| RF magnetron sputtering that has been broadly used to fabricate a variety of thin films is a kind of physical vapor deposition (PVD), which consists of two main microscopic processes, one is the generation and transportation of the vapor phase particles to form the thin film, the other is the diffusion and aggregation of the film atoms on substrate, which leads to the formation of the film. A majority of studies has to date been focused on studying the influence of fabricating conditions on the characteristics of thin films and finding the ideal conditions to fabricate the thin films with favorite characteristics via experiments which are expensive and time-consuming. Computer simulation that is now becoming a more and more important method for scientific research and can be used as a complementary to theory and experiment has been employed to research the growth of thin films. As to the simulation of the whole process of the generation and transportation of vapor phase film atoms, few attempts were made.Energies, incident angles and positions are the fundamental dynamic coefficients of atoms reaching the substrate to form the film and will greatly influence the forming process of the film and consequently the characteristics of the resulting film. The main purpose of this article- is to simulate the whole process of the generation and transportation of the vapor phase particles of the film in RF magnetron sputtering, which contains transportation of ions in RF glow discharge, sputtering of target and transportation of sputtered atoms, via models that are established on the basis of the physics of sheath theory for the RF magnetron glow discharge, sputtering theory and transportation theory. The software "SRIM" is employed to simulate the sputtering of target, and simulations of the other processes are performed with the software programmed by myself. The different processes can be simulated separately or sequentially with the results of the simulation of the former process as the inputs of the simulation of the closely following process. The results from the simulations consist of the energies, directions of movements and positions of the particles concerned.The main results of this article are:(1) The software that is to simulate the transportation of ions in RF glow discharge,in which a simple method to determine the original states of the ions (original velocities and positions) is recommended.(2) The software that is to simulate the transportation of sputtered atoms, in which the determination of the atom flowing direction after collision is recommended.(3) The simulation results of rare gas ion (argon is used here) sputtering metal (Al is used here) to deposit films, which are in good agreement with the fundamental experimental results. The results of simulations are:i) Energies of the incident ions to the target are determined mainly by the voltage across the cathode sheath, with a majority of ions' energy vary around the sheath voltage; ions nearly normally bombard the target; ions mainly locate above the sputtering holes because of the influence of the magnetic field, and the incident ions mainly come from the region; the ions undergo several collisions during transportation, but that don't matter much.ii) Energies of the sputtered atoms vary mainly from several to several teens eV, with few atoms' energy relatively high; the emitting positions of the sputtered atoms are close to the corresponding incident ions (in the order of angstrom); the sputtered atoms are emitted mainly normally, and few are slantways; energy and angular distributions of sputtered atoms are influenced by the energies and incident directions of incident ions, but the angular distributions are not influenced by the incident energy very greatly.iii) Transportation properties of the sputtered atoms are mainly influenced by the air pressure P in the vacuum chamber and the distance d between the target and the substrate, that is to say, the bigger the product PXd, the fewer the sputtered atoms reaching...
|
PDF Full Text Request