CU PRECIPITATION IN OXIDIZED WAFERS WITH AND WITHOUT A GEXSI1-X HETEROEPITAXIAL LAYER

Copper silicide precipitation in Czochralski silicon influenced by the existence of a GexSi1-x heteroepitaxial layer has been studied. Samples with and without a 100 nm Ge0.016Si0.984 heteroepitaxial layer were annealed together for different periods of time at 1000-degrees-C in air on copper containing iron plate and after copper plating of the backside, respectively. The absorption or emission of silicon self-interstitials (or vacancies) significantly influences the precipitation behavior of copper silicide. Undersaturation of silicon self-interstitials (or vacancy supersaturation) during oxidation of the heteroepitaxial layers is able to prevent the formation of copper silicide precipitate colonies in the surface region.