Reduced Trap-State Density of Ni-Silicide Seed-Induced Crystallized Poly-Si TFTs by Gettering

Polycrystalline silicon thin-film transistors (TFTs) fabricated by seed-induced crystallization (SIC) have large leakage currents due to defects that consist of Ni impurities. Here, we describe a novel method of gettering to remove Ni impurities using a Si gettering layer that is separated from the active layer by a chemical SiO
₂
etch stop interlayer formed by dipping into H
₂
SO
₄
. The leakage current, the on/off ratio, and a channel breakdown voltage were greatly improved. These results were explained by lowered trap-state density in the channel.