Kinetics of silicide-induced crystallization of polycrystalline thin-film transistors fabricated from amorphous chemical-vapor deposition silicon

Self-aligned, n-channel, polycrystalline silicon thin-him transistors with 15 mu m channels were fabricated by recrystallizing amorphous silicon for 6 h at 500 degrees C. A thin nickel silicide at the source and drain was used to seed the crystallization. The channel mobility was initially 87 cm(2)/V s, and improved to 170 cm2/V s after hydrogenating the devices. The recrystallization velocity in the channel was measured optically and electrically, and found to be 3.5 x 10(-8) cm/s; this value exceeds by two orders of magnitude the solid-phase epitaxial regrowth rate of amorphous silicon. This observation, together with the low activation energy of 0.3 eV measured for the silicide-assisted regrowth velocity as compared to 2.76 eV for epitaxial regrowth, suggest that the channel recrystallization is assisted by Ni diffusing to the recrystallization front. (C) 1998 American Institute of Physics.