Research And Implementation Of Key Technology Of 600V High Voltage Gate Driver Chip With Integrated Bootstrap Diode

The gate drive circuit(Gate Drivir)is mainly used to control the switching of power semiconductor devices.The current mainstream application target is Si material device,but with the gradual application of third-generation semiconductor materials such as GaN and SiC in the field of switching power devices,the demand for the corresponding gate drive circuit will greatly increase,so the research on its key technology is of great significance in giving full play to the unique advantages of power semiconductor devices,reducing circuit power consumption,and saving costs.The main work content of this subject is as follows: focus on the 600 V half-bridge high-voltage gate driver chip,and propose optimization schemes for the core modules such as bootstrapping and level shift to improve the performance and integration of the chip,and test it after the partner company tapes out verification.First of all,in the research of bootstrap module,this paper proposes an integrable bootstrap diode composite to play the role of the bootstrap diode in the chip.The composite device is specifically composed of a medium voltage diode and a high voltage junction field effect transistor through metal The designed HV-JFET device is mainly responsible for the withstand voltage and the protection of the MV-Diode by adjusting its own pinch-off voltage during the level shift work.The MV-Diode is mainly used for reducing the leakage current in the composite device when the bootstrap capacitor is charged.As a result,the problem of a large amount of leakage current generated by the traditional body diode with high breakdown voltage can be improved,and the integration level of the chip can also be improved,with the cost saved.Second,in the research of level shift module,first of all,in order to maintain good signal isolation and high-side drive stability at work,the level shift module studied in this paper adopts the Divided RESURF structure.In order to improve the breakdown voltage of the device,Based on the original Divided RESURF structure LDMOS,this article adjusts the margin of the NBL buried layer under the VB electrode and the P-type interconnection isolation to help broaden the width of the depletion region,thereby increasing the breakdown voltage of the whole level shift;in addition,the reliability of the isolation structure between devices plays an important role in the quality of signal transmission.Therefore,this article also improves the isolation part not only by adjusting the N-type buried layer on both sides of the isolation in the Divided RESURF level shift module but also the isolation width,so that the overall structure meets the basic signal isolation and high reverse bias voltage withstanding.Third,the layout of the above two modules is designed and integrated into a single chip,then taped out based on the 600 V ultra-thin epitaxial process of the cooperative company,after that,various electrical characteristics are tested.The composite bootstrap diode can reach the breakdown voltage of 960 V,129V for the internal medium voltage 853 V for the high voltage JFET.The pinch-off voltage is 15 V,which can ensure that the medium-voltage diode will not withstand high voltage in advance due to the premature pinch-off of the JFET and cause breakdown.As for the Divided RESURF level shift module,the tape-out test results show that the breakdown voltage of the core device LDMOS in the module increases from 705 V to 760 V as the isolation distance between the NBL and the P-type on the side of high-voltage island increases;The breakdown voltage increases as the isolation width increases,from 100 V to 130 V,which will negatively affect the breakdown voltage of adjacent LDMOS devices,from 760 V to 610V;In addition to the regular breakdown voltage test,the device,whose isolation area lies between 2 N buried layers,has also been subjected to the HTRB aging test.The results show that the average value breakdown voltage in the normal test is about 689.3V,and the average breakdown voltage after the aging test is 616.2V,the degradation rate does not exceed 10%.