GaAs rate recess etch

System 100 Cluster
with cassette and ICP380s

50nm GaAs layer etched selectively
over AlGaAs active layer

BCl3/SF6 based process for selective etching 
   to aluminium containing layers
ICP technology provides maximum control 
   over selectivity
Two step process to enhance selectivity
Very high selectivity to AlGaAs and AlAs layers
Controllable isotropic or anisotropic etch
BCl3/SF6 chemistry

DC Bias < -30 volts
Low damage, low noise
Etch rates
   GaAs > 100 nm/min.
   AlGaAs< 1 nm/min
   AlAs ~0.2 nm/min.
   PR < 10 nm/min.
Selectivities
   GaAs:AlGaAs > 100:1
   GaAs:AlAs > 500:1
   GaAs:PR > 10:1 

AlGaAs and GaAs rate
and selectivity vs SF6 flow

ICP RIE
technology