Accurate measurement of very small line patterns in critical dimension scanning electron microscopy using model-based library matching technique

Abstract

Our purpose is to reduce the critical dimension (CD) bias for very small patterns with line widths of <15 nm. The model-based library (MBL) method, which estimates the dimensions and shape of a target pattern by comparing a measured scanning electron microscopy image waveform with a library of simulated waveforms, was modified in two ways. The first modification was the introduction of line-width variation into the library to overcome problems caused by significant changes in waveform due to changes in both sidewall shape and line width. The second modification was the fixation of MBL tool parameters to overcome problems caused by the reduction in pattern shape information due to merging of right and left white bands. We verified the effectiveness of the modified MBL method by applying it to actual silicon patterns with line widths in the range 10-30 nm. The CD bias measured by MBL method for three heights (20, 50, and 80%) was consistent with the atomic force microscopy results. The CD biases at all heights were <0.5 nm, and the slopes of the CD biases with respect to the CD were <3%. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Scanning electron microscope line-profile analysis of less-than-10-nm patterns

“…There have been several studies on the analysis of SEM images using such a simulator. [14][15][16][17][18][19][20][21][22][23] Shishido et al reported that at an acceleration voltage of 800 V, Monte-Carlo simulation SEM images matched experimental SEM images for patterns with line widths of 8 to 32 nm. 19) As shown in Fig.…”

“…[14][15][16][17][18][19][20][21][22][23] Shishido et al reported that at an acceleration voltage of 800 V, Monte-Carlo simulation SEM images matched experimental SEM images for patterns with line widths of 8 to 32 nm. 19) As shown in Fig. 1(a), when the pattern size is larger than the PE scattering range, the SEM line profile has peaks at both ends of the line pattern.…”

Robust surface reconstruction by design-guided SEM photometric stereo

“…Despite these being essential difficulties encountered in SEM photometric stereo, an accurate estimation of all such brightness fluctuations is not realistic, given the high modeling and processing costs for various pattern variations (e.g. Monte Carlo simulation and the model-based library (MBL) method [17,18]). Furthermore, it is difficult to model accurately all the complicated physical phenomena associated with electronic behavior.…”