SPICE Modeling And Simulation Of IGBT Based On Finite Volume Charge Method

With the rapid development of the semiconductor industry,the field of power electronics has also entered a period of rapid development,with a large number of power electronic devices widely used in various energy conversion fields such as new energy and power systems.IGBT(Insulated Gate bipolar junction transistor)is one of the most important power semiconductor devices in modern power electronic devices.Because of its advantages of simple drive,easy protection,no need of buffer circuit,high switching frequency,it has attracted much attention.At present,the main models of IGBT include Hefner model,Kraus model,and lumped charge model.These three models have their own advantages and disadvantages,among which the Hefner model and Kraus model require less physical quantities compared to the lumped charge model.The lumped charge model has advantages such as fast simulation speed and good convergence compared to the Hefner model and Kraus model,but the traditional three node lumped charge model has the disadvantage of low simulation accuracy.By analyzing and researching various IGBT models,a finite-volume-charge method based IGBT model is proposed.The new model assumes that the local quasi neutral approximation holds in the undepleted N-base region,where the excess carrier concentrations of electrons and holes are equal.Due to the fact that the excess carrier concentration of holes is approximately equal to the concentration of holes,the electron concentration is approximately equal to the sum of the equilibrium concentration of electrons and the hole concentration.Using a one-dimensional drift diffusion model,establish spatial nodes for hole density in the undepleted N-base region,and define voltage at the nodes.At the center of the hole density node,establish a node for the current components of electrons and holes,and calculate the current components of electrons and holes at the node using the center difference based on the hole density and voltage at the node.Establish a continuous equation for the total current of nodes,and establish a charge conservation equation on each volume element containing hole density nodes.By using the SPICE behavior modeling method,the solution of these two equations is transformed into SPICE circuit simulation.As the foundation of SPICE circuit simulation,it is necessary to set the values of model parameters.By establishing the structure of IGBT devices,TCAD simulation was conducted,and the parameters of MOS transistors were extracted as the basis for establishing the SPICE simulation MOS transistor model.By using TCAD hybrid simulation,the values of capacitance parameters such as Cgs and Cgd are obtained.Comparing the results of SPICE simulation with those of TCAD simulation,it was found that there are certain differences between the two.Further consideration was given to the two-dimensional correction of the N-drift zone on the emitter side,and the SPICE simulation I-V curve was found to be in good agreement with the TCAD simulation I-V curve.The finite-volume-charge method can more easily increase the number of nodes compared to the lumped charge method to describe the rapidly changing carrier density in a certain part of the device during rapid transient processes,further improving the simulation accuracy of IGBT.The finite-volume-charge method also incorporates compensating electron and hole current components to correct dynamic grid errors,ensuring the correct description of the fast transient process in PIN diodes.