The best way you are likely to get 1:1 selectivity between metal and silicon
(which is what you need to duplicate the pattern) is to use ion beam
milling.  This tends to etch everything at roughly the same rate.  The best
match for etch rate between metal and silicon would be to use Ti.  If you
want to use different metals, then the selectivity would not be 1:1.  For
most materials, silicon will be removed more slowly than the original
pattern, so it would have to be elongated vertically to compensate.
Note, you would not be able to create any undercut structures using this
technique.
There is a list of comparative etch rates at
http://www.oxfordplasma.de/data/rates.htm.
Regards,
Martin
>Sun, 14 Jul 2002 15:50:35 +0300
>
>Hi,
>
>We have a rather unusual situation:
>
>1.We have a 3D pattern created on Si. The 3D pattern is created in a metal.
>2.We'd like to transfer the 3D pattern into Si by etching the metall AND Si
>(i.e., first the metal is etched, but since it has a varying thickness,
>etching of Si begins thereby transferring the pattern into Si).
>
>Question: can this be done? What process, parameters, etc?
>
>Any preference viz-a-viz the metal (Al, Cu, Ti, etc)?
>
>Thanx,
>David

Martin Walker B.Sc.(Tech.) M.Sc.
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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