Dear all,

I'm using Oxford Plasma 100 to etch through silicon wafer. The masking material
used in DRIE is hard baked AZP4620.

I did checked the PR mask after hard bake with microscope, which shows smooth
profile. But when I use it to get the wafter etched through, the sidewalls show
light striation from top to the bottom.

I know over-passivation will lead to striation on the sidewalls, but I'm sure my
case is not. Over-passivation induced striation will not occure from the
beginning.

Somebody says that sidewall stiation formation depends on:

1. Masking material

2. Etch chemistry

3. Power regime

I'm not sure what is wrong with my etch.

Can anyone help me out from the bad situation?

Thanks a lot!

BR,

YN WANG