The Breakdown Characteristics Research And Design Of Power Vdmosfet Temination

Power semiconductor devices are the basic stone for development of electronics and electronic power.Because of the characteristic of the power semiconductor devices inherent in MOSFET, For example, excellent frequencycharacteristics,rapid switch frenquency, smaller switching loss,high resistant of input,easy driver circuit and so on.At present it has been used in switching power supply,DC-DC transform,DC-AC transform,rapid switching transform,high fidelity audio amplification,the driver of relay and solenoid,motor control,automobile electronic,RF communication field.Power VDMOSFET is developed from VMOSFET and UMOSFET.Because of its drain at the back of silicon,the vertical conductive characteristics make it widely used in high-power power electronics industry.The development trend of power semiconductor devices is constantly shrinking devices sizes.Beacause of its smaller size means greater channel density and smaller Rds(on).or under the same RdS(on) can achieve a smaller chip area,and reduces the design cost of the chip.Semiconductor power devices at the main contradiction in design process is under the premise the breakdown voltage is guaranteed to reducing Rds(on).This is also the power semiconductor devices’s main research direction.This article mainly research the breakdown characteristics of terminal structure of power VDMOSFET.designing and optimizing a 700V VDMOSFET termination.Firstly studied the conditions and mechanism of avalanche breakdown for power semiconductor device.Generated into the infinite planar junction and mutation of columnar boundary conditions to get the analytic equation of breakdown voltage.Based on the research of the infinite planar junction,Found that the planar junction with selection of epitaxial layer parameters has a direct relationship,So we can calculate the concentration of epitaxial layer and the thickness parameter,Through simulation,the calculation of epitaxial layer parameters simulation results and actual error is very small.Mutation columnar knot is maily used for the main breakdown voltage of the research,results show that the radius of curvature and knot of the breakdown voltage has directly relate.The lower breakdown voltage of curvature,the greater the knot,lt also provides a theoretical basis for other terminal technology.And then introduces several common terminal technology,the brief analysis of the technology of horizontal change doping,the field limiting ring technology,terminal field plate technology has made the detailed analysis and simulation berification.By changing the depth limit ring,the field limiting ring spacing,composite plate structure,explore its ends the relationship between the self-breakdown characteristics.A high voltage power device the improved plate technology design,By adjusting the metal-silicon composite plate structure,making the edge of the metal floating open stoping covering polysilicon floating barnyard plate edge.finally make plate edge,finally make a plate within the field intensity weaken each other,reduce the surface the surface the maximum electric field.Through the above study of terminal technology,this paper designed a four field limiting ring metal polycrystalline composite VDMOSFET field plate structure,Through the optimization of epitaxial layer parameters optimization,field limiting ring number and position,the adjustment of the metal-poly compound field parameters,Finally in 151μm on the effective length of the terminal designed a terminal structure of withstand voltage of 772V,Under the precondition of the same pressure than other similar terminal can save 26% of chip area in literature.