Investigation On The Influence Of Annealing And Surface Treatment On The Performance Of IGZO-TFT

TFTs with IGZO active layer deposited through DC sputtering were fabricated using shadow mask. The dependence of performance on the deposition Parameter of active layer and configuration of TFTS were investigated in detail.(1)IGZO-TFTs were prepared using SiO2as the insulator, we studied the influence of the active layer deposition condition on the TFT performance. We prepare TFTs for active layer with fixed oxygen partial pressure range from10%to50%.it is found that TFTs fabricated by the oxygen partial pressure of10%and20%showed best transfer characteristics; TFTs with IGZO film thickness increasing from20nm to50nm,off current was gradually increased, especially at thickness of50nm,IGZO-TFT showed a large off current, leading device’s on-off ratio declined sharply and improperly shutting down station; sputtering power could affect the characteristics of IGZO thin film, the atomic composition of the In would change as the increase of sputtering power, XPS analysis showed that:it is inferred due to the biggest RMS of In.(2)In order to improve device performance, we use O2/N2O plasma to modify the surface of SiO2insulator. The defect states in the interface decrease in the case of insulator modified by plasma. Device performance test results show that:IGZO-TFT with SiO2insulator modified by plasma has a higher on/off current ratio, but a smaller threshold voltage; the threshold voltage with modified SiO2also can be controlled by plasma, which suggested that IGZO-TFT performance has been affected after modification.(3)It was found that annealing sequence and temperature could affect the performance of IGZO-TFT. We obtained better performances of device annealing treatment taken immediately after GI/ESL film deposition. IGZO-TFT with GI/ESL annealing has a higher on/off current ratio, a modulated threshold voltage, and a smaller Vth shift. However, Device with high temperature annealing taken after TFT fabrication shows poor electric performances, witch suggested that the best value approximately come with250℃.