Transport property improvements of amorphous In–Zn–O transistors with printed Cu contacts via rapid temperature annealing

The device performance of amorphous In–Zn–O (a-IZO) thin-film transistors (TFTs) with printed Cu contacts was significantly improved by the insertion of a diffusion barrier Ta layer and rapid thermal process (RTP) annealing. Furnace-annealed a-IZO TFTs with Cu/Ta contacts exhibited mobility values of 21.3cm2/Vs, subthreshold gate swing (SS) values of 1.9 V/decade, and ION/OFF of ~106. In contrast, the SS, mobility, and ION/OFF ratio of RTP-annealed a-IZO TFTs with Cu/Ta contacts were 30.6cm2/Vs, 0.68V/decade, and 3×107, respectively. We attributed the performance improvement of devices with Cu/Ta contacts to the suppression of Cu in-diffusion within the a-IZO channel due to the rapid heating associated with RTP annealing.