Dear everybody:

I am use the unaxis-Nextral 860L equipment to etch 6-8um sio2 film now with the
recipe:O2 10sccm,CHF3 80sccm,He 10sccm,rf power 250watt, UHF power 1800watt,
pressure 22mtorr.but found the selectivity is  very poor whatever the mask
material is Aluminium!"Titanium or a-si.how to etch this sample with CHF3,can
you give me some good advice.Thanking you in advance

regards.

Li-bing Zhou