Pseudoepitaxial transrotational structures in 14 nm-thick NiSi layers on [001] silicon

Alberti, Alessandra; Bongiorno, Corrado; Cafra, Brunella; Mannino, Giovanni; Rimini, E.; Metzger, T. H.; Mocuta, Cristian; Kammler, Thorsten; Feudel, Thomas

doi:10.1107/s0108768105022585

Cited by 31 publications

(22 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…One of those bending contour (b1), which is the most representative one, originates from the (020) NiSi planes which are known to be anchored to (220) Si planes through the layer/substrate interface. 9 It was found 9 that a 618 continuous rotation of the orthorombic NiSi lattice around the direction normal to the (020) planes moves the lattice configuration from the [102] to the [201] zone axis passing through [101] without meeting other relevant axes in between. This causes the domains to have just those three selective zone axes (identifying the crystallographic axis perpendicular to the interface), and, thus, to be of just three different types.…”

mentioning

confidence: 99%

Nanoscale study of the current transport through transrotational NiSi/n-Si contacts by conductive atomic force microscopy

Alberti

Giannazzo

2012

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

The average electrical behaviour of transrotational NiSi layers used as contacts in diode structures on n-type Si was correlated to the local structure and conduction paths inside each domain by using conductive-atomic force microscopy. It was found that, independently of the domain orientation, the central portion of the domain (core $ 20 nm) possesses a Schottky barrier lower than in the rest of the structure. This was ascribed to an effect of the structural coupling between the NiSi lattice and the silicon substrate as realised at the interface in virtue of the pseudoepitaxial relationship established since the early stages of the reaction. V C 2012 American Institute of Physics.It is well assessed that the use of nickel silicide on source and drain contacts of microelectronic devices has a significant impact to reduce series and contact resistances. 1,2 The drastic scaling down of devices and also the recent interest to use plastic substrates, which have low critical temperatures (e.g., Tc polyimide 200 C), pose more and more the need to optimize the material properties, and particularly, the interfaces quality on the nanoscale. It is thus mandatory to know in more detail the process of silicide formation since the very early stages of the reaction process to control the structure and the stoichiometry of the silicide, especially on very thin layers.The pioneering studies on the very early stages of Ni-Si reaction date from 1980. It was observed that, on a perfectly cleaned Si surface, a Ni-Si precursor layer is formed even at room temperature (RT) after deposition of a very thin nickel layer (<2 nm). 3 The precursor layer (or diffusion layer) is formed once nickel atoms come in contact with silicon, and reasonably maintained also after subsequent reaction: its presence is thus adduced as the reason why all the Ni-silicide phases have comparable Schottky barrier height (e.g., 0.66 eV on n-type Si). 4 The precursor layer has a disordered structure with Ni atoms having the short range environment similar to that encountered in the NiSi 2 lattice 3 and originates from the diffusion process of Ni atoms into the Si lattice by means of tetrahedral interstitial sites. Due to the similarity of the diffusion layer structure to that of the NiSi 2 lattice, an epitaxial silicide layer is formed upsetting the usual sequence of phases encountered in thick layers, without significant transport of matter, 3 by annealing at relatively low temperature ($450 C). A different scenario is instead observed by depositing at RT a supply of Ni atoms on top of the interfacial diffusion layer. When a supply of Ni is then present, the role of the diffusion layer, as precursor to the reaction process, is shadowed by the fast diffusion of nickel atoms, and a conventional phase sequence is observed with NiSi 2 formed at the end, at the NiSi-Si interface. 1 We have recently 5 shown that the direct transition to NiSi 2 can be assured even in the presence of a nickel supply ($7 nm) by using a $2 nm-thick precursor layer and by reducing anneali...

show abstract

mentioning

confidence: 99%

Nanoscale study of the current transport through transrotational NiSi/n-Si contacts by conductive atomic force microscopy

Alberti

Giannazzo

2012

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…Alberti et al observed the formation of so-called "transrotational" domains, both in Ni 2 Si and NiSi films. 49,111 These domains result from a bending (either spherical or cylindrical) of specific crystallographic planes of the film in order to adapt to the crystal structure of the substrate. 49 This transrotational NiSi has been observed to form under different experimental conditions (annealing ambient, substrate doping, etc.)…”

Section: Nisimentioning

confidence: 99%

“…49,111 These domains result from a bending (either spherical or cylindrical) of specific crystallographic planes of the film in order to adapt to the crystal structure of the substrate. 49 This transrotational NiSi has been observed to form under different experimental conditions (annealing ambient, substrate doping, etc.) as long as specific care is taken during the deposition of the initial Ni film: the Ni must be deposited at slightly elevated temperatures in order to obtain a Ni-rich intermixed Ni:Si layer and when the thickness of the deposited Ni surpasses $7 nm, a low temperature isothermal anneal is necessary to form transrotational NiSi.…”

Section: Nisimentioning

confidence: 99%

Texture in thin film silicides and germanides: A review

Schutter

Keyser

Lavoie

et al. 2016

Applied Physics Reviews

View full text Add to dashboard Cite

“…10) It was found that the layer has a transrotational structure. 6) The structure of a transrotational domain, as shown in the TEM plan-view image of Fig.…”

mentioning

confidence: 99%

“…We have additionally shown 7) that the composition of the precursor layer can be also modified by slightly increasing the deposition temperature. A 6 nm precursor layer (amorphous), with a Ni:Si concentration ratio of $3, can be formed on an oxygen-free Si substrate by depositing nickel atoms at $50 C. 8) From the amorphous mixed layer first transrotational Ni 2 Si 9) and, subsequently, transrotational NiSi domains originate 10,11) during lowtemperature annealing (e.g., 260 C).…”

mentioning

confidence: 99%

Schottky Barrier Inhomogeneities in Nickel Silicide Transrotational Contacts

Alberti

Roccaforte

Libertino

et al. 2011

Appl. Phys. Express

Self Cite

View full text Add to dashboard Cite

Ni-silicide/silicon Schottky contacts have been realised by promoting low-temperature Ni–Si interdiffusion during deposition (∼50 °C) and reaction (450 °C) on an oxygen-free [001] silicon surface. A 14 nm transrotational NiSi layer was produced made of extremely flat pseudo-epitaxial domains (∼200 nm in diameter). The current–voltage (I–V) characteristics (340–80 K) have indicated the presence of structural inhomogeneities which lower the Schottky barrier by Δ≈0.1 eV. They have been associated with the core regions of the trans-domains (wherein the silicide lattice is epitaxially aligned to that of Si) since their density (∼2.5×109 cm-2) and dimension (∼10 nm) fit the I–V curves vs temperature following the Tung's approach.

show abstract

Pseudoepitaxial transrotational structures in 14 nm-thick NiSi layers on [001] silicon

Cited by 31 publications

References 15 publications

Nanoscale study of the current transport through transrotational NiSi/n-Si contacts by conductive atomic force microscopy

Nanoscale study of the current transport through transrotational NiSi/n-Si contacts by conductive atomic force microscopy

Texture in thin film silicides and germanides: A review

Schottky Barrier Inhomogeneities in Nickel Silicide Transrotational Contacts

Contact Info

Product

Resources

About