Specific Process Knowledge/Etch/Etching of Bulk Glass/HF Etch of Glass

Wet HF-etch of bulk glass

	Fused silica	Borofloat glass
General description	40% pre-mixed HF	40% pre-mixed HF
Possible masking materials	LPCVD silicon (good adhesion and step coverage)	Sputtered silicon (Alcatel) (bad adhesion and step coverage) We are testing other masks at the moment (ask BGE)
Etch rate	~700 nm/min (patterned silica, slow stirring) ~800 nm/min (non-patterned silica, slow stirring)	~3.9 µm/min
Uniformity	~ 2% (slow stirring, horizontal wafer)
Batch size	1 wafers at a time	1 wafer at a time
Size of substrate	4" wafers	4" wafers
Allowed materials	No restrictions	No restrictions