Electrification of glass substrate surface by plasmas

It is probable that charge-up of a glass substrate during plasma processing, such as ashing and/or etching, deteriorates the production yield of TFT-LCD devices. In order to control the production yield, it is necessary to understand the electrification mechanism of glass surface in plasma and then offer countermeasure to the process. We measured the surface potential of the glass substrate during discharge. We exposed the glass substrate to plasma in a parallel-plate electrode system by introducing Ar, O-2 or SF6 gas into the plasma reactor and exciting with 13.56MHz RF or DC power supply. As a result, we found that the charging of the glass substrate in plasma was considerably affected by gas species and power sources. We discussed the phenomenon from a viewpoint of the ionizatiation and the movement of molecular ions in plasma.