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Proceedings Paper

Novel process for deposition of aluminum onto sidewalls of silicon trenches
Author(s): Harald Sehr; Alan G. R. Evans; Arthur Brunnschweiler; Graham J. Ensell
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Paper Abstract

We have investigated different techniques to deposit 1 micrometers to 2 micrometers thick aluminium onto sidewalls of trenches etched into silicon. This process is required for the fabrication of thermally excited vertical bimorph actuators. First, aluminium is deposited covering both horizontal surfaces and sidewalls. Then an etch-step removes the aluminium from the horizontal surfaces, retaining only aluminium spacers on the sidewalls. Sputtering of aluminium and a subsequent anisotropic dry-etch yields spacers of a thickness less than 0.5 microns having a rough surface. Evaporation of aluminium at a shallow angle between the wafer and the aluminium source allows controlling the thickness of the deposits on the sidewalls compared to those on the horizontal surfaces. Thus, the dry-etch time can be reduced resulting in aluminium spacers up to 2 microns thick and of improved surface quality. If the deposit on the sidewall is thicker than on the horizontal surfaces, isotropic wet-etching can be used to remove the aluminium on the horizontal surfaces, where as on the sidewalls it is only thinned by about the thickness of the aluminium on the horizontal surfaces. Spacers of up to 2.5 microns thickness with good surface quality have been achieved.

Paper Details

Date Published: 25 August 2000
PDF: 9 pages
Proc. SPIE 4174, Micromachining and Microfabrication Process Technology VI, (25 August 2000); doi: 10.1117/12.396445
Show Author Affiliations
Harald Sehr, Univ. of Southampton (United Kingdom)
Alan G. R. Evans, Univ. of Southampton (United Kingdom)
Arthur Brunnschweiler, Univ. of Southampton (United Kingdom)
Graham J. Ensell, Univ. of Southampton (United Kingdom)

Published in SPIE Proceedings Vol. 4174:
Micromachining and Microfabrication Process Technology VI
Jean Michel Karam; John A. Yasaitis, Editor(s)

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