Abstract
We investigated hydrogenation of low-temperature (LT) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) from the point of view of the gettering phenomenon, specifically, using self-aligned metal double-gate p-channel LT poly-Si TFTs that had a small subthreshold swing value and a high field-effect mobility. Hydrogenation of TFTs was carried out by forming gas annealing. Our results indicate that the conventionally used hydrogenation temperature of 400 °C is considerably high because annealing at this temperature results in the re-emission of gettered hydrogen. Moreover, when annealing in forming gas, hydrogenation actually occurs during cooling from 400 °C, but not at 400 °C. The most important parameter for effective hydrogenation is the rate of cooling from 400 °C, but not the hydrogenation temperature of 400 °C.