Hi Ruying,

Maybe you can tell us the recipe you are using right now, the one which gave
you the isotropical profile.
What gases (SF6, O2 ?, He? ... etc) the gas flow, the power and bias
voltage, and the pressure.
Depending on the parameters, you can tune your system to make it
anisotropical.

For your reference, the recipe I am using is:
CHF3: 50sccm, O2: 2.5 sccm
50W power, 8ubar pressure.
SiN etch rate ~21nm/min, PR etch rate ~ 10nm/min, Si etch rate ~ 10nm/min.

Hope this would be helpful, even though the gas used is different.

ck

----- Original Message -----
From: "R Zhang, Electrical & Electronic Engineering"

To: 
Sent: Monday, May 01, 2006 2:08 PM
Subject: [mems-talk] SiN RIE etching by SF6 veritcal profile


> Dear all,
>    Now, I try to use SF6 dry etching SiN by RIE due to so higher
> selectivity that photoresist can be as mask directly, but the problem is
> that the etching is almost isotropic. But I need the vertical SiN pattern.
> So do you have some good suggestions or ideas on how to get the vertical
> profile by SF6 RIE etching SiN?