Composition Control Of Boron Carbon Nitride Thin Films Prepared By Pulsed Laser Deposition

Boron carbon nitride (BCN) thin films were prepared on Si (100) substrates by laser ablation of two types of targets (B4C target, h-BN/graphite composited targets). The effects of deposition parameters (laser energy density, nitrogen pressure, deposition temperature), annealing parameters (annealing atmosphere, annealing temperature) and types of targets on the film deposition rate, morphology, bond structure and composition were investigated. The composition of BCN thin films can be varied over a greater range by process control.Firstly, boron carbon nitride thin films with different compositions were prepared using B4C target by changing laser energy density (1-6 J/cm2), nitrogen pressure (0-15 Pa) and deposition temperature (300-750℃). Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses indicated that the as-deposited BCN thin films contained B-C, N-C and B-N chemical bonds, implying the formation of ternary BCN compounds. The concentration of B, C and N can be controlled in the range of 47.3-62.8%,26.4-32.8%and 7.2-26.3%, respectively. BCN thin film prepared at 3 J/cm2,300℃and 5 Pa nitrogen pressure was annealed in vacuum atmosphere with annealing temperature of 700℃for 1 h. The results showed that the film structure did not change, implying good vacuum thermal stability. When the annealing temperature rose to 600℃in air, the film was oxidized and decompounded. At the same time, the formation of C≡N indicated that C≡N exhibited better thermal stability.Due to the limitation of carbon content, we chose h-BN/graphite composited targets to prepare BCN thin films by changing deposition atmosphere and types of targets. FTIR and XPS results suggested the formation of ternary B-C-N compound. With the increasing of graphite ratio of the h-BN/graphite composited target, the carbon content increased from 36.8%to 85.9%, meanwhile, boron and nitrogen contents decreased under the same deposition conditions. The nitrogen content and N-C bond increased when the nitrogen pressure increased from 0 to 3 Pa for the same target.BCN thin film prepared from h-BN/graphite composited targets was annealed in vacuum atmosphere with annealing temperature of 600℃for 1 h. The results showed that the film structure did not change, implying good vacuum thermal stability. When the annealing temperature rose to 600℃in air, the film was oxidized and decompounded.