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Proceedings Paper

Vertical oxide etching without inducing change in critical dimensions
Author(s): Andrew G. Nagy
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Paper Abstract

In order to reactive ion etch in a commercially available hex system a feature in silicon dioxide leaving a vertical sidewall profile with no change in the resultant linewidth relative to the photoresist mask it was found necessary to utilize a bi-level masking structure with polysilicon acting as the non-erodable hard mask. This hard mask prevents tapering and linewidth changes due to lateral photoresist erosion during the oxide etch. In addition the etch had to be performed under conditions producing very little fluorocarbon polymer deposition to prevent lateral mask growth during the etch and at very low pressure (5 mTorr) to reduce off-angle ion scatter-induced etching due to collisions in the plasma sheath. In a non-polymer depositing mode the lack of sidewall passivation was found to promote lateral etching of the oxide at pressures which allow this scattering to occur. The same phenomena were found to be present when etching non-photomasked oxide sidewall spacers. Etching spacers in a very non-polymerizing chemistry at normal operating pressures (50 mTorr) caused the spacers to significantly erode laterally. Use of a low pressure non-polymerizing chemistry gave faithful reproduction of the spacer width.

Paper Details

Date Published: 1 March 1991
PDF: 15 pages
Proc. SPIE 1392, Advanced Techniques for Integrated Circuit Processing, (1 March 1991); doi: 10.1117/12.48911
Show Author Affiliations
Andrew G. Nagy, Motorola, Inc. (United States)

Published in SPIE Proceedings Vol. 1392:
Advanced Techniques for Integrated Circuit Processing
James A. Bondur; Terry R. Turner, Editor(s)

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