Evaluation of Metal Contamination Behavior on Silicon Wafer Surfaces Rinsed with Deionized Water Containing pg/L-Level Impurities

Two tests were performed to investigate the contamination behavior of bare Si wafers by rinsing them using deionized water (DIW) contaminated with metals at the pg/L-level in a single-wafer cleaning process. First, we found that Al, Ti, Mn, Co, Cu, Sr, and Pb exhibited strong correlations between the metal concentrations in DIW and the wafer surface concentrations under different concentrations in DIW and the same rinse time of 480 min. Second, we observed that the wafer surface concentrations of Al, Ti, Cu, and Pb increased with the rinse time, whereas those of Mn, Co, and Sr were constant at rinse times ranging from 10 to 960 min at metal concentrations of 60 pg/L in DIW. In this test, Cu exhibited a high adsorption ratio on bare Si wafers, even at the pg/L level. These data provide novel insights into wet processes for device manufacturing.