Capability of spectroscopic ellipsometry-based profile metrology for detecting the profile excursion of polysilicon gate

Mike Yeh; Shu-Ping Fang; Bo-Jau Tsau; Chih-Chung Huang; Benjamin Szu-Min Lin; Steven Fu; Jay Chih-Chieh Chen; Regina Freed; Ted G. Dziura; Mike D. Slessor

doi:10.1117/12.536269

24 May 2004 Capability of spectroscopic ellipsometry-based profile metrology for detecting the profile excursion of polysilicon gate

Mike Yeh, Shu-Ping Fang, Bo-Jau Tsau, Chih-Chung Huang, Benjamin Szu-Min Lin, Steven Fu, Jay Chih-Chieh Chen, Regina Freed, Ted G. Dziura, Mike D. Slessor

Author Affiliations +

Proceedings Volume 5375, Metrology, Inspection, and Process Control for Microlithography XVIII; (2004) https://doi.org/10.1117/12.536269
Event: Microlithography 2004, 2004, Santa Clara, California, United States

Abstract

A small notch or foot existing at the bottom of a polysilicon gate is a common issue for etching processes. The small notch or foot could have a major impact on the length of the polysilicon gate, and the performance of the device would then be impacted significantly, especially for cutting-edge devices. This paper demonstrates the capability of a spectroscopic ellipsometry based profile technology, SpectraCD, as a new metrology tool to monitor polysilicon gate process at 130 nm and 90 nm nodes. Firstly, the capability of SpectraCD as a metrology technology was studied, including dynamic precision and CD correlation. Dynamic precision in the range of 0.1~0.4 nm was demonstrated repeatedly in this study. CD correlation with CDSEM also showed a very linear result. R-squared values of ~0.99 are presented. Secondly, by comparison with images from cross-sectional SEM (XSEM) and TEM (XTEM), it has been proved in this study that SpectraCD can consistently flag different profile excursions of polysilicon gate, e.g., small notching, footing, or undercut. The size of the footing or notch reported by SpectraCD shows a linear correlation with the size extracted from XTEM images, which demonstrates quantitatively SpectraCD capability for detecting profile excursions. Finally, linear correlation between the bottom CD from SpectraCD and the gate lengths determined from electrical test (Lcap) will be presented.

Citation Download Citation

Mike Yeh, Shu-Ping Fang, Bo-Jau Tsau, Chih-Chung Huang, Benjamin Szu-Min Lin, Steven Fu, Jay Chih-Chieh Chen, Regina Freed, Ted G. Dziura, and Mike D. Slessor "Capability of spectroscopic ellipsometry-based profile metrology for detecting the profile excursion of polysilicon gate", Proc. SPIE 5375, Metrology, Inspection, and Process Control for Microlithography XVIII, (24 May 2004); https://doi.org/10.1117/12.536269

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