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Circuits and AMOLED display with self-aligned a-IGZO TFTs on polyimide foil

2014; Wiley; Volume: 22; Issue: 10 Linguagem: Inglês

10.1002/jsid.281

1938-3657

Manoj Nag, Ajay Bhoolokam, Steve Smout, Myriam Willegems, Robert Müller, Kris Myny, Sarah Schols, Marc Ameys, Jan Genoe, Tung Huei Ke, Peter Vicca, Tim Ellis, Brian Cobb, Abhishek Kumar, Jan‐Laurens P. J. van der Steen, Gerwin Gelinck, Yusuke Fukui, Koji Obata, G. Groeseneken, Paul Heremans, Soeren Steudel,

Silicon and Solar Cell Technologies

A process to make self-aligned top-gate amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) on polyimide foil is presented. The source/drain (S/D) region's parasitic resistance reduced during the SiN interlayer deposition step. The sheet resistivity of S/D region after exposure to SiN interlayer deposition decreased to 1.5 kΩ/□. TFTs show field-effect mobility of 12.0 cm2/(V.s), sub-threshold slope of 0.5 V/decade, and current ratio (ION/OFF) of >107. The threshold voltage shifts of the TFTs were 0.5 V in positive (+1.0 MV/cm) bias direction and 1.5 V in negative (−1.0 MV/cm) bias direction after extended stressing time of 104 s. We achieve a stage-delay of ~19.6 ns at VDD = 20 V measured in a 41-stage ring oscillator. A top-emitting quarter-quarter-video-graphics-array active-matrix organic light-emitting diode display with 85 ppi (pixels per inch) resolution has been realized using only five lithographic mask steps. For operation at 6 V supply voltage (VDD), the brightness of the display exceeds 150 cd/m2.