The Preparation Of Anodic Alumina Insulation For Thin Film Transistors

In recent years,with the progress of society and science,flat panel display has gradually become an irreplaceable part of people's lives.As the core device of flat panel display technology driving panel,TFT has great research value and development potential.The Al₂O₃ thin film prepared by anodic oxidation is a gate insulating layer of the TFT,which has high stability,strong uniformity,excellent performance,low cost,etc.,and has become a hot spot in the current research.In this paper,Al₂O₃ thin films were prepared by anodic oxidation and their properties were characterized to find out the best preparation conditions.On this basis,a bottom gate staggered TFT device is fabricated with Al₂O₃ film as the gate insulating layer,and the electrical performance of the TFT is tested to investigate the effect of different experimental conditions on the performance of the anodized aluminum oxide TFT.The specific analysis includes the following three parts:Firstly,the Al₂O₃ thin films were prepared by anodic oxidation method.The type and concentration of the electrolyte were changed,the square resistance was measured,and the MIM structure was used to characterize the breakdown voltage.The results showed that the square resistance of Al₂O₃ films prepared with ammonium bitartrate ethylene glycol solution was higher than that of other electrolytes?oxalic acid,dilute sulfuric acid,and citric acid?,and the breakdown voltage was the highest,reaching 38V.Next,to prepare a TFT,an Al₂O₃ film is used as a gate insulating layer,a glass substrate is used as a substrate,Al is used as a gate,ZnON is used as an active layer,and metal Mo is used as a source-drain electrode.First,the Al film was prepared by radio frequency magnetron sputtering,the gate insulating layer was formed by anodic oxidation,and the active layer ZnON was prepared by magnetron sputtering with O₂and N₂ as reactive gases.a DC magnetron sputtering method was used to prepare the Mo thin film.Finally,through the photolithography,etching and other processes,we can complete the preparation of the TFT.Finally,the electrical properties of Al₂O₃-TFT under different anodizing conditions were measured.The output characteristics and transfer characteristics of TFT were measured by 4200 semiconductor tester.The data was visualized by Oringin software and the TFT's important characteristic parameters were extracted by the transfer characteristic curve.The results show that the TFTs prepared by anodizing ammonium aluminate tartrate solution for the alumina gate insulating layer have significantly higher carrier mobility and switching ratio than the TFTs prepared from other solutions?oxalic acid,dilute sulfuric acid,and citric acid?.When using ammonium tartrate ethylene glycol solution as the electrolyte,the higher the concentration of ammonium tartrate and ethylene glycol in the solution,the higher the carrier concentration and switching ratio of the TFT,and the case where the concentration of ammonium tartrate is not changed.The higher the concentration of diol,the subthreshold swing and threshold voltage of TFT increase first and then decrease.Therefore,the best preparation parameter is ammonium tartrate:ethylene glycol:water=2:70:35.At this time,the characteristic parameters of the Al₂O₃ TFT are:the carrier mobility of 3.63 cm²/V�s,and the switching ratio of 5.1�10⁴,threshold voltage of 3.57 V,and subthreshold swing of 3.95 V/dec.A positive value of the threshold voltage indicates that the prepared TFT is a n-channel enhancement TFT device.