Study On The Electrical Properties Of Trench Barrier Schottky Diode

With the enhancement of our national strength,a great deal of manpower and material resources have been put into the related fields of power electronics.As the main basic power semiconductor in power electronics technology,it is developing rapidly.Domestic power MOSFET devices gradually occupy the global market.Power MOSFET is made by virtue of its advantages of fast switching speed,high input impedance,high working frequency and simple driving circuits.It is a hot product in the market.Schottky diodes are widely used in clean energy rectifier conversion circuit and switch control circuit because of their high switching frequency and low switching power consumption.In the design of TMBS devices,in order to alleviate the contradiction between forward voltage drop and blocking leakage,several common Schottky rectifier structures are introduced,and the Schottky surface electric field and groove corner electric field existing in each structure are analyzed in detail.On this basis,the traditional TMBS devices and innovative TMBS devices are optimized and verified by simulation.In the application environment of new energy conversion circuit and switch circuit,TMBS device as the core determines the performance of the whole circuit,so the design of TMBS device is very important.In this paper,a 60V low-voltage TMBS device is designed.Before simulation,the main process flow in the simulation of this type of device is introduced in detail,and the theoretical mechanism of forward and reverse blocking of device structure is analyzed.On this basis,according to the key parameters affecting the electrical performance of the device,different simulation experiments are designed for these parameters.Finally,a set of better parameters are found.The TMBS devices with forward voltage drop of0.32V@3A,breakdown voltage of 106.4V and reverse leakage of 82.0?A@45V are obtained by simulation.The unpackaged wafers were tested after being fed into the factory.The results show that the forward voltage drop is 0.397V@3A,the reverse breakdown voltage is 65.4V and the reverse leakage current is 12.1?A@45V.Traditional silicon-based TMBS devices are mainly used in low voltage environment,but silicon is the most common semiconductor material.The research of medium and high voltage TMBS devices has great significance to reduce the process difficulty and processing cost.However,due to the breakdown limitation of large electric field at the corner of the MOS groove,the epitaxial layer of conventional TMBS devices cannot be completely depleted,and the low doping concentration of the epitaxial layer will also increase.The reverse interruption withstand voltage is almost entirely borne by the epitaxy layer on both sides of the groove and at the bottom of the groove due to the dramatic substrate diffusion phenomenon.Improving the utilization of epitaxy and withstand voltage can effectively improve the breakdown voltage of the device.Based on this idea,a new TMBS structure with deep groove and thick groove oxide layer is designed in this paper.The difference between the structure and the traditional TMBS structure is that by deepening the groove to the substrate,the Schottky contact electric field is reduced,and the reverse leakage current is greatly reduced;the oxide layer thickness in the groove is increased,the electric field of MOS structure at the corner of the groove is reduced,the breakdown of the body caused by the large electric field in the groove is alleviated,and the area of the drift zone is increased;at the same time,the groove gap is optimized.Longitudinal electric field distribution can compensate for the low voltage caused by deep grooves and improve the voltage withstanding ability of devices.Finally,the simulation results show that the reverse breakdown voltage is 103.3V,the reverse leakage current density is 4.5*10^-5A/cm²@90V,and the forward conduction voltage drop is 0.66V.Compared with the traditional structure,the reverse breakdown voltage increases by 11.7%and the reverse leakage current decreases by 50.1%at the current density of 180A/cm².