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Proceedings Paper

Piezoresistive effect: stable enough for high-accuracy sensor applications?
Author(s): Gerald Gerlach; Arne Nakladal; Reinhard Buchhold; Kurt Baumann
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Paper Abstract

To date, the usefulness of piezoresistive pressure sensors is still limited by their instability and inaccuracy. Therefore, the physical protection of the sensor elements and the robustness of the output signals with respect to environmental disturbances are important issues in the design and manufacturing of piezoresistive sensors. One approach to the encapsulation of small piezoresistive sensors is to adapt the passivation techniques commonly used in microelectronic manufacturing. An ideal passivation system is one that eliminates cross- sensitivities while not affecting the transfer behavior of the sensor. In reality, however, the same physical mechanisms that prevent cross-sensitivities will generally also modify the sensor's transfer function. The paper describes how accuracy and stability of non-encapsulated silicon pressure sensors can be optimized under consideration of mechanisms connected to environmental conditions like temperature and humidity. The performance of pressure sensors as a function of passivation layer properties and climatic conditions was experimentally studied. Valuation criteria were stochastic shares of the output voltage (noise). It was found that fast changes in the ambient climate induce significant measurement errors. Experimental results will be given that suggest new conclusions regarding the physics behind instabilities in piezoresistive sensors and yield approaches for improved sensor design.

Paper Details

Date Published: 8 September 1998
PDF: 9 pages
Proc. SPIE 3514, Micromachined Devices and Components IV, (8 September 1998); doi: 10.1117/12.323911
Show Author Affiliations
Gerald Gerlach, Dresden Univ. of Technology (Germany)
Arne Nakladal, Dresden Univ. of Technology (Germany)
Reinhard Buchhold, Dresden Univ. of Technology (Germany)
Kurt Baumann, Aktiv Sensor GmbH (Germany)

Published in SPIE Proceedings Vol. 3514:
Micromachined Devices and Components IV
Patrick J. French; Kevin H. Chau, Editor(s)

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