Structural control of nonequilibrium WSi2.6 thin films by external stress

Fujimura, Norifumi; Tachibana, Shoji; Itô, Taichiro; Hosokawa, Norio

doi:10.1063/1.353330

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…Информация об особенностях межфазного взаимодействия слоев вольфрама и кремния, кроме многослойной рентгеновской оптики, востребована при изготовлении СБИС (динамические запоминающие устройства [11], барьерных слоев [12,13], пленочных сопротивлений [14], разводки для микросхем [15,16] и т.д. ); однофотонных детекторов [17,18]; пассивирующих покрытий, работающих при повышенной температуре [19]; термоэлементов [20]; для термоядерного синтеза [21], и др.…”

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STRUCTURE AND PHASE COMPOSITION OF W-Si MULTILAYER X-RAY MIRRORS

Pershyn

Shipkova

Devizenko

et al. 2018

EEJP

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X-ray diffractometry in a hard region (l~0.154 nm) was used to study the phase structure, composition and construction of W/Si multilayer X-ray mirrors (MXMs) with thicknesses of tW<10 nm for tungsten layers obtained by direct-current magnetron sputtering. Two series of samples were fabricated with different tungsten deposition rates, which differ approximately by a factor of 4: ~0.60 nm/s and ~0.15 nm/s. It is shown that tungsten layers have a polycrystalline (BCC) structure at thicknesses tW>2.7 nm, and at tW<1.9 nm they are amorphous. Using the sin2Y-method, it was found that in thin crystalline layers of tungsten (tW<10 nm), more than 3 at.% Si can be contained. Tensile stresses in the layers of crystalline tungsten do not exceed 1.1 GPa. The construction of the radial distribution functions of atoms made it possible to establish that amorphous layers of tungsten have an arrangement of atoms close to b-W. In all samples, formation of silicide interlayers is observed at the interfaces, as a result of which the actual thickness of the tungsten layers is less than the nominal one. Amorphous silicide layers, necessarily formed at the stage of MXM manufacturing, contain tungsten disilicide. Depending on the deposition rate, disilicide can have an arrangement of atoms close to either the tetragonal phase, t-WSi2 (~0.6 nm/s), or to the hexagonal phase, h-WSi2 (~0.15 nm/s). An improved model for the construction of amorphous W/Si MXMs is presented. Mechanisms for the formation of silicide layers are proposed, according to which the bottom silicide interlayers (W-on-Si) are formed mainly by ballistic mixing of tungsten and silicon atoms, and the top ones due to diffusion inermixing. The interdiffusion coefficients were estimated, which made it possible to establish that the deposited surface of the layers can be heated at least 250° above the substrate temperature. The ways of reducing the interface interaction are suggested.

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STRUCTURE AND PHASE COMPOSITION OF W-Si MULTILAYER X-RAY MIRRORS

Pershyn

Shipkova

Devizenko

et al. 2018

EEJP

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Studies on structural, electrical, compositional, and mechanical properties of WSix thin films produced by low-pressure chemical vapor deposition

Santucci¹,

Lozzi²,

Passacantando³

et al. 1998

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Tungsten silicide (WSix) thin films have been deposited by low-pressure chemical vapor deposition using silane (SiH4) and tungsten hexafluoride (WF6) at different fluxes ratio ranging from 44 to 745 onto planar Si(100) wafers covered by 130 Å of SiO2 and 2000 Å of phosphorus-doped polysilicon layers to reproduce the control gate structure of a FLASH-EEPROM. The deposited films have been annealed in oxygen ambient at 900 °C. The composition of as deposited films as well as annealed films has been studied by x-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, and secondary ion mass spectroscopy. Cross section scanning electron microscopy and atomic force microscopy have been employed to study the thickness and the surface morphology of the deposited layers. The resistivity and the mechanical properties of the films have been also investigated. The as-deposited films have shown, growing the SiH4/WF6 ratio, an increase of the Si/W stoichiometric ratio (until 3), a decrease of the film thickness and stress while there is an increase of the sheet resistance. In the case of annealed films, which pass from amorphous state to crystalline structure, as detected by x-ray diffraction, there is a strong decrease of the sheet resistance values as well as of the silicide film thickness depending on the SiH4/WF6 ratio, while the presence of a silicon oxide layer with different thickness has been also detected on top of the silicide layer.

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Structural control of nonequilibrium WSi2.6 thin films by external stress

Cited by 2 publications

References 15 publications

STRUCTURE AND PHASE COMPOSITION OF W-Si MULTILAYER X-RAY MIRRORS

STRUCTURE AND PHASE COMPOSITION OF W-Si MULTILAYER X-RAY MIRRORS

Studies on structural, electrical, compositional, and mechanical properties of WSix thin films produced by low-pressure chemical vapor deposition

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