Analytical modeling and 3D finite element simulation of line edge roughness in scatterometry

TL;DR

This paper compares analytical and numerical models to accurately simulate how edge roughness affects optical diffraction in structured surfaces, improving scatterometry analysis in photolithography.

Contribution

It introduces a combined analytical and 3D simulation approach to characterize edge roughness effects in scatterometry, enhancing accuracy for 2D structures.

Findings

High agreement between analytical and numerical models

Diffraction intensities can be estimated with correction functions

Improves scatterometric analysis for practical 2D structures

Abstract

The influence of edge roughness in angle resolved scatterometry at periodically structured surfaces is investigated. A good description of the radiation interaction with structured surfaces is crucial for the understanding of optical imaging processes like, e.g. in photolithography. We compared an analytical 2D model and a numerical 3D simulation with respect to the characterization of 2D diffraction of a line grating involving structure roughness. The results show a remarkably high agreement. The diffraction intensities of a rough structure can therefore be estimated using the numerical simulation result of an undisturbed structure and an analytically derived correction function. This work allows to improve scatterometric results for the case of practically relevant 2D structures.