Interlayer mediated epitaxy of cobalt silicide on silicon (100) from low temperature chemical vapor deposition of cobalt - Formation mechanisms and associated properties

This paper reports the development of a methodology for the growth of epita xial CoSi2 that uses Co Films deposited by low temperature (390 degreesC) c hemical vapor deposition (CVD) from cobalt tricarbonyl nitrosyl [Co(CO)(3)N O] as source precursor. This CVD process exploits the reaction kinetics ass ociated with the adsorption and decomposition of Co(CO)3NO on Si surfaces t o ensure the ill situ, sequential growth of an ultrathin interfacial oxide layer followed by a Co thin film in a single deposition step. It is demonst rated that this interlayer, consisting of a Si-O or a Co-Si-O phase, inhibi ts silicidation for uncapped CVD Co regardless of annealing rimes and tempe ratures. Instead, Co agglomeration is observed, with the degree of agglomer ation bring proportional to the annealing temperature. The agglomeration is due to a reduction in the overall energy of the system through decrease of the Co/substrate interracial area. Alternatively, for Ti/TiN capped CVD Co samples, the interfacial layer appears to play a role similar to that obse rved for similar layers in interlayer mediated epitaxy (IME). This assessme nt is supported by the observation of epitaxial CoSi2 for capped CVD Co sam ples after a single-step anneal at 725 degreesC for 30 a. In contrast, Ti/T iN capped PVD Co samples annealed under identical processing conditions exh ibited a polycrystalline CoSi2 phase with a strong (200) texture. As such, the methodology presented herein represents a modified IME technique for th e growth of high quality, epitaxial CoSi2 films for applications in emergin g microelectronics device technologies. (C) 2000 The Electrochemical Societ y. S0013-4651(00)09-080-7. All rights reserved.