Research And Optimization Of Reverse Biased Safe Operation Area With 550V Multi-racetrack SOI-LIGBT Based On SOI Film

The single intelligent power chips have lower loss,smaller size and more abundant control and protect functions than traditional intelligent power modules,which are widely used in various electric motor and power supply applications.SOI-LIGBTs have many advantages such as high current ability,high breakdown voltage and easily drive.They are the core switch devices of the single intelligent power chips.The RBSOA of the SOI-LIGBTs determines the reliability of single intelligent power chips and related systems.Therefore,the optimization of RBSOA characteristics of SOI-LIGBT makes a lot of sense.The test results of RBSOA with developed SOI-LIGBT is introduced in this thesis.It is found that the critical failure current of single racetrack decreases drastically when multiple racetracks are connected in parallel during the test,which leads to the decrease of RBSOA.Some researches are done to reproduce the failure by simulation and theoretical analysis.Besides,the root cause of the failure are tried to explain.The failure is originated from edge isolation trenches,which leads to an inhomogeneous depletion behavior among the paralleled fingers during the turn-off.Inhomogeneous depletion behavior then gives rise to the non-uniform current-sharing and the subsequent current crowding in middle finger.As a result,the latch-up of the device takes place.Based on the above research conclusions,the thesis has optimized the paralleled SOI-LIGBT with the multiple racetracks.An improved structure with deep-oxide trenches arranged between the adjacent racetracks which can prevent the inhomogeneous depletion behavior is fabricated,which can make certain that the improved device show the desired RBSOA when the device turns off under high-voltage and high-current conditions.The thesis has designed the process and layout of the improved structure.It's shown that the improved structure exhibits the superior RBSOA of 450 V and 2A with no variation of any other parameters compared with the conventional device and the RBOSA is double than conventional device,which meets the current and reliability requirements of single intelligent power chip.