We here at SMC have had wafers polished on the back side, in order to allow for
through the wafer IR alignnment on a Karl Suss alignment tool.  We sent the
wafers to:

 CVD systems & Services
 Penn Center Plaza
 Quakertown, PA  18951

 Contact Person is: Bob Cambel,  215-536-2104

You will need to specify the starting wafer thickness, the final wafer
thickness you want, as well as the level of polishing that you need.  The turn
time is about 2 to 3 weeks.

Regards,

Tom Pumo
Director of R&D for MEMS Devices
Standard Microsystems Corporation (SMC)
Wafer Foundry Business Unit
(516) 435-6822
tom.pumo@smc.com