23 September 2009 SEM CD metrology on nanoimprint template: an analytical SEM approach
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Abstract
Critical dimension metrology is the most needed feedback in nanofabrication and automatic CDSEM-based methods are by far the industrial standard for its well-established methodology and ease of programming and flexibility in measurement setup and operation. The dimensional measurements from SEMs consist of two steps, the first being the pixel based electron emission signal intensity profile generation and the second being the algorithm treatment on the generated intensity profile for the dimension determination. However, SEM metrology involves uncertainty of the measurement in the signal processing step, because the SEM signal formation is an extremely complex process depending on the pattern geometry, materials, detector setup, and beam voltage. Analytical SEMs are even less optimized for the task of quantitative metrology, especially at the CD ranging below 100 nm. In this work, we used an analytical SEM for CD metrology applications on quartz nanoimprint template from the perspective that only analytical SEM is accessible. The machine was tuned and beam characterization was done first to find the best reasonable condition for consistent manual operation using BEAMETR beam measurement pattern and software. The optimized beam condition set was then used for image collection on pitch pattern quartz template and the measurements were done using regular imaging processing and physical model based processing tool myCD. In order to discuss the spot size on the scan signal and the resulting influence on CD measurements, we used CHARIOT simulation software for simulated intensity profile as demonstration. The quartz template was then measured through a mask CDSEM for final data comparison. Selected sites were cross sectioned to reveal profile information as metrology comparison reference. Through our exercise, the metrology capability and fundamental limitation of analytical SEM operation with regular imaging processing was identified and the improvement using the physical modeling imaging process was verified.
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Justin J. Hwu, Justin J. Hwu, Sergey Babin, Sergey Babin, Lorena Page, Lorena Page, Alex Danilevsky, Alex Danilevsky, Andy Self, Andy Self, Kazuhiro Ueda, Kazuhiro Ueda, Shunzuke Koshihara, Shunzuke Koshihara, Koichi Wago, Koichi Wago, Kim Lee, Kim Lee, David Kuo, David Kuo, } "SEM CD metrology on nanoimprint template: an analytical SEM approach", Proc. SPIE 7488, Photomask Technology 2009, 74881W (23 September 2009); doi: 10.1117/12.830699; https://doi.org/10.1117/12.830699
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