slightly undercutting you need to decrease your SF6 flow.

Dave

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org] On
Behalf Of shimul saha
Sent: 19 May 2009 11:12
To: General MEMS discussion
Subject: [mems-talk] Positive sidewall,dry etch of silicon using BOSCH process

Hello,

I am using BOSCH process for deep dry etching of silicon. The gases are SF6, O2
during etching cycles and C4F8 during deposition cycles.. At present I am
getting slightly negative sidewall, but I want a positive sidewall. Can you
please provide any hint, probably changing gas ratio (incerase or decrease any
of the gas content) or power to get a positive sidewall in etching. Any
suggestions will be greatly helpful for me. Thanking you in advance.

Best regards,
Shimul