Research On TFET Based On Composite Dielectric

Under the guidance of Moore's law,the feature size of integrated circuits is decreasing,and the leakage problem of MOSFET devices in nanometer scale is becoming more and more serious.The increasing power consumption limits the further reduction of transistor size.In order to keep Moore's law rolling,tunneling field effect transistor(TFET)has become a research hotspot.Based on quantum tunneling effect,TFET can obtain subthreshold swing of less than 60m V/dec and a very low off-state leakage current at room temperature.The research on TFET at home and abroad mainly focuses on increasing the on-state current and reducing the subthreshold swing.It can be seen from the basic device physics that enhancing the electric field of the tunneling junction is the most effective method.The introduction of high-?(dielectric constant)dielectric is an important way to improve the electric field distribution.However,there are many defects between high-?dielectric and silicon substrate.High-?/low-?composite dielectric can reduce the negative effects of high-?dielectric,and the electric field can be regulated more flexibly by adjusting the proportion,size or position of composite dielectric,so as to improve the performance or practicability of the device.This paper will discuss the application direction of high-?dielectric in different TFET structures,and introduce high-?/low-?composite dielectric to study the regulatory effect of composite dielectric on the electric field distribution of TFET,and study the fabrication technology of high-?composite dielectric.The main contents of this paper are as follows:TCAD software was used to simulate the TFET device,and the influence of different parameters on the electrical performance of the device was analyzed,which provides a basic device model for the application of Hf O₂ based composite dielectric.According to the influence of spacer permittivity and gate dielectric relative permittivity on device performance,the improvement of high-?dielectric on the electric field distribution of TFET was analyzed.After studying the improvement of high-?dielectric on electric field,high-?/low-?composite dielectric was introduced.By adjusting the proportion,size or position of composite dielectric,the electric field of TFET can be regulated more flexibly to obtain the required electric field distribution.The effects of composite dielectric as gate dielectric of horizontal TFET,vertical TFET and vertical channel TFET and composite sidewall of horizontal TFET on the performance of TFET were discussed.The potential of three TFET structures for small-scale applications was discussed.The atomic layer deposition(ALD)process were introduced,and the Hf O₂ based composite dielectric was prepared by ALD process.Due to the poor interface characteristics between high-?dielectric and Si substrate,it is necessary to select appropriate materials as the transition layer.Scanning electron microscopy and X-ray photoelectron spectroscopy(XPS)were used to characterize hafnium dioxide based composite dielectric films grown by ALD deposition process.The metal with appropriate work function was selected as the electrode to complete the preparation of Hf O₂ based composite dielectric devices.The electrical characteristics of Hf O₂ based composite dielectric devices were tested and analyzed.