Characteristics of cobalt films deposited by using a remote plasma ALD method with a CpCo(CO)(2) precursor

Abstract

Co films deposited by using a remote plasma atomic layer deposition (RPALD) method with cyclopentadienyl cobalt dicarbonyl (CpCo(CO)(2)) as a precursor were investigated. The process parameters, such as the deposition temperature, the plasma power, the process pressure, and the plasma gas, were varied, and the resulting Co films were characterized. The growth rate of the Co film was about 1.1 angstrom/cycle for a process window between 125 and 175 degrees C. The impurity content of the Co films was minimized using a H-2 plasma in the process pressure range between 0.1 and 2 Torr at a plasma power of 300 W. The carbon and the oxygen contents of the Co films were about 7 at.% and below 1 at.%, the detection limit, respectively. The Co films showed a very uniform surface with a root-mean-square (RMS) roughness of 1.51 angstrom, as determined by using an atomic force microscopy (AFM) analysis. The Co films deposited on contact holes, about 0.12 mu m wide and 1.8 mu m deep, showed excellent conformal coverage. The compositions of the Co films on the tops and the sidewalls of the contact holes were examined with Auger electron spectroscopy (AES), and the results showed nearly identical compositions.