Study On Nucleation And Growth Of Cubic Boron Nitride Films By Vapor Deposition

Cubic boron nitride (c-BN), a fascinating material with many promising applications, has raised extensive efforts to synthesize thin films of c-BN and to study the nucleation and growth of c-BN since 1930 because of its desirable mechanical, thermal, electrical, and optical properties.In this thesis, we critically and comprehensively review recent developments in the technologies of c-BN synthesis, the proposed mechanisms of c-BN formation, and the current impediments to the developments of the studies on c-BN thin films. The cBN films are prepared successfully with reduced negative bias voltage applied to the substrate at a higher temperature once the nucleation of c-BN occurs under the higher substrate negative bias voltage at a low temperature, i.e., the two-stage deposition process, using a radio frequency bias sputtering system. These films deposited by the two-stage deposition process have less stress and fewer defects, and the growth rate is increased substantially. Thus, it is concluded that the pre-nucleation process or the two-stage deposition process is an effective method for c-BN preparation.The c-BN-containing films are synthesized by using hot filament assisted microwave electron cyclone resonance chemical vapor deposition (ECR CVD). The samples are characterized by various techniques including FTIR, XRD, Ramanspectroscopy, XPS, and AFM. The results of AFM and FTIR show that high quality h-BN films are synthesized by ECR CVD. The c-BN-containing films are successfully synthesized under reduced negative bias voltage with hot filament assisting, and the grain size of c-BN films is 76 A, which is indicated by XRD. The XPS indicates that the B/N ratio is homogeneous throughout the films.