Power Deposition, Damage Monitoring, and End-Point Detection Using Photoluminescence Spectroscopy in rf Glow Discharges

Photoluminescence (PL) spectroscopy is used to measure wafer temperatures, damage, and process end-points during rf plasma etching of III- V compound semiconductors such as GaAs and AlGaAs. To discriminate against the plasma glow and minimize PL photo-degradation, we use pulsed excitation and gated electronic detection of the PL intensity. Exploiting the PL peak position dependence on temperature, we measure in situ wafer temperatures to better than 1C from 25C to 150C. Thus, power deposition to the surface is determined as a function of discharge frequency, gas composition, applied power, and pressure.