Patent ID: 8679905

Claim:
A method of forming ohmic source/drain contacts in a metal oxide semiconductor thin film transistor comprising the steps of: providing a gate, a gate dielectric, a high carrier concentration metal oxide semiconductor active layer with a band gap and spaced apart source/drain metal contacts in a thin film transistor configuration, the spaced apart source/drain metal contacts defining a channel region in the active layer, and further including an etch stop passivation layer positioned in overlying relationship on the channel region of the metal oxide semiconductor active layer and partially beneath the source/drain metal contacts, the etch stop passivation layer being formed with insulating material that has a glass transition temperature (Tg), where below the Tg the insulating material functions as a chemical barrier to O 2 , H 2 O, H 2 , N 2 , and to chemicals used in following fabrication processes above the etch stop passivation layer, and above the Tg the insulating material behaves as semi-liquid with high viscosity and with sufficient mobility to oxygen, hydrogen, and nitrogen atoms; providing an oxidizing ambient adjacent the channel region; and heating the gate and the channel region in the oxidizing ambient to reduce the carrier concentration in the channel area.