Metal Impurities near the SiO2 ‐ Si Interface

Abstract
The behavior of metal impurities (Cu, Fe, Cr, and Ni) near the interface during dry and oxidation was studied by means of defect etching and secondary ion mass spectroscopy methods using intentionally metal‐contaminated silicon wafers. Redistribution of metal impurities resulting from a thermal oxidation is different for each metal. Copper diffused into the silicon, showing concentration peaks 0.3–1.2 μm from the interface, and tended to be rejected by the silicon dioxide. Iron accumulated at the interface, while chromium tended to accumulate in the oxide having a lower concentration in silicon. Gettering ability using oxidations was excellent for copper, but poor for iron and chromium impurities. Copper and iron impurities precipitate in the silicon near the interface, but chromium and nickel impurities do not.