Impact of hydrogenation process on performance of self-aligned metal double-gate LT poly-Si TFTs

We investigated the hydrogenation of low-temperature (LT) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) in terms of the gettering phenomena using high-performance self-aligned metal double-gate p-ch LT poly-Si TFTs. Our results show that the conventionally used hydrogenation temperature of 400°C, using forming gas annealing, is considerably high for the hydrogenation process. The reason is that this temperature results in re-emission of gettered hydrogen. In the hydrogenation process using gas annealing, hydrogenation actually takes place during the cooling from 400°C, but not at 400°C. The most important parameter for effective hydrogenation is the cooling speed from 400°C.