The effects of nickel germanosilicide contacts on the biaxial compressive stress in thin epitaxial silicon-germanium alloys on silicon

Abstract

When a thin Si1−xGex epitaxial layer is grown on Si, it is under biaxial compression. In this letter, it is shown that a nickel germanosilicide (NiSi1−xGex) layer formed on Si1−xGex can significantly reduce the in-plane compressive strain in Si1−xGex. It is proposed that the observed reduction is due to the biaxial tensile stress applied by the NiSi1−xGex layer. Because the Si1−xGex bandgap is a strong function of the strain, this is expected to have a strong impact on the metal-semiconductor barrier height and the contact resistivity of the interface if the metal Fermi level is pinned near the Si1−xGex midgap.

Impact of an ultra-thin Ti interlayer on the formation of NiSiGe/SiGe

“…Recently, several attempts have been made to improve the morphology and thermal stability of NiSiGe layers by the addition of elements such as Pt, Pd, or C [9][10][11]. The effect of substrate strain on the morphological stability of Ni-germanosilicide was also studied by several group [12,13]. In our previous work, we reported the formation of the atomically flat NiSiGe layer by Al mediated epitaxy on the relaxed SiGe substrate [14].…”

Formation and Characterization of Nickel Germanosilicide on Si1-xGex/Si/SiO2/Si

“…[5][6][7][8] Formation and stability of thin metal germanosilicides have been studied for many popular metals, such as; Ti, Co, Ni, Cu, Pd and Pt. [9][10][11] For further device performance enhancement by designing fully depleted MOSFETs, device fabrication on Si 1-x Ge x /Si/SiO 2 /Si has been actively investigated for more than a decade. Detailed study and proper understanding of metal germanosilicide formation on Si 1-x Ge x /Si/SiO 2 /Si are necessary to properly integrate the system in device design and fabrication.…”

Micro-Raman Studies on Nickel Germanides Formed on (110) Crystalline Ge

“…The implement of different substrate orientations such as (110) substrate for the bulk Ge PMOS [2] is also an attractive way to further enhance the drive current. Owing to the recessed Si 1-x Ge x junction technology, currently employed in state-of-the-art CMOSFETs, introducing uniaxially compressive stress in the Si channel, the germano-silicide induced stress is a highly concerned issue to avoid the strain relaxation on underlying Si 1-x Ge x junction [3].…”

“…Fig 3. The Raman spectrum of bulk (110) Ge substrate and the germanides formed with varying annealed temperature.…”