MW-ECR Plasma Enhanced Unbalance Magnetron Sputtering And Carbon Nitride Films Preparation

The present work includes two main parts: The first part mainly investigates a new technique of thin film deposition, Twinned Microwave Electron Cyclotron Resonance(MW-ECR) Plasma Enhanced Unbalance Magnetron Sputtering(PEUMS). The second part dedicates to the carbon nitride(CNx) thin film deposition.Two MW-ECR discharge chambers, which locate oppositely at the two side of processing vacuum chamber, are used in this PEUMS technique. The magnetron target is at the above side in the vacuum chamber and the high purity graphite is used as sputtering materials. The magnetic fields of two faced MW-ECR sources and magnetron form a combined magnetic cusp geometry in processing chamber. The dense, highly ionic ECR plasma and reactive species can be confined in the low magnetic field region between magnetron and substrate holder. Tow kinds of magnetron I-V discharge characteristics are found at all working gas pressure: Voltage Mode and Current Mode, the first one is caused by the enhancement of ECR plasma and the last one the magnetron discharge as well as the enhancement of ECR plasma. This technique has the following features: 1) Because of the confinement of plasma by the cusp magnetic field the density of ion and reactive species near the film growing surface is high. 2) The reactive species of thin film growth are generated by MW-ECR discharge and magnetron discharge separately, the density and energy distribution of the reactive species can be controlled by the changing of the sputtering voltage and deposition bias voltage. 3) Because of the enhancement of ECR plasma and the confinement of plasma, this kind of PEUMS can work at ultra-low gas pressure, so it is easy to hybridize this technique with other materials surface modification techniques such as plasma source ion implantation (PSII).CNx films are deposited using PEUMS technique on silicon substrates. The characterization of the films by XPS, FT-IR, RAMAN, SEM, Micro-hardness, etc., indicates the films are composed mainly by sp3 C-N, the N/C ratio of the film is 4:3.2,which is close to that of C3N4, and the hardness is about 42GPa. Optical Emission Spectrum (OES) is used to diagnose the plasma during the films preparation. The N2+, N2 , and CN radicals are found in the plasma, which are the growing species of CNx films. The CN radical OES band intensity is far great at both magnetron negative zone and plasma zone when the working gas pressure is greater than 0.1 Pa and the CN band intensity at magnetron negative zone is weaker that that at plasma zone, on the contrary, the CN band intensity is stronger than at plasma zone when gas pressure is less than 0.1 Pa. A CN radical formation mechanism is composed based on the experiments results. Finally, the CNx film growing mechanism is also investigated and a surface reaction model is made, the model could explain why it is hard to get the stoichiometric composition during CNx films preparation using traditional sputtering techniques.