Characterization of Boron Carbonitride (BCN) Thin Films Deposited by Radiofrequency and Microwave Plasma Enhanced Chemical Vapor Deposition

Boron carbonitride (BCN) thin films with a thickness of ~4 µm were synthesized on Si (100) substrate by radiofrequency and microwave plasma enhanced chemical vapor deposition using trimethylamine borane [(CH₃)₃N.BH₃)] as a molecular precursor. The microstructures of the films were evaluated using field emission scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD). Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) were used to analyze the chemical bonding state and composition of the films. It has been observed that the films were adhered well to the silicon substrate even after being broken mechanically. XRD and FESEM results showed that the films were x-ray amorphous, rough surface with inhomogeneous microstructure. The micro hardness was measured by nano-indentation tester and was found to be approximately 2~7 GPa. FT-IR suggested the formation of the hexagonal boron carbonitride (h-BCN) phase in the films. Broadening of the XPS peaks revealed that B, C and N atoms have different chemical bonds such as B-N, B-C and C-N. The impurity oxygen was detected (13~15 at.%) as B-O and/or N-O.