Research For The Smart Power MOSFET Device With Wide SOA

The Metal Oxide Semiconductor Field Effect Transistor(MOSFET)has been widely applied in power electronic systems such as electric vehicle,5G network,and data center with the advantages of high current density,low on-resistance,and fast switch,which is the core device to determine the power conversion efficiency and the stability of these systems.Therefore,these applications force the power MOSFET improving towards to high power density and low loss.Despite the optimization of electrical parameters such as on-resistance,switching characteristics and current density of the power MOSFET devices,However,the safe operation area(SOA)of them has been reduced,which has seriously restricted the application and development of the device.In this paper,based on the practical system application requirements,the problem of the reduction of the SOA caused by the reduction of the linear working ability of power MOSFET devices is studied in details,the inner thermal instability mechanism and the influence of the on-resistance on the SOA have been presented,the thermal instability boundary conditions have been clarified.Moreover,an architecture for the smart power MOSFET device with wide SOA is proposed,which uses the built-in gate drive method to detect and judge the operating mode of the power MOSFET device in real time,and adjust the working state of the power MOSFET device adaptively.breaking through the compromise between on-resistance and SOA of the power MOSFET device.Main innovation points in this thesis are shown as follows.1、It has been shown that the failure mechanism caused by power dissipation in the SOA of the power MOSFET device is that the positive temperature coefficient of current causes the local current to increase,causing hot spots to burn out the device,and there is an obvious trade-off relationship between the current temperature coefficient and the on-resistance.Base on the mechanisms,an architecture for the smart power MOSFET device with wide SOA is proposed,the built-in gate driver chip is used to adaptively control the time-division and partition conduction of the power MOSFET device,and achieves the characteristics of low temperature coefficient and low on-resistance at the same time.2、A double-layer epitaxy split-gate main power MOSFET chip with low temperature coefficient is researched and designed.Based on the RESURF effect,the epitaxy doping concentration of the split-gate trench area is increased,which is beneficial to improve the breakdown voltage and reduce the on-resistance of the device.The tape-out results show that the off-state breakdown voltage of the main power MOSFET device is 116V,and the specific on-resistance is 31mΩ*mm~2.Compared with the traditional split-gate structure,the specific on-resistance is reduced by 35%.At the same time,the local turn-on and turn-off of the main power MOSFET chip is realized by means of double gate-bus,and the maximum temperature coefficient of the device is reduced by 92%.3、A gate driver chip with voltage detection and adaptive control is is researched and designed,the sampling circuit and logic processing circuit are analyzed and designed in detail,and the layout design and tape-out of the whole chip are carried out.The tape-out results show that the breakdown voltage of the gate driver chip is 596V,the static leakage current is1.24μA,the gate switching voltage is 7.5V,and the drain-source threshold voltage is 3V.It realizes the functions of(1)when the voltage of the sampling signal is high,logic processing circuit outputting low voltage;(2)when the voltage of sampling signal is low,logic circuit output following external gate drive signal.4、Completed the stacking package of the smart power MOSFET device with wide SOA,and a comprehensive evaluation of electrical parameters has been carried out.The experimental results show that the breakdown voltage of the smart wide SOA power MOSFET device is 115.9V,the on-resistance is 2.83mΩ,the threshold voltage is 3.39V,the linear operating current reaches 13.9A,when the drain-source voltage is 56V,and the on-time is 10ms,the limit operating current in the direction of power dissipation in the SOA is improved by more than 13 times.