Thermal stability of sputter-deposited TiSi₂ films with crystal orientation

TiSi₂ thin films were prepared by dc magnetron sputtering using a composite TiSi_x target in the substrate temperature range of 150-550 °C. The as-sputtered TiSi₂ films at low temperatures (<250 °C) have an amorphous structure with a resistivity of approximately 250 μΩ cm, whereas those deposited over 450 °C have C49 TiSi₂ phase with (060) and (131) orientations. The C54 TiSi₂ phase having random orientations of (311) and (040) is attained after rapid thermal annealing (RTA) at 750 °C when deposited at a low temperature regime. The C54 TiSi₂ films prepared at 450 °C exhibited a preferred orientation of (040) after RTA over 650 °C. The sheet resistance (R_s) of patterned TiSi₂/polycrystalline silicon structure is as low as approximately 3 Ω/□, regardless of substrate temperature, for patterned lines 0.18 μm wide after furnace annealing of 800 °C for 60 min. We found the R_s dependency of C54 TiSi₂ lines on the crystal orientation after furnace annealing of 850 °C for 30 min: the structure of C54 TiSi₂(040) orientation is more susceptible than that of randomly oriented C54 TiSi₂(311) and (040) in terms of thermal stability.