Effects of atomic hydrogen on Cu(II)bishexafluoroacetylacetonate interactions with a TiN surface

Abstract

Cu(II)bishexafluoroacetylacetonate [Cu(II)(hfac) 2] adsorbed onto a partially oxidized TiN substrate [TiN(O)] is reduced to Cu(0) by exposure to atomic deuterium at 450 K. Initial precursor interaction with the TiN(O) surface at 450 K results in an ad-layer consisting of Cu(I)hfac and hfac. Subsequent exposure to atomic deuterium at 450 K results in volatilization of organic species and reduction of Cu(I) to Cu(0). This reduction is concurrent with the removal of 50% of the Cu atoms from the surface. This indicates that the reduction involves a disproportionation of adsorbed Cu(I) species to yield adsorbed Cu(0) and a volatile Cu(II) species. The disproportionation is not observed in the absence of atomic deuterium and volatilization of adsorbed hfac. Atomic deuterium also removes adventitious carbon from a TiN(O) surface prior to precursor exposure. The removal of carbon is accompanied by substantial reduction of Ti(IV) to Ti(II) within the substrate surface region. Diffusion of Cu into the cleaned TiN(O) substrate begins above 450 K, but only becomes significant as the sample is heated above 750 K in ultra-high vacuum. These results indicate that atomic-hydrogen-assisted CVD is effective at inhibiting organic contamination at the Cu/TiN interface, and does not significantly degrade the diffusion barrier properties of the TiN substrate.