IR absorption property in NaNo-thick nickel cobalt composite silicides

Thermal evaporated 10 nm-Ni₅₀Co₅₀/(70 nm-poly)Si films were deposited to examine the energy saving properties of suicides formed by rapid thermal annealing at temperature ranging from 500 to 1, 100°C for 40 seconds. Thermal evaporated 10 nm-Ni/(70 nm-poly)Si films were also deposited as a reference using the same method for depositing the 10 nm-Ni ₅₀Co₅₀/ (70 nm-poly)Si films. A four-point probe was used to examine the sheet resistance. Transmission electron microscopy (TEM) and X-ray diffraction XRD were used to determine cross sectional microstructure and phase changes, respectively. UV-VISNIR and FT-IR (Fourier transform infrared spectroscopy) were used to examine the near-infrared (NIR) and middle-infrared (MIR) absorbance. TEM analysis confirmed that the uniform nickel-cobalt composite suicide layers approximately 21 to 55 nm in thickness had formed on the single and polycrystalline silicon substrates as well as on the 25 to 100 nm thick nickel suicide layers. In particular, nickel-cobalt composite suicides showed a low sheet resistance, even after rapid annealing at 1,100°C. Nickel-cobalt composite suicide and nickel suicide films on the single silicon substrates showed similar absorbance in the nearIR region, while those on the polycrystalline silicon substrates showed excellent absorbance until the 1,750 nm region. Suicides on polycrystalline substrates showed high absorbance in the middle IR region. Nickel-cobalt composite suicides on the polySi substrates annealed at 1,000°C superior IR absorption on both NIR and MIR region. These results suggest that the newly proposed Ni₅₀Co₅₀ composite suicides may be suitable for applications of IR absorption coatings.