A Metal-Oxide Thin-Film Transistor Technology with Donor-Species Drive-In Pretreatment

Accompanying a reduction in process temperature from 400 °C to 300 °C, the channel current of an elevated-metal metal-oxide (EMMO) thin-film transistor (TFT) is found to change from one insensitive to the size of the conductive source/drain (S/D) regions to one suppressed with decreasing size of the regions. The different behavior is attributed to the distinct donor-species responsible for the formation of the thermally induced S/D regions at the two process temperatures. Such sensitivity, often undesirable, can be reduced by completing a donor drive-in thermal treatment before the patterning of the S/D electrodes. This alternative process flow with drive-in pretreatment allows the construction at 300 °C of an EMMO TFT with a significantly reduced footprint while still exhibiting a relatively low S/D resistance.