10 nm Three-Dimensional CD-SEM Metrology

Published

April 10, 2014

Author(s)

Andras Vladar, John S. Villarrubia, Bin Ming, Regis J. Kline, Jasmeet Chawla, Scott List, Michael T. Postek

Abstract

The shape and dimensions of a challenging pattern have been measured using a model-based library scanning electron microscope (MBL SEM) technique. The sample consisted of a 4-line repeating pattern. Lines were narrow (10 nm), asymmetric (different edge angles and significant rounding on one corner but not the other), and situated in a complex neighborhood, with neighboring lines as little as 10 nm or as much as 28 nm distant. The shape cross-section determined by this method was compared to transmission electron microscopy (TEM) and critical dimension small angle x-ray scattering (CD-SAXS) measurements of the same sample with good agreement. A recently-developed image composition method was used to obtain sharp SEM images, in which blur from vibration and drift were minimized. A Monte Carlo SEM simulator (JMONSEL) produced a model-based library that was interpolated to produce the best match to measured SEM images. Three geometrical and instrument parameterizations were tried. The first was a trapezoidal geometry. In the second one corner was significantly rounded. In the last, the electron beam was permitted to arrive with stray tilt. At each stage, the fit to the data improved by a statistically significant amount, demonstrating that the measurement remained sensitive to the new parameter. Because the measured values represent the average unit cell, the associated repeatabilities are at the tenths of a nanometer level, similar to scatterometry and other area-averaging techniques, but the SEM’s native high spatial resolution also permitted observation of defects and other local departures from the average.

Proceedings Title

SPIE Advanced Lithography

Conference Dates

February 24-28, 2014

Conference Location

San Jose, CA

Conference Title

SPIE Advanced Lithography 2014

Pub Type

Conferences

Keywords

nanometer-scale, modeling, simulation, measurement, three dimensional, 3D, critical dimension, scanning, transmission, electron microscope, SEM, TEM, small angle x-ray scattering, CD-SAXS, matching, combined metrology

Citation

Vladar, A. , Villarrubia, J. , Ming, B. , Kline, R. , , J. , List, S. and Postek, M. (2014), 10 nm Three-Dimensional CD-SEM Metrology, SPIE Advanced Lithography, San Jose, CA (Accessed October 5, 2024)