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

Self-aligned, n-channel, polycrystalline silicon thin-film transistors with 15 μm channels were fabricated by recrystallizing amorphous silicon for 6 h at 500 °C. A thin nickel silicide at the source and drain was used to seed the crystallization. The channel mobility was initially 87 cm2/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 3.5×10−8 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.