8 June 1998 Limitation of CD AFM on resist foot detection
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CD SEM (two dimension X-Y scan) is usually calibrated using X- SEM (two dimension X-Z scan). However, CD uncertainty associated with line roughness, location error (large scale), ruler measurement error and X-SEM scale error could be as large as 20 nm. In recent years, AFM (three dimension X-Y-Z scan) started to get people's attention for its non- destructive cross section scans and has been used as a calibration tool for CD SEM. The focus of the study is AFM and X-SEM correlation. Two types of CD AFM tip shape (sharp corner type and smooth corner type) are identified based on SEM photos. For line width measurements in our study, for one AFM tip, 50 nm has to be added to the tip width calibrated from the built-in calibration standard (Silicon Nano-Edge) in order to match X-SEM line widths. A limitation of AFM in resist foot detection was also found for the same tip. An attempt was made to explain the limitation based on sharp corner tip shape. Based on the explanation, a desirable tip shape calibration procedure is proposed for tip type identification. Since AFM tip width is the tip scan length (or time) dependent, AFM tip calibration is critical for CD SEM calibration.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Bo Su, Bo Su, K. C. Rajkumar, K. C. Rajkumar, Mahesh Agrawal, Mahesh Agrawal, } "Limitation of CD AFM on resist foot detection", Proc. SPIE 3332, Metrology, Inspection, and Process Control for Microlithography XII, (8 June 1998); doi: 10.1117/12.308763; https://doi.org/10.1117/12.308763

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