Deep Reactive
Ion Etching prevents lateral etching of the silicon
resulting in highly anisotropic etch profiles at
high etch rates and with high aspect ratio compared
to wet chemical etching.
|
 |
|
Fig.
1: The "SHARP" Process for submicron
features. (Courtesy ESIEE) |
Current maximum etch rates are now exceeding 50
µm/min, with an excellent etch depth uniformity.
Better sensitivity
of MEMS devices requires increasingly higher aspect
ratio features. The Aspect Ratio of a given feature,
like a trench, is defined as the ratio between the
depth of the trench and the width. It has been demonstrated
that an Aspect Ratio as high as 110 is achievable,
using the Alcatel patented SHARP process, as shown
in Fig. 1.
DRIE Etching at Micralyne
Micralyne's
DRIE technology is established for full-scale manufacturing.
With etching capabilities varying from under 1µm
to over 700µm's in depth, Micralyne's expertise
lies in its DRIE recipes. Standard DRIE recipes are
incapable of releasing heat sensitive membrane structures.
This is because of excessive heat buildup that results
in a loss of sidewall passivation and ultimately destruction
of the device. Micralyne has developed specific low
heat generating recipes that have successfully
been implemented into multiple designs and process
flows.
Micralyne
has also developed multiple ways of mounting DRIE
etch samples onto full sized wafer carriers, allowing
R&D work to be completed on wafer pieces. This
results in reduced material cost and faster experimental
results. Micralyne has successfully developed DRIE
recipes for over 50 product designs. Many customers
require very specific etch specifications such as
sidewall angle, sidewall roughness, etch rate, uniformity,
selectivity, max temperatures, etch stop, low polymer
production and others.
Micralyne has extensive experience customizing DRIE
recipes to meet these varying customer requirements.
