Plasma Etching Monitor by Electric Probe

An electric probe method provides a great deal of useful information about the plasma etching process. In the present work, the discharge characteristics are studied with a double probe method. The probe current-voltage characteristics are dependent on the etching conditions, i.e., rf power, pressure and reaction gas. Moreover, it is found that they change with the etched materials. Therefore, the double probe method makes accurate end point detection for etching of the subject thin film layer possible. This method is used effectively for etching poly-Si and Si3N4 on SiO2 in CF4-O2 plasma, and photoresist removal in O2 plasma.