Studies On Preparation And Properties Of CN_x Films By DC Magnetron-reactive-sputtering Deposition

A detailed studies are given on deposition of amorphous carbon nitride thin film by DC magnetron reactive sputtering techniques. The thesis gives an overview of the superhard materials and their history of the development.We review the advantage and disadvantage of the earliest discovered superhard material-Diamond in the industrial application. Since the calculation results of ab initio pseudpotential method by Dr. Cohen and Dr. Liu showed that the bulk modulus and hardness are comparable to or higher than diamond, the worldwide experimental and theoretical research activities on superhard materials especial ofβ-C3N4 have been arising. The thesis gives a detailed theoretical discussion for superhard thin film. And give the comparison and overview on the physical and chemical properties of the various superhard materials. The models of atom arrangment of networks ofβ-C3N4, the various preparations of β-C3N4 thin film and their respective physical and chemical properties were detailed discussed. An overview of the facilities, instruments and testers of preparation, testings and measurings was given. The thesis main parts are as followings:(1) the mechanical properties of the CNx thin film on the various substrate materials by DC magnetron reactive sputtering.(2) the study of the CNx film structure by X-ray diffraction.(3) the study of carbon nitrogen bonds in the CNx film by FTIR.(4) the study of the optical band gap of CNx film by UV-VIS spectrophotometer.(5) by using the microhardness tester, we study the hardness of CNx film on the ceremic substrate by DC magnetron reactive sputtering with the feed Ar and N2 flow rate, film thickness, substrate temperature and substrate bias. By using the various substrate such as glass, stainless steel, ITO film and ceremic wafer, we discover that we can deposite the high quality CNx thin film with the high cohesion, high hardness and low friction coefficient on the ceremic substrate. The X-ray diffraction data indicate that the CNx film structures are amorphous. This agrees with the most publicized literature. The study of IR spectra exhibit characteristic bands of carbon nitrogen bonds around 2200cm-1,1500cm-1 and 1350cm-1, showing that the C and N atoms are chemically bonded in the films in the forms of C≡N,C=N and C―N respectivly. It also tells us the reason lead to the high hardness of the CNx film. By using the UV-VIS spectrophotometer and data processing, we get to know that The carbon nitride films have a wide optical band gap of 4.14ev, which is 2.2ev lower than the theoratical band gap of 6.6±0.5ev. Microhardness tester indicate that the hardness increases with the increase of N2 flow rate(Ar flow rate is fixed) and decreases with the increases of Ar flow Rate(N2 flow rate is fixed). It also shows that hardness increases with the increase of film thickness,substrate temperature and substrate bias. And among these processing parameters, the substrate temperature and bias have the more prominent influences.