日本大学生産工学部　生産工学部研究報告A51-2

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─ 5 ─for (a) N, (b) N2, and (c) NH3 injections. Here, we denote20) single and double carbon-nitrogen bonds as CN=1 and CN=2, i. e., the rst two letters represent atomic species and the num-ber represents the bond order. Similarly, we denote the sp2 hy-bridized carbon-nitrogen bond as CN=1.5. The gures indi-cate that, in the CN layer, carbon and nitrogen atoms make chemically stable network which is mainly constructed by CN=1.5 bonds. For the case of NH3 injections, compearing with the other two cases we can also see the fact that the mul-tiple bonds (CN=1.5 and CN=2) are suppressed by the lot of incident hydrogen atoms and, in contrast, the number of single bonds (CN=1) shows a signicant increase.3.2N and NH3 injections at 50 eVThe energy dependences of averaged sputtering yields of substrate C atom for N and NH3 injectins are shown in Fig.7. In order to show that the increment of the sputtering yield for the change of the injection energy from 25 eV to 50 eV is sig-nicantly large, the sputtering yields for injection energies smaller than 25 eV are also plotted. The injection dose is up to 24.0×1015cm−2 for 2, 5, and 10 eV of injection energy cases, and up to 73.4 × 1015cm−2 for 25 and 50 eV injections. Each value indicated as lled squares (N injections) or circles (NH3 injections) in the gure is obtained by averaging the dose de-pendent sputtering yields over some injection dose region in which each systems can seem achieving some stable state.Fig.7: Sputtering yields of the substrate C atoms for N and NH3 injections versus injection energy. Values are averaged in some dose region in which the systems can be seen reaching to a stable state.0510152025303540455000.10.20.30.40.5N injectionssdleiygnirettupsdegarevaincident energy [eV]NH3 injectionsfor substrate carbon atomsFrom 25 eV to 50 eV, the yield is strongly increased with the increase of the injection energy rather than the case of be-tween 10 eV and 25 eV. Ratio of increment of the sputtering yield between 10 eV and 25 eV to those of 25 eV and 50 eV for NH3 injection case(~ 3.7) is larger than those for N injec-tion case(~ 2.4). Then, energy dependence of the sputtering yield for NH3 injections is stronger than for N injections, be-cause desorbed H atoms eectively break carbon bonds in the substrate when the injection enrgy becomes higher than a cer-tain value within 25 eV to 50 eV.We consider here, the dierence between the sputtering yields shown in Fig.8 and inuences of the injection energy on the ecthing characteristics comparing with those of the in-Fig.6: The densities of bond number of carbon-nitrogen bonds (NCN=x, x = 1, 1.5, or 2) per unit volume vs. the height of the substrate for (a) N, (b) N2, and (c) NH3 injections. In the gures, we denote the densities of bond number as “bond densities” for simplicity.(a)00.91.82.73.64.5020406080height [nm]mn[seitisneddnob−3]NCN=1NCN=1.5NCN=2N injections (25ev)(b)00.91.82.73.64.5020406080height [nm]mn[seitisneddnob−3]NCN=1NCN=1.5NCN=2N2 injections (25ev)(c)00.91.82.73.6020406080height [nm]mn[seitisneddnob−3]NCN=1NCN=1.5NCN=2NH3 injections (25ev)Fig.8: Sputtering yields of the substrate C atoms for N and NH3 injections versus injection dose up to 73.4 × 1015cm−2.09.619.228.838.44857.667.200.20.40.6dose[1015 / cm2]sdleiygnirettupsNH3 injections (50eV)N injections (50eV)