Tungsten

About: Tungsten is a research topic. Over the lifetime, 35225 publications have been published within this topic receiving 456213 citations. The topic is also known as: W & element 74.

Plasma etching apparatus

Abstract: An apparatus for etching a WSi film on a wafer by using a plasma of a gas containing a halogen element includes a vacuum process chamber in which upper and lower counter electrodes are provided. An electrostatic chuck is provided on a table at the center of a susceptor or the lower electrode. The wafer is held on the electrostatic chuck. A focus ring surrounding the wafer in a complementary manner is placed on a flange of the susceptor. The temperature of the wafer surface is set to be lower than that of the surface of the focus ring while the plasma is being generated. The focus ring comprises an inner part of amorphous carbon and an outer part of tungsten. While the plasma is being generated, a halide of tungsten generated from the outer part is diffused on the wafer surface, thereby correcting a distribution of the amount of the halide of tungsten on the wafer surface. Thus, the uniformity within the wafer surface of the etching rate and etching anisotropy is enhanced.

Microstructure and hydroabrasive wear behaviour of high velocity oxy-fuel thermally sprayed WCCo(Cr) coatings

Abstract: Sand erosion tests were performed on WC-Co and WC-CoCr coatings deposited by the high velocity oxy-fuel spraying method. Several analytical techniques, including X-ray diffraction, Auger electron spectroscopy and energy-dispersive spectroscopy in a transmission electron microscope were used to characterize the microstructures formed during powder processing and spraying. It was found that a substantial fraction of WC decomposed into W2C or reacted with the cobalt matrix to form ternary carbides such as Co3W3C and other mixed compounds. In both cases the binder phase had a nanocrystalline structure of size 4-8 nm containing tungsten, cobalt, carbon and chromium elements. The addition of chromium inhibits to a large extent the decomposition of WC and avoids the formation of metallic tungsten. In addition, chromium improved the erosion resistance by several times compared with the WC-Co coating. Scanning electron microscopy showed that the CoCr matrix binds carbides better than the cobalt matrix, thereby inhibiting carbide loss at the spray particle boundaries. The hydroabrasive wear behaviour of coatings and the mechanisms for material removal are discussed with respect to the microstructures formed during spraying.

Wafer-scale laser pantography: Fabrication of n-metal-oxide-semiconductor transistors and small-scale integrated circuits by direct-write laser-induced pyrolytic reactions

Abstract: A complete set of processes sufficient for manufacture of n‐metal‐oxide‐semiconductor (n‐MOS) transistors by a laser‐induced direct‐write process has been demonstrated separately, and integrated to yield functional transistors. Gates and interconnects were fabricated of various combinations of n‐doped and intrinsic polysilicon, tungsten, and tungsten silicide compounds. Both 0.1‐μm and 1‐μm‐thick gate oxides were micromachined with and without etchant gas, and the exposed p‐Si [100] substrate was cleaned and, at times, etched. Diffusion regions were doped by laser‐induced pyrolytic decomposition of phosphine followed by laser annealing. Along with the successful manufacture of working n‐MOS transistors and a set of elementary digital logic gates, this letter reports the successful use of several laser‐induced surface reactions that have not been reported previously.

Activation of plasmons and polarons in solar control cesium tungsten bronze and reduced tungsten oxide nanoparticles

Abstract: Dispersions of reduced tungsten oxide and tungsten bronze nanoparticles are known to show a remarkable absorption of near-infrared (NIR) light applicable to solar control filters for automotive and architectural windows. Origin of the NIR absorption has been investigated by analyzing dielectric constants of CsxWO3 (x = 0.15, 0.25, and 0.33) and WO2.72, and using Mie scattering theory. The optical analysis and Mie scattering theory analysis indicate that a localized surface plasmon resonance and polarons of localized electrons contribute alongside to the observed NIR absorption at different wavelengths.