The Deposition And Doping Technics Of Diamond-like Carbon Films

DLC films and gradient composition DLC films were deposited on Si substrates in plasma-ion beam enhanced deposition system for the industrial applications and improving the adhesion. Closed-field unbalanced magnetron sputtering (CFUBMS) and 90° bend toroidal duct magnetic filtered cathodic vacuum arc (FCVA) were chosen to prepare DLC films for they are the better deposition technologies for industrial application, and the influences of deposition parameters on the structures and properties were investigated. In order to improve the adhesion between DLC film and substrate, metal ion implantation technology and cathodic arc-unbalanced magnetron sputtering duplex technology were applied to deposite Ti-DLC films and Ti/TiN/TiCN/TiC/DLC gradient composition films.Smooth, dense and uniform DLC films were successfully prepared by CFUBMS. It is found that the target current plays an important role in the DLC film deposition. Deposition rate of 3.48μm/h is obtained by using the target current of 30A due to the increasing of sputtering ability of the target. The structure of the films tends to have a growth of sp~3 bonds content at high target current for the increasing of C~+ ion energy. The increase of the ion energy is beneficial to the formation of smoother surface and higher hardness, while critical load reduced due to higher intrinsic stress.Ta-C films with high sp~3 bond content were obtained by 90° bend toroidal duct magnetic filtered cathodic arc method. The influence of substrate bias voltage on the structures and properties of ta-C films was also investigated. High quality film with high hardness of 31GPa and low friction coefficient of 0.1 was achieved at bias voltage of -75V (ion energy about 100eV). The macroparticles produced by cathode can be effectively filtered by the 90° bend toroidal duct. The higher the bias voltage is, the higher the ion energy is. The increase of the ion energy can increase the sputtering of macroparticles and thus improves surface properties of ta-C films. The increasing of ion energy also leads to the decrease of hardness and intrinsic stress, and the adhesion between ta-C film and Si substrate is improved at the same time. The bias voltage of -300V is considered to be the best parameter to achieve ta-C film with excellent performances.The effect of Ti~+ ion implantation on the structures and properties of the sputtered DLC films was investigated. The hardness and elastic modulus of DLC films are increased after Ti~+ion implanted into DLC films, while RMS roughness and friction coefficient of the films are decreased. The compressive stress of DLC films is changed to tensile stress by ion implantation. TEM and XPS analyses indicate that TiC nanocrystallines are formed in the films, and the interface between Si and C is widened by ion implantation. The adhesion of DLC-Si interface and anti-wear behavior of the ion implanted film is improved as well. Thus, it can be seen that the properties of DLC films are increased after implantation with Ti+ at a larger dose or at a lower energy.Duplex technology of cathodic arc and unbalanced magnetron sputtering was adopted to fabricate gradient composition DLC films. The results show that gradient composition DLC films have good adhesion to their substrates (especially Ti alloy substrates). The multilayer films are hardness gradient films which have excellent anti-wear behavior and adhesion property of DLC films. RMS roughness of the gradient composition DLC films is 12.3nm which is higher than single DLC films, while the friction coefficient is equal to (even lower than) single DLC films. It is inferred that the structure and hardness of the films are major factors affecting the friction coefficient and RMS roughness of surface has no effect on friction coefficient.A new oscillating cantilever beam method was applied to measure micro-tribological property of ta-C film, which applied loads are varied from lmN to 50mN. The results imply that status of contact between slider and ta-C film is almost elastic contact. RMS roughness of surface plays a great role in friction coefficient of ta-C films in micro-tribology field, and the roughness of surface can lead to the increasing of friction coefficient. The adhesion between ta-C film and slider is weak, it is the reason that ta-C film has smaller friction coefficient than sputtering DLC film does. Therefore, ta-C film can be applied as a protective layer in micro-electronmachnical systems (MEMS).