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Controlling the formation and stability of ultra-thin nickel silicides : an alloying strategy for preventing agglomeration

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Abstract
The electrical contact of the source and drain regions in state-of-the-art CMOS transistors is nowadays facilitated through NiSi, which is often alloyed with Pt in order to avoid morphological agglomeration of the silicide film. However, the solid-state reaction between as-deposited Ni and the Si substrate exhibits a peculiar change for as-deposited Ni films thinner than a critical thickness of t(c) = 5 nm. Whereas thicker films form polycrystalline NiSi upon annealing above 450 degrees C, thinner films form epitaxial NiSi2 films that exhibit a high resistance toward agglomeration. For industrial applications, it is therefore of utmost importance to assess the critical thickness with high certainty and find novel methodologies to either increase or decrease its value, depending on the aimed silicide formation. This paper investigates Ni films between 0 and 15 nm initial thickness by use of "thickness gradients," which provide semi-continuous information on silicide formation and stability as a function of as-deposited layer thickness. The alloying of these Ni layers with 10% Al, Co, Ge, Pd, or Pt renders a significant change in the phase sequence as a function of thickness and dependent on the alloying element. The addition of these ternary impurities therefore changes the critical thickness t(c). The results are discussed in the framework of classical nucleation theory.
Keywords
NI SILICIDES, FILMS, NUCLEATION, ELEMENTS, NISI2, CMOS, CO, CONTACT, SILICON, SI(001)

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MLA
Geenen, Filip et al. “Controlling the Formation and Stability of Ultra-thin Nickel Silicides : an Alloying Strategy for Preventing Agglomeration.” JOURNAL OF APPLIED PHYSICS 123.7 (2018): n. pag. Print.
APA
Geenen, F., van Stiphout, K., Nanakoudis, A., Bals, S., Vantomme, A., Jordan-Sweet, J., Lavoie, C., et al. (2018). Controlling the formation and stability of ultra-thin nickel silicides : an alloying strategy for preventing agglomeration. JOURNAL OF APPLIED PHYSICS, 123(7).
Chicago author-date
Geenen, Filip, K van Stiphout, A Nanakoudis, S Bals, A Vantomme, J Jordan-Sweet, C Lavoie, and Christophe Detavernier. 2018. “Controlling the Formation and Stability of Ultra-thin Nickel Silicides : an Alloying Strategy for Preventing Agglomeration.” Journal of Applied Physics 123 (7).
Chicago author-date (all authors)
Geenen, Filip, K van Stiphout, A Nanakoudis, S Bals, A Vantomme, J Jordan-Sweet, C Lavoie, and Christophe Detavernier. 2018. “Controlling the Formation and Stability of Ultra-thin Nickel Silicides : an Alloying Strategy for Preventing Agglomeration.” Journal of Applied Physics 123 (7).
Vancouver
1.
Geenen F, van Stiphout K, Nanakoudis A, Bals S, Vantomme A, Jordan-Sweet J, et al. Controlling the formation and stability of ultra-thin nickel silicides : an alloying strategy for preventing agglomeration. JOURNAL OF APPLIED PHYSICS. 2018;123(7).
IEEE
[1]
F. Geenen et al., “Controlling the formation and stability of ultra-thin nickel silicides : an alloying strategy for preventing agglomeration,” JOURNAL OF APPLIED PHYSICS, vol. 123, no. 7, 2018.
@article{8590890,
  abstract     = {The electrical contact of the source and drain regions in state-of-the-art CMOS transistors is nowadays facilitated through NiSi, which is often alloyed with Pt in order to avoid morphological agglomeration of the silicide film. However, the solid-state reaction between as-deposited Ni and the Si substrate exhibits a peculiar change for as-deposited Ni films thinner than a critical thickness of t(c) = 5 nm. Whereas thicker films form polycrystalline NiSi upon annealing above 450 degrees C, thinner films form epitaxial NiSi2 films that exhibit a high resistance toward agglomeration. For industrial applications, it is therefore of utmost importance to assess the critical thickness with high certainty and find novel methodologies to either increase or decrease its value, depending on the aimed silicide formation. This paper investigates Ni films between 0 and 15 nm initial thickness by use of "thickness gradients," which provide semi-continuous information on silicide formation and stability as a function of as-deposited layer thickness. The alloying of these Ni layers with 10% Al, Co, Ge, Pd, or Pt renders a significant change in the phase sequence as a function of thickness and dependent on the alloying element. The addition of these ternary impurities therefore changes the critical thickness t(c). The results are discussed in the framework of classical nucleation theory.},
  articleno    = {075303},
  author       = {Geenen, Filip and van Stiphout, K and Nanakoudis, A and Bals, S and Vantomme, A and Jordan-Sweet, J and Lavoie, C and Detavernier, Christophe},
  issn         = {0021-8979},
  journal      = {JOURNAL OF APPLIED PHYSICS},
  keywords     = {NI SILICIDES,FILMS,NUCLEATION,ELEMENTS,NISI2,CMOS,CO,CONTACT,SILICON,SI(001)},
  language     = {eng},
  number       = {7},
  pages        = {10},
  title        = {Controlling the formation and stability of ultra-thin nickel silicides : an alloying strategy for preventing agglomeration},
  url          = {http://dx.doi.org/10.1063/1.5009641},
  volume       = {123},
  year         = {2018},
}

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