25 August 2000 Novel process for deposition of aluminum onto sidewalls of silicon trenches
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Proceedings Volume 4174, Micromachining and Microfabrication Process Technology VI; (2000); doi: 10.1117/12.396445
Event: Micromachining and Microfabrication, 2000, Santa Clara, CA, United States
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.
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Harald Sehr, Alan G. R. Evans, Arthur Brunnschweiler, Graham J. Ensell, "Novel process for deposition of aluminum onto sidewalls of silicon trenches", Proc. SPIE 4174, Micromachining and Microfabrication Process Technology VI, (25 August 2000); doi: 10.1117/12.396445; https://doi.org/10.1117/12.396445



Deposition processes


Semiconducting wafers

Sputter deposition

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