Deep through holes DRIE problem - Bubble shape formation
Pradeep Dixit
2005-05-18
Dear All,
I am trying to eatch through holes in 450 micron thicks wafer in STS
machine, but i am getting very rough surface(bubble type of shapes)
after some etching time.
I have SEM pics of through etched holes and trenches which I can
forward if you contact me directly.
Feature size diameter is 30-35 microns and total thickness of wafer is
450 microns. Total process time is also very high 4 hrs 30 mins (etch
rate ~ 1.6 um/min)
Process parameters used are
Coil Power - 800 W,
Platen Power - 12 W
SF6 flow - 130 sccm
O2 - 13 sccm
C4F8 - 100 sccm
Etch /Passivation time - 13/7
APC - 75%
I am using 10 um AZ9260 as mask.
This very rough surface (bubble type shape ) are occuring at almost same
place and after some time.
Can anyone suggest me any idea why this strange thing is occuring and
any suggestions to overcome this problem.
I will be very thankful to any suggestions.
Thanks,
Pradeep Dixit
Research Student