Share Email Print
cover

Journal of Micro/Nanolithography, MEMS, and MOEMS

Determination of line edge roughness in low-dose top-down scanning electron microscopy images
Author(s): Thomas Verduin; Pieter Kruit; Cornelis W. Hagen
Format Member Price Non-Member Price
PDF $20.00 $25.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

We investigated the off-line metrology for line edge roughness (LER) determination by using the discrete power spectral density (PSD). The study specifically addresses low-dose scanning electron microscopy (SEM) images in order to reduce the acquisition time and the risk of resist shrinkage. The first attempts are based on optimized elliptic filtering of noisy experimental SEM images, where we use threshold-based peak detection to determine the edge displacements. The effect of transversal and longitudinal filterings cannot be ignored, even when considering an optimized filter strength. We subsequently developed a method to detect the edge displacements without the use of a filter and thus avoiding biasing. This makes it possible to study how much image noise is acceptable and still determine the LER. The idea is to generate random images of line edges using the model of Palasantzas and the algorithm of Thorsos. We study the simulated PSDs as a function of the number of line edges and report on the convergence of the parameters (LER, correlation length, and roughness exponent) by fitting the Palasantzas model extended with a white noise term. This study demonstrates that a very noisy image with 12 line edges and about 2 electrons per pixel on average (charge density ≈10  μC) already produces an estimation for LER with a relative error (one-sigma) of about 10%. Furthermore, increasing the dose beyond 20 electrons per pixel does not significantly improve the LER determination.

Paper Details

Date Published: 13 August 2014
PDF: 10 pages
J. Micro/Nanolith. 13(3) 033009 doi: 10.1117/1.JMM.13.3.033009
Published in: Journal of Micro/Nanolithography, MEMS, and MOEMS Volume 13, Issue 3
Show Author Affiliations
Thomas Verduin, Technische Univ. Delft (The Netherlands)
Pieter Kruit, Technische Univ. Delft (The Netherlands)
Cornelis W. Hagen, Technische Univ. Delft (Netherlands)


© SPIE. Terms of Use
Back to Top