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Proceedings Paper

Binary 193nm photomasks aging phenomenon study
Author(s): Félix Dufaye; Luca Sartelli; Carlo Pogliani; Stuart Gough; Frank Sundermann; Hiroyuki Miyashita; Yoshioka Hidenori; Nathalie Charras; Christophe Brochard; Nicolas Thivolle
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Paper Abstract

193nm binary photomasks are still used in the semiconductor industry for the lithography of some critical layers for the nodes 90nm and 65nm, with high volumes and over long period. These 193nm binary masks seem to be well-known but recent studies have shown surprising degrading effects, like Electric Field induced chromium Migration (EFM) [1] or chromium migration [2] [3] . Phase shift Masks (PSM) or Opaque MoSi On Glass (OMOG) might not be concerned by these effects [4] [6] under certain conditions. In this paper, we will focus our study on two layers gate and metal lines. We will detail the effects of mask aging, with SEM top view pictures revealing a degraded chromium edge profile and TEM chemical analyses demonstrating the growth of a chromium oxide on the sidewall. SEMCD measurements after volume production indicated a modified CD with respect to initial CD data after manufacture. A regression analysis of these CD measurements shows a radial effect, a die effect and an isolated-dense effect. Mask cleaning effectiveness has also been investigated, with sulphate or ozone cleans, to recover the mask quality in terms of CD. In complement, wafer intrafield CD measurements have been performed on the most sensitive structure to monitor the evolution of the aging effect on mask CD uniformity. Mask CD drift have been correlated with exposure dose drift and isolated-dense bias CD drift on wafers. In the end, we will try to propose a physical explanation of this aging phenomenon and a solution to prevent from it occurring.

Paper Details

Date Published: 19 May 2011
PDF: 11 pages
Proc. SPIE 8081, Photomask and Next-Generation Lithography Mask Technology XVIII, 80810W (19 May 2011); doi: 10.1117/12.898867
Show Author Affiliations
Félix Dufaye, STMicroelectronics Crolles (France)
Luca Sartelli, DNP Photomask Europe (Italy)
Carlo Pogliani, DNP Photomask Europe (Italy)
Stuart Gough, STMicroelectronics Crolles (France)
Frank Sundermann, STMicroelectronics Crolles (France)
Hiroyuki Miyashita, DNP Photomask Europe (Italy)
Yoshioka Hidenori, DNP Photomask Europe (Italy)
Nathalie Charras, STMicroelectronics Crolles (France)
Christophe Brochard, STMicroelectronics Crolles (France)
Nicolas Thivolle, STMicroelectronics Crolles (France)

Published in SPIE Proceedings Vol. 8081:
Photomask and Next-Generation Lithography Mask Technology XVIII
Toshio Konishi, Editor(s)

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