Specific Process Knowledge/Etch/AOE (Advanced Oxide Etch)/Quartz etch using AOE

Nanoetch in quartz 65mmx65mmx6.25mm substrates

by bge@danchip

Some priliminary results

The tests were done on 2" quartz wafers with a thickness of 1mm. These were placed on a 65mmx65mmx6,25mm quartz plate with a 2" groove. This 65mmx65mmx6,25mm plate was placed on a 4" Si wafer with a 65mmx65mm groove. the masking material was Cr sputter deposited in Wordentec and and patterned with ZEP520A resist by e-beam and ICP metal Cr etch.

Recipe used STS65x65:

Parameter	Crom mask
Coil Power [W]	1200
Platen Power [W]	500
Platen temperature [oC]	50
CF$_{4}$ flow [sccm]	43
C$_{4}$F$_{8}$ flow [sccm]	20
O$_{2}$ flow [sccm]	10
Pressure [mTorr]	8

Parameter	Results
Etch rate	~300nm/min
Etch profile	86-87 degrees
ARDE	There does not seem to be a significant aspect ratio dependency in the etch rate up to aspect ratio 1:2 ~ 1:3
Mask selectivity	20nm Cr is enough to etch 200nm in the quartz
Images	.