Physical force optimization for advanced photomask cleaning

C. W. Shen; K. W. Lin; C. L. Lu; Luke Hsu; Angus Chin; Anthony Yen

doi:10.1117/12.2028484

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28 June 2013 Physical force optimization for advanced photomask cleaning

C. W. Shen, K. W. Lin, C. L. Lu, Luke Hsu, Angus Chin, Anthony Yen

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Proceedings Volume 8701, Photomask and Next-Generation Lithography Mask Technology XX; 870106 (2013) https://doi.org/10.1117/12.2028484
Event: Photomask and NGL Mask Technology XX, 2013, Yokohama, Japan

Abstract

We investigated methods to extend the damage-free process window for fragile Sub-Resolution Assist Features (SRAF) in mask cleaning using MegaSonic and binary spray techniques. Particle removal efficiency (PRE) was found to increase by 8% and damage reduced from 7 ppm to 0 ppm with the optimization of the spray droplet characteristics through liquid media control. MegaSonic damage was eliminated completely from 10 ppm to 0 ppm by varying physical and chemical properties of the cleaning media. Since particles in the deep trenches are very difficult to remove using droplet spray alone, a combination of MegaSonic and Binary Spray processes was tested. The acoustic effects generated through the MegaSonic combined with optimized droplet impact showed an improvement of 4% in PRE of hard-to-remove trench particles. Overall, the improved process points to a promising solution for overcoming the roadblock in mask cleaning for the advanced mask cleaning.

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C. W. Shen, K. W. Lin, C. L. Lu, Luke Hsu, Angus Chin, and Anthony Yen "Physical force optimization for advanced photomask cleaning", Proc. SPIE 8701, Photomask and Next-Generation Lithography Mask Technology XX, 870106 (28 June 2013); https://doi.org/10.1117/12.2028484

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