We are etching through-holes in silicon wafers using 20% TMAH and a thermal oxide etch mask. The roughness on the backside of our wafers is causing some problems with breakthrough of the oxide mask. Does anyone know of a material that we can paint, spin, or otherwise apply to the backside of our wafers that will stand up to the TMAH and can also be cleanly removed? Thanks, Timothy A. Postlethwaite, Ph.D. Chief Scientist Constellation Technology Corporation 7887 Bryan Dairy Road, Suite 100 Largo, FL 33777 office: (727) 547-0600 x6177 fax: (727) 545-6043 tpost@contech.com