Conformance Analysis of ASML's Test Process

Process mining allows for the automated discovery of process models from event logs. These models provide insights and enable vari- ous types of model-based analysis. However, in many situations already some normative process model is given, and the goal is not to discover a model, but to check its conformance. The process mining framework ProM provides a conformance checker able to investigate and quantify deviations between the real process (as recorded in the event log) and the modeled process. The conformance checker is one of the few tools available today that is able support regulatory compliance, i.e., ensuring that organizations and people take steps to comply with relevant laws, regulations, and procedures. In this paper, we report on a case study where the ProM framework has been applied to the test processes of ASML (the leading manufacturer of wafer scanners in the world). In this case study, we focus on the conformance aspect and compare the test process as it is really executed to the idealized reference model that ASML is using to instruct their test teams. This revealed that the real process is much more complicated than the idealized reference process. Moreover, we were able to suggest concrete improvement actions for the test process at ASML.