Abstract
We report the effects of excess Si phase on the C54 transformation and the thermal stability of TiSi2 thin films as a function of Si/Ti (x) ratio. The resistivity and x-ray diffraction data of TiSix (x = 2.1-2.4) films showed a retardation of C54-TiSi2 transformation with incremental molar ratio x; the TiSix (x = 2.1-2.3) films were completely transformed to C54-TiSi2 with rapid thermal annealing (RTA) of 750°C, while the TiSix (x = 2.4) films were transmuted to C54-TiSi2 over the RTA of 800°C. Transmission electron microscopy study revealed that the growth of Si precipitates in the Si-rich TiSix films competes with the grain growth during the transformation of C49 to C54 TiSi2 phase, resulting in the increase of C54 transformation temperature. An excellent sheet resistance (Rs) and its standard deviation in concert with a reliable gate oxide integrity were attained from the Si-rich TiSi2/polycrystalline-Si (poly-Si) structure up to the solid state annealing of 850°C for 60 min. These attributes are due to the reduced solid state reaction at TiSi2/Si interface and the suppressed TiSi2 agglomeration by Si precipitates. The average Rs of the 0.12-μm-wide TiSi2(800 Å)/poly-Si gate lines is lower than 4.5 Ω/□, demonstrating a robust gate electrode structure for gigabit scale device application.
Original language | English |
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Pages (from-to) | 2760-2764 |
Number of pages | 5 |
Journal | Journal of Applied Physics |
Volume | 87 |
Issue number | 6 |
DOIs | |
State | Published - 15 Mar 2000 |