Soft fast recovery diode of multi-mixture structure and preparation method thereof

Abstract

The main purpose of the invention is to provide a high-voltage soft fast recovery diode and a preparation method thereof. According to the invention, a structure in which Schottky is mixed with high-concentration and low-concentration PN junctions is adopted, and varied lateral doping (VLD) plane terminal protection is made synchronously. Thus, the breakdown voltage and anti-surge capability are improved, the recovery time is reduced, the soft recovery characteristic is formed, and a good low-leakage effect is achieved. High-concentration P+ / N- junction, Schottky junction, low-concentration P- / N- junction and Schottky junction structures are made and arranged at intervals on N- / N / N+ silicon wafers. By adding the P- / N- structure, the efficiency of hole injection is reduced, the time for reverse recovery is reduced, reduction in barrier height of a Schottky junction is avoided, and soft fast recovery and low leakage are both achieved. The original structure and the added P- / N- structure form a VLD terminal structure, which ensures high voltage and high anti-surge capability, simplifies the manufacturing process, and reduces the cost. Compared with the tradition fast recovery diode of a PIN and MPS structure, the diode of a multi-mixture structure recovers faster, and has a wider application range.

Description

technical field [0001] The invention belongs to the technical field of diodes and their preparation, in particular to a high-voltage, soft and fast recovery diode and its preparation method. Background technique [0002] In power electronics, switching power supply circuits, and various motor drive circuits, higher and higher operating frequencies will greatly reduce the volume of passive components (inductors and capacitors) and the power loss on them, but for the components used in the circuit High-power switching diodes require shorter reverse recovery time and lower switching losses. At present, fast recovery and ultra-fast recovery diodes with PIN structure are still the most widely used in these circuits. However, ordinary PIN diodes do not have reverse soft recovery characteristics. During the reverse recovery process, there will be a large reverse peak recovery current and reverse peak voltage, which will increase the loss and electromagnetic interference (EMI) of t...

AI Technical Summary

Problems solved by technology

like figure 1 The structure shown, this structure can improve the soft recovery characteristics, but if you want to achieve faster recovery characteristics, you must increase the P+ junction spacing, which will lead to a weakened shielding effect on the Schottky junction and an increase in the reverse leakage current; the P+ junction spacing is small, too many carriers are injected into the drift region, which reduces the speed

At the same time, for the improvement of the reverse avalanche surge capability of high-power high-voltage fast recovery diodes, the terminal protection of the chip is very important. The commonly used voltage divider ring structure has the disadvantage of low ability to generate dynamic current wires, and the variable doping extended terminal technology ( VLD) has been proven to effectively improve the ability to resist avalanche breakdown, but the manufacturing process needs to increase the injection of low-concentration P-type impurities, which increases the number of steps. In view of the above problems, the present invention provides a multi-hybrid structure soft fast recovery diode and its preparation method, this method adopts the Schottky mixed high and low concentration PN junction structure, and simultaneously manufactures the variable doping planar terminal (VLD) protection, which improves the breakdown voltage and anti-surge capability, reduces the recovery time, forms soft recovery characteristics, and Good low leakage effect can be achieved

Images