Real time endpoint detection in plasma etching using Real-Time Decision Making Algorithm

The endpoint detection (EPD) is the most important technique in plasma etching process. In plasma etching process, the Optical Emission Spectroscopy (OES) is usually used to analyze plasma reaction. And Plasma Impedance Monitoring (PIM) system is used to measure the voltage, current, power, and load impedance of the supplied RF power during plasma process. In this paper, Real-Time Decision Making Algorithm is proposed to improve the performance of EPD in SiOx single layer plasma etching. To enhance the accuracy of the endpoint detection, both OES data and PIM data are utilized and a real-time decision making algorithm is applied. The proposed method successfully detected endpoint of silicon oxide plasma etching.