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 95-100C on a hot plate.

3) While etching, cover the solution with a designated glass cover.

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.

II. PATTERNING:

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

III. STORAGE AND REUSE:

You may save your solution in a plastic bottle (cool it first) as long as it is properly labeled and in a secondary containment (ie the bottom of the cart).

IV. DESIGNATED TMAH BEAKERS AND HOLDERS:

If they need to be cleaned, use a room temperture solution of 1:1:1 H20:H2O2:HCL for 20 minutes and then rinse well. [See KOH cleanup procedure]

The TMAH quartzware 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 GENERAL WETBENCH beakers and holders etc... because if they are not designated for TMAH they could have been used for anything -- including gold