Segregation of ion implanted sulfur in Si(100) after annealing and nickel silicidation

Abstract

Diffusion of sulfur (S) in S+ ion implanted Si(100) was investigated after rapid thermal annealing as well as after nickel silicidation. At lower S doses, S segregates to the Si(100) surface when the defects created by the S implantation are reduced during annealing. If the S dose exceeds the amorphization threshold, two heavily damaged regions with dislocation loops appear after annealing. It seems that S atoms form stable complexes with dislocation loops that survive even after high-temperature anneals at 900 °C. In contrast, when silicidation comes into play, S atoms appear more mobile. Even during Ni silicidation at 550 °C, segregation yields an enrichment of S at the NiSi/Si interface while the defect density and the S content in the deeper Si regions decrease.

Cold Silicon Preamorphization Implant and Presilicide Sulfur Implant for Advanced Nickel Silicide Contacts

“…6(b)]. It is believed that the substantial n B reduction of the NiSi/n-Si contacts is attributed to the segregated S at the interface caused by the snowplowing effect during silicidation [6]- [15]. However, the detailed mechanism of n B reduction caused by S segregation still needs to be further investigated.…”

“…The cold S implant was not investigated in this paper. The S implantation condition used in this paper was chosen to ensure that sufficient S would be pushed to the NiSi/Si interface during silicidation for tuning of effective SBH [6]- [14]. The cold Si PAI and S implant steps were 0018-9383 © 2014 IEEE.…”

“…The electron Schottky barrier height (SBH) of NiSi on n-type silicon (n-Si) is 0.65 eV, and should be lowered to reduce the contact resistance (R C ) and increase the drive current (I Dsat ) in n-channel field-effect transistors [3]- [5]. It has been reported that segregated sulfur (S) atoms at the NiSi/n + Si interface can reduce the effective SBH to ∼0.1 eV [6]- [14]. The S atoms near the interface could act as donor-like traps for narrowing the tunneling width of Schottky barrier [14] or enhance the effective doping concentration under the NiSi/Si interface [15].…”

Atomistic study of sulfur diffusion and S2 formation in silicon during low-temperature rapid thermal annealing

“…A pre-exponential factor of S int migration frequency was determined by the experimental diffusion coefficient of sulfur [7]. And pre-exponential factors of emissions were determined so as to reproduce experimental results of sulfur diffusion in Si [1], as shown in Fig. 4.…”

“…Sulfur doping at NiSi/Si junction has bee Schottky barrier height ultimately small, rev junction resistance [1][2]. Theoretical analys large barrier reduction is induced by S atom vicinity of NiSi/Si junction [3].…”