Characteristics of Ti-capped Co films deposited by a remote plasma ALD method using cyclopentadienylcobalt dicarbonyl

Abstract

Co films were deposited by a remote plasma atomic layer deposition (RPALD) method using cyclopentadienylcobalt dicarbonyl [CpCo(CO)(2)] as the Co precursor with H-2 plasma. The impurity contents in the Co films were minimized under the optimized process conditions with H2 plasma using a process pressure range between 0.1 and 2 Torr and a plasma power of 300 W. The ALD process window of the Co films showed a saturated temperature range between 125 and 175 degrees C. The carbon and oxygen contents of as-deposited Co films were about 8 and 1 atom %, respectively. However, the carbon content in the Co films decreased from 8 to 4 atom % after in situ annealing at 400 degrees C. For in situ annealed Co films deposited on Si substrates, a polycrystalline CoSi2 phase was observed. The surface and interface morphologies of CoSi2/ Si were rough compared to Ti-capped CoSi2/ Si after ex situ annealing at 600 degrees C. In addition, CoSi was completely transformed to CoSi2 at 600 degrees C. However, in the in situ annealed Co films with Ti-capped layer, the diffraction peak of CoSi2(200) began to appear at 700 degrees C. The formation temperature of the Ti-capped CoSi2 phase was retarded by about 100 S C compared to the Co film without the Ti-capped layer. In addition, the surface and interface morphologies of the Ti-capped CoSi2 layer were smooth.