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Shape-Sensitive Linewidth Measurements of Resist Structures

Published

Author(s)

John S. Villarrubia, Andras Vladar, Michael T. Postek

Abstract

Widths of developed 193 nm resist lines were measured by two methods and compared. One method was a new model-based library method. In this method the scanning electron microscope (SEM) images corresponding to various edge shapes are simulated in advance, and the measured images are compared to the simulated ones to find the best match. For the second measurement the lines were cross-sectioned and imaged in the SEM. Similar studies have been previously performed for polycrystalline silicon lines, but this is the first such comparison for resist, a material for which additional measurement issues related to charging and/or shrinkage under electron beam exposure are widely anticipated. Comparisons were made for 48 different image targets, each of which contained 3, 5, or 10 lines depending upon whether that targets linewidths were nominally 350 nm, 200 nm, or 100 nm respectively. The average difference between the two methods was 3.5 nm. Individual measurements deviated from this average value with a standard deviation of approximately 5 nm, of which 3 nm could be attributed to roughness of the lines edges. The effect on linewidth metrology of the resists charging or shrinkage for these samples were at most a few nanometers. (12 references)
Citation
NIST Interagency/Internal Report (NISTIR) - 7089
Report Number
7089

Keywords

193 nm resist, linewidth metrology, model-based library, scanning electron microscopy (SEM), simulation

Citation

Villarrubia, J. , Vladar, A. and Postek, M. (2004), Shape-Sensitive Linewidth Measurements of Resist Structures, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed April 23, 2024)
Created January 1, 2004, Updated February 19, 2017