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24 March 2006 CD-etch depth measurement from advanced phase-shift masks and wafers using optical scatterometry
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In this paper, we report on a Scatterometry based metrology system that provides line width, line thickness, and trench depth measurements on APSM and EPSM photomasks. Measurements were made with scatterometer in DUV to visual wavelength range. Calculation of profile information was performed by a library-based analysis software. We characterized the CD uniformity, linearity, trench depth uniformity. Results show that linearity measured from fixed-pitch, varying line/space ratio targets show good correlation to top-down CD-SEM with R2 of more than 0.99. EPSM FCCD data was obtained from both scatterometer and CDSEM. Results show that MEEF calculation based on scatterometer CD shows about 40% improvement in removing mask-induced CD non-uniformity, compared to calculation based on CD SEM data. This is thought to be due to 'averaging' effect of scatterometer. Depth measurements from APSM show that scatterometer makes good correlations to AFM, generally within 3nm of each other. The data show that Scatterometry provides a nondestructive means of monitoring PSM profiles combined with relatively little time loss.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kyung M. Lee, Sanjay Yedur, Sven Henrichs, and Malahat Tavassoli "CD-etch depth measurement from advanced phase-shift masks and wafers using optical scatterometry", Proc. SPIE 6152, Metrology, Inspection, and Process Control for Microlithography XX, 61521P (24 March 2006);

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