Formation and stability of silicides on polycrystalline silicon

Colgan, E. G.; Gambino, J.; Hong, Q. Z.

doi:10.1016/0927-796x(95)00186-7

Cited by 204 publications

(110 citation statements)

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“…Owing to its chemical inertness and its high thermodynamic stability a PtSi counter body was used as a reference and in order to realize the case of complete immiscibility with Ag and Au(111). The thermodynamic stability of PtSi is demonstrated by its high melting point T m = 1,504.74 K [12] and its highly negative standard enthalpy of formation H f = −118 kJ/mol [13]. In contrast, a gold counter body was selected owing to its full miscibillity with Ag so as to exemplify the case of a negative enthalpy of mixing (   mix Au Ag H = −4.5 kJ/(g·atom) at 800 K) [14], on the one hand.…”

Section: Experimental Methodsmentioning

confidence: 99%

Chemical effects on the sliding friction of Ag and Au(111)

Kwan

Park

et al. 2017

Friction

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Abstract:We have investigated the sliding friction behavior of metallic couples with different enthalpy of mixing or reaction by friction force microscopy. Comparing the friction behavior of miscible and immiscible couples we find that in the first case friction is governed by adhesion while the shear strength is low (τ = 3-6 MPa). In the latter case of immiscible couples, adhesion is found to be low and the shear strength is large (τ ≈ 70 MPa). Statistical analysis of atomic stick-slip images recorded on an Au(111) surface with tips of different affinities with gold allows for a deeper understanding of our results. The periodicity of atomic stick-slip images corresponds to the interatomic distance of gold for immiscible counter-bodies. In contrast, for a reactive couple the periodicity of atomic stick-slip significantly differs from the gold interatomic distance and may correspond to the structural length of an ordered intermediate phase at the tip-surface interface.

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Section: Experimental Methodsmentioning

confidence: 99%

Chemical effects on the sliding friction of Ag and Au(111)

Kwan

Park

et al. 2017

Friction

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“…1,2 Feature size has shrunk to a few tens of nanometers, and for nickel monosilicide ͑NiSi͒ layers, this results in a particularly severe tendency to agglomerate, 3 leading to a large increase in the electrical resistance of the contact, and an increased mobility of the nickel as it starts to move on the defects, both resulting in a low yield. Since the agglomeration of thin films is driven by a minimization of interface energy, it is expected that thinner films will agglomerate faster ͑i.e., have a lower agglomeration temperature͒.…”

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Phase formation and thermal stability of ultrathin nickel-silicides on Si(100)

Keyser

Bockstael

Meirhaeghe

et al. 2010

Applied Physics Letters

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The solid-state reaction and agglomeration of thin nickel-silicide films was investigated from sputter deposited nickel films ͑1-10 nm͒ on silicon-on-insulator ͑100͒ substrates. For typical anneals at a ramp rate of 3°C / s, 5-10 nm Ni films react with silicon and form NiSi, which agglomerates at 550-650°C, whereas films with a thickness of 3.7 nm of less were found to form an epitaxylike nickel-silicide layer. The resulting films show an increased thermal stability with a low electrical resistivity up to 800°C. © 2010 American Institute of Physics. ͓doi:10.1063/1.3384997͔Nickel-silicides are currently used as contacting materials in state-of-the-art microelectronic devices.1,2 Feature size has shrunk to a few tens of nanometers, and for nickel monosilicide ͑NiSi͒ layers, this results in a particularly severe tendency to agglomerate, 3 leading to a large increase in the electrical resistance of the contact, and an increased mobility of the nickel as it starts to move on the defects, both resulting in a low yield. Since the agglomeration of thin films is driven by a minimization of interface energy, it is expected that thinner films will agglomerate faster ͑i.e., have a lower agglomeration temperature͒. 4 In this letter, we show that this holds true only for films with a thickness of at least 5 nm ͑as-deposited thickness of the nickel layer͒, while for thinner layers the resulting nickel-silicide layer is much more resistant to agglomeration.Nickel films with a thickness between 1 and 10 nm were sputter deposited onto lightly p-doped ͑ =14-22 ⍀ cm͒, Radio Corporation of America ͑RCA͒ cleaned, and HF dipped silicon-on-insulator substrates, with a top layer of 117 nm of Si ͑100͒. The deposition chamber was first evacuated to 10 −4 Pa during deposition, the samples were mounted on a rotating carousel to ensure a uniform deposition thickness. An argon pressure of 0.5 Pa and a sputtering power of 100 W were used, resulting in a deposition rate of 0.04 nm/s. After deposition, the samples were annealed in a high-purity He atmosphere, from 100 to 850°C at a rate of 3°C / s, and the surface roughness ͑using laser light scattering, recording the intensity of nonspecular reflection of the laser light͒, and the sheet resistance ͑using a four point probe͒ were recorded in situ. The thickness of both the as-deposited and annealed films was determined using x-ray reflectivity and cross section transmission electron microscopy, resulting in the reported thicknesses with a precision of Ϯ0.2 nm.An overview of the in situ sheet-resistance is shown in Fig. 1. All of the samples with more than 3.7 nm of nickel ͑6, 8, and 10 nm are shown͒, exhibit a sheet resistance qualitatively similar to what was previously reported 5 for 10 nm layers of nickel on Si ͑100͒; a complex phase sequence of high-resistive metal rich nickel-silicides at low temperatures, and the formation of the low-resistive NiSi phase at 400-450°C. This layer then agglomerates at 550-650°C, leading to the observed increase in sheet resistance. In contrast, for the thinn...

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“…This result was very surprising, as previous studies of the morphological stability of thin silicide films systematically showed a better stability on single-crystal substrates. 122 Indeed, a typical process to stabilize a film on a polycrystalline Si substrate is to anneal the substrate prior to metal deposition. This anneal results in an increase of the grain size in the polycrystalline substrate, improving the morphological stability of the film.…”

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confidence: 99%

“…These NiSi (112) agglomeration of a silicide/germanide film is considered to be a reduction of the surface and interface energy. 122,124 However, from the TEM cross-section visible in the bottom left of Fig. 21, it seems that for an agglomerated NiSi film, only the silicide/silicon interface is severely roughened while the surface remains flat, suggesting that minimizing the interface energy is the main driving force for the agglomeration.…”

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confidence: 99%