Deformation pattern recognition method, pattern transferring method, processing device monitoring method, and lithographic apparatus

A lithographic apparatus arranged to transfer a pattern from a patterning device onto a substrate, the apparatus comprising:

• a substrate table constructed to hold a substrate;
• an alignment sensor configured to measure the positions of alignment marks on the substrate relative to a reference;
• a control unit configured to control the transfer onto the substrate by reference to the positions of the alignment marks on the substrate measured by said alignment sensor;
• wherein the control unit comprises a storage medium configured to store at least one deformation pattern which is representative of a deformation of a substrate that may be caused by a processing device when said substrate is processed by said processing device, and wherein the control unit is configured:
• to control the lithographic apparatus in order to transfer a first pattern to a substrate,
• said first pattern including at least N alignment marks,
• to receive data from the alignment sensor representative for a position of the N alignment marks in order to determine an alignment mark displacement for each of the N alignment marks from the respective nominal position by comparing the respective nominal position of an alignment mark with the respective measured position of said alignment mark, each alignment mark displacement being representative of a respective local deformation of the substrate resulting from the processing of the substrate,
• to fit the at least one deformation pattern to the measured alignment mark displacements,
• to determine an accuracy value for each fitted deformation pattern, each accuracy value being representative for the accuracy of the corresponding fit, and
• to use the obtained accuracy values in order to determine whether an associated deformation pattern is present in the measured alignment mark displacements.