Method to selectively etch silicon nitride to silicon oxide using water crystallization
US12424447B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 18, 2022 |
| Grant date | Sep 23, 2025 |
| Priority date | — |
| Expiry date | Jan 23, 2044 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/3105
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
Embodiments of improved processes and methods that provide selective etching of silicon nitride are disclosed herein. More specifically, a cyclic, two-step dry etch process is provided to selectively etch silicon nitride layers formed on a substrate, while protecting oxide layers formed on the same substrate. The cyclic, two-step dry etch process sequentially exposes the substrate to: (1) a hydrogen plasma to modify exposed surfaces of the silicon nitride layer and the oxide layer to form a modified silicon nitride surface layer and a modified oxide surface layer, and (2) a halogen plasma to selectively etch silicon nitride by removing the modified silicon nitride surface layer without removing the modified oxide surface layer. The oxide layer is protected from etching during the removal step (i.e., step 2) by creating a crystallized water layer on the oxide layer during the surface modification step (i.e., step 1).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.