Processes for the deposition of copper films on transition metal barrier layers by means CVD using organometallic precursors are often found to lead to poor adhesion characteristics of the grown film. By means of first-principles molecular dynamics simulations, we show that the source of the problem is the strong reactivity of the surfaces toward the precursors, which decompose spontaneously upon contact with the surface leading to contamination of the interface. Our simulations consider Ti, Ta, and W as barrier layers, and Cu(hfac)-(tmvs) as precursor. In contrast, we show that surfaces of these metals properly passivated with nitrogen, in such a way that only N atoms are exposed on the surface, are much less active and do not lead to decomposition of the precursor. We propose this passivation procedure as a practical solution to the adhesion problem.
Chemical vapor deposition Copper films CupraSelect Ab initio molecular dynamics
Norman AT, Muratore BA (1992) U. S. Patent No. 5,085,731Google Scholar