Showing papers by "Karl Opsomer published in 2005"

The barrier height inhomogeneity in identically prepared Au/n-GaAs Schottky barrier diodes

Abstract: We have prepared small Au/n-GaAs Schottky barrier diodes (SBDs) using e-beam lithography (EBL), and obtained their effective barrier heights (BHs) and ideality factors from current–voltage ( I / V ) characteristics, which were measured using a conducting probe atomic force microscope (CP-AFM). Although the diodes were all identically prepared, there was a diode-to-diode variation: the effective BHs ranged from 0.795 eV to 0.836 eV, and the ideality factor from 1.025 to 1.101. Lateral homogeneous BHs were computed from the observed linear correlation between BH and ideality factor using the method of Schmitsdorf et al. [Schmitsdorf RF, Kampen TU, Monch W. J Vac Sci Technol B 1997;15(4):1221]. These homogeneous BHs were also obtained from the fit to the experimental I / V characteristics of the current through a “patchy” diode. From our model, the barrier height in the patches and their diameter could be determined. It are however the homogeneous BHs which should be used to make theories of the physical mechanisms responsible for the Schottky barrier height of the metal–semiconductor combination considered.

Demonstration of Ni fully germanosilicide as a pFET gate electrode candidate on HfSiON

Abstract: We report for the first time on the use of a Ni fully germano-silicide (FUGESI) as a metal gate in pFETs. Using HfSiON dielectrics and comparing to Ni FUSI devices, we demonstrate that the addition of Ge in poly-Si gate results in 1) Fermi-level unpinning with >200 mV increase in work function; 2) improved dielectrics integrity: such as decreased 1/f and generation-recombination noise, improved channel interface, reduced gate leakage, and superior NBTI characteristics. The above experimental observations are correlated to oxygen vacancies related defects in the HfSiON layer

Method for forming a self-aligned germanide and devices obtained thereof

Abstract: A method for removing unreacted metal from a germanium layer, a germanide layer and or a dielectric material. The method includes removing the unreacted metal using a chemical composition that includes one or more hydrohalides, such as in an aqueous form. In certain embodiments, the chemical composition may also include H 2 SO 4 . Also, in certain embodiments, the chemical composition may be heated to increase the etch rate of the unreacted metal and/or improve the etch selectivity to the germanium, the germanide and/or the dielectric material.

Use of composition, aqueous composition, formation method of self-aligning germanide and semiconductor device

Abstract: PROBLEM TO BE SOLVED: To form a germanide structure within a germanium region on a semiconductor substrate through a self-alignment method. SOLUTION: The method for forming the germanide structure within the germanium region on the semiconductor substrate through the self-alignment method includes a step of depositing a metal layer on the substrate and the germanium region, a step of heating the structure to form a metal and a germanium compound, and a step of selectively removing unreacted metals from germanide and the substrate. This invention discloses use of hydrogen halide for selectively removing the metal from a compound layer produced through a reaction between the metal and germanium. In a preferred embodiment, nickel is used as the metal for forming nickel germanide, and HCl is used as an etchant for selectively removing nickel. COPYRIGHT: (C)2005,JPO&NCIPI

Thermomechanical Properties of Nickel Silicide: Dependence on the Microstructure

Abstract: Nickel monosilicide (NiSi) is a key material in microelectronics and its thermomechanical properties play an important role in determining the stress/strain field generated in a transistor structure. The Coefficient of Thermal Expansion (CTE) is of particular importance in the determination of such a field. As NiSi is used in microelectronics in its polycrystalline form, it becomes of particular interest to study the thermomechanical behaviour of the NiSi aggregate, considered as a unique macroscopic body. The grain orientation of a 120 nm polycrystalline NiSi film grown on single crystal silicon has been studied by means of electron diffraction, and the evaluation of the CTE tensor of the film in the wafer reference frame has been performed by weighted averaging the single grain contributions. The results clearly show the importance of orientation distribution in determining the value of the equivalent coefficient of thermal expansion of the aggregate.