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TMAH Etching of Silicon

TMAH ETCHING PROCEDURE

The process is to be done at the wbflexcorr-3 and -4 or wbflexcorr-1 and -2.

1) Fill a designated TMAH beaker with a TMAH solution in water; enough to submerge a wafer in a Teflon TMAH single wafer holder or multiple wafers in a designated Teflon boat.

2) Heat the solution to not more than 80C on a  hot plate.

3) While etching, cover the solution with a condenser lid.

NOTE: Most people use a 20% TMAH solution. It etches at ~68 microns per hour, or through a wafer of standard thickness (500 microns) in approximately 7-7.5 hours.

I. LONG ETCHES:

The bath may be left over night, keep the bench enabled.

II. PATTERNING:

Nitride and Oxide can be used as a mask. Photoresist does not hold up to TMAH (it dissolves immediately).


IV. DESIGNATED TMAH BEAKERS AND HOLDERS:

If they need to be cleaned, follow the KOH cleanup procedure.

The TMAH quartz ware is not to be used with metals or nonstandard materials because wafers that get TMAH etched often go back into the main stream processing equipment.

Do NOT use contaminated beakers and holders etc... because if they are not designated for TMAH they could have been used for anything -- including gold

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