Flexible Substrate Stacking Gate Dielectric Thin Film Transistor Preparation And Research

With the rapid development of the information age,people’s requirements for all kinds of new electronic equipment are also increasing,and higher standards are put forward for display technology.Future display applications will require higher drive currents,miniaturization,lower power consumption,lower operating voltages,and even faster switching speeds,so it is essential to further improve the overall performance of thin-film transistors.One way to achieve these requirements is to increase the gate capacitance.One approach is to reduce the thickness of the gate dielectric layer,however,the exact thickness of the gate dielectric is difficult to control and can lead to high gate leakage currents.Another approach is to use high K gate dielectric materials to increase the coupling of the gate electric field.At the same time,the current thin-film transistor research mostly adopts single gate dielectric structure,which generally has the problem of semiconductor layer/gate dielectric layer interface and affects the electrical performance of the device,and the stacking gate dielectric structure is considered as one of the most effective methods to solve this problem.Therefore,this paper focuses on two promising high K gate dielectric materials,H_fO₂and Ta₂O₅.The use of flexible substrates,which are more ductile and lighter than rigid substrates.The electrical properties and characterization results of thin film transistors structured with Ta₂O₅dielectric layer growth process and single and stacking gate dielectric structure are analyzed and investigated.The main research work of this paper is as follows:By controlling the growth process of Ta₂O₅dielectric layer,such as sputtering time,oxygen-argon ratio,sputtering pressure and sputtering power,the influence of RF magnetron sputtering on the electrical properties of stacking gate dielectric thin film transistor was explored,and the thin film was characterized by AFM,SEM and XRD.Finally,when the sputtering time is 60min,the ratio of oxygen to argon is 10:90,the sputtering pressure is 8m T,and the sputtering power is 150W,the best electrical performance of the device is obtained,with a current on-off ratio of 1.27×10⁶,a threshold voltage of 9.1V,a sub-threshold swing of 0.54V/decade and a carrier mobility of 7.03cm²/V·s.Based on the optimum growth process conditions of Ta₂O₅dielectric layer obtained from the above work,we continue to explore the electrical performance differences between Ta₂O₅single-layer gate dielectric thin film transistor and H_fO₂/Ta₂O₅stacking gate dielectric thin film transistor.According to the characteristic curve:the stacking gate dielectric structure significantly improves the current-to-switch ratio from 6.33×10²to 1.27×10⁶,and the off-state current is three orders of magnitude different,and it shows good output characteristics.The introduction of the H_fO₂layer improves the dielectric/semiconductor layer interface and reduces the surface roughness of the film as a modification layer,as also shown by the SEM images and AFM images of the cross-section of the film.