Hello All,

I have the problem of occurance of grass during
polyimide etch in O2 plasma.

The polyimide i hvae used was PI2611. I went with low
power and low pressures for the O2 plasma etch.
(100mT, 100W). Aluminum was used as a hard mask for
the polyimide. After etching 15 microns of PI in O2
plasma, i have observed grass in the etched regions. I
presume that the grass arised due to the Al sputtering
during O2 plasma that deposited in the regions where
the PI was supposed to be etched and finally causing
the micromasking of the polyimide in these regions
resulting in grass.

Can somebody suggest me in eliminating the grass.

I would appreciate your help.

Thanks,
Kris