A method for the fabrication of low leakage polysilicon thin film transistors

摘要

According to one aspect of the invention thin film transistors exhibiting a reduced reverse leakage current are manufactured according to a method which includes the following steps:;Depositing a relatively thick layer of silicon oxide on a substrate by chemical vapor deposition, depositing a relatively thin polysilicon layer, annealing the relatively thin polysilicon layer at a temperature of less than 650°C in a nitrogen atmosphere to cause large grain formation, forming islands by etching the thin polysilicon layer, forming a thin gate oxide layer on at least one of the islands by oxidation under high pressure at a temperature below 650°C, depositing a relatively thick doped polysilicon layer on the gate oxide layer, forming a gate from the, relatively heavily doped, relatively thick polysilicon layer while having exposed laterally adjacent areas of the gate oxide layer and the underlying polysilicon island, lightly doping portions of the resultant exposed areas of the island of polysilicon laterally adjacent to the gate to form lightly doped source and drain areas, depositing a thin layer of silicon oxide on the gate and lightly doped source and drain areas, relatively heavily doping exposed areas of the layer of polysilicon laterally adjacent to the lightly doped source and drain areas to form relatively heavily doped source and drain areas, annealing the source and drain areas at a temperature of 600°C to 750°C and then hydrogenating the resultant device at a temperature of less than about a 400°C with the hydrogen plasma.