Fabrication And Performance Study On Flexible Oxide Bottom Gate Thin Film Transistors

Thin film transistors are basic devices in the field of integrated circuits.The traditional method of fabrication is using hard silicon as a substrate,forming a dielectric layer on the top of the substrate by high-temperature plasma enhanced chemical vapor deposition,and then taking a series of complex processes to manufacture devices.Thin film transistors with such a rigid structure have a number of disadvantages,such as bulky,difficult to bend,unstable mechanical properties and complicated manufacturing processes.In order to solve these problems,scientists have conducted extensive research on flexible thin film transistors in recent years.Most scientists focus on changing materials and improving device structure.However,these researches can not meet all following requirements that devices are compatible with the current semiconductor mainstream silicon manufacturing process,owning simple production process and good flexibility.Flexible bottom gate oxide thin film transistor that we have made can meet these requirements at the same time,showing a good development prospect.Because it uses the flexible plastic as the substrate,electroplates dielectric layer through the low temperature magnetron sputtering technology to realize the bottom gate structure,and selects the silicon material to fabricate.After overcoming lots of key technical problems in the production process,a new type of flexible oxide bottom gate thin film transistor was successfully fabricated through low temperature magnetron sputtering technology,dry etching technology and thin film transfer technology.This paper mainly introduces the following parts of the work.The first part is the structure analysis and layout design of the flexible oxide bottom gate thin film transistor.First of all,the structure of the device is analyzed and it is mainly composed of flexible poly terephthalate plastic,indium tin oxide transparent conductive film,oxide dielectric layer,silicon nano-film and metal electrode.Considering the new device requires repeated lithography process,so the layout of the process steps such as ion implantation,dry etching and deposition metal are separately designed to make a mask for lithography.The second part is the fabrication of flexible oxide bottom gate thin film transistor.The fabrication process includes photolithography,ion implantation,annealing,dry etching,wet etching,thin film transfer and metal deposition.In the specific experimental operation,some key technical problems such as annealing,dielectric layer growth,film transfer,the formation of electrodes on the film,and so on.Through many experiments,these problems have been solved well and the subject is successfully carried out.The third part is the performance test of the flexible oxide bottom gate thin film transistor.The transfer characteristic curve,transconductance curve,output characteristic curve and the experimental parameters of different bending states are measured by the semiconductor analyzer.