Simulation And Analysis Of Dynamic Process Distribution Effect Of High Voltage IGBT

Insulated Gate Bipolar Transistor(IGBT),as a high-voltage high-power semiconductor switching device,often works under the environment of high voltage and large current.In order to ensure that IGBT can work stably,efficiently and safely for a long period of time,the electrical characteristics such as current and voltage inside the IGBT and the temperature distribution should be distributed as uniformly as possible to prevent the device from being burned due to excessive local temperature.Therefore,it is necessary to study the distribution of current,voltage and temperature inside the chip during the dynamic process of the high-voltage IGBT chip.When the IGBT is turned on or off,it first obtains the driving signal from the gate pad,and then relies on the polysilicon layer to reach various areas and corners of the chip.However,due to the distributed resistance effect of the gate formed by the polysilicon layer,each primary cell in the chip cannot be turned on or off at the same time.Therefore,there is a current concentration phenomenon in the dynamic process of the IGBT chip,especially when the chip area is large,the current concentration phenomenon is particularly obvious,which leads to the problem of the dynamic process distribution effect.This paper will study the dynamic process distribution of high-voltage IGBT chips around the electrical and temperature characteristics of IGBTs.This article uses Sentaurus-TCAD simulation software to model the device structure of the IGBT chip,and build a Spice circuit to build an IGBT model with gate resistance and gate distributed resistance,and analyze the changes of voltage,current and power during the dynamic process of IGBT chip.Using the ICEPAK module in ANSYS simulation software to build a cell-level IGBT thermal simulation model,the impact of current concentration in the dynamic process distribution on the temperature distribution of the device surface is analyzed.The specific analysis results and conclusions are as follows:There will be a phenomenon of current concentration in the IGBT during turn-off and turn-on.The degree of current concentration is related to the magnitude of the gate resistance and the gate distributed resistance.During the turn-off process,the current concentration phenomenon first appears at the cell far away from the gate drive voltage source,while the turn-on process is opposite to the turn-off process.The current concentration phenomenon first appears at the cell closer to the gate drivevoltage source.The current concentration in the switching process of the IGBT is affected by the gate resistance and the gate distributed resistance.When the gate resistance is large,the current concentration increases,the longer the gate drive signal reaches the gate voltage of each cell,the longer the IGBT turn-off delay time,and the turn-off loss also becomes larger.However,a reasonable increase in the resistance of the gate resistance can effectively improve the phenomenon of voltage overshoot.In the steady state,the IGBT chip exhibits a temperature distribution with a high central temperature and a low four-corner temperature.In the longitudinal direction of the chip,the temperature from the chip surface to the bottom of the copper heat sink gradually decreases and the rate of temperature decrease increases.During the IGBT turn-off process,the cell power at the center of the chip is larger and the temperature value rises higher.Contrary to the IGBT turn-off process,the cell power at the four corners of the chip is larger and the temperature value rises higher.At the same time,with the increase of the gate distributed resistance,the more obvious current concentration effect causes the surface temperature of the IGBT chip to increase during the turn-off and turn-on process.The larger gate distribution resistance makes the temperature difference on the surface of the chip larger after the IGBT chip is turned off,while the opening process of the IGBT chip will reduce the temperature difference between the center of IGBT and the corners,which is beneficial to the uniform temperature distribution in the dynamic process of the IGBT.In summary,this paper uses the simulation results to reasonably analyze the distribution of electrical characteristics and temperature during the dynamic process of high-voltage IGBTs,which provides an important reference for improving the uniformity of the current and temperature distribution of the device.