Dry Etch Recipe for Ge in Chlorine Based RIE

Recipe

Gasses:

BCl3

15.0 sccm

Cl2

15.0 sccm

He

17.5 sccm
Pressure2.00 Pa
RF Power65 W
Substrate temperature20 °C

Etch characteristics

Etch rate: 195 nm/min
Etching is anisotropic

Selectivity

Etch rate of AZ 1420: 75 nm/min (selectivity 2.5)

Remarks

Considerable loading effect
Reproducibility: 10 %
Almost no aspect ratio dependence
The wafer heats up considerably during etching (mask choice!)
Recommended mask is hard baked AZ 1420 or HPR (120 0C)
This process is also used for three layer mask processing (descumming of PMMA is necessary before etching the germanium