Method for providing lateral thermal processing of thin films on low-temperature substrates
A method for thermally processing a minimally absorbing thin film in a selective manner is disclosed. Two closely spaced absorbing traces are patterned in thermal contact with the thin film. A pulsed radiant source is used to heat the two absorbing traces, and the thin film is thermally processed via conduction between the two absorbing traces. This method can be utilized to fabricate a thin film transistor (TFT) in which the thin film is a semiconductor and the absorbers are the source and the drain of the TFT.
1. A method for thermally processing a very thin film, said method comprising:
patterning a metal absorbing trace located adjacent to a very thin film that is located on top of a substrate;
after said patterning, irradiating said metal absorbing trace with at least one electromagnetic pulse to heat up said metal absorbing trace, wherein a pulse length of said at least one electromagnetic pulse is shorter than a thermal equilibration time of said substrate; and
after said irradiating, allowing heat from said metal absorbing trace to thermally process said very thin film.
2. The method of claim 1 , wherein said substrate has a maximum working temperature of less than 450° C.
3. The method of claim 1 , wherein said absorbing trace is made of materials more absorptive of said electromagnetic pulse than said very thin film.
4. The method of claim 1 , wherein said method further includes providing a heat spreading layer adjacent to said very thin film.
5. The method of claim 4 , wherein said method further includes providing a high-temperature, low-thermal conductivity film between said heat spreading layer and said substrate.
6. The method of claim 1 , wherein said electromagnetic pulse is provided by a flashlamp.
7. The method of claim 1 , wherein said electromagnetic pulse is provided by a directed plasma arc.