Dopant activation after ion shower doping for the fabrication of low-temperature poly-Si TFTs

Ion shower doping with a main ion source of P2Hx using a source gas mixture of PH3/H2 was conducted on excimer-laser-annealed (ELA) poly-Si. The crystallinity of the as-implanted samples was measured using a UV transmittance. The measured value of as-implanted damage was found to correlate well with the one calculated using TRIM-code simulation. The sheet resistance decreases as the acceleration voltage increases from 1 to 15 kV at the moderate doping conditions. It, however, increases as the acceleration voltage increases under the severe doping conditions. Uncured damage after activation annealing seems to be responsible for the rise in sheet resistance. Three different annealing methods were investigated in terms of dopant activation and damage recovery, such as furnace annealing (FA), excimer laser annealing (ELA) and rapid thermal annealing (RTA), respectively.