Etching Processes

Process Description
Cryogenic etch

Low temperature silicon etch for high aspect ratio features

O2 Descum

Microwave plasma O2+Ar slow ashing process used to remove residual photoresist.

Bulk Silicon etch

A process for anisotropic bulk etching of silicon wafers is available at MMF. A dedicated temperature controlled bath with a cooled lid is located in the Base/Litho bench. This bath has 0.1C temperature control and features a coolant loop around the bath lid acting as a condenser, preventing loss of etchant thereby maintaining etchant concentration.
MMF stocks 25% by weight electronic grade TMAH in water.

R1 S1813 on Si ashing

No faraday cage; wafer in vertical position, centered in chamber

1.3um S1813 on 100mm Silicon wafer
Ash time 4 min

R2 S1813 on Al Ashing

With faraday cage; wafer in vertical position, centered in chamber

1.3 uM S1813 on 100 mm Aluminum coated Silicon wafer
36 minute ash

R3 S1813 on Si Descum

With faraday cage, wafer in vertical position, centered in chamber.

1.3 uM S1813 on 100 mm Silicon wafer.

2 min descum removes 45 +/- 6 nm

R4 S1813 on Al Descum

With faraday cage; wafer in vertical position, centered in chamber.

1.3 uM S1813 on Al coated Si wafter

4 min descum removes 21 +/- 15 nm

Alumina Dry Etch Recipe

-The Alumina etch utilizes a C4F8, CHF3 and Ar chemistry to slowly etch away the resistant alumina film.
-The Oxford ICP 100 etcher is used with this chemistry and the etch rate has been measured to be about 50 nm/min
-This gas chemistry will etch Si, so be sure to stop fairly quickly after the alumina is completely etched.
-Surface roughness seems to vary on etch time. Be sure to measure with the Ambios Profilometer

Chromium Dry Etch Recipe

-The chromium dry etch recipe utilizes a chlorine and oxygen chemistry to etch the metal
-The Oxford ICP 100 etcher is used with this recipe, and the etch rate is about 25 nm/min.

Silicon Dioxide Dry Etch Recipe

-The Oxford Plasmalab ICP 100 etcher utilizes an etch chemistry of C4F8 and oxygen to etch the silicon dioxide while stopping quite well on microscope glass and Si.
-The etch rate has been measured to be about 300 nm/min.

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