The measurement and analysis were carried out on the Si(111) surface implanted by N+1,N+2,N+10 cluster ions with high doses (1.7×1017ions/cm2) at 76keV energy using ellipsometry,Fourier-transform infrared (FT-IR) absorption spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy.It was found that the medium layer containing Si-N bond on the surface appeared,and their complex refractive index turned into real;however,at the same implantation dose their surface morphologies were different from each other.Expect for a few pittings,the N+1-implanted surface had a best fineness (average roughness Ra≈4.2nm), close to the unimplanted original surface.The N+2-implanted surface had a black dendritic area,and had a poorer fineness (Ra≈16nm).While in the N+10-implanted surface appeared a ripple structure,with the poorest fineness (Ra≈40nm).It was indicated that the roughness of the material surface increased with the ion size and fluence at the high energy in contrast to the cluster implantation at the low energy.