Establishment of the principle of the synthesis of the super-hard carbon nitride films based on the diagnosis by the threshold ionization mass spectrometry

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The present study reports the guideline of synthesizing the mechanically-hard carbon nitride (CN_x) films with high nitrogen content based on the high-resolution emission spectroscopy and the threshold ionization mass spectrometry. The following results are obtained.1. Synthesis of CN_x films using the microwave CVD and the processing based on the high-resolution emission spectroscopyHigh-resolution emission spectrum of the CN radical was observed for the reaction of BrCN with the microwave (MW) discharge flow of Ar. It was found that the dissociative excitation reaction of BrCN proceeded competitively via [1] energy transfer from Ar(^3P_<0,2>) and [2] charge transfer from Ar^+ followed by the ion-electron recombination.2. Synthesis of CN_x films using the ECR plasma CVD and the processing based on the high-resolution emission spectroscopyAccording to the measurements of (a) the CN(B-X) emission, (b) the resonance lines of ArI and ArII, and (c) the electron probe, the CN(B) state was f … More ound to be formed from the high-energy electron-impact excitation of BrCN in the ECR plasma of the BrCN/Ar system.3. Process of formation of CN_x films based on the threshold ionization mass spectrometryMass spectra of BrCN were observed with varying the electron energy of ionization. It was confirmed that C^+ was formed by the electron impact dissociative ionization BrCN. According to this result, the difference of the nitrogen content of the films formed from the MW and ECR plasma CVD processes was explained as follows.The threshold of the production of the C atom is 11.6 eV. This value is dose to the energy, 11.5-11.9 eV, transferred to BrCN in MWCVD. Thus, the cross section of the production of the C atom from BrCN is considered to be negligibly small. The production of C^+ is energetically impossible. Hence, the precursor of the film formation is confirmed to be predominantly the CN radical, leading to the high concentration of the N atoms in the films (50%). On the other hand, the energy transferred to BrCN in ECRCVD is evaluated to be much higher than the threshold energies of production of C and C^+ from BrCN. Thus, they are produced with significant concentrations. Therefore, C and C^+ are considered to be the precursors for the film formation as well as the CN radicals. As a result, the concentration of the N atoms is suppressed in the films produced in the ECRCVD system (【less than or equal】20%). Less