MoSi stain defect reduction in photo resist strip process

Ewin Zhuo; Ansel Huang; Zain Zhang; Joyce Wang; Mazer Li; Josh Cheng; Kuang Huang; Zack Huang

doi:10.1117/12.2684159

29 September 2023 MoSi stain defect reduction in photo resist strip process

Ewin Zhuo, Ansel Huang, Zain Zhang, Joyce Wang, Mazer Li, Josh Cheng, Kuang Huang, Zack Huang

Proceedings Volume 12915, Photomask Japan 2023: XXIX Symposium on Photomask and Next-Generation Lithography Mask Technology; 129150F (2023) https://doi.org/10.1117/12.2684159
Event: Photomask Japan 2023, 2023, Online Only

Abstract

The PR (Photo Resist) strip process before MoSi etch is a critical step in the manufacture of high-end PSM (Phase Shift Mask). Any impurity on MoSi film before MoSi etch would generate killer defect which leading to mask reject and yield loss. A super-thin opaque MoSi type defect called as MoSi stain in this paper was observed by KLA mask inspection that is almost unrepairable due to the characteristic of large defect size. This defect locates on Qz (quartz) area and adjacent to MoSi pattern of the mask. It was analyzed by SEM (Scan Electron Microscope) and TEM (Transmission Electron Microscope) that the components of this defect are Mo/Si/O/N, which are same as mask MoSi film. The root cause was proved in this paper to be the chemical residuals in PR strip process on Qz area of the mask that was not fully removed by clean process before MoSi etch, hence, those impacted area of MoSi film was not completely etched in MoSi etch process. In addition, the PR strip recipe was also optimized to prevent mask from encountering chemical residual to address this MoSi stain defect from occurring again without any side-effect impact on mask.

Citation Download Citation

Ewin Zhuo, Ansel Huang, Zain Zhang, Joyce Wang, Mazer Li, Josh Cheng, Kuang Huang, and Zack Huang "MoSi stain defect reduction in photo resist strip process", Proc. SPIE 12915, Photomask Japan 2023: XXIX Symposium on Photomask and Next-Generation Lithography Mask Technology, 129150F (29 September 2023); https://doi.org/10.1117/12.2684159

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