Method of etching tungsten or tungsten nitride electrode gates in semiconductor structures
US6423644B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 2000 |
| Grant date | Jul 23, 2002 |
| Priority date | — |
| Expiry date | Jul 12, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/28123
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a method of etching tungsten or tungsten nitride in semiconductor structures, and particularly to the etching of gate electrodes which require precise control over the etching process. We have discovered a method of etching tungsten or tungsten nitride which permits precise etch profile control while providing excellent selectivity, of at least 175:1, for example, in favor of etching tungsten or tungsten nitride rather than an adjacent oxide layer. Typically the oxide is selected from silicon oxide, silicon oxynitride, tantalum oxide, zirconium oxide, and combinations thereof. The method appears to be applicable to tungsten or tungsten nitride, whether deposited by physical vapor deposition (PVD) of chemical vapor deposition (CVD). In particular, an initial etch chemistry, used during the majority of the tungsten or tungsten nitride etching process (the main etch), employs the use of a plasma source gas where the chemically functional etchant species are generated from a combination of sulfur hexafluoride (SF6) and nitrogen (N2), or in the alternative, from a combination of nitrogen trifluoride (NF3), chlorine (Cl2) and carbon tetrafluoride (CF4). T…
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