日本大学生産工学部　生産工学部研究報告A51-2

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─ 9 ─experimental results, HCN cluster has been observed as the one of the main etching products12–14).4CN layer as a passivation layer against H and H2 injectionsTo examine the reactions of the CN layer on the PPP sur-face to H and H2 atom/molecule exporsures, these species of 73.4×1015cm−2 dose are injected after 24.5 × 1015cm−2 dose of N atom injections. All species are injected at 5 eV.The net erosion yields and species of main etching products including N or C atoms are given in Figs.17 and 18 for (a) H atom injections and (b) H2 molecule injections. It is clearly observed that the substrate carbon atoms are hardly sputtered in both cases. Especially, for H2 injections, N atoms accumu-lated in the CN layer are also rarely sputtered whereas some-what sputtered for H injections. Indeed, sputtering yields of obtained main etched species including N atoms shown in Fig.18 are larger than those including C atoms. The main etching products are H atom and H2 molecule as shown in Tab.1. In this table, we can see that YN is ten times of YC for H injections. Moreover, YC = 0 for H2 injections.From these results, it can be speculated that after once CN layer formed, certain amount of injected H atoms are adsorbed by N atoms in the layer and desorbed from the substrate as NxHy . Then, substrate C atoms are hardly sputtered.In this process, although few C atoms are sputtered from the CN layer, constructions of chemical bonds between C and N atoms are changed as shown in Fig.19. In the gures, we plot the area densities of CN=1　and CN=1.5　bonds be-tween C and N atoms as a function of injection dose. The re-sult for H2 injections can be consistently understood with chemical intuitions in which absorbed H atoms break the π bonding of CN=1.5 bonds, then this bonds are changed into CN=1 bonds. In Fig.19(b), reduction of CN=1.5 bonds and increment of CN=1 are observed. For H injections, after once CN=1 increased up to 48.0 × 1015cm−2 dose, both of CN=1 and CN=1.5 are decreasing. It can be attributed to rather high area density of injected H atoms due to limitations of compu-tational conditions. Therefore, injected H atoms rstly break π bonds of CN=1.5 similarly to the case of H2 injections. In the next step, for more H injections CN=1 bonds are also broken and small but apparent number of N atoms are sputtered (Figs.17 (a) and 18(a)). This is consistent with gure 2 of Ref.9).Consequently, we have obtained that H or H2 injections into the well-nitrided PPP surface reduces CN=1.5 bonds and in-creases CN=1 bonds at least in early phase of injections al-Fig.17: The net erosin yields Yα (α =C, H, or N atoms) vs. injection dose in the case of (a) H and (b) H2 after N atom injections. The injectin energy is 5 eV and its direction is normal to the surface.(a)019.238.457.676.896−101dose[1015 / cm2]dleiynoisoretenH injections (5eV) into nitrided PPPYHYCYNH injections N injections(b)019.238.457.676.896−101dose[1015 / cm2]dleiynoisoretenH2 injections (5eV) into nitrided PPPYHYCYNH2 injections N injectionsFig.18: Main etching product species including C or N atom(s) during injections of (a) H, (b) H2 atoms/molecules after N atom injections at 5 eV.(a)024[1×10−3]sputtering yieldsNHNH2CNH5CNH8speciesH injections (5eV)into nitrided PPPNH3CH4CNH6(b)01[1×10−3]sputtering yieldsNH2speciesH2 injections (5eV)into nitrided PPPNH3