Black wax (Apiezon) is the protective coating that we have used. It can be
dissolved by xylene or trichloroethylene.

Good luck.

Bin Yuan
Department of Mechanical Engineering
The Johns Hopkins University
Baltimore, MD 21218
(410) 516-6665

On Fri, 9 May 1997, James R. Stackhouse wrote:

> We are trying to use KOH to place a 5 micron deep etch on one side of
> silicon wafer, and 25 micron on other side.  We are looking for a
> protective coating we could apply to one side of the wafer after we've
> done the first 5 microns of the etch, then continue with the final etch
> on the other side.  Can anyone suggest a solution to this two step etch
> process ?  Possibly a spin-on layer to be removed after the etching ?
>
> Thanks,
> Jim Stackhouse
> Phil Klauder
>
>