CD-SEM and e-beam defect inspection of high-aspect ratio contact holes: measurement and simulation of precharge

S. Babin; S Borisov; G. Kwon; C. H. Lee; J. H. Oh; D. Y. Mun; H. W. Yoo

doi:10.1117/12.916441

5 April 2012 CD-SEM and e-beam defect inspection of high-aspect ratio contact holes: measurement and simulation of precharge

S. Babin, S Borisov, G. Kwon, C. H. Lee, J. H. Oh, D. Y. Mun, H. W. Yoo

Author Affiliations +

Proceedings Volume 8324, Metrology, Inspection, and Process Control for Microlithography XXVI; 832428 (2012) https://doi.org/10.1117/12.916441
Event: SPIE Advanced Lithography, 2012, San Jose, California, United States

Abstract

The metrology and inspection of contact hole layers is an extremely complex task. At feature sizes below 45 nm, an aspect ratio higher than 1:10 is required. SEM metrology and electron beam defect inspection both face extreme difficulties due to the fact that the secondary electrons from the bottom of the contact holes are absorbed by the walls and do not reach the detector. In this paper, the pre-charging of a large area before taking images of the hole was explored. An understanding of the physics involved in contrast formation and optimization of the system setup may improve SEM imaging. Pre-charge and imaging were simulated using CHARIOT Monte Carlo software with varying pre-charge and observation conditions. It was found that at specific parameters in the e-beam setting, image contrast is sufficient for metrology and defect inspection. The simulations involved high aspect ratio contact holes without defects, as well as with two types of defects: the remaining under-etched layer at the bottom, and a particle defect at the bottom. The experimental results of the e-beam defect inspection and CD-SEM of the contact holes involving the flood beam are presented. The results of the simulation qualitatively agreed with the measured data.

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S. Babin, S Borisov, G. Kwon, C. H. Lee, J. H. Oh, D. Y. Mun, and H. W. Yoo "CD-SEM and e-beam defect inspection of high-aspect ratio contact holes: measurement and simulation of precharge", Proc. SPIE 8324, Metrology, Inspection, and Process Control for Microlithography XXVI, 832428 (5 April 2012); https://doi.org/10.1117/12.916441

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