Comparison of N2 and ar plasma treatment for source/drain formation in self-aligned top-gate amorphous InGaZnO thin film transistor

We propose a self-aligned top-gate amorphous InGaZnO thin film transistor (a-IGZO TFT) with source/drain treated by N2 plasma. By comparing the performances of the self-aligned top-gate a-IGZO TFTs with N2 and Ar plasma treatment, it is found that N2 plasma treatment can effectively decrease the resistivity of the a-IGZO. The TFTs with N2 plasma treated source/drain have the comparable electrical performance and superior stress stability compared to the Ar plasma treated one. The fabricated self-aligned top-gate a-IGZO TFT with N2 plasma treatment exhibits field-effect mobility of 5.1cm2/V·s, threshold voltage of -0.33 V, a subthreshold swing of 0.26V/dec, and a shift of Vth of -0.65 V and 0.52 V under PBS and NBS with gate-bias stress voltage of+30V respectively.