日本大学生産工学部　生産工学部研究報告A51-2

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─ 8 ─have been given in Ref.24).Our results shown so far in the present paper consistently prove that the CN layer formed on the PPP surface due to par-ticle bombardment evolves sputtering of the surface; injected N atoms make robust bonds with substrate C atoms mainly CN=1.5 bond, however, since N atoms hardly make chain structures by its own, the chemical bonding network can be broken by more injected N atoms whereas C atoms show a tendency to make chemically bonded amorphous layer on the PPP surface15, 21). This difference of chemical nature of N atom from C atom leads to the etching of the PPP surface. Once chemically bonded CN layer is formed by particle injectins, robust CN clusters are sputtered by more injected N atoms, because if the amount of N atoms reaches its saturation (NN/NC ~ 1) additional N atoms bombarded can not make clusters including over consecutive three N atoms by its chemical na-ture.Consequently, small CN clusters are sputtered as main etch-ing products from the CN layer by N atom injections over the saturation and it turns out that the substrate C atoms are sput-tered mostly as a cluster including single C atom. In the actual Fig.14: Distributions of the sputtering yields for C atoms under (a) N, N2, and NH3 injections at 25 eV and (b) N and NH3 injections at 50 eV. The vertical axis represents the number of C atoms removed from the surface per injection as a form of Hx Cy Nz for any x and z and the horizontal axis represents the number y of C atoms in a cluster Hx Cy Nz.(a)051000.030.060.090.120.150.180.210.24 number of C atoms in a desorbed clustersnoitubirtsiddleiyN injectionsN2 injectionsNH3 injectionsat 25 eV(b)051000.030.060.090.120.150.180.210.24 number of C atoms in a desorbed clustersnoitubirtsiddleiyNH3 injectionsN injectionsat 50 eVFig.15: Main etching product species including C atom(s) for (a) N, (b) N2, and (c) NH3 atoms/molecules injections at 25 eV.(a)00.050.1sdleiygnirettupsCCN2CNspeciesN injections (25eV)HCN2C2N2(b)00.050.1sdleiygnirettupsHCN2CN2CNspeciesN2 injections (25eV)C2C2N2(c)00.050.1sdleiygnirettupsHCNH2CN2H3CNH2C2NspeciesNH3 injections (25eV)H4CN2CNFig.16: Main etching product species including C atom(s) for (a) N and (b) NH3 atoms/molecules injections at 50 eV.(a)00.050.10.15sdleiygnirettupsC2CN2CNspeciesN injections (50eV)HCNHCN2(b)00.050.1sdleiygnirettupsCNHCNH2CNC2H2speciesNH3 injections (50eV)H2CN2H3CN