日本大学生産工学部　生産工学部研究報告A51-2

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─ 10 ─though substrate C atoms are hardly sputtered after 73.4 × 1015cm−2 dose of injections.5　Conclusion and DiscussionIn this paper, we have performed that numerical analysis of organic polymer etching characteristics by means of classical MD simulations. Here, we separately summarize our results in mainly two parts; (1) formation process of the CN layer on the PPP surface and (2) how to react the CN layer to ions/radicals bombardments.First, injected N atoms chemically/physically break into among carbon-carbon bonds and make robust chemical bonds with C atoms, and then, a chemically stabel CN layer are formed (Figs.6 and 11). We can speculate that C and N atoms align alternatively each other due to chemical nature of N at-oms which can not make clusters including over successive three N atoms. Therefore, one of the most eective way of ac-cumulations of N atoms into organic polymer surface is mak-ing alternate structure of C and N atoms. This fact can be comrmed indirectly from stoichiometric structures of sput-tered species or the particle number ratio of C and N atoms in the resultant substrate12, 14). The ratios, NN/NC for N and N2 in-jections, are almost unity around the surface except the case of NH3 injections at 25 eV (Figs.4 (a), 4(b) and 10). The most of the chemical bonds between C and N is CN=1.5 bond, i. e., sp2 hybridized bond for N and N2 injections (Figs.6(a), 6 (b) and 11 (a)). For NH3 injections, however, CN=1.5 bond and CN=1 (single) bond have almost same numbers and distribu-tions (Figs.6 (c) and 11 (b)) due to H atoms in injected NH3. Indeed, in this case, main sputtered species observed in our simulations have the form NxHy (Figs.12(c) and 13(b)).Next, commonly in our simulations, most eective etchant species is N atom. After particles injections, the region of NN/NC ~ 1 is larger than the other cases for N atom injections (Figs.4(a) and 10(a)) for the height range is about 1.8 nm to 2.8 nm. And, for NH3 injections, with the increase of the in-jection energy, the sputtering yield of the substrate C atom is increased (Fig.7) and NN/NC is getting closer to unity (Figs.4(c) and 10(b)). These fact manifests that the existence of the CN layer is crucially important for sputtering of the PPP surface. Furthermore, main sputtered species including C atom(s) is CN (Figs.15(a), (b) and 16(a)) or HCN (Fig.16(b)). This construction of sputtered species, CN, indicate NN/NC ~ 1 and then, alternative structure of C and N atoms on the PPP surface. However, in the case of NH3 injections at 25 eV, the sputtering of carbided clusters have been strongly suppressed (Fig.15(c)) by incident H atoms with relatively lower injection energy. Then, NN/NC < 1 is obtained (Fig.4(c)). We can specu-late that injected H atoms as NH3 molecule inhibit the forma-tion of the CN layer.On the other hand, the CN layer shows strong resistance for sputtering due to H and H2 injections with lower kinetic ener-gy (Figs.17 and 18). In both injectins, the substrate C atoms are hardly sputtered. Due to high chemical reactivity of H atom, π bonds between C and N atoms are broken, and then CN=1.5 bonds are decreased whereas CN=1 bonds are in-creased (Fig.19). Then, we can infer that when the PPP sur-face is bombarded by nitrogen- hydrogen plasmas, the CN layer is formed on the surface and after that, the sputtering is proceeding for N atom injections on the horizontal face, how-Table 1: Sputtering yields of H atom and H2 molecule, and C and N atoms.HH2YCYNsputtering yields (H injections)0.4050.1943.33×10−34.07×10−2sputtering yields (H2 injections)5.33×10−30.9810.002.00×10−3Fig.19: The area densities of CN=1 and CN=1.5 bonds vs. injection dose for (a) H and (b) H2 injections into the nitrided PPP surface. The injectin energy is 5 eV and its direction is normal to the surface.(a)019.238.457.676.896012345601[seitisneddnob15/cm2]dose [1015/cm2]NCN=1.5NCN=1H injections (5eV)into nitrided PPPH injections N injections(b)019.238.457.676.896012345601[seitisneddnob15/cm2]dose [1015/cm2]NCN=1.5NCN=1H2 injections (5eV)into nitrided PPPH2 injections N injections