Interaction between copper and point defects in silicon irradiated with 2-MeV electrons

The interaction between copper and irradiation-induced defects in silicon has been investigated with the use of Schottky-barrier structures formed by the deposition of copper on n- and p-type silicon irradiated with 2-MeV electrons at room temperature. It is found that the annealing rate of the divacancy (V₂) centers is anomalously high at temperatures below 150 ^∘{}C in both n- and p-type silicon. This is attributed to passivation of the V₂ centers by the highly mobile Cu through the formation of neutral complexes. A prominent level located 0.52 eV above the valence-band edge (Eᵥ) appears in p-type silicon after Cu deposition at room temperature. It is suggested that this level originates from a complex formed by reaction between Cu and the carbon-oxygen centers which give rise to the ``ordinary'' irradiation-induced level at Eᵥ+0.35 eV. This latter level, which is normally stable up to temperatures of {~}350 ^∘{}C, anneals rapidly at 100 ^∘{}C through the formation of the Cu-associated level at Eᵥ+0.52 eV which disappears upon silicide formation. Furthermore, the present results show that no injection of Si self-interstitials into the silicon substrate takes place during the formation of the metal-rich silicide {η}'-Cu₃Si, contrary to the conclusions of recent studies.