Haze classification based on location for COG mask

Yilei Zeng; Yu Zhang; Debao Ding; Hunter Li

doi:10.1117/12.2640331

1 December 2022 Haze classification based on location for COG mask

Yilei Zeng, Yu Zhang, Debao Ding, Hunter Li

Proceedings Volume 12293, Photomask Technology 2022; 122930W (2022) https://doi.org/10.1117/12.2640331
Event: SPIE Photomask Technology + EUV Lithography, 2022, Monterey, California, United States

Abstract

As the medium that transfers integrate circus design graphics to wafer, reticle has irreplaceable importance. DRAM lithography process below 20nm needs multi-patterning technology without EUV adoption, which means more masks need to be used to reach a certain process target. At present, the conventional masks in the industry are divided into phase shift mask(PSM) and chrome on glass (COG) mask. This paper focuses on haze research for COG mask. Haze has always been an unavoidable topic for mask management. In CXMT some traditional haze like ammonium sulfate has almost disappeared. However, several COG masks in a set of products still suffered haze issues which caused very short lifetime. This haze has very typical characteristics, which is different from ammonium sulfate haze or molybdenum oxide haze widely recognized in worldwide. Based on the mask layout, the correlation between haze and mask pattern was explored, as well as the specific location relationship between haze and line in the pattern. Two different haze types named type L and type C were identified based on their aggregation map, of which the growth rate and frequency were tracked, and the chemical sources were identified based on the microscopic results. Based on what we found, the mask manufacture process in mask house and mask management process in fab were optimized to maximum mask lifetime.

Citation Download Citation

Yilei Zeng, Yu Zhang, Debao Ding, and Hunter Li "Haze classification based on location for COG mask", Proc. SPIE 12293, Photomask Technology 2022, 122930W (1 December 2022); https://doi.org/10.1117/12.2640331

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