日本大学生産工学部　生産工学部研究報告A51-2

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─ 7 ─tion dose increased.In conclusion, from comparative consideration of the re-sults for both 25 and 50 eV of injection energies, clear dier-ences of chemical features on the etching mechanisms are hardly observed while the injection energy rise changes the dose dependences3.3Etching productsFigure 12 and 13 show main sputtered species and their sputtering yields during particle injections, and all values of yields indicated in the gures are averaged over the dose from 36.7 × 1015cm−2 to 73.4 × 1015cm−2. Here, “main” means the sputtering yield values of the species are above 0.05. It can be seen that there is no sputtered clusters including C atom(s) as the main products for N2 and NH3 injections. For N2 injec-tions, this fact and the result indicated in Figs.3(b) and 5 are consistent each other in the sense that the low sputtering yield of the substrate C atoms. It has seemed also consistent for NH3 injections at 25 eV, however, at 50 eV, no carbided clus-ters are observed as main byproducts against the fact that the substrate C atoms are enough sputtered as indicated in Fig.8. It can be attributed to productions of a wide variety of carbid-ed clusters. Additionally, there are many types of the main products of clusters consisted of N and H atoms reecting a number of incident H atoms (Fig.13).In the previous work17), we have shown that, within all sput-tered clusteres including C atom(s), the type of most frequent-ly sputtered cluster is involving two C atoms for CH4 injec-tions into the PPP surface; C2H4 is the most frequently observed cluster and the other main carbided etching product species are CH3, CH4 and C2H2. In the present work, also, sputtered clusters show similar property (Fig.14), however, the most frequently sputtered carbided clusters have single C atom reecting dierences of chemical bonding properties be-tween CN and CC bonds. This results support our speculation that incident N atoms make CN layer on the PPP surface breaking into the chemical network among C atoms and form alternating array of C and N atoms.And then, we show the sputtering yields of highest ve etching product species including C atom(s) (Figs.15 and 16).The most frequently observed cluster is CN in the present simulations. More detailed lists of etching products including C atoms generated by N and N2 atom/molecule bombardment Fig.12: Main etching product species for (a) N, (b) N2, and (c) NH3 atoms/molecules injections at 25 eV. The species are listed only having yields above 0.05.(a)00.51sdleiygnirettupsNN2CNspeciesN injections (25eV)(b)00.51sdleiygnirettupsNN2speciesN2 injections (25eV)(c)00.51sdleiygnirettupsNNHNH2NH3HH2speciesNH3 injections (25eV)Fig.13: Main etching product species for (a) N and (b) NH3 atoms/molecules injections at 50 eV. The species are listed only having yields above 0.05.(a)00.51sdleiygnirettupsNNHN2CNHspeciesN injections (50eV)(b)00.51sdleiygnirettupsNN2NHHH2speciesNH3 injections (50eV)