Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 23, 2018 - November 25, 2018
There is an increasing demand for “impurity gettering” technology for removing metal impurities from the active region of Large Scale Integration (LSI), such as Complementary Metal Oxide Semiconductor (CMOS) image sensors. Since the efficiency of impurity gettering is determined by the competition of target metal atoms between an internal gettering site and the silicon (Si) wafer surface, an understanding of both the gettering mechanism and the stability of metal atoms near the Si (001) wafer surface is necessary. Density functional theory calculations are preformed to investigate the stability of twelve metal atoms (Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo, Hf, Ta, and W) near the Si (001) surface. The main results are as follows. (1) Metal atoms are more stable up to around fifth layer from Si (001) surface. (2) Surface gettering is energetically very favorable in comparison to the internal B gettering. By taking into account all possible atomic configurations, the ratio of the thermal equilibrium concentration in the i-th layer and that in the bulk of Fe atom was obtained.
