“Driving”-Stress-Induced Degradation in Polycrystalline Silicon Thin-Film Transistors and Its Suppression by a Bridged-Grain Structure

In this letter, degradation of polycrystalline silicon (poly-Si) thin-film transistors (TFTs) under “driving” stress is characterized and analyzed for the first time. Dynamic hot carrier (HC) effect, related to pulse falling time, dominates device degradation. To suppress such “driving”-stress-induced dynamic HC degradation, a bridged-grain (BG) structure is applied to the active channel of poly-Si TFTs. Due to the lateral electric field reduction at source/drain junctions, “driving”-stress-induced dynamic HC degradation is significantly improved by the BG structure. Incorporated with transient simulations, the degradation mechanism is elucidated.