Preparations And Properties Of DLC:N Thin Films

DLC: N thin films contain a certain number of sp³ bonds, which contain a series of excellent properties closer to the diamond. Chemical stability and thermal stability of DLC: N thin films are similar to that of TiN thin film. DLC: N thin films were grown on Si(100) wafer substrates by radio frequency magnetron sputtering with a high pure graphite target. Gas mixtures containing argon and nitrogen were used as sputtering atmosphere. This method has advantages both low deposition temperature and large deposition area, so it has been widely studied.In the first chapter, the history and the present research situation of DLC: N films have been introduced. We summarized the DLC films' preparing methods and the chemical bonding of C and N bonds in the films.In chapter two, we introduced the fundamentals of magnetron sputtering methond. In the meanwhile, we summarized the inspective methods and principles of the DLC: N films such as Raman spectrum (Raman), X-ray photoelectron spectrum (XPS), infrared absorption spectrum (FTIR), atomic force microscope (AFM), scanning electron microscope(SEM).In chapter three, the RF magnetron sputtering method and the operational steps of sputtering equipment were introduced. The DLC thin films and DLC: N films were prepared. With Raman spectrum and XPS, the composition and structure of the films were studied. The morphologies of the films were studied with AFM and SEM. According to Raman spectra, DLC: N films remains a DLC structure; D and G peaks shift slightly to lower wavenumber and the radio of ID/IG is smaller than that of the DLC films. The surface of DLC: N film is smoother and its grain size is smaller by SEM, AFM.In chapter four, FTIR spectra show that N atoms are bonded to C atoms in different bonding types of sp³ C-N, sp² C=N and C≡N in the films. XPS spectra are used to character the chemical bonding of C and N bonds in the films. The results show that N atoms are bonded to C atoms in different bonding types of sp³ C-N, sp² C=N and C≡N by lorentzian fitting of C1s and N1s, which indicates that the structures of non-crystalline carbon nitride are formed in the films. In the meanwhile, with increasing of N₂ gas flow rate and bias, the nitrogen content of films increases too. When the bias is -100V, sp³ content of the films is the largest, and the roughness of film is the smallest. With the sputtering power increasing, sp³ bond content of the films increases. The film adhered to its substrate tightly under different N₂ pressure by SEM.