Impact of a Germanium and Carbon Preamorphization Implant on the Electrical Characteristics of NiSi/Si Contacts With a Presilicide Sulfur Implant

Abstract

This letter reports the demonstration of preamorphization implant (PAI) using germanium (Ge) and carbon (C) and its combination with presilicide sulfur (S) implant for Schottky barrier height (SBH) tuning of nickel silicide (NiSi)-silicon contacts. Ge and C PAI increases the threshold temperature for agglomeration of a NiSi film, thus enhancing its thermal stability. A presilicide S implant and its segregation at metal/semiconductor interface effectively lowers the effective electron SBH Φ n B to 0.18 eV. In addition, the distribution of reverse current in the NiSi/n-type Si contact is improved with the introduction of Ge and C PAI.

Silicon-Carbon Source and Drain Stressors: Carbon Profile Design by Ion Implantation

“…It is well known that carbon can effectively enhance the thermal stability of nickel silicide Ni 1-x Si x . [41][42][43][44][45] However, a higher resistivity is also observed for Ni 1-x Si x formed on Si:C where carbon is incorporated in the silicide film. To minimize the carbon-induced R s increase in Ni 1-x Si x , a retrograde carbon profile can be used so that Ni 1-x Si x is formed in a region with lower carbon concentration.…”

Selenium Segregation for Effective Schottky Barrier Height Reduction in NiGe/n–Ge Contacts

“…Se and S implants were performed at energies of 8 and 5 keV, respectively. For S implant, the implant conditions are similar to those in prior reports [1]- [4], [10]- [14]. For Se implant, the energy was selected so that the peak Se concentration is within the top 20 nm of Ge which will later be consumed during NiGe formation.…”

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

“…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].…”

“…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]. Another important technique used in advanced contact formation is the preamorphization implant (PAI) before silicidation.…”

“…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.…”