Mechanism and solution of sharp defects in trench double-diffused metal-oxide semiconductor polysilicon recess etching

The sharp defects were observed in the center of the trench during trench double-diffused metal-oxide semiconductor polysilicon recess etching using HBr and He-O2 gas plasma. To understand this phenomenon, external controllable parameters such as pressure and etch gas were used to study the changes...

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Veröffentlicht in:Journal of vacuum science and technology. B, Nanotechnology & microelectronics Nanotechnology & microelectronics, 2021-12, Vol.39 (6)
Hauptverfasser: Zhang, Wenwen, Fang, Yongzhi, Huang, Renrui, Zhu, Wenming
Format: Artikel
Sprache:eng
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Zusammenfassung:The sharp defects were observed in the center of the trench during trench double-diffused metal-oxide semiconductor polysilicon recess etching using HBr and He-O2 gas plasma. To understand this phenomenon, external controllable parameters such as pressure and etch gas were used to study the changes in the morphology of polysilicon in over etching. The result shows that there are two key factors for the generation of sharp defects, one is the gap left by incomplete polysilicon filling in the trench and the other is the flow rate of He-O2 in over etching. Component analysis shows that the main components of defects are Si and O. Hence, the theory of sidewall oxidation is proposed to explain the generation of oxide, and the accuracy of the theory was also confirmed by subsequent orthogonal experiments. Finally, a solution to this kind of defect problem is proposed, that is, to reduce the flow of He-O2 to eliminate the generation of defect.
ISSN:2166-2746
2166-2754
DOI:10.1116/6.0001395