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The Schottky barrier height ͑SBH͒ of NiSi on Si͑100͒ was tuned in a controlled manner by the segregation of sulfur ͑S͒ to the silicide/silicon interface. S was implanted into silicon prior to silicidation. During subsequent Ni silicidation, the segregation of S at the NiSi/ Si interface leads to the change of the SBH. The SBH of NiSi decreased gradually on n-Si͑100͒ from 0.65 eV to 0.07 eV and increased correspondingly on p-Si͑100͒. © 2005 American Institute of Physics. ͓DOI: 10.1063/1.1863442͔ Self-aligned silicidation is one of the key technologies in the state-of-art complementary metal-oxide-semiconductor ͑CMOS͒ process to make Ohmic or Schottky contacts at source/drain and gate. Amongst of them, NiSi silicide has emerged as a leading choice in Si nanometer electronics due to its low resistivity and high scalability. Recently, Schottky barrier source/drain metal-oxide-semiconductor field-effect transistors ͑MOSFETs͒ have been receiving a lot of attention because of the lower parasitic series resistance at source/ drain, possible zero junction depth and simpler fabrication process.1-4 However, for a typical Schottky barrier ͑SB͒ MOSFET, the on-current is limited by the tunneling through the Schottky barrier at the source. If a very low or a negative SBH could be realized, the on-current of SB-MOSFET could be increased substantially. 4 NiSi has an experimental SBH of 0.65 eV on n-Si͑100͒. This high SBH value hinders the application of NiSi in SB-MOSFETs. If we can lower the SBH of silicides to very low value, the device exhibits the same intrinsic performance as conventional MOSFET but also benefits from the advantages of SB-MOSFETs mentioned above.In an ideal metal-semiconductor system the SchottkyMott theory suggests that the SBH ͑⌽ B ͒ is simply determined by the difference between the work function of the metal ͑ M ͒ and the electron affinity of the semiconductor5 In practice, however, the presence of interface states leads to the SBH being less dependent on the metal work function. Dangling bonds at the semiconductor surface can be eliminated by valence-mending adsorbates. 6 S and Se are two possible valence-mending candidates for the Si͑100͒ surface.6 Lacharme et al. 7 reported that surface states on Si can be removed by S exposure at room temperature. Tao et al. [8][9][10] have used a monolayer of Se to eliminate the surface states on the Si͑001͒ surface by terminating dangling bond and relaxing strained bonds. Pure metals, like Mg, Al, Cr, and Ti, on Se-passivated n-Si͑001͒ showed very low and even negative SBH values which can be predicted by the Schottky-Mott theory.8-10 However, deposition of these elements seems inappropriate for silicide contacts on Si due to the suppression of silicide formation. 10 In order to benefit from advantages of silicides in state-of-art MOSFET technology, methods to tune the SBH of silicides on Si are required. In this paper we show an effective method to tune the SBH value of NiSi on both n-and p-type Si͑100͒. A small dose of S ions was implanted into Si before Ni de...

Gadolinium scandate thin films deposited on silicon substrates using electron beam evaporation were investigated. Measurements with Rutherford backscattering spectrometry, high temperature x-ray diffraction, x-ray reflectometry, transmission electron microscopy, and atomic force microscopy were performed. A stoichiometric transfer of material from the source to the substrate in high vacuum could be demonstrated. Homogeneous, amorphous, and smooth films ͑root mean square surface roughness Ͻ1 Å͒ stable up to 1000°C were obtained. Electrical characterization of capacitor stacks revealed a dielectric constant of Ϸ23, C-V curves with small hysteresises and low leakage current densities ͑770 A/cm 2 for a capacitance equivalent thickness of 1.5 nm͒.

We present an investigation of the use of dopant segregation in Schottky-barrier metal-oxide-semiconductor field-effect transistors on silicon-on-insulator. Experimental results on devices with fully nickel silicided source and drain contacts show that arsenic segregation during silicidation leads to strongly improved device characteristics due to a strong conduction/valence band bending at the contact interface induced by a very thin, highly doped silicon layer formed during the silicidation. With simulations, we study the effect of varying silicon-on-insulator and gate oxide thicknesses on the performance of Schottky-barrier devices with dopant segregation. It is shown that due to the improved electrostatic gate control, a combination of both ultrathin silicon bodies and gate oxides with dopant segregation yields even further improved device characteristics greatly relaxing the need for low Schottky barrier materials in order to realize high-performance Schottky-barrier transistors.