1 November 2004 Application of wavelet analysis to lithography metrology
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Proceedings Volume 5607, Wavelet Applications in Industrial Processing II; (2004) https://doi.org/10.1117/12.571002
Event: Optics East, 2004, Philadelphia, Pennsylvania, United States
Abstract
We try to measure lithography line edge roughness (LER) from a noisy SEM image using wavelet analysis. First, we evaluated the edge detection performance of the wavelet multiscale edge detection method without and with denoising by applying them to a modeled secondary electron (SE) signal of photoresist without and with noise. As denoising, the method called soft thresholding was used. Many modulus maxima lines with short lengths for a modeled SE signals with low SNR such as 3 appears and characteristic modulus maxima lines with long lengths do not come out. After denoising, the characteristic modulus maxima lines come out. When SNR was larger than 10, the standard deviation was less than 1 pixel and the average position converged to a point. Then we applied the wavelet multiscale edge detection method to a noisy SEM image of photoresist. LERs (1 sigma evaluated along a distance) along ninety scan lines were measured with the number of average line scans as a parameter. The measured LER for one scan line was determined to be reliable from results of averaging effects and LER for this photoresist pattern was about 3 pixels.
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Jiro Imada, Jiro Imada, Koji Nakamae, Koji Nakamae, Masaki Chikahisa, Masaki Chikahisa, Hiromu Fujioka, Hiromu Fujioka, } "Application of wavelet analysis to lithography metrology", Proc. SPIE 5607, Wavelet Applications in Industrial Processing II, (1 November 2004); doi: 10.1117/12.571002; https://doi.org/10.1117/12.571002
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