Effect of VUV Lamp on Wafer Charging by Single-Wafer Wet Clean

Vacuum ultraviolet (VUV) is investigated for removing single-wafer clean-related charging. Very short exposure time, within 10 s, successfully removed both positive and negative charging created by the single-wafer wet clean process. Comparing to results from other wavelength and past studies, an electron-hole pair excitement mechanism is proposed to explain the VUV charging removal of embedded charging in SiO2 films. The proposed mechanism raised a concern for film damage. Oxide capacitance/voltage (CV) curves and MOS capacitor oxide leakage currents are measured. CV curves showed a negative impact from VUV, but MOS capacitors can tolerate short VUV exposure times. The positive and negative impacts from VUV exposure are discussed.