Preparation method of fast recovery diode

Abstract

The invention relates to a preparation method of a fast recovery diode matched with an integrated gate commutated thyristor in use. The preparation method comprises the steps of: 1) polishing an arbitrary surface of an N type silicon wafer; 2) carrying out aluminum pre-deposition, performing boron ion implantation on the polished surface of the silicon wafer, and carrying out oxidation propelling technology, so that a P+PNP type longitudinal structure is formed in the silicon wafer; 3) grinding the unpolished surface of the silicon wafer, so that a P+PN type longitudinal structure is formed in the silicon wafer; 4) conducting phosphorus impurity doping diffusion on an N type side of the silicon wafer, so that a P+PNN+ type longitudinal structure is formed in the silicon wafer; 5) evaporating an aluminum layer on the surface of the silicon wafer to form an extraction electrode, and carrying out an alloying process to form ohmic contact between aluminum and silicon; 6) carrying out proton irradiation on a chip anode surface; 7) bonding the chip anode surface with a molybdenum plate; 8) performing molding and protection processing; 9) and carrying out electron irradiation.

Description

technical field [0001] The invention relates to a method for preparing an industrial element, in particular to a method for preparing a diode. Background technique [0002] In practical applications, IGCT (Integrated Gate Commutated Thyristor, integrated gate commutated thyristor) supporting FRD (FastRecoveryDiode, fast recovery diode) needs to withstand a high forward current drop rate-di F / dt (generally up to -500~-5000A / μs), fast turn-off capability, short reverse recovery time trr (generally 2~10μs) and soft reverse recovery characteristics (softness factor S≥0.8) . Although there are many types of FRDs for IGBTs on the market, their rated voltage and current are too small to meet the application requirements of IGCTs; while the rated voltages and rated currents of FRDs for fast thyristors can meet the application requirements of IGCTs, but Its forward current drop rate-di F The / dt tolerance is low and the softness factor is too small. It is very easy to damage when...

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Problems solved by technology

[0004] Most of the IGCT supporting fast recovery diodes on the market adopt a full crimping structure. The full crimping fast recovery diode (FRD) has the following disadvantages: due to structural limitations, the heat dissipation capacity of the device is limited, and during the reverse recovery process , it is easy to cause local overheating of the chip, resulting in chip failure. When the power of the application circuit continues to increase, the failure rate of the full-press FRD increases sharply; the full-press FRD generally applies a large dose of electron radiation to reduce the device The reverse recovery loss, but it will cause the FRD's softness factor S to decrease, when the forward current decline rate -di F When the / dt is large, the device is prone to oscillation and failure during the reverse recovery process; when the softness factor S of the device is increased, the reverse recovery loss of the device will increase. Considering the above parameters in compromise, the softness factor cannot be adjusted S is increased to a larger value, resulting in a peak reverse recovery voltage V of the device RM Too large, easy to cause device breakdown

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