Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Effect of partial coherence on dimensional measurement sensitivity for DUV scatterfield imaging microscopy

Published

Author(s)

Yoon Sung Bae, Martin Sohn, Dong-Ryoung Lee, Sang-Soo Choi

Abstract

Optical scatterfield imaging microscopy technique which has the capability of controlling scattered fields in the imaging mode is useful for quantitative nanoscale dimensional metrology that yields precise characterization of nanoscale features for semiconductor device manufacturing process control. To increase the sensitivity in the metrology using this method, it is required to optimize illumination and collection optics that enhance scatterfield signals from the nanoscale targets. Partial coherence of the optical imaging system is used not only for enhancing image quality in the traditional microscopy or lithography but also for increasing the sensitivity of the scatterfield imaging microscopy. This paper presents an empirical investigation of the effect of partial coherence on measurement sensitivity using a deep ultraviolet scatterfield imaging microscope platform that uses a 193 nm excimer laser as a source and a conjugate back focal plane as a unit for controlling partial coherence. Dimensional measurement sensitivity is assessed through analyzing scatterfield images measured at the edge area of periodic multiline structures with linewidths ranging from 44 - 80 nm on a Molybdenum Silicide (MoSi) photomask. Intensities scattered from the targets under the illuminations with various partial coherence factors and two orthogonal polarizations are assessed with respect to dimensional measurement sensitivity. Combinations of partial coherence factors, target size ranges, and polarizations for higher sensitivity are identified and discussed.
Citation
Optics Express
Volume
27
Issue
21

Keywords

optical microscopy, dimensional measurement, measurement sensitivity, partial coherence, deep ultraviolet, scatterfield, photomask, MoSi

Citation

Bae, Y. , Sohn, M. , Lee, D. and Choi, S. (2019), Effect of partial coherence on dimensional measurement sensitivity for DUV scatterfield imaging microscopy, Optics Express, [online], https://doi.org/10.1364/OE.27.029938, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=928348 (Accessed November 11, 2024)

Issues

If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.

Created October 1, 2019, Updated October 12, 2021