Fast and efficient characterization of photolithographic systems by optical scatterometry

The increasing demands to the performance of lithography tools require extensive efforts for monitoring the lithography processes. Relevant parameters for the lithography process are the critical dimension (CD), the profile of the structure and the defect density. CD and profiles are influenced by parameters like focus and dose settings of the lithography process. Another important parameter is the film thickness of the used bottom antireflective coating (BARC) and resist. Up to now the monitoring of these parameters requires the application of various measurement tools like ellipsometers for the thickness measurement, scanning electron microscope (SEM) for CD and profile analysis. The defect inspection is additionally used for focus monitoring. Here we present an investigation of the application of the scatterometry method to obtain all of these parameters on one single wafer with only one single measurement step. It turns out that the scatterometry measurement is not only much faster than the conventional methods, but even more stable and reliable. We demonstrate the potential of scatterometry to enhance the quality of process monitoring accompanied by a significant reduction of costs for the process monitoring.