Hi Chenyan

You can etch glass using an RIE tool and fluorine chemistry, but as Bob
says, it is difficult.  The problem is that some oxides in glass do not form
volatile fluorides.  The only way to get rid of them is to turn up the ion
bombardment and to use a mixture of CHF3 and Ar.  Even then, RIE is still
pretty slow (10-25nm/min).  You can get higher rates with ICP
(50-100nm/min), but that is not much use to you if you have an RIE tool!
Watch out for the chromium mask sputtering at high bias.  This can cause
grass on the etching surface.  Your mask selectivity will not be
particularly high, so you will need thick masks.  Resist selectivity is
around 1:1, while selectivity to aluminium or chromium will be around 4:1.

Martin

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