LOW-TEMPERATURE (LESS-THAN-OR-EQUAL-TO-600-DEGREES-C) POLYSILICON THIN-FILM TRANSISTORS HAVING IN-SITU DOPED POLYSILICON SOURCE AND DRAIN CONTACTS

Low temperature (less than or equal to 600 degrees C) polysilicon thin film transistors are fabricated through a four mask gate aluminum pro cess. Active layer is undoped LPCVD polysilicon, source and drain regi ons are made of in-Situ doped polysilicon layer and gate oxide is APCV D SiO2. Before hydrogenation, TFT's exhibit good source and drain ohmi c contacts but poor electrical properties due to a high interface stat e density, After plasma hydrogen passivation, contacts remain ohmic an d good electrical properties are obtained because of a decrease of the interface state density; a low threshold voltage (V-T approximate to 0 V), a high held effect mobility (mu = 35 cm(2)/Vs) and a high channe l conductance g(ds) = 14.7 x 10(-6) S at the gate voltage V-gs = 10 V.