Formation of transition metal silicides by solid–gas reactions: thermodynamic and kinetic considerations

Acker, Jörg; Röver, I.; Otto, R.; Roewer, Gerhard; Bohmhammel, K.

doi:10.1016/s0167-2738(01)00768-8

Cited by 17 publications

(23 citation statements)

References 7 publications

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“…La and Y were found to form silicon nanoclusters; 15 metals such as Cr or Mn form stable, but under our reaction conditions, volatile chlorides; 13 and Fe, Co, Ni, and Pt belong to one group 9,10,13 and form trichlorosilane. Taking into account only the metals that are able to form silicide phases, the results in Tables 1 and 2 are similar in the manner of instigating the attachment of hydrogen atoms or methyl groups to silicon.…”

Section: Introductionmentioning

confidence: 63%

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Reactivity of Intermetallic Compounds: A Solid State Approach to Direct Reactions of Silicon

Acker

Bohmhammel

2002

J. Phys. Chem. B

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The present work is focused on a new approach to describe, quantify, and compare the reactivity of various transition metal silicide phases toward hydrogen chloride. Thermodynamic and kinetic parameters are obtained from isothermal calorimetric studies of these reactions. The reactivity of the silicide phases is discussed in terms of reaction start temperatures, rate constants, and apparent activation energies. Negative apparent activation energies are observed at low temperatures and are attributed to an initial stage of reaction where chlorine is chemisorbed and then incorporated into the silicide lattice near the surface. At a later time, a chlorine-containing reaction layer is formed having a composition and reactivity remarkably different from that of the bulk phase. On the basis of solid-state investigations, a diffusion model of the microscopic structure of these layers is presented, where a displacement of nickel atoms occurs followed by the occupation of nickel sites by chlorine. A model is suggested in which the electron level of the reaction layer is adjusted by the chlorine content of this layer, resulting in a electronic stabilization of silylenoide species at the surface. The model is applied to explain product distribution in the induction period during the direct reaction of silicon and methyl chloride.

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Section: Introductionmentioning

confidence: 63%

“…13,30,31 By dehydratation of nickel(II) chloride (containing 1 wt % water), a very low hydrogen chloride partial pressure is built up, and the reaction proceeds less rigorously than it does under a hydrogen chloride partial pressure of 1 bar. At temperatures below 350°C, hydrogen chloride chemisorbs on the silicide phase.…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Intermetallic Compounds: A Solid State Approach to Direct Reactions of Silicon

Acker

Bohmhammel

2002

J. Phys. Chem. B

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“…These reactions are both displayed in Figure 15. Both cases have been reported in the literature, 13,18 and it is likely that both reactions happen simultaneously. This stage is represented by the data after 24 hours.…”

Section: 8mentioning

confidence: 81%

“…Acker did a significant amount of work characterizing the behavior of metals in chlorosilane environments both as a way to synthesize metal silicides and catalyze the conversion of STC to TCS for polysilicon production. [16][17][18] Mui also studied the corrosion behavior of many structural high temperature metals in a chlorosilane environment simulated by a packed C667 bed reactor. 9 However, his work was largely application based and did not focus on the underlying mechanisms of chlorosilane corrosion.…”

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confidence: 99%

High-Temperature (550–700°C) Chlorosilane Interactions with Iron

Aller

Mason

Walls

et al. 2016

J. Electrochem. Soc.

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Chlorosilane species are commonly used at high temperatures in the manufacture and refinement of ultra-high purity silicon and silicon materials. The chlorosilane species are often highly corrosive in these processes, necessitating the use of expensive, corrosion resistant alloys for the construction of reactors, pipes, and vessels required to handle and produce them. In this study, iron, the primary alloying component of low cost metals, was exposed to a silicon tetrachloride-hydrogen vapor stream at industrially-relevant times (0-100 hours), temperatures (550-700 • C), and vapor stream compositions. Post exposure analyses including FE-SEM, EDS, XRD, and gravimetric analysis revealed formation and growth of stratified iron silicide surface layers, which vary as a function of time and temperature. The most common stratification after exposure was a thin FeSi layer on the surface followed by a thick stoichiometric Fe 3 Si layer, a silicon activity gradient in an iron lattice, and finally, unreacted iron. Speculated mechanisms to explain these observations were supported by thermodynamic equilibrium simulations of experimental conditions. This study furthers the understanding of metals in chlorosilane environments, which is critically important for manufacturing the high purity silicon required for silicon-based electronic and photovoltaic devices.

