External high voltage control for a laser system

摘要

An external control system for a laser system, used as an illumination source for a stepper system, is provided. The external control allows for a measuring of the energy actually distributed to a wafer and a correction of the energy dose distribution based upon this measurement. In this way, a more precise energy dose control is achieved. The external control communicates with the laser's own internal control system to provide serial inputs which allow for corrections to be made to the High Voltage setting based upon the aforementioned measurements, and coordinates with the laser's internal control system to initiate laser operation at the required intervals.