Fabrication of micromechanical devices from polysilicon films with smooth surfaces

H. Guckel, J. J. Sniegowski, T. R. Christenson, S. Mohney, T. F. Kelly

Research output: Contribution to journalArticle

143 Scopus citations

Abstract

Micromechanical devices such as bearings require smooth surfaces. Fine-grained polysilicon can be produced with a surface roughness near 8 Å rms. The ability to anneal films of this type into tension eliminates size restrictions due to compressive buckling. The use of these films in micromechanical devices has been restricted because hydrogen fluoride-etched structures are covered by an etch residue that leads to contact welding. Contact between opposing surfaces is induced mainly by surface tension effects. This problem may be avoided by removing the deflection mechanism. Thus, freezing of a water-methanol rinse after sacrifical ethcing all but eliminates surface tension. Removal of the ice mixture via sublimation at 0.15 millibar occurs readily. Free-standing structures with smooth surfaces and small gaps are next passivated by silicon deposition or other techniques.

Original languageEnglish (US)
Pages (from-to)117-122
Number of pages6
JournalSensors and Actuators
Volume20
Issue number1-2
DOIs
StatePublished - Nov 15 1989

All Science Journal Classification (ASJC) codes

  • Engineering(all)

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