A study of self-activation and low temperature furnace annealing for source/drain formation in AMLCD

Phosphorous and boron self activation followed by low temperature (450°C) furnace annealing were investigated for source/drain formation in polysilicon thin films. The effect of hydrogen content in the ion beam was thoroughly studied, For phosphorous doped polysilicon, the hydrogen content is critical because too high a hydrogen content generates defects as well as passivation. Too low a hydrogen content results in low substrate temperature. Both extremes result in sheet resistance increase. The lowest sheet resistance was obtained with 55% hydrogen in the ion beam. On the other hand, the sheet resistance of a boron doped polysilicon decreases significantly with hydrogen content and substrate temperature during ion doping, Boron self-activation can be improved by about 30% in 55% hydrogen content ion doping compared with 45% hydrogen content. The different effects of low temperature furnace annealing on phosphorus and boron doped polysilicon film was also discussed