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Spectral Analysis of Line Edge and Line Width Roughness using Wavelets

Published

Author(s)

Ndubuisi George Orji

Abstract

Although line edge and line width roughness (LER/LWR) have been key metrology challenges over the last 15 years, the advent of extreme-ultraviolet lithography (EUV) has increased the importance of its measurement and control. Lithographically printed features are now small enough that randomness in resist chemistry and in EUV photon speed during exposure results in noise in the patterned resist. This not only affects LER/LWR, but also defect density, missing holes, shifted features, bridged lines and holes, and line shorts, among others. Well before these stochastic induced roughness variations, there have existed various techniques to analyze roughness. These include power spectral density algorithms, methods to account for instrument bias in the data, identify and filter noise, and specify measurement uncertainty. In this work, analysis methods to evaluate LER and LWR spatial wavelengths, including partitioning and filtering out instrument errors, such as noise and probe effects are presented. Our approach is based on wavelet-transform multiresolution analysis. One of the key advantages of wavelet transform over other signal processing techniques are its spatial-frequency localization and multi-scale view of the components of a profile or surface. This allows decomposing the data into different bands based on specific cutoffs and evaluating different approximations and surface-details at each cutoff band. A priori noise and probe information are used to determine and remove instrument-effects from the data, before calculating the unbiased roughness.
Proceedings Title
Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV (Conference 11611)
Volume
11611
Conference Dates
February 22-26, 2021
Conference Location
Virtual, MD, US
Conference Title
SPIE Advanced Lithography - Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV (Conference 11611)

Keywords

Line edge roughness, Linewidth roughness, Wavelet Transform, Spectral Analysis. nanometrology

Citation

Orji, N. (2021), Spectral Analysis of Line Edge and Line Width Roughness using Wavelets, Metrology, Inspection, and Process Control for Semiconductor Manufacturing XXXV (Conference 11611), Virtual, MD, US, [online], https://doi.org/10.1117/12.2584649, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932010 (Accessed May 28, 2022)
Created April 1, 2021, Updated January 4, 2022