Method and apparatus for computing electromagnetic scattering properties of structures and reconstruction of approximate structures

A technology of electromagnetic scattering and computational structure, applied in opto-mechanical equipment, microlithography exposure equipment, circuits, etc., can solve the problems that cannot be solved iteratively and reliably, the integral equation is highly unstable, and the condition number is high.
CN105814489BActive Publication Date: 2017-10-27ASML NETHERLANDS BV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
ASML NETHERLANDS BV
Publication Date
2017-10-27

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Abstract

A method of computing the electromagnetic scattering properties of a structure comprising materials of different properties and the structure is periodic in at least one transverse direction and extends in a perpendicular direction, comprising: by analyzing a plurality of modes in at least one transverse direction Each corresponding mode in , performs a pseudospectral polynomial (Chebyshev) expansion in the vertical direction multiplied by the integral of the 1D Green's function using the same sample points in the orthogonal direction for all of the modes (1350 ), numerically solve the volume integral equation for electromagnetic scattering for each mode. The integration is performed by solving a regularized linear system of equations between the first (1116) and second (1120) discrete transformation steps to compute (1118) the values ​​of the regularized Chebyshev polynomial coefficient vector (γ). The results of the numerical solution are used to calculate the electromagnetic scattering properties of the structure.
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Description

[0001] Cross References to Related Applications

[0002] This application claims priority to US Provisional Application 61 / 875,340, filed September 9, 2013, which is hereby incorporated by reference in its entirety. technical field

[0003] This application relates to the calculation of electromagnetic scattering properties of structures.

[0004] The invention can be applied, for example, in the metrology of microstructures, for example to evaluate the critical dimension (CD) performance of a lithographic apparatus. Background technique

[0005] A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. Photolithographic equipment may be used, for example, in the manufacture of integrated circuits (ICs). In this case, a patterning device, alternatively called a mask or reticle, may be used to generate the circuit pattern to be formed on the individual layers of the IC. The pattern may be transfe...

Claims

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