Research On New High-current IGBTs And Technologies For Condition Monitoring Of Devices

Power semiconductor devices act as the core components of high-end power electronic equipment,which is playing a crucial role in the modern manufacturing sector.Among the commercially available power semiconductor devices,insulated gate bipolar transistor(IGBT)has become the most suitable solution for medium and high power-level equipment with its good comprehensive performance.Therefore,the research on new high-current IGBTs with independent intellectual property rights and technologies for condition monitoring of devices has great significance for the domestic manufacturing sector.This thesis focuses on the urgent need of high performance power semiconductor device in domestic power electronic equipment manufacturing industry,and takes IGBT device as a main research topic.From the aspects of boosting individual device’s power capacity and density,technologies of new high-current IGBT device’s packaging and fabrication are studied.Furthermore,given the importance of IGBT device and the requirement of reliability improvement in state of the art equipment,monitoring technologies for the health condition of IGBT device is arranged as another main research topic.Effective methods to obtain device’s health information are investigated with consideration of diversity in power electronic equipment for practical application.The research work and achievements are as follows:(1)A new high-current IGBT device and a new pressure contact package technology are proposed.The new high-current IGBT chip(3300V/1000A)with a special layout and its new pressure contact package are co-designed.The mechanical and thermal finite element simulation of this new package structure is carried out.Then,an ultra-high current large-die IGBT chip is fabricated and packaged.The performance of the device sample is tested and compared with commercial press-pack IGBT devices,which shows the superiority of the former in power density and junction to case thermal resistance,about 1.5 times and 72% of a commercial device with identical package size,respectively.(2)Based on silicon-silicon direct bonding principle,a new manufacturing process flow for monolithically integrated bi-directional IGBT(BD-IGBT)chip is proposed to match the practical conditions of domestic process platforms,which is different from the wafer-scale bonding process in industry.A conventional IGBT wafer with thick substrate layer is chosen as the start wafer followed by front surface protection treatment,back thinning and chemical mechanical polishing.Then,the wafer is diced and the BD-IGBT chip is fabricated by bonding a pair of single dies.This process flow of manufacturing is developed and integrated in general,and the key technologies are investigated,including wafer back thinning,chemical mechanical polishing,bonding of single dies bearing a small size and so on.The electrical characteristics of the BD-IGBT chip sample are tested,which verifies the feasibility of this new manufacturing process flow.(3)In order to promote the effectiveness of peak gate current(a typical temperature sensitive electrical parameter)based method for junction temperature estimation of IGBT device in various power electronic equipment,the influence of gate loop parasitic inductance on the transient peak gate current of IGBT device is revealed,and an improved IGBT device’s junction temperature estimation model considering parasitic inductance is proposed.The effect of gate loop parasitic inductance on peak gate current is analyzed in detail from the perspective of the gate loop’s time domain model and SPICE simulation.A dedicated test bench is established to achieve accurate calibration for junction temperature,peak gate current and gate loop parasitic inductance.Based on the calibrated data,an improved junction temperature estimation model is proposed by considering the gate loop parasitic inductance,and this new model for different gate loop conditions is experimentally verified.(4)The influence of IGBT device aging on the peak gate current,a typical TSEP,is investigated.An experimental platform for IGBT device’s power cycle accelerated aging test is built,and the measurement methods and related circuits for forward conduction voltage drop and peak gate current are designed.A number of electrical parameters of IGBT device are measured before,during and after power cycle accelerated aging test.The changing trends of these parameters are analyzed in detail.Results of DC mode accelerated aging test show that the peak gate current peak can be seen as a long-term stable temperature sensitive electrical parameter,which is less affected by the IGBT device’s aging.Furthermore,the proposed measurement method and related circuit can be applied to on-line condition monitoring of IGBT devices.