Characteristics of Cobalt Films Deposited by Metal Organic Chemical Vapor Deposition Method Using Dicobalt Hexacarbonyl tert-Butylacetylene

Abstract

Cobalt films were deposited by metal organic chemical vapor deposition (MOCVD) using C12H10O6(Co)2 (dicobalt hexacarbonyl tert-butylacetylene, CCTBA) as the Co precursor and H2 reactant gas. The impurity content of the Co films was monitored as a function of the partial pressure of H2 reactant gas. The carbon and oxygen content of as-deposited Co films greatly decrease with the increase of H2 partial pressure, and at H2 partial pressure of 10 Torr and a substrate temperature of 150 °C were 2.8 at. % and less than 1 at. %, respectively. As the H2 partial pressure increased, carbon and oxygen content decreased markedly. Excellent conformality of Co film over 80% was achieved on a patterned wafer with aspect ratio of 15:1, 0.12 µm wide and 1.8 µm deep. The phase transition was analyzed with X-ray diffraction (XRD) depending on RTA temperature. CoSi was observed at 500 °C annealing, and was transformed to CoSi2 at 600 °C annealing. In addition, Auger electron spectroscopy (AES) data showed a 1:2 atomic ratio of Co:Si in the CoSi2 layer.