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Proceedings Paper

Loading effects in deep silicon etching
Author(s): Jani Karttunen; Jyrki Kiihamaki; Sami Franssila
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Paper Abstract

Feature scale pattern dependencies and chip and wafer level loading effects complicate the use of deep silicon etching in MEMS applications. They have major effect on uniformity and etch rate on the wafer scale and on a feature scale. The aim of this study was to find the limitations that these phenomenon set on deep silicon etching. Wafer scale, chip scale and feature scale structures were etched in pulsed ICP. Etched depths were 10-500 micrometers , and aspect ratios up to 20:1. Strong dependence of etch rate on loading was observed. On the wafer scale average etch rate was greatly reduced, from 5.4 micrometers /min to 1.7 micrometers /min. At same time uniformity deteriorated from excellent 2 percent to 35 percent which is too high value to practical applications. Chip pattern density did not affect etch rate on an isolated small chips but for 10 by 10 mm2 chip 10 percent etch rate reduction was seen at high chip scale load. In this case wafer scale etchable area was 6 percent. We show that feature scale and wafer scale pattern dependencies in ICP etching are strongly coupled.

Paper Details

Date Published: 25 August 2000
PDF: 8 pages
Proc. SPIE 4174, Micromachining and Microfabrication Process Technology VI, (25 August 2000); doi: 10.1117/12.396475
Show Author Affiliations
Jani Karttunen, VTT Electronics (Finland)
Jyrki Kiihamaki, VTT Electronics (Finland)
Sami Franssila, Helsinki Univ. of Technology (Finland)

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

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