Printed, self-aligned, top gate thin film transistor

A method of forming a thin film transistor (TFT), comprising:

• a) forming a semiconductor thin film layer;
• b) prior to forming a gate electrode of the TFT, printing doped glass on or over the semiconductor thin film layer in a pattern that forms a gap in the doped glass defining a channel region and a cross-sectional width of at least part of the gate electrode;
• c) after printing the doped glass in the pattern, forming the gate electrode on or over the channel region and in the gap, the gate electrode comprising a gate dielectric film and a gate conductor thereon;
• d) diffusing a dopant from the doped glass pattern into the semiconductor thin film layer;
• e) forming a patterned interlayer dielectric film over the doped glass pattern and the gate electrode, the patterned interlayer dielectric film having an exposed upper surface;
• and
• f) etching the doped glass pattern using the exposed patterned interlayer dielectric film as a mask.

A method of forming a thin film transistor (TFT), comprising:

• a) forming a semiconductor thin film layer;
• b) forming a gate dielectric film on an entire surface of the semiconductor thin film layer;
• c) prior to forming a gate electrode of the TFT, printing a doped glass formulation in a pattern on or over the gate dielectric film, in a manner leaving a gap in the doped glass pattern exposing a portion of the gate dielectric film and defining a channel region and at least one dimension of at least part of the gate electrode;
• d) after printing the doped glass pattern, forming the gate electrode in the gap, the gate electrode filling a width of the gap and comprising the gate dielectric film and a gate conductor thereon;
• and
• e) diffusing a dopant from the doped glass pattern into the semiconductor thin film layer.