ECR RIE-Enhanced Low Pressure Plasma Etching of GaN/InGaN/AlGaN
Heterostructures
Bedwyr Humphreys, Matthew Govett
Oxford Instruments Plasma Technology
This article was received on June 3, 1996 and
accepted on October 30, 1996. Abstract
A room temperature (RT) plasma etch process has been developed to
non-selectively etch GaN/InGaN/AlGaN structures, grown on sapphire substrates,
using an electron cyclotron resonance (ECR) plasma source with RIE enhancement.
The process chemistry chosen was Cl2/CH4 based in order
to facilitate the formation of volatile etch by-products, typically to form
group III halides and group V hydrides, although indium is more likely to form
an organo-metallic compound as opposed to a chloride. A characteristic of this
process is the very smooth sidewall features obtained and the controllability
of the etch profile via ECR power, table bias and/or gas flow ratio. Typical
results obtained using a RT process were etch rate above 100 nm/min.,
selectivity to resist mask above 30:1 and smooth anisotropic profile at low
ion-energies (below 100 eV). The process etch rate showed a characteristic
increase with increasing table bias (above 130 nm/min.) with only small changes
in the relative etch rate of each compound (i.e. selectivity maintained at
roughly 1:1), however, this etch does rely upon competing etching and
deposition mechanisms and thus too large a variation in one parameter without a
corresponding compensation with another leads to a rough surface and a more
selective etch. The process has also been demonstrated using a metal mask (e.g.
Ni) and present work is progressing onto other gas combinations and the use of
high temperature electrodes.Outline
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Cite this article as: MRS Internet J. Nitride Semicond. Res. 1, 28(1996).
last updated October 29, 1997 12:59:16 PM.© 1996-1997 The Materials Research Society
