Design And Research Of The Low Loss High Reliability Insulated Gate Bipolar Transistor

Recently,the Insulated Gate Bipolar Transistors(IGBTs),as the core power switch components,have been widely used in the field of electric vehicles,home appliance and industrial motor driver.The power loss of the IGBT determine the energy efficiency the power electronic system.The high power loss results in the high temperature rise of the IGBT.And it influence the reliability of the IGBT and system.Therefore,the IGBTs have been developing continuously by reducing on-state voltage drop and switching loss since its invention.Meanwhile,the high voltage,high current,high frenquency in the power electronic system require the IGBT with the high avalanche reliability and low EMI noise.However,there is the trade-off relationship between the power loss,avalanche reliability and EMI noise.And limited the development of the low power loss IGBT.In this dissertation,the power loss,avalanche reliability and EMI noise characteristics of IGBTs are systematically studied in depth.The research details achievements are concluded as follows.1.Modeling the on-state voltage and the turn-off loss of the IGBT.It points out that the trade-off relationship between the on-state voltage and the turn-off loss of the IGBT can be improved by increase the carriers density at the emitter side of the IGBT.Furthermore,a novel IGBT with shallow p-well and carriers store layer(SP-IGBT)is proposed to improve the trade-off between the on-state voltage and the turn off loss.The experiment results show that the SP-IGBT reduce the turn off loss by 42%with the same on-state(1.55V),improve the power loss characteristics of the IGBT.2.The avalanche robustness mechanism of the IGBT is investigated.It points that the avalanche robustness of the IGBT is determined by the negative differential resistance characteristics during the avalanche.And there is a trade-off relationship between the on-state voltage and the negative differential resistance characteristics of the IGBT.A novel IGBT structure with electric field modulation layer(EFM-IGBT)is proposed.The EFM-IGBT optimized the surface electric field distribution and reduce the impact ionization effect at the emitter side of the IGBT.As a consequence,the EFM-IGBT shows the positive differential resistance characteristics during the avalanche,and the avalanche reliability is improved.Meanwhile,the on-state voltage of the EFM-IGBT is reduced by 16.3%than the conventional IGBT due to the carriers store effect.3.The inhomogeneous avalanche current in the IGBT die during the avalanche of the IGBT is investigated.It is found that the hole current drift from the cell region to the termination region and concentrate in the transition region during the avalanche of the IGBT.It results in the severely impact ionization in the transition region and the device breakdown.In this article,a novel termination structure with double isolated trenches is proposed.It eliminates the consentrated current and improves the avalanche reliability.Compared with the conventional IGBT,the avalanche current of the proposed structure achieves 10m A,which is improved 150%.4.The EMI noise mechanism in the switching mode power supply is researched.It is found that the di/dt in the zero current of the IGBT is the main reason of the larger EMI noise.And the turn of di/dt of the IGBT is hard to control by the gate resistance.It results in that the gate resistance in the system is very lager to achieve the low EMI noise.And the turn on loss of the IGBT is increased.In this section,the relationship between the turn on di/dt and RG of the IGBT is investigated.A novel structure with deep P-well is proposed to improve the turn on di/dt controllability.The experiment results shows that,the EMI noise of the system which employing the proposed IGBT is reduced by 7d B when the gate resistance is 27ohm.5.A novel trench self-adjust conductivity modulation trench IGBT structure is proposed and experiment.The results shows that the breakdown voltage of the proposed structure achieve 1250V,the on-state voltage is 1.5V@300A/cm~2,and the turn off loss is 23m J/cm~2,and the EAS is 23m J,the dv/dt of the IGBT during the turn on process is 1.38V/ns(R_G=100ohm)?...