Citation

Song O, Yoon K. Metals and Materials International 2007; 13(3): 229-234.

Copyright

(Copyright © 2007)

DOI

10.1007/BF03027810

PMID

unavailable

Abstract

To improve the thermal stability of the conventional nickel monosilicide, 10 nm-Ni/1 nm-Ir/p-Si(100)or polycrystalline Si) was thermally annealed using rapid thermal annealing for 40 s at 300-1200°C. The annealed bilayer structure developed into Ni(Ir)Si, 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 Ni(Ir)Six formed on single crystal silicon was approximately 40 nm, and it maintained a sheet resistance of below 20 Ω/sq. during the silicidation annealing at 1200°C. The suicide formed on polysilicon had a thickness of 55 nm, and its low resistance was maintained up to 850°C. An additional annealing of silicides at 900°C for 30 min. resulted in a drastic increase in sheet resistance. A possible reason for the improved thermal stability of the suicides formed on single crystal silicon substrate is the role of indium in preventing NiSi2 transformation. Iridium also improved the thermal stability of the silicides formed on the polysilicon gate, but this enhancement was lessened due to the formation of NiIrSix and also as a result of silicon mixing during high temperature diffusion. In conclusion, the proposed iridium-inserted nickel suicides may be superior to the conventional nickel monosilicides due to improved thermal stability.

Language: en

Keywords

Stability; Thermodynamic stability; Scanning electron microscopy; Sheet resistance; Silicon wafers; Nickel; Silicide; Polysilicon; Ion beams; Rapid thermal annealing; Silicides; Substrates; Iridium; Thermal stability; Rapid thermal processing; Auger electron spectroscopy; Single crystals; Nickel compounds; Iridium compounds; Nickel monosilicide; Bi-layer structure; Bilayer structure; Silicidation annealing; Ni silicide; Additional annealing; High-temperature diffusion; Monocrystalline silicon; Ni silicides; Single crystal silicon; X ray diffractometers; Iridium addition; Nickel metallography