Investigations of Tin and Ti Film Deposition by Plasma Activated Cvd Using Cyclopentadienyl Cycloheptatrienyl Titanium, a Low Oxidation State Precursor

Sequential Ti and TiN thin film deposition by CVD is highly desirable for advanced Si integrated circuit applications. To date, most CVD TiN work has been performed using Ti(IV) compounds. We have investigated plasma assisted CVD using a lower oxidation state precursor, cyclopentadienyl cycloheptatrienyl titanium, (C 5 H 5 )Ti(C 7 H 7 ) (CPCHT), which might provide a more facile pathway to both Ti and TiN film formation. CPCHT was introduced with H 2 carrier gas into the downstream region of an NH 3 , N 2 or H 2 plasma. Low resistivity (100-250 μΩ-cm), nitrogen rich TiN films with little C or O incorporation were deposited at 300 to 600°C, inclusive with either activated N 2 or NH 3 . Although the film texture was influenced by the chosen plasma gas, the average grain size of the N 2 and NH 3 plasma deposits was similar. Annealing studies showed that the CVD TiN was an effective diffusion barrier between aluminum and silicon to at least 575°C. TEM micrographs revealed that, in contrast to many CVD metal films, the growth of this TiN was not columnar. Film conformality was investigated by scanning electron microscopy (SEM). Experiments performed with activated H 2 resulted in deposits of Ti contaminated with C. No depositions were observed in the absence of plasma excitation.