| Summary: | 碩士 === 國立清華大學 === 材料科學工程學系 === 87 === The effects of stress on the formation of cobalt silicides have been investigated by sheet resistance measurements, glancing-angle x-ray diffraction analysis and transmission electron microscopy. The tensile stress present in the silicon substrate was found to influence significantly the growth kinetics of silicides.
Tensile stress and compressive stresses were induced on the front side of silicon substrate by the formation of CoSi2 and SiO2 films on the backside of the substrate. 30-nm-thick Co thin films were then deposited onto the front side of stressed samples by sputtering. All as-deposited samples were annealed in a rapid thermal annealing apparatus at 400-700 ℃ for 30 s.
For Co on blank and stressed (001)Si substrate after rapid thermal annealing (RTA) at 450℃ for 30 sec, the thicknesses of Co2Si in compressively stressed samples are thinner than those in blank and tensily samples. In the mean time, the thicknesses of CoSi in compressively stressed samples are thicker than those in blank and tensily samples. The results indicated that the tensile stress retards the phase transformation from Co2Si to CoSi. In contrast, the compressive stress promotes the phase transformation from Co2Si to CoSi. Mechanisms for the stress effect are discussed.
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