Browsing by Author "Chiou, SY"

Now showing 1 - 3 of 3

Barrier capability of HfN films with various nitrogen concentrations against copper diffusion in CuHf-N/n(+)-p junction diodes
(2005)
Ou, KL
;
Chiou, SY
;
Lin, MH
;
Hsu, RQ
;
機械工程學系
Hafnium-based (Hf-N) films were prepared by reactive radio frequency (rf)-magnetron sputtering on blank silicon wafers. Nitrogen incorporation and phase transformation of hafnium-based thin film were analyzed by cross-sectional transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The as-deposited Hf film has a hexagonal close-packed structure and a low resistivity of 48.29 muOmega cm. With increasing nitrogen concentration of Hf-N film, phase transformations are identified as alpha-Hf --> HfN0.4 --> epsilon-Hf3N2 --> fcc-HfN. The thermal stability of the Cu/Hf-N/Si contact system is evaluated by thermal stressing at various annealing temperatures. For the Cu/Hf/Si contact system, the inter-facial reaction between the Hf barrier layer and the Cu layer is observed after annealing at 550degreesC for 30 min, and copper-hafnium compounds form. Highly resistive copper silicide forms after annealing at 600degreesC for 30 min. The Elf barrier fails due to the reaction of Cu and the Hf barrier, in which Cu atoms penetrate into the Si substrate after annealing at high temperature. However, no copper-hafnium and copper silicide compounds are found for the Cu/HfN0.47/Si contact system even after annealing at 650degreesC for 30 min. A hafnium diffusion barrier incorporated with nitrogen can suppress the formation of copper-hafnium compounds and copper penetration, and thus enhance the thermal stability of the barrier layer. (C) 2005 The Electrochemical Society.
Electron inelastic interactions with overlayer systems
(1999-06-15)
Kwei, CM
;
Chiou, SY
;
Li, YC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
An overlayer system composed of a thin film on the top of a semi-infinite substrate was studied in this work for electron inelastic interactions. Analytical expressions for the depth-dependent inelastic differential and integral inverse mean free paths were derived for both incident and escaping electrons. The interface (film-substrate) effect and the surface (vacuum-film) effect were analyzed by comparing the results of an overlayer system and a semi-infinite system. It was found that the interface effect extended to several angstroms on both sides of the interface for a 500 eV electron incident into or escaping from the vacuum-SiO2-Si and the vacuum-Au-Ni systems. An application of the spatial-varying inelastic differential inverse mean free paths was made by Monte Carlo simulations of the electron elastic backscattering from an overlayer system. Good agreement was found between results calculated presently and data measured experimentally on the elastic reflection coefficient. (C) 1999 American Institute of Physics. [S0021-8979(99)00712-4].
Improved TaN barrier layer against Cu diffusion by formation of an amorphous layer using plasma treatment
(2002-09-01)
Ou, KL
;
Wu, WF
;
Chou, CP
;
Chiou, SY
;
Wu, CC
The thermal stability and electrical properties of plasma-treated TaN films have been investigated by Cu/TaN/Si systems. The properties of diffusion barrier were evaluated by sheet resistance, x-ray diffraction (XRD), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), energy-dispersive spectroscopy (EDS), Auger electron microscopy (AES), and reverse-biased junction leakage current. A new amorphous layer is found to form on the surface of TaN film after the plasma treatment, Plasma-treated TaN films show better barrier performance than untreated TaN films. The sheet resistance of Cu/TaN(10 nm)/Si increases apparently after annealing at 625 degreesC for 1 h, while the Cu/plasma-treated TaN(10 nm)/Si is fairly stable up to annealing at 750 degreesC. The resistance to copper diffusion in plasma-treated TaN film is more effective. This is attributed that an amorphous layer that forms on the surface of TaN film after the plasma treatment. The thermal stabilities of Cu/TaN/n(+)-p junction diodes are enhanced by plasma treatment. The Cu/TaN(10 nm)/n(+)-p and Cu/TaN(50 nm)/n(+)-p junction diodes result in large reverse-biased junction leakage currents after annealing at 525 and 575 degreesC, respectively. On the other hand, plasma-treated TaN diffusion barriers improve the integrity of junction diodes up to 650 degreesC. Nano crystallization and stuffing effects of plasma treatments are believed to impede Cu diffusion into the Si substrate and hence improve the barrier performance. (C) 2002 American Vacuum Society.