Removal method for super junction sacrificial oxide layer

Abstract

The invention discloses a removal method for a super junction sacrificial oxide layer. The method comprises the following steps: preprocessing a silicon slice by using deionized water (DIW); and removing a sacrificial oxide layer by using dilute hydrofluoric acid (DHF). Due to the fact that the silicon slice is preprocessed by water before the super junction sacrificial oxide layer which is in a deep trench groove is etched by the DHF, the water can infiltrate the deep trench groove, and then the DHF can directly replace the water in the deep trench groove and has a fast and thorough reaction with the sacrificial oxide layer in the deep trench groove, so that high-concentration DHF can be used for completely removing the sacrificial oxide layer in the deep trench groove. Finally, process time is shortened, production efficiency is improved, meanwhile, super junction puncture voltage random failure rate can be reduced, and product yield is improved.

Description

technical field [0001] The invention relates to a method for removing an oxide layer, in particular to a method for removing a super junction sacrificial oxide layer. Background technique [0002] In the manufacturing process of a super junction device, after forming a deep trench and before filling the deep trench with an epitaxial layer (EPI), it is necessary to form a sacrificial oxide layer on the bottom surface and sidewall surface of the trench. The defect on the sidewall of the deep trench is repaired, and a sacrificial oxide layer is also formed on the surface of the silicon wafer outside the deep trench at the same time. In the prior art, the thickness of the sacrificial oxide layer is about 500 angstroms, and a wet etching process is generally used to completely remove the sacrificial oxide layer. [0003] The existing super junction sacrificial oxide layer removal method is to form a super junction deep trench on the silicon wafer and form a sacrificial oxide lay...

AI Technical Summary

Problems solved by technology

However, when a high concentration of DHF is used to etch the sacrificial oxide layer, the slice results show that only the sacrificial oxide layer on the sidewall within 6 microns at the top of the deep trench will be removed, and the sacrificial oxide layer on the sidewall at the bottom of the deep trench will be removed. The oxide layer cannot be removed and will eventually lead to random breakdown of the superjunction formed, resulting in yield loss

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