Abstract: A method for determining a spatially varying process offset for a lithographic process, the spatially varying process offset (MTD) varying over a substrate subject to the lithographic process to form one or more structures thereon. The method includes obtaining a trained model (MOD), having been trained to predict first metrology data based on second metrology data, wherein the first metrology data (OV) is spatially varying metrology data which relates to a first type of measurement of the one or more structures being a measure of yield and the second metrology data (PB) is spatially varying metrology data which relates to a second type of measurement of the one or more structures and correlates with the first metrology data; and using the model to obtain the spatially varying process offset (MTD).

Abstract: Methods and associated apparatus for identifying contamination in a semiconductor fab. The methods include determining contamination map data for a plurality of semiconductor wafers clamped to a wafer table after being processed in the semiconductor fab. Combined contamination map data is determined based, at least in part, on a combination of the contamination map data of the plurality of semiconductor wafers. The combined contamination map data is combined to reference data. The reference data include one or more values for the combined contamination map data that are indicative of contamination in one or more tools in the semiconductor fab.

Abstract: Apparatus and methods of configuring an imputer model for imputing a second parameter. The method includes inputting a first data set including values of a first parameter to the imputer model, and evaluating the imputer model to obtain a second data set including imputed values of the second parameter. The method further includes obtaining a third data set including measured values of a third parameter, wherein the third parameter is correlated to the second parameter; obtaining a prediction model configured to infer values of the third parameter based on inputting values of the second parameter; inputting the second data set to the prediction model, and evaluating the prediction model to obtain inferred values of the third parameter; and configuring the imputer model based on a comparison of the inferred values and the measured values of the third parameter.