Oxide etch process using hexafluorobutadiene and related unsaturated hydrofluorocarbons
US6174451A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 16, 1998 |
| Grant date | Jan 16, 2001 |
| Priority date | — |
| Expiry date | Nov 16, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/31116
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
An oxide etching process, particular 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 unsaturated 3- and 4-carbon fluorocarbons, specifically hexafluorobutadiene (C.sub.4 F.sub.6), pentafluoropropylene (C.sub.3 HF.sub.5), and trifluoropropyne (C.sub.3 HF.sub.3), all of which have boiling points below 10.degree. C. and are commercially available. The unsaturated hydrofluorocarbon together with 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, a two-step etch is used process is used in which the above etching gas is used in the main step to provide a good vertical profile and a more strongly polymerizing fluorocarbon such as difluoromethane (CH.sub.2 F.sub.2) is added in the over etch to protect the nitride corner.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.