Abstract
In order to analyze the trace metals at the level of 108−109 atoms/cm2 on the silicon wafers, it is important to control the analytical environment, water and chemicals, and to clean and to handle carefully the analytical equipments and implements. These notes lead to decrease the contamination in the original acid solution that is used to collect metals in it. Some metals slightly contaminated in the original acid solution analyzed by ICP-MS for about three years were controlled within the range of 1-25 wt·ppt in our experiments. The detection limits of each metal for 8-inch silicon wafers are 3×108 −1×109 atoms/cm2. The intensity analyzed by ICP-MS for each metal tended to decrease to 80% with increasing the concentration of Si matrix more than 50 wt·ppm, while that by GF-AAS recorded virtually the same. The recovery rates for each metal except Cu were at least 95% for original concentration levels of 1010-1012 atoms/cm2. The recovery rate of Cu was 80-90%.
