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Proceedings Paper

Cycling of implantation step and remote plasma process step for nitride spacer etching applications.
Author(s): Nicolas Alexandre Loubet; Cécile Jenny; Camille Petit-Etienne; Erwine Pargon
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Paper Abstract

The etching of silicon nitride spacers is one of the most challenging steps of transistor fabrication. It requires anisotropy to preserve the sidewalls and a high etch selectivity over the underlying substrate to achieve a high surface quality. Recently, an interesting approach using a two step-process was proposed for the etching of silicon nitride spacers with high anisotropy and minimal induced damage [1]. The first step uses an H2 implantation to selectively modify the horizontal SiN surfaces over the vertical ones, while the second step selectively removes the modified layer either via HF exposure or via a remote plasma (RP). This paper explores a new route to implement those two steps in a cycling process achieved in the same plasma reactor chamber. The reactor has the capability to produce both a capacitive plasma discharge (CCP) for the implantation step and a remote discharge for the removal step. This study demonstrates that the remote plasma process, whose etching mechanisms are driven by reactive neutrals, is highly sensitive to the material surface state and consequently an incubation time exists before the etching starts when exposed to neutrals. The modifications induced by the first implantation step shortens the incubation time offering a process window with infinite etch selectivity between horizontal implanted and vertical non-implanted surfaces. Based on this understanding a two-step cycling process was developed and applied successfully to the etching of Si3N4 spacer patterns for imager applications.

Paper Details

Date Published: 23 March 2020
PDF: 9 pages
Proc. SPIE 11329, Advanced Etch Technology for Nanopatterning IX, 113290G (23 March 2020); doi: 10.1117/12.2551888
Show Author Affiliations
Nicolas Alexandre Loubet, STMicroelectronics (France)
CNRS-LTM, Univ. Grenoble Alpes (France)
Cécile Jenny, STMicroelectronics (France)
Camille Petit-Etienne, CNRS-LTM, Univ. Grenoble Alpes (France)
Erwine Pargon, CNRS-LTM, Univ. Grenoble Alpes (France)

Published in SPIE Proceedings Vol. 11329:
Advanced Etch Technology for Nanopatterning IX
Richard S. Wise; Catherine B. Labelle, Editor(s)

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