Atomic diffusion in Cu/Si (111) and Cu/SiO2/Si (111) systems by neutral cluster beam deposition

The Cu films are deposited on two kinds of p-type Si (111) substrates by ionized cluster beam (ICB) technique. The interface reaction and atomic diffusion of Cu/Si (111) and Cu/SiO2/Si (111) systems are studied at different annealing temperatures by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Some significant results are obtained: For the Cu/Si (111) samples prepared by neutral clusters, the interdiffusion of Cu and Si atoms occurs when annealed at 230 degrees C. The diffusion coefficients of the samples annealed at 230 degrees C and 500 degrees C are 8.5 x 10(-15) cm(2).s(-1) and 3.0 x 10(-14) cm(2).s(-1), respectively. The formation of the copper-silicide phase is observed by XRD, and its intensity becomes stronger with the increase of annealing temperature. For the Cu/SiO2/Si (111) samples prepared by neutral clusters, the interdiffusion of Cu and Si atoms occurs and copper silicides are formed when annealed at 450 degrees C. The diffusion coefficients of Cu in Si are calculated to be 6.0 x 10(-16) cm(2).s(-1) at 450 degrees C, clue to the fact that the existence of the SiO2 layer suppresses the interdiffusion of Cu and Si.