(Color online) (a) Schematics illustrating the process flow used for fabricating contact structures comprising NiSi on p-type Si. The contact structures received Al implant prior to nickel silicidation using a pulsed laser anneal (PLA). Silicidation was performed in the 100 μm × 100 μm square-shaped active regions defined by the SiO2. TEM images of NiSi formed after PLA of (b) 100 mJ/cm2, (c) 200 mJ/cm2, (d) 300 mJ/cm2, and (e) 600 mJ/cm2 reveal atomically flat NiSi/Si interface. The thickness of silicide formed with pulsed laser anneal increases with increasing laser fluence.
(Color online) I-V characteristics of nickel silicide contact structures formed by pulsed laser annealing of Al-implanted p-type Si. Various laser fluences ranging from 200 to 700 mJ/cm2 were used. A reference sample that received no Al implant and that was nickel-silicided using RTA at 450 °C 30 s is also included for comparison. For nickel silicides formed by laser anneal, the I-V curves show less rectifying characteristics with increasing laser fluence.
(Color online) TOF-SIMS profiles of Al after Ni deposition and silicidation at a laser fluence of 500 mJ/cm2 and 700 mJ/cm2. Al segregation near the interface between nickel silicide and Si could be observed.
(Color online) Measurements for extraction of Φ B p of NiSi on p-Si. The slope of the linear fit of the curves in the low temperature regime is used to extract the Φ B p for samples irradiated at laser fluence of (a) 500 mJ/cm2 and (b) 700 mJ/cm2. The p-Si samples were implanted with an Al dose of 1016 cm−2 at 1.5 keV. (c) The presence of negatively charged Al on the Si side of the silicide/Si interface could result in the narrowing of the depletion width for enhanced hole tunneling.
Φ B p as a function of integrated interfacial dose of Al. Integrated interface dose of Al is extracted by integrating the Al concentration profiles in the Si region within 5 nm from the silicide/Si interface.
(Color online) TOF-SIMS profile of Al after Ni deposition and silicidation at laser fluence of 200 mJ/cm2, as well as the as-implanted Al profile (in silicon).
(Color online) I-V characteristics of samples with various Al doses ranging from 0 to 1016 cm−2 and silicided at a fixed laser fluence of 200 mJ/cm2. The rectifying I-V behavior of NiSi increases with aluminum ion implantation dose.
(Color online) (a) Comparison of the average Φ B p as a function of Al implantation dose. For each split, 5 samples were measured. (b) Schematic depicting the energy-band diagram of NiSi/Si junctions with and without Al incorporation. Presence of Al within metal silicide is believed to have tuned the intrinsic workfunction of the metal silicide, leading to an increase in Φ B p .
Article metrics loading...
Full text loading...