Cu CONTAMINANT REMOVAL USING UV/O3 AND REMOTE HYDROGEN PLASMA

Abstract

Removal of Cu contaminants from Si wafer was carried out using remote hydrogen plasma (RHP) and UV/O 3 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/O 3 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 20 W and the exposure time of 5 min. The optimum exposure time of the UV/O 3 cleaning for Cu impurity removal is 1 min. A two-step cleaning process composed of remote hydrogen plasma cleaning first and UV/O 3 cleaning next has been found to be more effective than a single UV/O 3 cleaning process, a single remote hydrogen plasma cleaning process, or a two-step cleaning process composed of UV/O 3 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.