Method for improving upper corner edge thickness of shallow trench isolation (STI) groove

Abstract

The invention relates to a method for improving the upper corner edge thickness of a shallow trench isolation (STI) groove. A traditional STI-HDP formula is reasonably regulated; argon gas flow quantity or radio frequency power is strengthened; a ratio between etching and sedimentation is regulated; a top SiN linear structure is effectively reduced; thereby a slit of phosphate etching cannot be formed; a sequential acid washing process also cannot cause a deeper groove; and therefore, an important factor of causing a sequential risk is avoided from the initial stage of a making process.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for improving the edge thickness of the upper corner of an STI groove by removing the SiN linear structure at the corner. Background technique [0002] Such as figure 1 As shown, the traditional shallow trench isolation (shallow trench isolation, STI) process is STI etching + SiN linear structure. In this process, the SiN thin layer as a linear structure will extend to the top corner 2. During the removal process of the mask layer SiN (hard mask SiN, HM SiN)1, phosphoric acid will erode this thin layer, and the etching selectivity ratio of hot phosphoric acid to SiN and oxide is very high, especially the linear structure 3 at the corner 2, Thereby forming a gap 4 along the linear structure, such as figure 2 As shown, since multiple picklings are required in the whole process, and the subsequent pickling mainly etches oxides, the original gaps will form deep ...

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Problems solved by technology

[0002] like figure 1 As shown, the traditional shallow trench isolation (shallow trench isolation, STI) process is STI etching + SiN linear structure. In this process, the SiN thin layer as a linear structure will extend to the top corner 2. During the removal process of the mask layer SiN (hard mask SiN, HM SiN)1, phosphoric acid will erode this thin layer, and the etching selectivity ratio of hot phosphoric acid to SiN and oxide is very high, especially the linear structure 3 at the corner 2, Thus forming a gap 4 along a linear structure, such as figure 2 As shown, since multiple picklings are required in the whole process, and the subsequent pickling mainly etches oxides, the original gaps will form deep grooves 5, and these grooves 5 will not only affect the performance of the device, but are also very important. May cause polysilicon residue, which can cause electrical hazards

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