A fast recovery diode and its manufacturing method

Abstract

The invention discloses a fast recovery diode and a manufacturing method thereof, wherein the manufacturing method includes: oxidizing the surface of the N-type buffer layer on the back of the diode body to form an oxide layer; etching the oxide layer in a predetermined area on the back of the diode body, Form an open window; perform P well implantation on the diode body through the open window to form a P well region; etch the remaining oxide layer to expose the N++ implant window; inject N++ impurities into the N++ implant window and activate it to make the P well region Formed in a floating state, together with the anode region and the drift region constitute a built-in thyristor. By forming a P well region and then performing N++ implantation, the P well region is formed in a floating state, and forms a built-in thyristor with the anode region and drift region of the diode body, and coordinates the compromise between the conduction voltage drop of the diode and the soft recovery performance. The relationship makes it possible to obtain a better trade-off relationship between conduction voltage drop and soft recovery characteristics without thinning the silicon wafer, and obtain high-quality fast recovery diodes.

Description

technical field [0001] The invention relates to the technical field of semiconductor device preparation, in particular to a fast recovery diode and a manufacturing method thereof. Background technique [0002] Fast recovery diode (FRD for short) is a semiconductor diode with good switching characteristics and short reverse recovery time. It is mainly used in electronic circuits such as switching power supplies, PWM pulse width modulators, and frequency converters. Freewheeling diodes or damping diodes are used. The internal structure of the fast recovery diode is different from the ordinary PN junction diode. It belongs to the PIN junction diode, that is, the base region I is added between the P-type silicon material and the N-type silicon material to form a PIN silicon chip. Because the base region is very thin and the reverse recovery charge is very small, the reverse recovery time of the fast recovery diode is short, the forward voltage drop is low, and the reverse break...

AI Technical Summary

Problems solved by technology

This FCE diode obtains better soft recovery characteristics by sacrificing part of the cathode area, resulting in a higher forward voltage drop

The area of ​​the P-type region directly determines the soft recovery performance of the FCE diode. If the area of ​​the P-type region is larger, the soft recovery performance of the FCE diode will be better, but at the same time, the forward conduction voltage drop of the diode will be higher. If the P-type region If the area of ​​the type region is small, the soft recovery performance of the FCE diode is poor, but at the same time the forward conduction voltage drop of the diode is low

A better compromise is usually obtained by reducing the thickness of the diode drift region, but this often results in a reduction in the safe operating area and robustness of the diode

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