Improvement of chrome CDU by optimizing focus ring design

Rex B. Anderson; Guenther G. Ruhl; Pavel Nesladek; Gerhard Prechtl; Winfried Sabisch; Alfred Kersch; Melisa J. Buie

doi:10.1117/12.504199

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28 August 2003 Improvement of chrome CDU by optimizing focus ring design

Rex B. Anderson, Guenther G. Ruhl, Pavel Nesladek, Gerhard Prechtl, Winfried Sabisch, Alfred Kersch, Melisa J. Buie

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Proceedings Volume 5130, Photomask and Next-Generation Lithography Mask Technology X; (2003) https://doi.org/10.1117/12.504199
Event: Photomask and Next Generation Lithography Mask Technology X, 2003, Yokohama, Japan

Abstract

Uniform radical distribution in the etching plasma is essential to meet chrome critical dimension (CD) uniformity for future technology nodes on chrome masks. The Etec Systems Tetra photomask etch chamber utilizes an alumina focus ring in order to optimize the etch uniformity of the chrome mask by minimizing gas flow effects and shaping the radial distribution of the etching radicals over the mask surface. This paper describes a systematic investigation to optimize the current focus ring, in order to improve etch critical dimension uniformity. The focus ring (FR) optimization work was made possible by manufacturing a modular focus ring that allowed the geometry to be varied at different heights and diameters. The circular shape of the modular focus ring, along with the height and diameter combinations, has a large influence on the etch performance at the mask corners and edges. The underlying mechanism was investigated by modeling and simulation. Based on simulation results the focus ring geometry was varied and the optimum FR configuration was found. The critical dimension uniformity could be adjusted on uniformly patterned masks with different pattern loads to meet production specifications.

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Rex B. Anderson, Guenther G. Ruhl, Pavel Nesladek, Gerhard Prechtl, Winfried Sabisch, Alfred Kersch, and Melisa J. Buie "Improvement of chrome CDU by optimizing focus ring design", Proc. SPIE 5130, Photomask and Next-Generation Lithography Mask Technology X, (28 August 2003); https://doi.org/10.1117/12.504199

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