Design And Research Of 3300V RB-IGBT Composite Terminal Structure

Since the Insulated Gate Bipolar Transistor(IGBT)itself does not have reverse blocking capability,it is usually used in combination with a diode in a practical application circuit.In order to reduce the cost of use and reduce the parasitic inductance generated when welding the two,people began to try to integrate the freewheeling diode and IGBT on the same chip through process integration,thus proposing an IGBT chip with reverse blocking capability,Reverse-blocking IGBT(Reverse-Blocking Insulated Gate Bipolar Transistor,RB-IGBT).The structural characteristics of discrete and integrated IGBT devices was first summarized.The forward and reverse blocking mechanism of RB-IGBT was analyzed,and The cell parameters of 3300V RB-IGBT was optimized by using semiconductor simulation software.Then the RB-IGBT terminal area is designed,and the field limit ring field plate structure is used to reach the target value of 4000V in forward and reverse blocking voltage,and the rule of the parameters affecting the terminal breakdown voltage is given.Then,in view of the problem that the high-voltage RB-IGBT terminal occupies a large chip area,an improved composite terminal structure is designed and its main process flow is given.Using field plates of different lengths to slow down the rate at which the depletion layer expands outward,alleviate the corner electric field of the ring,shield the effect of movable charges,and increase the reliability of the device;introducing an N-type shallow ring on the basis of the P-type field limit ring.The lateral expansion width of the depletion region is effectively reduced,the peak electric field is reduced,and the terminal size is saved.In order to overcome the defects in the manufacturing difficulty of the high-voltage reverse resistance IGBT in the prior art,the double-sided shallow trench P-type isolation technology is used to form a double-sided P-type isolation region with a preset depth using a trench etching process for P-type doping,Then the laser scribing process is used,and the high temperature generated by the laser melts the P-type isolation region to communicate with the shallow trench isolation region on the back.Compared with other isolation technologies,in the field of high voltage,this isolation technology is feasible,and takes up the smallest chip area,which takes a short time and effectively reduces the manufacturing cost.