| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2005: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2004: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
High-κ dielectrics have been studied extensively as an alternative to silicon oxide in the next generation of MOSFETs. Transition metal oxides such as HfO_2, ZrO_2 and rare earth metal oxide such as La_2O_3 and their silicates and aluminates have attracted much attention because of high dielectric constant, high thermal stability and high energy barriers at the interface for electrons and holes in Si. In the formation process of high-κ dielectrics on Si substrate, the transition layer (TL) consisting of silicate layer is intentionally or inevitably formed between high-κ dielectrics and Si substrate. SiO_2/Si interfacial TL must be also formed between this silicate layer and Si substrate. The interface state density and the carrier transport in the channel region must be seriously affected by the composition and electronic structure of this TL. Therefore, in the this study, the non-destructive compositional depth profiling of TL between LaOx and Si(100) substrate is performed using AR-X
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PS. 4-nm-thick lanthanum oxide films were deposited on Si(100) at room temperature by electron beam evaporation of La_2O_3. After post deposition annealing (PDA) in nitrogen gas under atmospheric pressure at 300℃, 400℃ and 500℃, Hard X-ray (5.95 keV photons) excited Si 1s and La 3d_<5/2> spectra arising from these samples were measured at photoelectron take-off angle of 6, 13, 18, 28, 50 and 78 degrees at undulator beam line(BL47XU) using high resolution electron energy analyzer R-4000 modified for Hard X-ray photoelectron spectroscopy. The samples were also measured by High resolution Rutherford backscattering (HRBS). The compositional and the chemical structures of lanthanum oxide/Si(100) system were determined by applying the maximum entropy concept to the angle-resolved Si 1s and La 3d photoelectron spectra. Results obtained are as follows : The compositional depth profile of lanthanum oxide/Si(100) structure change slightly by PDA in nitrogen gas under atmospheric pressure at 300℃, while that changes significantly by PDA at temperature above 400℃. The analyses of O 1s and Si 1s spectra indicated that the lanthanum silicate was produced by the deposition of lanthanum oxide on Si(100) and the amount of lanthanum silicate increases by PDA at temperature above 400℃. The dependence of conduction and valence band discontinuity at lanthanum oxide/Si on the annealing temperature was also determined by measuring the O 1s photoelectron energy loss and valence band spectra using a Scienta ESCA-300 electron spectrometer. Less
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