Groove forming method

Abstract

A groove forming method comprises the steps of providing a silicon substrate which comprises a first area and a second area; performing plasma etching on the silicon substrate, wherein the plasma etching comprises the steps of performing etching of a first stage, forming a first opening and a second opening in the silicon substrate, and enabling the width of the first opening to be smaller than that of the second opening; performing oxidation of a second stage, forming a first oxidation layer at the bottom and a side wall of the first opening, forming a second oxidation layer at the bottom and a side wall of the second opening; performing etching of a third stage, etching and removing the first oxidation layer and the second oxidation layer of a partial thickness; performing etching of a fourth stage, forming a third opening and a fourth opening; and repeating the steps of oxidation of the second stage, etching of the third stage and etching of the fourth stage until a plurality of first grooves are formed in the first area of the silicon substrate and a plurality of second grooves are formed in the second area of the substrate. The influence on the etching process caused by the etching load effect is effectively eliminated.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for forming a trench. Background technique [0002] With the progress of semiconductor technology, shallow trench isolation (Shallow Trench Isolation, STI) method has gradually replaced other isolation structures such as local silicon oxidation method used in traditional semiconductor device manufacturing. Compared with other isolation directions, the shallow trench isolation method has many advantages, mainly including: 1. The shallow trench isolation method can obtain a narrower isolation width of semiconductor devices, thereby increasing the device density; 2. Shallow trench isolation The method can improve the flatness of the surface, so that the minimum line width can be effectively controlled during photolithography. [0003] For existing methods of forming trench isolation structures, please refer to Figure 1 ~ Figure 2 . [0004] First, please refer ...

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Problems solved by technology

[0007] However, when the first trench 104 and the second trench 105 are formed by the above method, the depth of the first trench 104 formed in the first region 11 will be smaller than that of the second region 12 due to the etch loading effect. The depth of the formed second trench 105 affects the isolation characteristics of the formed isolation structure

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