Title page for etd-0723110-144658


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URN etd-0723110-144658
Author Shuo-yang Sun
Author's Email Address No Public.
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Department Materials and Optoelectronic Science
Year 2009
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title Effect of additive Ag in TiSi2 thin films for phase transformation and mechanical behavior under nanoindentation
Date of Defense 2010-06-28
Page Count 112
Keyword
  • electrical resistivity
  • Ag
  • phase transformation
  • Titanium silicides
  • Abstract The C54 TiSi2 thin films are widely applied in semiconductor devices due to the low electric resistance and high thermal stability. Through the annealing processing in this study, the metastable C49 TiSi2 with an electric resistivity of 219.3 μΩ-cm transforms to the stable C54 TiSi2 phase at a higher annealing temperature, with a resistivity of 30.5 μΩ-cm. Hence the transformation temperature of C49 → C54 is of great concern in metallization of gates and local interconnections. In this thesis, it is found that the oxygen content and Ag addition impose significant influence on the transformation temperature of C49 → C54. The as-sputtered TiSi2 thin films are confirmed to be amorphous. After annealing at 600oC or 900oC, the silicides would transform to the metastable C49 TiSi2 or C54 TiSi2 phase, respectively. The current transformation temperatures are much higher than 200oC and 600oC for the normal TiSi2 system, due to high oxygen content in the current films (up to 15-20 at% as a result of our old sputtering system). Nevertheless, the co-sputtered TiSi2 thin films with 5 and 20 at% Ag can decrease the formation temperature of C54 TiSi2 phase to 800oC. Compare with the as-sputtered TiSi2 thin films, the desirable electric resistivity of the C54 phase in the 20 at% Ag thin films is also further reduced to 22.9 μΩ-cm. The time-dependent mechanical responses of the amorphous, crystalline C49, and C54 TiSi2 thin films are investigated by room-temperature nanoindentation at the different loading rates ranging from 0.0125 to 5 mN/s. The anelasticity response plays an important role in the current TiSi2 thin films and is found to be sensitive to the loading rate. The displacement of time-dependent anelasticity recorded during the period of hold time increases with increasing loading rate. The anelasticity behavior can be analyzed by the Kelvin model. The as-deposited amorphous phase, with a lower atomic packing density and higher degree of defects and free volumes, exhibits the higher anelasticity deformation and longer relaxation time.
    Advisory Committee
  • Po-we Kao - chair
  • Ker-chang Hsieh - co-chair
  • Chih-ching Huang - advisor
  • Files
  • etd-0723110-144658.pdf
  • indicate in-campus access immediately and off_campus access in a year
    Date of Submission 2010-07-23

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