Cu Contaminants Removal Using UV/O3 and Remote Hydrogen Plasma

초록

Removal of Cu contaminants from Si wafer surface was carried out using remote hydrogen plasma (RHP) and UV/O3 cleaning techniques. The concentration of Cu impurities on the wafer surface was monitored by TXRF (total reflection x-ray fluorescence) and XPS (x-ray photoelectron spectroscopy). Our results show that Cu impurities can be effectively removed by hydrogen plasma and UV/O3 cleaning techniques, if it is performed under optimum process conditions. The optimum process parameters for the remote hydrogen plasma cleaning are the rf power of 20W and the exposure time of 5 min. The optimum exposure time of the UV/O3 cleaning for Cu impurity removal is 1 min. A two step cleaning process composed of remote hydrogen plasma cleaning, first and UV/O3 cleaning, next has been found to be more effective than a single UV/O3 cleaning process, a single remote hydrogen plasma cleaning process, or a two step cleaning process composed of UV/O3 cleaning, first and remote hydrogen plasma cleaning, next. Cleaning efficiency is maximized at optimum process conditions where Cu contaminant removal effect and recontamination effect are traded off. Increasing the process parameters higher than the optimum values would decrease the cleaning efficiency.