Turn-off Behavior And Short-Circuit Ruggedness Of High-Power Trench Gate/Field-Stop IGBTs

Insulated Gate Bipolar Translators(IGBTs)are core components in medium and high-power converter applications,such as the high-speed traction and renewable energy generation systems.The increasing requirements of practical applications concerning superior performance drive continuous device structure advancements.Meantime,these new device structures lead to significant changes in IGBT performance.Therefore,how to guarantee enough ruggedness and reliability of IGBTs is important for the safe operation of power conversion systems.However,both the device robustness and reliability problems are essentially attributed to lack of a deep understanding on device behaviors.Especially,the understanding of dynamic characteristics and failure mechanisms of new-structure IGBTs lags far behind the development of IGBT structures.Therefore,by focusing on one of the current mainstream IGBT structures,trench gate/field-stop structure,this dissertation gives a deep insight into how the device intrinsic turn-off behaviors and short-circuit unstable behaviors can be shaped by this structure.Further,available methods are developed to quantify the safe operation area(SOA)boundary for IGBT dominating transient short-crcuit failures by considering the impact of external operating condition and gate driver parameters.More specifically,At first,A numerical model is constructed for simulating the trench gate/field-stop IGBT,which provides a deep insight into physical mechanisms dominating the device behaviors.By combing the device characteristic design criteria with main electrical parameters,the geometry-dimension and doping-profile extractions of an INFINEON 1700V/1000A trench gate/field-stop IGBT(FF1000R17IE4)are realized.With them,the numerical model creation of this IGBT is enabled.Based on the built model,not only the device electrical characteristics can be accurately reproduced,it also allows exploring the complex interactions among the external operation condition parameter,device electrical characteristic,device physical mechanism,and device structure property,previously impossible to explain by using the measured waveforms.Secondly,based on the storage-carrier extraction behavior modeling considering the influence of IGBT structure properties,the self-controlled turn-off characteristic of trench gate/field-stop IGBTs is disclosed.By numerical simulations of IGBT turn-offs,the dominating role of storage-carrier extraction behavior in device turn-off characteristics is found.With this basic principle,in combination with the impact of the device structure properties,a physical-based analytical turn-off model is proposed for trench gate/field-stop IGBTs.Then,benefiting from the built model,the device collector-emitter voltage rising rate self-limiting behavior is disclosed.More importantly,a consequent non-monotonic relationship between the device collector-current falling rate and turn-off resistance is also revealed.Further,how the self-controlled turn-off characteristics of trench gate/field-stop IGBTs are shaped by busbar voltage,load current and junction temperature is investigated,which provides a good foundation for the proper designs of driving and protection circuits for trench gate/field-stop IGBTs.Thirdly,with disclosing dominating roles of short-circuit pulse and short-circuit turn-off failures in limiting the trench gate/field-stop IGBT short-circuit ruggedness,physics of failure(PoF)based methods are developed to realize the device short-circuit safe operation area boundary specification and quantification.Benefitting from device short-circuit numerical simulations,the occurrence of two-peak electric-field distribution characteristic is disclosed as the necessary destruction precondition for the short-circuit pulse failure.And the indispensable triggering condition for short-circuit turn-off failure is proved as the presence of partly overlapping between device short-circuit locus and NDR branch of static avalanche curve.Then,in order to correlate the busbar voltage and short circuit current with these failure destruction preconditions,PoF-based methods are proposed.Consequently,the V-I short-circuit safe operation area boundary is quantified to provide a practical guide to prevent the device from short-circuit pulse and short-circuit turn-off failures.Fourthly,the three-dimensional(3D)short-circuit safe operating area(SCSOA)considering the impact of junction temperature,gate turn-off resistance and parasitic inductance is proposed and quantified for trench gate/field-stop IGBTs.Based on the device short-circuit numerical simulations and the proposed short-circuit turn-off model considering the avalanche multiplication effect,the impact of junction temperature,gate turn-off resistance and parasitic inductance on the device V-I short-circuit safe operation area boundary are quantified.As a result,the 3D-SCSOA with different external operation parameters for trench gate/field-stop IGBTs are generated,which provide a good foundation for further IGBT short-circuit ruggedness evaluation.Finally,a summary of this dissertation is given at last.The main contributions of this dissertation are summarized,and the future works are presented.