Coordinate transformation method for the solution of inverse problem in 2D and 3D scatterometry

Sekar Ponnusamy

doi:10.1117/12.599716

10 May 2005 Coordinate transformation method for the solution of inverse problem in 2D and 3D scatterometry

Sekar Ponnusamy

Proceedings Volume 5752, Metrology, Inspection, and Process Control for Microlithography XIX; (2005) https://doi.org/10.1117/12.599716
Event: Microlithography 2005, 2005, San Jose, California, United States

Abstract

For scatterometry applications, diffraction analysis of gratings is carried out by using Rigorous Coupled Wave Analysis (RCWA). Though RCWA method is originally developed for lamellar gratings, arbitrary profiles can be analyzed using staircase approximation with S-Matrix propagation of field components. For improved accuracy, more number of Fourier waves need to be included in Floquet-Bloch expansion of the field components and also more number of slices are to be made in staircase approximation. These requirements increase the time required for the analysis. A coordinate transformation method (CTM) developed by Chandezon et. al renders the arbitrary grating profile into a plane surface in the new coordinate system and hence it does not require slicing. This method is extended to 3D structures by several authors notably, by Harris et al for non-orthogonal unit cells and by Granet for correct Fourier expansion. Also extended is to handle sharp-edged gratings through adaptive spatial resolution. In this paper, an attempt is made to employ CTM with correct Fourier expansion in conjunction with adaptive spatial resolution, for scatterometry applications. A MATLAB program is developed, and thereby, demonstrated that CTM can be used for diffraction analysis of trapezoidal profiles that are typically encountered in scatterometry applications.

Citation Download Citation

Sekar Ponnusamy "Coordinate transformation method for the solution of inverse problem in 2D and 3D scatterometry", Proc. SPIE 5752, Metrology, Inspection, and Process Control for Microlithography XIX, (10 May 2005); https://doi.org/10.1117/12.599716

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