Hi Mathieu

One way of etching high aspect ratio structures either in quartz or in thick
deposited SiO2 layers involves high density plasmas.  Typically, these would
be generated in an inductively coupled plasma system (ICP).  This has some
advantages over conventional RIE, in particular relating to rate.  Oxides
are etched in these systems using C4F8 (possibly with O2 or H2 additions).
The selectivity to photoresist is not great, so normally a metal mask (Cr,
Al or Ni) would be used.  There are several companies offering this process
(including the one I work for) who would like to sell you a system, but
there are also a number of other places who could run a few wafers for you.
Drop me an email if you would like to know more about the process we have
for this application.

Regards,

Martin Walker BSc(Tech) MSc
Tactical Marketing Engineer
Oxford Instruments Plasma Technology
North End, Yatton,
Bristol BS49 4AP  UK
T. +44 (0) 1934 837031
F. +44 (0) 1934 837001
E. 
W. 


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