EFFECT OF SILICON SURFACE-CLEANING PROCEDURES ON THE GROWTH OF CU3SI ON SI(100)-ORIENTED WAFERS

The effect of a SiO2 layer, partially removed by wet chemical processes or thermally grown, on the mechanism of nucleation and growth of Cu3Si from the reaction between a Si(100) wafer and gaseous copper chloride was studied. For oxide layer thicknesses less than 2 nm, the number of Cu3Si nuclei and the area of silicon reacting with CuCl per unit area are inversely proportional to thickness, whereas the size of the more numerous nuclei increases from 4-10-mu-m. In this case, the nuclei are octahedrally shaped. The superficial erosion of Cu3Si nuclei and the formation of "pits" have been explained by the reaction between Cu3Si and CuCl. For thicker layers, 10<e>40nm, the Cu3Si nuclei are deformed, and the reaction is strongly inhibited. A SiO2 layer of 45 nm prevented active-site formation.