etching InAs / InAlAs / AlSb / GaSb

[Mark Topinka]

If anybody has any experience, good references, or ideas about etching any 
or all the materials in the subject line (which are: InAs, InAlAs, AlSb, 
and GaSb) I would really appreciate hearing your advice!  Thanks very 
much.  Sincerely -Mark Topinka

PS- I so have one recipe which uses Argon, Hydrogen, and Methane.  I'm 
interested in trying it, but it is rather slow at etching AlSb (2nm/minute) 
which makes me a bit worried about my mask material (either PMMA or chrome, 
or possibly other material?)