Asml Netherlands B.v.

Nicolaas Petrus Van Der Aa

Arie Jeffrey Den Boef

Sicco Ian Schets

Allan Reuben Dunbar

Jeroen Huijbregstse

Robert Martinus Maria Mattheij

Henricus Gerhardus Ter Morsche

An optical metrology system is disclosed that has a measuring system configured to irradiate a metrology mark and record a portion of a reflected, a transmitted, or both, electromagnetic field and a characterization device configured to determine from the recorded field a mark shape parameter indicative of the structure of the metrology mark, the characterization device comprising: a field calculation unit configured to calculate an expected field for reflection, transmission, or both, from a theoretical reference mark based on an algebraic eigenvalue-eigenvector representation of the expected field, a field derivative calculation unit configured to calculate a first order derivative, a higher order derivative, or both, of the expected field with respect to the mark shape parameter by first deriving analytical forms for corresponding derivatives of eigenvalues and eigenvectors of the eigenvalue-eigenvector representation, and an optimization unit configured to use the outputs from the field and field derivative calculation units to determine an optimized mark shape parameter for which the expected field substantially matches the recorded field.

Optical metrology system and metrology mark characterization device

A method for optimizing an alignment condition of a lithographic projection apparatus. This method comprises projecting a beam of radiation on a target portion of a substrate and measuring a plurality of diffracted signals emitted by the target portion. This method further comprises calculating a variance for each of the plurality of diffracted signals, such that a plurality of variances of the diffracted signals is determined, and adjusting the alignment condition of the lithographic projection apparatus based on analysis of the plurality of variances.

Method for position determination, method for overlay optimization, and lithographic projection apparatus

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Helmond, Netherlands

Nicolaas Petrus Van Der Aa