Method for manufacturing back face of power semiconductor device

Abstract

The invention relates to a method for manufacturing the back face of an IGBT device. The method at least comprises the following steps that (a) the back face of a silicon wafer with the front face structure processed completely is thinned; (b) protons H+ are injected into the back face of the silicon wafer through a high-powered ion implanter; (c) low-temperature annealing is conducted on the silicon wafer; (d) phosphorus and / or boron impurities are injected into the back face of the silicon wafer through the ion implanter; (e) a crystal lattice on the surface layer of the back face of the silicon wafer is repaired through the laser annealing technology and the impurities are activated. According to the method, a minority carrier control zone is formed by a recombination center generated by ion implantation defects, and the minority carrier lifetime is effectively shortened. When an IGBT is switched off in the forward direction, through the improvement of the recombination efficiency of carriers, the switch-off time of the IGBT is effectively shortened, power consumption of the IGBT is effectively reduced, and the method is simple, effective and convenient to popularize.

Description

technical field [0001] The invention relates to the technical field of semiconductor processing and manufacturing, and more specifically, relates to a method for manufacturing a back surface of a power semiconductor device. Background technique [0002] IGBT is a minority carrier device, which not only has good conduction characteristics, but also has many characteristics of power MOSFETs, such as easy driving, wide safe working area, large peak current, and durability. [0003] The biggest limitation of the IGBT turn-off speed is the minority carrier lifetime in the N epitaxial layer (that is, the base area of ​​the PNP tube). Because this base area is not affected by external circuits, an external drive circuit cannot be used to shorten the IGBT switching time. The stored charge in the base area will cause a significant delayed pulse in the current waveform when the IGBT is turned off, and the current of the IGBT cannot be quickly reduced to the hole recombination current...

AI Technical Summary

Problems solved by technology

In addition, with the recent development of RC-IGBT (reverse conduction IGBT), although the structure of FS-TRENCH (field stop trench) is adopted, the IGBT itself does not need to reduce the minority lifetime, but the IGBT device integrated in parallel Diodes also have requirements to shorten the minority carrier lifetime in a limited area

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