1. School of Medicine, Comenius University, Bratislava, Slovak Republic; 2. Institute of Scientific and Industrial Research, Osaka University and CREST, Japan Science and
Abstract：SiO2 thin films still belong to extensively studied material because if they are prepared in the form of high quality ultrathin and very thin oxides, they can be used in different actual applications, e.g. as gate oxides in the formation of VLSI as well as in the LCD production. We analyzed properties of very-thin SiO2 layer structure with thickness of 3 nm and 5 nm formed on moderately doped n-type Si (100) wafers, which were cleaned before formation of oxide layers using the standard RCA method and consequently they were annealed in nitrogen and parts of samples were passivated in aqueous HCN solutions. FTIR spectroscopy was used for obtaining information on different types of bonds in the structure. In passivated and non-passivated samples were identified the longitudinal optical (LO) and transverse optical (TO) modes, respectively, of the Si-O-Si asymmetric stretching vibration for SiO2. It was found that TO mode position (~1 107 cm-1) and amplitude are independent on thickness of the sample. On the other hand, LO mode position varied from ~1 230 cm-1 (thickness ~1.5 nm) to ~1 244 cm-1 (thickness ~4.5 nm). From FTIR peak shifts we were able to suggest inhomogeneity in ultra-thin and very thin SiOx based structures. Detailed deconvolution of FTIR spectra was performed to obtain relevant information. Atomic composition of the samples was investigated by SIMS method. Surprisingly, there were identified also NH bonds of different amounts in dependence on technological conditions. Structural properties, densities of layers, roughnesses of surfaces and corresponding interfaces were determined, also, by original method based on theoretical treatment of data recorded of samples by X-ray reflectivity. The results are compared and discussed with ones obtained by AFM. By charge version of deep level transient spectroscopy we have confirmed strong passivation influence of HCN solutions on the SiO2/Si interface density of states. After passivation procedure we have registered, on negligible density level, also newly formed interface deep defect traps. Their origin we relate with just formed NH atomic couples introduced to the interface region by passivation procedure.
KOPANI M, KOBAYASHI H, TAKAHASHI M, MIKULA M, IMAMURA K, VOJTEK P , PINCIK E. 湿法化学制备的超薄和极薄二氧化硅/硅膜的光学性能研究[J]. 冶金分析, 2012, 32(10): 64-67.
KOPANI M, KOBAYASHI H,TAKAHASHI M, MIKULA M,IMAMURA K, VOJTEK P, PINCIK E. Study on optical properties of ultra-thin and very-thin silicon oxide/silicon structures prepared by chemical wet methods. , 2012, 32(10): 64-67.
