Plasma Technology  

single step process:
thin sidewall deposition visible
on brocken line: Si:Cl:O

gas chopping process:
sidewall deposition gets thinner
towards the bottom
Aspect Ratio Dependent
Deposition "ARDD"

with kind permission of TU Vienna
S. Golka, W. Schrenk, G. Strasser


laser interferometer trace



for a grating etch
As the etch continues it takes less
time to sputteretch off the deposited
film (Si:Cl:O)


gas chopping process:
roughness at the top 200 nm
for the non optimised process

gas chopping process:
roughness < 20 nm
for the optimised process

GaAs ICP Etching by Gas Chopping

Plasmalab System 100
with ICP180 source

Inductive Coupled Plasma


rate > 0.5 µm/ min

selectivity to SiN mask 60 - 100 : 1

low bias process for low substrate damage


published at JVST-B 25, 839 (2007)



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