Method of making short channel thin film field effect transistor

摘要

Methods for producing field effect transistors having short current-conduction channels and reduced parasitic capacitance are disclosed. The methods allow the channel length to be substantially less than the minimum feature size of the photolithographic mask if desired, thereby enabling very short channel length transistors to be formed using conventional ten micron photolithography. An exemplary method involves: (a) depositing a thick film of photoresist over a multilayered sandwich structure forming part of the transistor, said structure having a bottom gate electrode, an insulator layer thereover, followed by a layer of deposited semiconductor material and a thin film of etchable conductive material thereover; (b) exposing the photoresist through a mask; (c) wetting the photoresist to cause it to swell before development to create an overhang, if desired; (d) etching the etchable material to undercut a portion of the photoresist, and (e) shadow depositing material on top of the uncovered semiconductor layer beyond the shadow of the undercut and overhanging photoresist, thereby locating said channel, and one of the two current-carrying electrodes of the transistor.