OPT application lab:
lenses etched into Si

Reactive Ion Etching
with Inductive Coupled Plasma Source (ICP)

Plasmalab System 100
with ICP380 sources

Rate: > 200 nm /min

Selectivity to PR: 2:1 (adjustable)

uniformity ± 3 % (6”)

Lenses: smooth, no residues

Fluorine based process

(Lower 2 SEMs from ECR etching in 1993)

The photoresist profile is reproduced in silicon. Lens profile may be produced in photoresist either by reflowing or by grey-scale exposure. This process can be adjusted to give the desired selectivity silicon to resist around 2:1. This adjustment can be made during the process, to create changing radius lenses. Laser endpoint detection can be used on large areas of resist, to identify when all the resist has been removed.