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Proceedings Paper

Study of the airborne SO2 and NH3 contamination on Cr, MoSi, and quartz surfaces of photomasks
Author(s): H. Fontaine; G. Demenet; V. Enyedi; S. Cetre
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Paper Abstract

The study of the airborne SO2 and NH3 contamination on Cr, MoSi and Quartz photomask surfaces was addressed by the intentional exposure to controlled contaminated air. Experimentally, mask-like layers (representative Cr, MoSi and SiO2 layers) deposited on wafers were used and then characterized by LPE-IC. Results showed that Cr surfaces clearly present a higher ability to be contaminated than MoSi and even more than Quartz, both for SO2 and NH3 (Cr >> MoSi > Quartz). For each mask surface, the NH3 contamination occurred more rapidly than the SO2 deposition. The contamination of Cr and MoSi surfaces respectively for the 2 contaminants and for SO2, are governed by Langmuir-type adsorption models allowing then the forecasting of the deposited contaminant amounts depending on the time and the airborne concentration. A very slow and low adsorption process of SO2 on Quartz is observed whereas the NH3 deposition on MoSi and quartz appear very rapid at ambient concentrations such as a way saturation levels are likely reached in few minutes. Furthermore, a significant enhancement of the SO2 and NH3 deposition is characterized in clean room humidity versus drier conditions, this effect being extremely drastic for SO2 on Cr. The knowledge of the contamination behavior of the SO2 and NH3 on photomask surfaces is very relevant for the control of the crystal growth /haze occurrence on reticles. Their application led to recommend SO2 and NH3 threshold levels lower than 10 pptv in the mask environment to avoid haze beyond one year.

Paper Details

Date Published: 24 September 2010
PDF: 12 pages
Proc. SPIE 7823, Photomask Technology 2010, 782328 (24 September 2010); doi: 10.1117/12.864268
Show Author Affiliations
H. Fontaine, CEA-LETI MINATEC (France)
G. Demenet, CEA-LETI MINATEC (France)
V. Enyedi, CEA-LETI MINATEC (France)
S. Cetre, CEA-LETI MINATEC (France)

Published in SPIE Proceedings Vol. 7823:
Photomask Technology 2010
M. Warren Montgomery; Wilhelm Maurer, Editor(s)

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