Microstructure Evolution of the Ir-inserted Ni Silicides with Additional Annealing

다국어 초록 (Multilingual Abstract)

Thermally-evaporated 10 nm-Ni/1 nm-Ir/(poly)Si structures were fabricated in order to investigate the thermal
stability of Ir-inserted nickel silicide after additional annealing. The silicide samples underwent rapid thermal
annealing at 300℃ to 1200℃ for 40 s, followed by 30 min annealing at the given RTA temperatures. Silicides
suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates,
mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution
x-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively.
Transmission electron microscope and scanning probe microscope were used to determine the cross-section
structure and surface roughness. The silicide, which formed on single crystal silicon substrate with surface
agglomeration after additional annealing, could defer the transformation of Ni(Ir)Si to Ni(Ir)Si2 and was stable
at temperatures up to 1200℃. Moreover, the silicide thickness doubled. There were no outstanding changes
in the silicide thickness on polycrystalline silicon. However, after additional annealing, the silicon-silicide mixing
became serious and showed high resistance at temperatures >700℃. Auger depth profiling confirmed the increased
thickness of the silicide layers after additional annealing without a change in composition. For a single crystal
silicon substrate, the sheet resistance increased slightly due to the significant increases in surface roughness
caused by surface agglomeration after additional annealing. Otherwise, there were almost no changes in surface
roughness on the polycrystalline silicon substrate. The Ir-inserted nickel monosilicide was able to maintain
a low resistance in a wide temperature range and is considered suitable for the nano-thick silicide process.

다국어 초록 (Multilingual Abstract)

Thermally-evaporated 10 nm-Ni/1 nm-Ir/(poly)Si structures were fabricated in order to investigate the thermal
stability of Ir-inserted nickel silicide after additional annealing. The silicide samples underwent rapid thermal
annealing at 300℃ to 1200℃ for 40 s, followed by 30 min annealing at the given RTA temperatures. Silicides
suitable for the salicide process were formed on the top of the single crystal and polycrystalline silicon substrates,
mimicking actives and gates. The sheet resistance was measured using a four-point probe. High resolution
x-ray diffraction and Auger depth profiling were used for phase and chemical composition analysis, respectively.
Transmission electron microscope and scanning probe microscope were used to determine the cross-section
structure and surface roughness. The silicide, which formed on single crystal silicon substrate with surface
agglomeration after additional annealing, could defer the transformation of Ni(Ir)Si to Ni(Ir)Si2 and was stable
at temperatures up to 1200℃. Moreover, the silicide thickness doubled. There were no outstanding changes
in the silicide thickness on polycrystalline silicon. However, after additional annealing, the silicon-silicide mixing
became serious and showed high resistance at temperatures >700℃. Auger depth profiling confirmed the increased
thickness of the silicide layers after additional annealing without a change in composition. For a single crystal
silicon substrate, the sheet resistance increased slightly due to the significant increases in surface roughness
caused by surface agglomeration after additional annealing. Otherwise, there were almost no changes in surface
roughness on the polycrystalline silicon substrate. The Ir-inserted nickel monosilicide was able to maintain
a low resistance in a wide temperature range and is considered suitable for the nano-thick silicide process.

참고문헌 (Reference)

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