INTERACTION OF COPPER WITH CAVITIES IN SILICON

Copper in Si was shown to be strongly bound at cavities formed by He i on implantation and annealing. Evolution of this system during heating was observed by Rutherford backscattering spectrometry and transmissi on electron microscopy. Results were mathematically modeled to charact erize quantitatively the binding of Cu in the cavities and, for compar ison, in precipitates of the equilibrium silicide, eta-Cu3Si Binding o f Cu to cavities occurred by chemisorption on the walls, and the bindi ng energy was determined to be 2.2+/-0.2 eV relative to solution in Si . The heat of solution from the silicide was found to be 1.7 eV, consi stent with the published phase diagram. These findings suggest the use of cavities for metal-impurity gettering in Si devices. Hydrogen in s olution in equilibrium with external H-2 gas displaced Cu atoms from c avity walls, a mechanistically illuminating effect that is also of pra ctical concern for gettering applications.