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14 June 1999 CD-SEM edge width applications and analysis
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As groundrules shrink, the need for improved metrology and characterization is essential in maintaining process control. Keeping the process in control relies heavily on the CD SEM providing consistent high quality measurements. Typically the bottom CD is extracted from the signal acquired and this result is then used to determine litho quality for lot dispositioning and stepper feedback. It is also used for determining etch quality in terms of uniformity and bias. But does the bottom CD provide enough information to make intelligent processed decisions. The answer is, in many cases, no. The bottom CD, used in most every fab for determining process latitudes, does not carry with it any information about the profile. It will be shown how a process or tool might be considered 'in control' when in fact there are problems. The key concept is being able to extract more information from the SEM. This has been suggested previously and must be further incorporated in to CD SEM technology in the future. By using edge width measurements in addition to bottom CD measurements, it will be shown that there is more to CD metrology than bottom CDs. Data is presented on how edge width measurements improved the yield in one of our process lines. Combining the additional edge width information derived from the CD SEM signal with the traditional bottom CD will prove to be a valuable addition to the metrology sector, better enabling the sector to provide more accurate and detailed feedback in its role to improve tools and control processes.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Eric P. Solecky and Roger S. Cornell "CD-SEM edge width applications and analysis", Proc. SPIE 3677, Metrology, Inspection, and Process Control for Microlithography XIII, (14 June 1999);

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