Abstract:
A method to determine the usefulness of an alignment mark of a first pattern in transferring a second pattern to a substrate relative to the first pattern already present on the substrate includes measuring the position of the alignment mark, modeling the position of the alignment mark, determining the model error between measured and modeled position, measuring a corresponding overlay error between first and second pattern and comparing the model error with the overlay error to determine the usefulness of the alignment mark. Subsequently this information can be used when processing next substrates thereby improving the overlay for these substrates. A lithographic apparatus and/or overlay measurement system may be operated in accordance with the method.
Abstract:
In a lithographic process, product units such as semiconductor wafers are subjected to lithographic patterning operations and chemical and physical processing operations. Alignment data or other measurements are made at stages during the performance of the process to obtain object data representing positional deviation or other parameters measured at points spatially distributed across each unit. This object data is used to obtain diagnostic information by performing a multivariate analysis to decompose a set of vectors representing the units in the multidimensional space into one or more component vectors. Diagnostic information about the industrial process is extracted using the component vectors. The performance of the industrial process for subsequent product units can be controlled based on the extracted diagnostic information.
Abstract:
Estimating model parameters of a lithographic apparatus and controlling lithographic processing by a lithographic apparatus includes performing an exposure using a lithographic apparatus projecting a pattern onto a wafer. A set of predetermined wafer measurement locations is measured. Predetermined and measured locations of the marks are used to generate radial basis functions. Model parameters of said substrate are calculated using the generated radial basis functions as a basis function across said substrate. Finally, the estimated model parameters are used to control the lithographic apparatus in order to expose the substrate.