Tuning the Schottky barrier height of nickel silicide on p-silicon by aluminum segregation

2008 ◽  
Vol 92 (22) ◽  
pp. 222114 ◽  
Author(s):  
Mantavya Sinha ◽  
Eng Fong Chor ◽  
Yee-Chia Yeo
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Nickel Silicide

Ultimately Low Schottky Barrier Height at NiSi/Si Junction by Sulfur Implantation after Silicidation for Aggressive Scaling of MOSFETs

2009 ◽  
Vol 1155 ◽  
Author(s):  
Yen-Chu Yang ◽  
Yoshifumi Nishi ◽  
Atsuhiro Kinoshita
Keyword(s):  
Contact Resistance ◽  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Nickel Silicide ◽  
High Concentration ◽  
Cross Sectional ◽  
Deep Impurity ◽  
Fermi Level Pinning ◽  
Parasitic Resistance

AbstractParasitic resistance, particularly source/drain contact resistance becomes one of the most serious problems to extend MOSFET scaling recently. Nickel silicide (NiSi), with advantages of low resistivity and high scalability, has been chosen as the material for source/drain formation. However, its Schottky barrier height (SBH) of 0.65eV for electrons is so high that it would block electrons from tunneling, therefore becomes an obstacle to further reduce the contact resistance, which is necessary to achieve the future scaling. Among several solutions, high concentration impurity-segregation layers have been introduced at NiSi/Si interfaces to reduce SBH of MS-MOSFETs. Sulfur (S) has been considered to be an efficient material for the segregation-layer to reduce SBH owing to Fermi-level pinning effect. Previous studies have investigated segregation by implanting S before NiSi formation. Because of the high diffusivity of S in Si, S profile becomes broad during silicidation process, which leads to loss of S concentration at the interface. Moreover, S ions spread into the substrate and channel region generate deep impurity levels that induce junction leakage and off leakage, resulting in device performance degradation. In this paper, S implantation after Ni silicidation is proposed to suppress S diffusion because NiSi is expected to be an efficient barrier for S diffusion. In addition, NiSi/Si interface can serve as a potential energetic valley which may trap S during thermal treatment after implantation. In this work, S was implanted into NiSi/n-Si diodes at the energy of 10keV with dose of 5�1014 and 1015 cm-3 after NiSi is formed. The projection range of S in NiSi is about 6nm, while thickness of NiSi is 16nm. Some devices were annealed at 300C and 450C. The I-V characteristics show that SBH is sufficiently reduced as the annealing temperature becomes higher, and it reaches as low as 3.4meV for 450C annealing. SBH of 3.4meV is much lower than the previously reported value of 70meV for which S was implanted before silicidation. The SIMS analysis result also proves the S profile is much sharper than having S-implantation before Ni silicidation, which supports our hypothesis that S diffusion is suppressed through our process and avoid the loss of S concentration at the interface. Moreover, despite the worry that S-implantation might damage the NiSi/Si interface morphology, cross sectional TEM images show that the interfacial flatness is completely the same as that of non-implanted NiSi/Si, indicating that no degradation occurs by S implantation. In summary, S-implantation after NiSi formation, which provides ultimately low SBH at NiSi/Si interface, is a promising technique to realize ultra-low parasitic resistance source/drain for future LSI beyond 16nm generation.

STUDY OF THE INHOMOGENEITY OF SCHOTTKY BARRIER HEIGHT IN NICKEL SILICIDE BY THE INTERNAL PHOTOEMISSION SPECTROSCOPY

2006 ◽  
Vol 20 (28) ◽  
pp. 1825-1832
Author(s):  
SHIHUA HUANG ◽  
FENGMIN WU
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Annealing Temperature ◽  
Nickel Silicide ◽  
Photoemission Spectroscopy ◽  
Internal Photoemission ◽  
Fermi Level Pinning ◽  
Different Temperatures ◽  
The Individual

The inhomogeneity of Schottky barrier height (SBH) in nickel silicide/ Si contacts was observed by the internal photoemission spectroscopy. New Fowler equations were introduced to analyze the observed properties. We assumed that two or three regions with different SBHs coexist in Ni silicide/ Si contacts, and then the individual barrier height was evaluated. We found that SBH increases monotonously with the increase of annealing temperature in the case of T annealing <600° C . When T annealing is 600°C, SBH becomes maximal, then decreases monotonously with the increase of annealing temperature in the case of T annealing > 600° C . The formation of the two regions (Regions II and III) in nickel silicide/ Si Schottky contacts annealed at different temperatures, was explained by the model of the Fermi-level pinning or the metal-induced gap states.

Selective Growth, Diffusion Layers and the Schottky Barrier Height in Nickel Silicide-Silicon Interfaces

1983 ◽  
Vol 25 ◽  
Author(s):  
J. L. Erskine ◽  
Yu-Jeng Chang
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Schottky Barrier Height ◽  
Theoretical Work ◽  
Nickel Silicide ◽  
Selective Growth ◽  
Silicon Surfaces ◽  
Diffusion Layers ◽  
Semiconductor Contacts ◽  
Nickel Silicon

ABSTRACTSelected interface phenomena associated with metal semiconductor contacts are discussed in relation to recent experimental and theoretical work on the electronic properties, interface formation and structure, and device characteristics of nickel-silicon interfaces. Evidence is presented which suggests that a well-defined interfacial phase is present at all nickel silicide-silicon boundaries formed by deposition of nickel atoms onto silicon surfaces. The existence of this phase is shown to account for several important interface properties of the nickel silicide system including selective growth, the rotational twin structure of epitaxial films and the observed invariance of the nickel silicide-silicon Schottky barrier height as the silicide contact stoichiometry is varied.

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