Patent ID: 8089065

Claim:
A method of forming an organic thin film transistor of the top-gate type comprising: providing a structure comprising source and drain electrodes with a channel region therebetween, a gate electrode, and a dielectric layer disposed between the source and drain electrodes and the gate electrode, the providing step comprising: forming the source and drain electrode over a transparent substrate, the source and drain electrode being spaced apart with the channel region therebetween; forming a layer of organic semi-conductive material in at least the channel region between the source and drain electrodes; and patterning the dielectric layer using the source and drain electrodes as a mask to form a region of dielectric material in the channel region which is thinner than regions of dielectric material adjacent the channel region, the patterning step comprising: projecting light through the transparent substrate to treat the dielectric layer in the channel region; forming a region of the dielectric layer in the channel region which is preferentially etchable relative to regions of the dielectric layer over the source and drain electrodes; and etching said region of the dielectric layer in the channel region to reduce the thickness of the dielectric layer in the channel region, the method further comprising forming the gate electrode over the dielectric layer in at least the channel region.