Wafer temperature measurements and end-point detection during plasma etching by thermal imaging

Thermal imaging by an infrared television camera has been successfully employed as an in situ method for end-point detection during plasma etching of polycrystalline silicon layers on a SiO₂/Si substrate. In addition, it is also shown that thermal imaging can be used for remote sensing of etch rate, heat of reaction, wafer temperature, and for measuring thermal time constants during plasma etching. From these measurements, the heat-transfer coefficient of the thermal contact between the silicon wafer and the water-cooled electrode can be determined.