Improvement in Bias Stability of IGZO TFT With Etching Stop Structure by UV Irradiation Treatment of Active Layer Island

Abstract

In this paper, the effect of ultraviolet (UV) irradiation treatment of active layer IGZO on the bias stability of amorphous IGZO thin film transistor with etch stop (ES) structure is studied. Along with the increase in UV irradiation time, the surface of the IGZO film becomes smoother. An appropriate UV irradiation treatment cannot only improve the bias stress stability but also suppress the lump behavior generated by light illumination. The devices with irradiation time of 1 min exhibits an excellent properties with the field effect mobility of 15.07 cm2/V·s, subthreshold swing of 0.2 V/dec, and all bias stress less than 0.2 V including NIBS and PIBS. However, a relative long UV treatment would result in deteriorating the bias stability of devices. The fact implies that the reasonable UV irradiation treatment on the active layer island before depositing the ES layer is advantageous for improving the stability of the a-IGZO TFT device.

Keywords

• a-IGZO thin film transistor
• UV irradiation
• stability