High-voltage fast recovery diode FRED manufacturing process

Abstract

The invention provides a manufacturing process of a high-voltage fast recovery diode (FRED), which comprises the following steps of: (1) forming an N + cut-off ring region, and injecting phosphorus impurities; (2) forming an active region and injecting and annealing an N well of the active region, wherein the injected impurity of the N well is phosphorus impurity; (3) forming a P + voltage dividing ring, injecting boron impurities, and annealing; (4) forming a P well, injecting boron impurities, and annealing; (5) opening a lead hole, enriching P + on the surface of the hole, injecting boron into the P +, and annealing; (6) Pt heavy metal doping and annealing are carried out, and minority carrier lifetime is adjusted; (7) front metal is formed, aluminum-silicon-copper is adopted, and the thickness is about 4 microns; (8) forming a passivation layer; (9) thinning the back surface; (10) carrying out heavy doping injection on the back surface, wherein the injected impurities are phosphorus-based alloy; (11) performing proton injection and annealing on the back surface, wherein the thickness of the whole N-region buffer layer is 10-15 microns; and (12) processing metal on the back surface to obtain the high-voltage fast recovery diode FRED. According to the method, the FRED processing cost can be effectively reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductor components, in particular to a manufacturing process of a high-voltage fast recovery diode FRED. Background technique [0002] Epitaxial Fast Recovery Diode (FRED) is a new type of semiconductor power device prepared by CMOS technology. It is a semiconductor diode with good switching characteristics and short reverse recovery time. It is mainly used in switching power supplies, pulse width modulators, frequency conversion It can be used as a high-frequency rectifier diode, freewheeling diode or damping diode in electronic circuits such as circuit breakers. At present, most FREDs are made of double epitaxial structures. The structure diagram of conventional FREDs is shown in the following figure. figure 1 shown. The double epitaxy FRED technology has two N regions, the most critical of which is the selection of the buffer N region. If the concentration is too low, the expansion of space cha...

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Problems solved by technology

At present, the method of manufacturing FRED with a double epitaxial structure is to grow an epitaxial N- layer on a heavily doped N+ substrate as a substrate for processing. However, in order to improve the reverse recovery performance of FRED and improve the softness of reverse recovery, in fact 1350V The FRED product adopts a double-layer epitaxial structure. The lowermost epitaxial layer adopts an epitaxial layer with a thicker resistivity. The epitaxial thickness is about 30um, and then grows an epitaxial layer with a lighter resistivity. The epitaxial thickness is about 80um. The overall thickness is about 110um. Due to the thicker epitaxial thickness, the cost of epitaxial materials is high, and the cost of epitaxial materials accounts for more than 60% of the processing cost of the entire device. Therefore, the current processing technology is not conducive to cost optimization.

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