Top gate thin-film transistor and method of producing the same

A method as claimed in any preceding claim, wherein the gate insulator comprises first and second gate insulator layers, the first gate insulator layer being patterned with the amorphous silicon layer to define a semiconductor island of the transistor with an overlying first gate insulator layer.

A method as claimed in any preceding claim, wherein the gate insulator layer comprises silicon nitride, and the surface insulator comprises silicon oxide.

A method as claimed in any preceding claim, wherein the laser annealing process comprises exposing the structure to laser light of predetermined wavelength, the thickness of the surface insulator being selected depending on the wavelength, to reduce the effect of thickness variations in the gate insulator layer and/or the surface insulator on the reflectance of the structure at the predetermined wavelength.

A top gate thin-film transistor comprising:

• a silicon layer provided over an insulating substrate;
• an insulated gate structure over the silicon layer, comprising a gate insulator and an upper gate conductor, the gate conductor being patterned to be narrower than a spacing between source and drain electrode contacts to the silicon layer, the silicon layer in the region of the source and drain electrodes comprising polycrystalline silicon,
• wherein the gate insulator comprises a gate insulator layer of first refractive index, and an overlying upper gate insulator layer of second, lower, refractive index, the gate conductor being provided over the upper gate insulator layer, the gate insulator layer and the upper gate insulator layer extending fully across the spacing between contacts of the source and drain to the silicon layer.