Metrology method and apparatus, lithographic system and device manufacturing method

    公开(公告)号:US10331041B2

    公开(公告)日:2019-06-25

    申请号:US16159884

    申请日:2018-10-15

    Abstract: Disclosed is a method of measuring a parameter of a lithographic process, and associated inspection apparatus. The method comprises measuring at least two target structures on a substrate using a plurality of different illumination conditions, the target structures having deliberate overlay biases; to obtain for each target structure an asymmetry measurement representing an overall asymmetry that includes contributions due to (i) the deliberate overlay biases, (ii) an overlay error during forming of the target structure and (iii) any feature asymmetry. A regression analysis is performed on the asymmetry measurement data by fitting a linear regression model to a planar representation of asymmetry measurements for one target structure against asymmetry measurements for another target structure, the linear regression model not necessarily being fitted through an origin of the planar representation. The overlay error can then be determined from a gradient described by the linear regression model.

    Metrology method and apparatus, computer program and lithographic system

    公开(公告)号:US10261427B2

    公开(公告)日:2019-04-16

    申请号:US15869661

    申请日:2018-01-12

    Abstract: Disclosed are a method, computer program and associated apparatuses for measuring a parameter of a lithographic process. The method comprising the steps of: obtaining first measurements comprising measurements of structural asymmetry relating to a plurality of first structures, each of said plurality of measurements of structural asymmetry corresponding to a different measurement combination of measurement radiation and a value for at least a first parameter; obtaining a plurality of second measurements of target asymmetry relating to a plurality of targets, each of said plurality of measurements of target asymmetry corresponding to one of said different measurement combinations, determining a relationship function describing the relationship between said first measurements and said second measurements, for each of said measurement combinations; determining, from said relationship function, a corrected overlay value, said corrected overlay value being corrected for structural contribution due to structural asymmetry in at least said first structure.

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