Coatings and microstructures of monolithic TiB₂ films and double layer and composite TiCN/TiB₂ films from alkoxide solutions by thermal plasma CVD

Monolithic TiB₂ films and double layer and composite TiCN-TiB₂ films were deposited on Si wafers from a mixture of titanium tetra-ethoxide and boron tri-ethoxide solutions at a 1:2 mole ratio at 800 °C for 20 min by chemical vapor deposition in a thermal N₂/H₂ plasma. The TiB₂ films were deposited without N₂, while the double layer and composite TiCN-TiB₂ films of various compositions were deposited by varying N₂ flow rates in N₂/H₂ plasma. The surfaces and cross-sections of the films were observed by SEM, exhibiting the microstructures and thickness of the films. The relative atomic percentages of Ti, N, B, bonded and free C, and O in the films were determined semi-quantitatively from their XPS peak areas. Microstructures of the composite films with the composition 3TiC_0.5N_0.5/2TiB₂ formed at N₂ = 50 mL min^{- 1} were observed by TEM, revealing the sizes and orientations of the particles with the distribution of Ti and B elements in the film.