H-assisted plasma CVD of Cu films for interconnects in ultra-large-scale integration

H-assisted plasma CVD (HAPCVD), in which Cu(hfac)₂ is supplied as the source material, realizes control of qualities of Cu films, since H irradiation is effective in purifying the Cu films, increasing the grain size, and reducing the surface roughness. Conformal deposition in fine trenches can be realized by decreasing dissociation degree of Cu(hfac)₂ using the HAPCVD. Cu(hfac) is identified as the radical mainly contributing to the deposition. Based on the results, we proposed a model in which Cu(hfac) and H react on surfaces to deposit Cu films. We also demonstrated conformal deposition of smooth Cu films of 30 nm thickness and 1.9 μΩ cm resistivity and almost complete Cu filling in trenches 0.35 μm wide and 1.6 μm deep using the HAPCVD.