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“…24,25 They proposed several reactions in the metal-chlorosilane system that can take place to form metal silicides. The first is the direct reaction of a metal with STC to form a silicon rich metal silicide as modeled by Equation 1.…”

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confidence: 99%

High Temperature Chlorosilane Corrosion of AISI 316L

Aller

Ellingwood

Jacobson

et al. 2016

J. Electrochem. Soc.

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Chlorosilanes are used at high temperatures throughout the world's semiconductor industries primarily as a way to refine and deposit silicon and silicon containing materials. They are most prevalent in the manufacture of solar grade polycrystalline silicon; an industry that has historically used high cost alloys to effectively handle corrosive chlorosilane species. This study focused on understanding the corrosion behaviors of AISI 316L stainless steel, a low cost alloy, in chlorosilane environments at a variety of industrially-relevant times (0-200 hours), temperatures (500-700 • C), and hydrogen chloride (HCl) mole fractions (0.0-0.06). It was observed that AISI 316L can form either predominately metal chloride or metal silicide corrosion products depending on the mole fraction of HCl. Increasing temperatures tend to favor metal silicide formation, a trend predicted by thermodynamically generated predominance diagrams. Additionally, metal silicide surface layer growth appears to be diffusion controlled with an apparent parabolic rate at long times and high temperatures. There is also evidence for reaction-limited iron silicide formation at lower temperatures. Improved understanding of metals in high-temperature chlorosilane environments will help guide materials selection processes, and ultimately facilitate cost-competitive deployment of silicon-based photovoltaic systems. Chlorosilane species are used throughout the semiconductor, polycrystalline silicon, and fumed silica industries, primarily as a way to refine, deposit, and produce silicon and silicon containing materials. 1-4A typical chlorosilane gas stream usually contains some mixture of silicon tetrachloride (SiCl 4 , STC), trichlorosilane (HSiCl 3 , TCS), dichlorosilane (H 2 SiCl 2 , DCS), silane (SiH 4 ), hydrogen chloride (HCl), and hydrogen (H 2 ). The presence of both silicon-and chlorinecontaining species creates a unique corrosion environment for the metallic materials tasked with handling chlorosilane gas streams due to the propensity of many metals to form both metal-chlorides and metal-silicides.Metal-silicide and metal-chloride formation has been studied extensively for other applications. For example, metal chlorides have been studied due to the presence of chlorine in many industrial processes and metal silicides have been studied due to their use in electronics. It is generally considered that chloride formation is more problematic than silicide formation in industrial applications. This is because metal chlorides have high vapor pressures (at elevated temperatures) and can reactively evaporate 5 while metal silicides are potentially protective by forming dense, well-adhered surface layers. Consequently, for chlorosilane service, many industrial plants use alloys that resist chloride attack; however, the implementation of expensive corrosion resistant alloys comes at great cost. This is especially true in the polysilicon industry, where economic silicon refinement requires many large reactors and other process vessels. Because of process...

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Formation of transition metal silicides by solid–gas reactions: thermodynamic and kinetic considerations

Cited by 17 publications

References 7 publications

Reactivity of Intermetallic Compounds: A Solid State Approach to Direct Reactions of Silicon

Reactivity of Intermetallic Compounds: A Solid State Approach to Direct Reactions of Silicon

High-Temperature (550–700°C) Chlorosilane Interactions with Iron

High Temperature Chlorosilane Corrosion of AISI 316L

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