AVS 46th International Symposium
    Thin Films Division Thursday Sessions
       Session TF-ThA

Paper TF-ThA6
Effect of Rapid Thermal Annealing Temperature on the Formation of CoSi Studied by X-ray Photoelectron Spectroscopy and Micro Raman Spectroscopy

Thursday, October 28, 1999, 3:40 pm, Room 615

Session: Ex-situ Characterization
Presenter: J. Zhao, Advanced Micro Devices
Authors: J. Zhao, Advanced Micro Devices
L. Ballast, Advanced Micro Devices
T. Hossain, Advanced Micro Devices
R. Trostel, Advanced Micro Devices
B. Bridgman, Advanced Micro Devices
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Silicides are widely used on poly-Si as low resistance gate electrodes and local interconnects. Among all silicides, CoSi@sub 2@ attracts a special interest, not only because of its low resistance and its technical advantages in processing, but also its excellent match with Si. CoSi is the intermediate phase in the conversion sequence of pure Co, CoSi and CoSi@sub 2@. In this paper, we investigated the effect of rapid thermal annealing (RTA) temperature on the formation of CoSi using X-ray photoelectron spectroscopy (XPS) and micro Raman spectroscopy. With pure Co deposited on single crystalline Si wafer and capped by Ti thin film, the wafers were rapid thermal annealed at 450, 460, 470, 480 and 490@super o@C, respectively. These wafers were then stripped with SPM (H@sub 2@SO@sub 4@/H@sub 2@O@sub 2@). XPS was used to determine the chemical composition of the CoSi thin films and Auger parameter was continuously monitored along with ion sputtering to provide chemical state depth profile. XPS depth profile shows that uniform CoSi film was developed with RTA at 470@super o@C. The wafer with RTA at 450@super o@C has a pure Co layer in between the CoSi film and Ti cap. After strip, the thinnest CoSi film was observed with this wafer among the five. On the other hand, the wafer with RTA at 490@super o@C shows significant amount of Ti diffusion into the CoSi film. After strip, XPS depth profile indicates that this wafer has residue Ti on the top of CoSi surface. Micro Raman spectroscopy was used as a non-destructive method to characterize the film thickness and uniformity of the CoSi films on Si wafer. The product, @theta@d (@theta@ - absorption coefficient, d - film thickness) was calculated from both the Si excitation wavelength of 521cm@super -@ and CoSi excitation wavelengths of 206cm@super -@ and 224cm@super -@. The correlation of the measured Raman peak intensity ratio, the calculated product @theta@d and the sheet resistance of CoSi thin film were also elucidated.