Enhanced Adhesion of Copper Films to SiO2, PSG and BPSG by Refractory Metal Additions

Abstract

ABSTRACTCopper films generally exhibit poor adhesion on dielectrics. It has been shown that the addition of refractory metals promotes adhesion via an interfacial reaction or better wetting to the dielectric. We investigate the adhesion of Cu-refractory metal (Cr, Ti) alloy films and bilayers on various silicon oxide substrates (SiO2, PSG, BPSG) after annealing in the temperature range 400-600°C by conventional furnace using N2/H2 forming gas. Rutherford backscattering spectrometry (RBS) was used to determine the interfacial reaction characteristics. The efficacy of a variation of the standard Scotch™ tape testing was evaluated. We found that the combined Scotch™ tape/scribe adhesion test revealed excellent qualitative bonding information and could be correlated well to RBS characterization. We were able to optimize the sample configurations and chemical compositions to achieve the best adhering film.