Title :
Threshold voltage control in NiSi-gated MOSFETs through SIIS
Author :
Kedzierski, J. ; Boyd, D. ; Cabral, C., Jr. ; Ronsheim, P. ; Zafar, S. ; Kozlowski, P.M. ; Ott, J.A. ; Meikei Ieong
Author_Institution :
IBM T. J. Watson Res. Center, Yorktown Heights, NY, USA
Abstract :
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.
Keywords :
MOSFET; impurities; nickel compounds; semiconductor doping; voltage control; NiSi; NiSi-gated MOSFET; complete gate silicidation; dual silicidation; full silicidation; gate workfunction; local workfunction stability; metal gate; mid-gap gate; segregated impurities; semiconductor impurities; silicidation-induced impurity segregation; threshold voltage control; transistor scaling; ultrathin body; undoped body; workfunction engineering; Impurities; MOSFETs; Nickel compounds; Semiconductor device doping; Voltage control; Dual silicidation; NiSi; full silicidation (FUSI); gate workfunction; metal gate; mid-gap gate; silicidation-induced impurity segregation (SIIS); silicide gate; thin body; threshold voltage; transistor scaling; ultrathin body; undoped body; workfunction engineering;
Journal_Title :
Electron Devices, IEEE Transactions on
DOI :
10.1109/TED.2004.841264
