Manufacturing method of shallow trench isolation

Abstract

The invention provides a manufacturing method of a shallow trench isolation. The manufacturing method comprises the steps that a semiconductor substrate is provided, and a pad oxide layer and a nitride layer are formed on the semiconductor substrate in sequence; a trench is etched in the semiconductor substrate; a nitrogen doping process is performed on the side wall of the trench; an etching-back process is performed on the nitride layer for the first time, and the nitride layer near a part of the trench is removed; the etching-back process is performed on the oxide layer for the first time, and the pad oxide layer near a part of the trench is removed; a linear oxide layer is formed in the trench; the etching-back process is performed on the nitride layer for the second time, and the nitride layer near a part of the trench is removed; the trench is filled with a depositing medium layer. The nitrogen doping process is performed on the side wall of the trench, so that the linear oxide layer with uniform thickness can be formed, the problem of electric leakage caused by over thin linear oxide layer at the bottom due to etching for solving the problem of thick linear oxide layer on the side wall of the trench in subsequent steps is prevented, and the reliability and insulation of the STI (shallow trench isolation) are good after the nitrogen doping process is performed on the side wall of the trench.

Description

technical field [0001] The invention relates to the field of integrated circuit manufacturing, in particular to a manufacturing method for shallow trench isolation. Background technique [0002] In the field of semiconductor manufacturing, shallow trench isolation (STI, shallow trench isolation) technology is widely used. In advanced flash memory technology, corner rounding is also considered in the manufacturing process of STI, making the top of STI The corners and bottom corners are rounded to reduce the impact of tip discharge on the yield of sensitive flash devices. [0003] refer to figure 1 , is a flow chart of an existing shallow trench isolation manufacturing method, specifically including the following steps: refer to Figure 2A and step S011, providing a semiconductor substrate 101, on which a pad oxide layer (pad oxide) 102 and a nitride layer (nitride layer) 103 are sequentially formed; refer to Figure 2B and step S012, etching a trench 104 on the semiconduct...

AI Technical Summary

Problems solved by technology

[0005] The present invention provides a manufacturing method of shallow trench isolation to solve the problems of the prior art that the thickness of the linear oxide layer formed on the sidewall and bottom of the trench is not uniform, and it is easy to cause STI leakage

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