Method removing semiconductor substrate mask layer

Abstract

A method removing a semiconductor substrate mask layer comprises the following steps: thinning the front side of the substrate so as to remove partial the first mask layer; using wet method corrosion technology on the substrate so as to remove residual first mask layer and partial the second mask layer. An LTO structure close to the backside of the substrate is protected by the second mask layer, and cannot be damaged by the wet method corrosion technology, thus well protecting the LTO structure, preventing wafer damages, and reducing wafer discarding risks.

Description

technical field [0001] The invention relates to the technical field of semiconductor devices, in particular to a method for removing a mask layer of a semiconductor substrate. Background technique [0002] A trench double diffused field effect transistor (Double Diffused MOSFET, DMOS) product needs to form a trench (Trench) to make a gate structure. In order to obtain trenches, tetraethyl orthosilicate (TEOS) is usually decomposed into silicon dioxide to form a hard mask, and then the trench structure is obtained through an etching or etching process. The silicon dioxide film layer blocks the positions that do not need to be etched or etched, thereby obtaining the trench structure. [0003] The silicon dioxide film formed by TEOS decomposition is usually deposited through a low-pressure furnace tube, so that the silicon dioxide film is deposited on the front and back of the wafer. During the deposition process, abnormalities may occur, resulting in excessive particles in t...

AI Technical Summary

Problems solved by technology

However, there is a layer of Low Temperature Oxide (LTO) on the back of the wafer used in DMOS products to form a back seal structure. After the silicon dioxide film layer exceeds the standard, when the front silicon dioxide film layer is reworked and removed, the acidic liquid usually corrodes to the LTO structure on the back of the wafer, thereby damaging the LTO structure and thus damaging the wafer, and may even cause the wafer to be directly scrapped and cannot be used again

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