CD variation analysis technique and its application to the study of PSM mask misalignment

Yuri Granik; Nicolas B. Cobb; Emile Y. Sahouria

doi:10.1117/12.410768

22 January 2001 CD variation analysis technique and its application to the study of PSM mask misalignment

Yuri Granik, Nicolas B. Cobb, Emile Y. Sahouria

Proceedings Volume 4186, 20th Annual BACUS Symposium on Photomask Technology; (2001) https://doi.org/10.1117/12.410768
Event: Photomask Technology, 2000, Monterey, CA, United States

Abstract

We study the influence of process parameters on strong phase shifted and binary mask designs. The impact of a poly gate alternate phase shifting technique on CD control is analyzed for a microprocessor design. A combination of OPC and PSM tools are used to assess sensitivity of CD to the variations of defocus, exposure dose, and mask misalignment, with and without PSM. A simulation region of 640x310 microns with 20000 MOSFETs is cut out from a random logic design. The edge placement error measurement sites are assigned each 200 nm across the transistor channels to fine-monitor CD variations. Four additional measurement sites are put close to the channel ends to monitor these regions susceptible to the CD variation. We use fast simulation technique that employs optical SOCS (Sum of Coherent Systems) decomposition and Extended Variable Threshold model. Optical parameters settings are chosen to be different for the binary and PSM masks to ensure comparable CD distributions in the center of the process windows. The PSM design is a 2-mask strong phase shifter design for poly gate level. Model-based OPC is applied to all relevant layers of the design including trim masks. To explore exposure-dose-misalignment input parameter space we setup partial factorial DOE with more than 100 runs each resulting in an EPE distribution for a parameter combination. We analyzed EPE shift and EPE dispersion. A definition of an EPE-based process window is proposed to capture the “proximity signature” of the design and its dependence on the process parameters. Comparison of binary and PSM designs yielded reliable quantitative measures of the PSM design performance gain.

Citation Download Citation

Yuri Granik, Nicolas B. Cobb, and Emile Y. Sahouria "CD variation analysis technique and its application to the study of PSM mask misalignment", Proc. SPIE 4186, 20th Annual BACUS Symposium on Photomask Technology, (22 January 2001); https://doi.org/10.1117/12.410768

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