Low Damage
Dielectric Etching on GaAs Using a
F.S. Pool, W.A.
Wohlmuth, E. Maxwell, B. Berggren, S. Roadman,
B. Howell and W. Mickanin
TriQuint
Semiconductor
(503) 615-9454, fpool@tqs.com
Keywords: helicon wave plasma
Abstract
An RF helicon wave high
density plasma source has been used to develop a low damage SiO etch process
for fabrication of submicron features on GaAs substrates. Etch rate and damage
measurements were made on implanted GaAs substrates, coated with SiO deposited
by RF plasma CVD. Increases in post-etch sheet resistance as low as 12% could
be achieved using a CF4/O2 chemistry and 10% overetch. A 0.36 µm gate
structure was fabricated yielding a residue free, anisotropic etch, with an
increase in critical dimension of 600 ± 100Å from the photolithography and excellent device characteristics.
This represents the first demonstration of this etch technology in the
fabrication of submicron GaAs devices for digital and mixed signal
applications.