Method for forming shallow trench isolation structure

Abstract

The invention relates to a method for forming a shallow trench isolation structure, comprising the following steps of: providing a substrate, sequentially forming a lining oxidation layer and a silicon nitride layer, wherein openings exposing the substrate are formed in the lining oxidation layer and the silicon nitride layer; etching the substrate along with the openings to form a shallow trench, wherein the corner at the top of the side wall of the shallow trench is in an arc shape; removing the silicon nitride layer corresponding to the top of the side wall of the shallow trench until the lining oxidation layer is exposed; forming a protective oxidation layer at the bottom and top of the shallow trench and on the side wall of the shallow trench; forming isolated dielectric layers filling the shallow trench are formed on the surfaces of the silicon nitride layer and the lining oxidation layer; removing the isolated dielectric layer until the silicon nitride layer is exposed; and removing the silicon nitride layer and the lining oxidation layer. The shallow trench isolation formed in the invention produces no side ditch.

Description

Technical field [0001] The present invention relates to the field of semiconductor manufacturing, in particular to a method for forming a shallow trench isolation structure. Background technique [0002] As the semiconductor process enters the deep sub-micron era, most of the components below 0.18 microns, such as the active regions of CMOS circuits, use shallow trench isolation structures for lateral isolation. More information can be found in the US patent number US7112513 Information about shallow trench isolation technology. [0003] The formation process of the shallow trench isolation structure specifically includes: forming a shallow trench on a substrate, the shallow trench is used to isolate the active area on the substrate, and the method for forming the shallow trench may be an etching process Fill the shallow trench with a dielectric, and form a dielectric layer on the surface of the substrate. The dielectric material may be silicon oxide; annealing the dielectric; pro...

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Problems solved by technology

[0004] However, due to the defects of the existing shallow trench isolation structure, the area adjacent to the shallow trench and the active region will form a downward concave shape, which is called a side trench (Divot), and a semiconductor is formed on the substrate with the side trench. The device is prone to generate parasitic current, which affects the electrical characteristics of the semiconductor device, and the existence of the side ditch will lead to the formation of impurity residues (Residue) in the side ditch during the etching process of forming the semiconductor device, resulting in low performance of the formed semiconductor device

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