Design Of 3300v SiC VDMOS Integrated With Temperature Sensor

With the development of power electronics technology,the demand of industry has gradually changed from functional requirement to performance and reliability requirement.However,silicon-based power devices have been approaching their theoretical limits.In this context,silicon carbide is an ideal material for power devices due to its excellent properties.However,silicon carbide brings not only good performance but also a lot of reliability problems,and most of them are related to temperature.4H-SiC MOSFET is particularly affected by temperature.In order to make 4H-SiC MOSFET work steadily in the safe operating area(SOA),overtemperature protection circuit is generally used in intelligent power module to protect power devices from damage.And the temperature sensor is the core device of overtemperature protection circuit.In this dissertation the 3300 V 4H-SiC MOSFET with integrated temperature sensor will be designed by TCAD Slivaco.Above all,the design of 3300 V 4H-SiC MOSFET cell is carried out.Athena and Atlas are combined to simulation.Firstly,the considered impurity distribution of Pwell,N+ and P+ regions is obtained by Athena simulation.In addition,the sensitive parameters of 4H-SiC MOSFET are optimized.Considering the influence of process error the threshold voltage of VDMOS is designed to be 4.2V.The optimized structure shows that the breakdown voltage is 4688 V,leaving 30% margin.Next,the junction termination is optimized.In this work,the field limiting ring is used to relieve curvature effect.The field limiting ring is compatible with the main device process and it is formed with Pwell in the same time.By adjusting the sensitive parameters,the terminal efficiency of this field limiting ring reaches 96.81%.In addition,a new termination expansion structure is designed to reduce the size of the terminal area.This terminal structure is formed by compensating injection.By adjusting the distribution of the surface electric field of the device,the terminal efficiency of this structure reaches 98.3%,furthermore,the process window of ion implantion is expanded to 1.6 times of the traditional JTE.The next part of this dissertation is the design of integrated temperature sensor.In this work,the integrated transverse Schottky diode is used as the temperature sensor.The optimized linearity and sensitivity are obtained by choosing the appropriate static operating point.When the operating current is 5mA,the linearity and sensitivity are 1.18mV/K and 0.99927 respectively.In order to meet the requirement of monolithic integration,sufficient electrical isolation is carried out.Then,the crosstalk between the temperature sensor and the VDMOS is simulated and analyzed,the results show that there is almost no crosstalk.And then,the temperature sensor is simulated in transient high power application environment,the result shows that the measurement has a delay of 0.5?s.At the end of this dissertation,the key technology of this 3300 V 4H-SiC MOSFET is briefly introduced,and the layout design is completed according to the actual conditions of domestic SiC process platform.The layout adopts the design rules that meet the actual process conditions,and achieves the maximum active area of the chip under the conditions allowed by the process.