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.
Aluminum HBr Dry Etch Recipe
  • The Oxford Plasmalab ICP 100 uses a gas chemistry of chlorine for the initial aluminum oxide breakthrough and then HBr gas to etch the Al.
  • The etch rate has be measure at about 1075 nm/min for a thick film of Al with a thickness of 2.7um.
  • This gas chemistry will etch Si so silicon dioxide is needed to stop the etching beneath the Al.
Aluminum Cl2 Dry Etch Recipe
  • The Oxford Plasmalab ICP 100 uses a chemistry of chlorine for both the breakthrough of aluminum oxide and the etching of aluminum underneath.
  • The etch rate has been measure at about 600 nm/min for thin films of Al with a thickness of 100 nm.
Lithium Niobate Dry Etch Recipe
  • The Oxford Plasmalab ICP 100 uses CHF3, oxygen and argon to etch lithium niobate.
  • The etch rate seems to vary significantly but was measured at about 20 nm/min.
  • As etch time increases the etch seems to slow as a passivation layer is formed on the lithium niobate sample.