Research Of 3D HkMOS Devices With Interface Charge

Power semiconductor devices is a hot field of the research at present.According to how to break through the"silicon limit"trade-off relationship between the specific on-resistance and breakdown voltage of traditional VDMOS devices,the superjunction structure provides a breakthrough idea.However,the superjunction device is limited by the condition of charges balance,so the high dielectric constant(High-k,Hk)device is proposed,which can solve the problem caused by charge imbalance.In order to make the performance of Hkdevice close to the performance of superjunction device,the dielectric layer must have a high enough dielectric constant.This paper focuses on the study of two kinds of power devices:cylindrical HkMOS devices with interface charges and polygonal HkMOS devices with interface charges,and completes the following contents in the research process:Firstly,this paper studies a kind of HKMOS device which structure features are that the drift region is on the inside and the Hkregion is on the outside,interface charges with the interface between the drift region and the Hkregion,and the overall shape is cylindrical.The working principle is mainly due to the electric field modulation of the HK region.Most of the electric field lines generated by the ionization donor in the drift region are attracted through the Hkregion and finally terminate at the ionization recipient in the P+region.On this basis,this paper summarizes the influence of various structural parameters for the electric field distribution,the breakdown voltage and specific on-resistance of the device systematically,analyzes the cause of their tendency to change with parameters.It is found that the increase of appropriately negative interface charges concentration will lead to the increase of breakdown voltage.In this paper,the trade-off relationship between the specific on-resistance R_on,sp and breakdown voltage V_B of cylindrical HKMOS devices with interfacial charges under the special groups of structural parameters are optimized.For the devices with longitudinal length of 100?m and breakdown voltage of about 1600V,the negative interfacial charge concentration is increased from-5×10¹¹ cm^-2 to-1×10¹² cm^-2,and the specific on-resistance of the optimized device is reduced from 59.49 m?·cm² to 43.47m?·cm².Finally,a polygonal HkMOS device with interfacial charge on the interface of drift region and Hkregion is studied in this paper.Its working principle is similar to that of cylindrical device.The breakdown voltage and specific on-resistance of four polygons of regular triangle,regular square,regular pentagon and regular hexagon are studied in order of the number of edges from the least to the most,and how the change of the number of edges causes such influence is analyzed.In general,as the number of edges increases,the breakdown voltage decreases,but at the same time the breakdown resistance increases.In this paper,the trade-off relationship between the specific on-resistance R_on,sp and breakdown voltage V_B of cylindrical and polygonal HkMOS devices with interfacial charges under the special groups of structural parameters are optimized finally.As the number of polygonal device edges increases,the curve of tradeoff relationship gradually approaches that of cylindrical device.For cylindrical and polygonal devices with a longitudinal length of 100?m and a breakdown voltage of about 1450V,the optimized specific on-resistance of equilateral,hexagonal and cylindrical devices is 29.63 m?·cm²,43.19 m?·cm² and 48.42m?·cm²,respectively,as the number of sides increases.