Citation

Kim S, Song O. Metals and Materials International 2007; 13(3): 239-247.

Copyright

(Copyright © 2007)

DOI

10.1007/BF03027812

PMID

unavailable

Abstract

10 nm-Ni1-xCox (x = 0.2, 0.5, and 0.8) /p-Si(100)(or poly crystalline Si) was thermally annealed using rapid thermal annealing for 40 s at 600-1100°C. The annealed film structures developed into NiCoSi x, and the resulting changes in sheet resistance, microstructure, and composition were investigated using a four-point probe, a scanning electron microscope, a field ion beam, an X-ray diffractometer, and an Auger electron spectroscope. The final thickness of NiCoSix formed on single-crystal silicon was approximately 12.64 nm, and it maintained its sheet resistance below 20 Ω/sq. during the silicidation annealing at 1100°C. The NiCoSix formed on polysilicon had a thickness of 35.04 nm, and its low resistance was maintained up to 900°C. Additional annealing of suicides at the given RTA temperature for 30 min resulted in a drastic increase in sheet resistance. We identified Ni3Si2 and a NiSi phase at 700°C and 1000°C for single-crystal silicon substrates. Moreover, Ni3Si2, NiSi, and CoSi2 phases were stable at 700°C, and then NiSi2 and Ni3Si2 became stable for polycrystalline silicon substrates at 1000°C. When the amount of Co was 80 %, only a Ni3Si2 phase was confirmed at 700°C and 1000°C in both the single and polycrystalline substrates. With less Co (Co = 0.2, 0.5), Ni3Si2, NiSi, and CoSi 2 phases were observed at 700, and Ni3Si2 and NiSi2 phases were observed at 1000°C. Cobalt also improved thermal stability of the suicides formed on the polysilicon gate, but this enhancement was lessened due to the silicon mixing during high temperature diffusion. In conclusion, the proposed nickel cobalt composite silicides formed from the nano-thick alloy films may be superior to conventional nickel monosilicides due to improved thermal stability.

Language: en

Keywords

Polycrystalline materials; Thermodynamic stability; Thin films; Scanning electron microscopy; Sheet resistance; Silicon wafers; Nickel; Silicide; Polysilicon; Cobalt; Ion beams; Rapid thermal annealing; Silicides; Substrates; Thermal stability; Salicide; Rapid thermal processing; Salicides; Auger electron spectroscopy; Single crystals; Silicidation annealing; Ni silicide; Additional annealing; Composite silicide; High-temperature diffusion; Monocrystalline silicon; Nanocomposite films; Ni silicides; Polycrystalline substrates; Single crystal silicon; X ray diffractometers