Improvement of Performance of Back Channel Etching InGaZnO Thin-Film Transistors by CF4 Plasma Treatment

The performance of back channel etching (BCE) amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) was improved using a carbon tetrafluoride (CF
$_{{4}}{)}$
plasma treatment of the back channel (BC) after the wet-etching process of source–drain (SD) electrodes. X-ray photoelectron spectroscopy (XPS) analysis showed that the wet-etching of
$\text{H}_{{2}}\text{O}_{{2}}$
-based etchant may result in Mo-related residue, which deteriorate a-IGZO BC. In comparison with as-etching indium gallium zinc oxide (IGZO) TFT, the saturation field effect mobility increases from 7.8 to 16.4 cm2/Vs, subthreshold swing (SS) decreases from 0.82 to 0.34 V/decade, the ratio of on current and off current improves from
$7.3\times 10^{{5}}$
to
$1.1\times 10^{{10}}$
, and the threshold voltage shift of negative bias illumination stability (NBIS) improves from −3.4 to −0.6 V. The fact confirmed that CF4 plasma treatment of the BC can effectively reduce BC defects and improve the electrical characteristics of BCE IGZO TFT comprehensively.