Study of etching process for LER and resolution

Tomohiro Imoto; Yosuke Kojima; Norihito Fukugami; Takashi Haraguchi; Tsuyoshi Tanaka

doi:10.1117/12.866417

26 May 2010 Study of etching process for LER and resolution

Tomohiro Imoto, Yosuke Kojima, Norihito Fukugami, Takashi Haraguchi, Tsuyoshi Tanaka

Proceedings Volume 7748, Photomask and Next-Generation Lithography Mask Technology XVII; 77480D (2010) https://doi.org/10.1117/12.866417
Event: Photomask and NGL Mask Technology XVII, 2010, Yokohama, Japan

Abstract

The miniaturization of pattern size on photomask is advanced year by year. It becomes more important to improve Line Edge Roughness (LER) and resolution because of their impacts on lithography performances. When miniaturization is advanced, high sensitivity inspection is also indispensable. Therefore, LER becomes the key factor to reduce the nuisance defect for high sensitivity mask inspection. Basically, LER originates from resist materials and EB writer. If resist pattern LER is good, final pattern LER can be good too. One of the easiest solutions for LER is using thick resist. Thick resist can vertically smooth down the LER. However, it deteriorates resolution due to the high aspect-ratio. Another solution for LER is using low sensitivity resist. Low sensitivity resist needs many electron exposures by EB writer. Therefore, electronic density of EB pattern increases and pattern edge becomes clear. However, it deteriorates throughput, which is essential to production. Only by mask resist, it is difficult to satisfy all items, that is mask LER, resolution and throughput. In this study, the improvement of LER without deterioration of resolution is tried by dry etching process. It is found that remaining resist after Cr etching has its limitation for mask LER. And Cr over etching and source power of Cr and MoSi etching are effective factors for mask LER. On the basis of these results, the optimal etching process is determined. It is confirmed that mask LER can be improved without deterioration of resolution by the optimal etching process.

Citation Download Citation

Tomohiro Imoto, Yosuke Kojima, Norihito Fukugami, Takashi Haraguchi, and Tsuyoshi Tanaka "Study of etching process for LER and resolution", Proc. SPIE 7748, Photomask and Next-Generation Lithography Mask Technology XVII, 77480D (26 May 2010); https://doi.org/10.1117/12.866417

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