A Novel Four-Mask Low-Temperature Polycrystalline Silicon PMOS Thin-Film Transistor With Advanced Terrace Structure for AMOLED Application

We propose a novel four-mask low-temperature polycrystalline-silicon PMOS structure. In this letter, we obtain the utmost simplified thin-film transistor (TFT) structure by eliminating the storage doping, passivation, and anode photomask steps. The proposed four-mask structure has a self-aligned terrace structure whose lightly doped drain (LDD) and gate-overlapped LDD are formed with only one photomask step. The on current of the four-mask PMOS TFT with an advanced terrace structure is similar to that of the conventional seven-mask TFT, while the off current of the new structure is lower than that of the conventional seven-mask TFT.