Dear MEMS-Talk-Members,

for my PHD I am developing minaturized force sensors.

The mechanical tension is measured by piezoresistive resistors, which are
aligned at an edge of a beam. For good resolution its recommanded to adjust
the resistors next to the edge and far away from the neutral axis of the
beam.

To structure the element, a dry-etching process, which enables high AR, is
recommended, eg. bosch or drie etch.

My question to you is now: Does anybody know how much distance between edge
of the beam and resistor should be kept? Is there disturbace of the
cristallographic
lattice from the sidewalls into the crystal when using deep-etching? Is there
an underetch of the mask? Do you know any reliable literature where i can
find these values? Because of tolerances in mask design we like to keep a
distance between resistor and edge of the beam of 3µm, but this distance
may be reduced in further designs.

Can anybody give me reliable information or good hints for literature with
detailed measurement results? Is there anybody like to help me by offering
me an 180µm deep etch in approximately ten 4-inch silicon wafers. The wafers
have a thickness of 315 microns and are structured with photoresist as
maskmaterial.

Thanks and best regards,

Thorsten

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Dipl.- Ing. Thorsten Meiß
Institut für Elektromechanische Konstruktionen Merckstrasse 25
64283 Darmstadt
Tel.: 06151 / 16 - 3795
Fax: 06151 / 16 - 4096
E-Mail: [email protected]
Web: http://www.emk.e-technik.tu-darmstadt.de
http://www.emk.tu-darmstadt.de

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