Threshold voltage control in NiSi-gated MOSFETs through SIIS

Complete gate silicidation has recently been demonstrated as an excellent technique for the integration of metal gates into MOSFETs. From the various silicide gate materials NiSi has been shown to be the most scalable. In this paper, a versatile method for controlling the workfunction of an NiSi gat...

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Bibliographic Details
Published in:IEEE transactions on electron devices 2005-01, Vol.52 (1), p.39-46
Main Authors: Kedzierski, J., Boyd, D., Cabral, C., Ronsheim, P., Zafar, S., Kozlowski, P.M., Ott, J.A., Meikei Ieong
Format: Article
Language:English
Subjects:
Applied sciences
Dual silicidation
Electronics
Exact sciences and technology
full silicidation (FUSI)
gate workfunction
Impurities
metal gate
mid-gap gate
MOSFETs
Nickel compounds
NiSi
Semiconductor device doping
Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
silicidation-induced impurity segregation (SIIS)
silicide gate
thin body
threshold voltage
transistor scaling
Transistors
ultrathin body
undoped body
Voltage control
workfunction engineering
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Summary:Complete gate silicidation has recently been demonstrated as an excellent technique for the integration of metal gates into MOSFETs. From the various silicide gate materials NiSi has been shown to be the most scalable. In this paper, a versatile method for controlling the workfunction of an NiSi gate is presented. This method relies on doping the poly-Si with various impurities prior to silicidation. The effect of various impurities including B, P, As, Sb, In, and Al is described. The segregation of the impurities from the poly-Si to the silicide interface during the silicidation step is found to cause the NiSi workfunction shift. The effect of the segregated impurities on gate capacitance, mobility, local workfunction stability, and adhesion is studied.
ISSN:0018-9383
1557-9646
DOI:10.1109/TED.2004.841264