Cobalt thin films were deposited by a remote plasma atomic layer deposition (ALD) system with a metalorganic precursor of dicobalt octacarbonyl (Co2(CO)8) . To investigate the reaction kinetics and the characteristics of the Co films, we carried out experiments, varying parameters such as precursor flow rate and injection time, reactant gas flow rate, plasma power, and substrate temperature. The deposition rate of Co films was ∼1.2Å∕cycle in the ALD window of 75–110°C . The extent of impurity content such as oxygen and carbon was highly affected by plasma power. Two Co films deposited with a plasma power of 50 and 300W showed different compositional variations. The carbon content of the samples was about ∼22% and ∼15% , and oxygen content was about ∼15% and ∼2% , for deposition with plasma powers of 50 and 300W , respectively. The incorporation of impurities was caused by the incomplete decomposition of Co-CO and suppressed Co reaction on Si substrate, retarding silicide formation.
Co films were deposited by a remote plasma atomic layer deposition ͑RPALD͒ method using cyclopentadienylcobalt dicarbonyl ͓CpCo͑CO͒ 2 ͔ as the Co precursor with H 2 plasma. The impurity contents in the Co films were minimized under the optimized process conditions with H 2 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°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°C. For in situ annealed Co films deposited on Si substrates, a polycrystalline CoSi 2 phase was observed. The surface and interface morphologies of CoSi 2 /Si were rough compared to Ti-capped CoSi 2 /Si after ex situ annealing at 600°C. In addition, CoSi was completely transformed to CoSi 2 at 600°C. However, in the in situ annealed Co films with Ti-capped layer, the diffraction peak of CoSi 2 ͑200͒ began to appear at 700°C. The formation temperature of the Ti-capped CoSi 2 phase was retarded by about 100°C compared to the Co film without the Ti-capped layer. In addition, the surface and interface morphologies of the Ti-capped CoSi 2 layer were smooth.
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