Process for etching oxide using a hexafluorobutadiene and manifesting a wide process window
US6387287B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 25, 1999 |
| Grant date | May 14, 2002 |
| Priority date | — |
| Expiry date | Mar 25, 2019 |
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 one of three hydrogen-free fluorocarbons having a low F/C ratio, specifically hexafluorobutadiene (C4F6), hexafluorocyclobutene (C4F6), and hexafluorobenzene (C6F6). At least hexafluorobutadiene has a boiling point below 10° C. and is commercially available. 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. Preferably, one of two two-step etch process is used. In the first, the source and bias power are reduced towards the end of the etch. In the second, the fluorocarbon is used in the main step to provide a good vertical profile and a more strongly polymerizing fluorocarbon such as difluoromethane (CH2F2) is added in the over etch to protect the nitride corner. The same chemistry can be used in a magnetically enhanced re…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.