Study of a line width estimation model for laser micro material processing using a photodiode

Estimation of the line width for a laser marking on the silicon wafer is very important to improve the productivity of the final product which use nonpackaged chip. Until now, only theoretical and numerical estimation models have been studied. However, it is not easy for these models to apply to real systems. In this study, a process monitoring system was used to develop an estimation model for the laser marking width. The plasma produced by interaction between the laser and the wafer was measured using an optical sensor. For each laser power setting, the correlation between the signal acquired from the optical sensor and the resulting line width was analyzed. Estimation models were developed for laser marking width through statistical regression analysis and an artificial neural network algorithm.