Atomic Layer Epitaxy of Copper on Tantalum

Abstract

Abstract The decreasing size and increasing complexity of the components in future microelectronics devices present a great challenge in the development of new deposition techniques. One method for the deposition of semiconductor materials which has generated considerable interest is atomic layer epitaxy (ALE). This method has been shown to yield films with excellent step coverage and high conformity, even on very complex shaped substrates. In this paper we report, for the first time, the deposition of copper using the ALE technique. The films were deposited on tantalum substrates using copper(I) chloride as the precursor and hydrogen as the reducing agent. The films were found to be polycrystalline and practically free from texture. They were also very low in chlorine contamination and possessed a rather rough surface morphology. An initial fast substrate reduction, yielding a film thickness of approximately 300 À, was observed, the rate determining step being the reaction of hydrogen with the adsorbed copper chloride. The activation energy for this step was estimated to be 80 kJ mol −1 .