The study of high-sensitivity metrology method by using CD-SEM

K. Ueda; S. Koshihara; T. Mizuno; A. Miura

doi:10.1117/12.878946

20 April 2011 The study of high-sensitivity metrology method by using CD-SEM

K. Ueda, S. Koshihara, T. Mizuno, A. Miura

Proceedings Volume 7971, Metrology, Inspection, and Process Control for Microlithography XXV; 797124 (2011) https://doi.org/10.1117/12.878946
Event: SPIE Advanced Lithography, 2011, San Jose, California, United States

Abstract

The earliest semiconductor device manufacturing employed optical microscopes for measurement and control of the manufacturing process. The introduction of the Critical Dimension Scanning Electron Microscope (CD-SEM) in 1984 provided a tremendous increase in capability for process monitoring and has been the standard for in-line metrology for over 25 years. The advantages of the CD-SEM are highly accurate and stable measurement reproducibility at very specific locations throughout the device. The evolution of the CD-SEM in Metrology has included improved resolution, development of advanced measurement and pattern recognition algorithms, all required by performance improvement demands from the market. Current conventional metrology using the in-line CD-SEM involves measuring about ten points per wafer (one point per one chip). at a magnification of over x150k(Field of View is about 1μm²). In contrast, the area of measurement pattern on chip is much larger than the area of CD-SEM measurement (mm² : (on chip) versus μm² : (CD-SEM measurement)). This would mean that the result of the CD-SEM measurement is influenced by local pattern variation. The very stringent requirements placed on in-line Metrology for the last couple of technology nodes has produced an additional metrology methodology, beyond the CD-SEM, that involves large area measurements with very high precision for the most critical levels. We will refer to this methodology as "Macro Area Measurements". We investigated the applicability of using a CD-SEM Macro Area Measurement methodology in this paper. The areas investigated focused on the following points: 1) Determining the optimum CD-SEM sampling plan for a macro area measurement. 2) Optimization of the measurement parameters. 3) Optimization of the measurement condition. 4) Verification of Macro Area Measurement with an FEM (Focus Exposure Matrix) wafer. In the results, we are able to validate a new methodology that we called "Macro Area Measurement" which is demonstrated to successfully detect small process variations with the same throughput and reduced damage to the pattern.

Citation Download Citation

K. Ueda, S. Koshihara, T. Mizuno, and A. Miura "The study of high-sensitivity metrology method by using CD-SEM", Proc. SPIE 7971, Metrology, Inspection, and Process Control for Microlithography XXV, 797124 (20 April 2011); https://doi.org/10.1117/12.878946

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