Highly selective process for etching oxide over nitride using hexafluorobutadiene
US6849193B2 · kind B2 · utility
Inventors
Key dates
| Filing date | May 13, 2002 |
| Grant date | Feb 1, 2005 |
| Priority date | — |
| Expiry date | Jan 3, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/31116
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
An oxide etching process, particularly useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. The invention uses a heavy perfluorocarbon, for example, hexafluorobutadiene (C4F6) or hexafluorobenzene (C6F6). The fluorocarbon together with a substantial amount of a noble gas such as argon is excited into a high-density plasma in a reactor which inductively couples plasma source power into the chamber and RF biases the pedestal electrode supporting the wafer. A more strongly polymerizing fluorocarbon such as difluoromethane (CH2F2) is added in the over etch to protect the nitride corner. Oxygen or nitrogen may be added to counteract the polymerization. The same chemistry can be used in a magnetically enhanced reactive ion etcher (MERIE) or with a remote plasma source.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.