Methods of modeling systems such as lithography systems or performing predictive maintenance of systems and associated lithography systems

摘要

A method of determining a causal relationship between events in a plurality of parameter time series, the method comprising: identifying a first event associated with a parametric excursion event and identifying a second event associated with a failure event, the first events and a plurality of events including second events; determining values of transfer entropy for the pairs of events to establish a causal relationship for each of the pairs of events; determining a process network using the determined values of transfer entropy and the identified causal relationships, wherein each of the events is a node within the process network, and edges between nodes depend on the determined values of transfer entropy; identifying a directional cycle within the plurality of events and the causal relationships; classifying the directional cycle; and classifying one or more event(s) having a causal relationship with the classified directional cycle.