Method of forming shallow trench isolation structure

By forming a third dielectric layer in the shallow trench and doping it with nitrogen ions to form a fourth dielectric layer, and then using different etching processes to remove the multiple dielectric layers, the problems of pits and edge depressions in the shallow trench isolation structure are solved, thus improving the yield of semiconductor devices.

CN121171972BActive Publication Date: 2026-07-10HEFEI WANXIN INTEGRATED CIRCUIT CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
HEFEI WANXIN INTEGRATED CIRCUIT CO LTD
Filing Date
2025-09-18
Publication Date
2026-07-10

AI Technical Summary

Technical Problem

In existing technologies, shallow trench isolation structures with high aspect ratio processes are prone to pitting defects and edge depressions, which affect the yield of semiconductor devices.

Method used

By forming a third dielectric layer in shallow trenches and incorporating nitrogen ions to form a fourth dielectric layer, and combining different etching processes to remove multiple dielectric layers, particle deposition is prevented and pit defects and edge depressions are avoided after chemical mechanical polishing.

Benefits of technology

It effectively removes particles from the surface of shallow trenches, prevents pitting defects, avoids edge area depressions, and improves the efficiency of semiconductor devices.

✦ Generated by Eureka AI based on patent content.

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Abstract

This invention provides a method for forming a shallow trench isolation structure. First, a third dielectric layer is formed within the shallow trench. An isolation layer is formed on the sidewalls of the first and second dielectric layers. The third dielectric layer is then formed. Next, nitrogen ions are doped into the top portion of the third dielectric layer to form a fourth dielectric layer. The bottom surface of the fourth dielectric layer is flush with the top surface of the substrate, and the top surface of the fourth dielectric layer is not higher than the bottom surface of the second dielectric layer. Then, a fifth dielectric layer is filled into the opening of the shallow trench. Finally, different dielectric layers on the substrate and at the opening of the shallow trench are sequentially removed to form the shallow trench isolation structure. An unexpected benefit is that the nitriding process removes particles from the surface of the shallow trench, preventing pit defects on the surface of the shallow trench isolation structure. Furthermore, the use of different etching selectivity ratios in the etching process prevents depressions from forming at the edges of the shallow trench isolation structure.
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