Method for purification of etching solution
US5470421A · kind A · utility
28Cited by
7References
9Claims
0Family size
Assignee
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Key dates
| Filing date | Sep 15, 1994 |
| Grant date | Nov 28, 1995 |
| Priority date | — |
| Expiry date | Sep 15, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L21/67075
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for purifying an etching solution consisting of an aqueous phosphoric acid solution which has been used in etching of a silicon nitride film. In the process, hydrogen fluoride is added to an etching solution consisting of an aqueous phosphoric acid solution which has been used for etching of a silicon nitride film, and the resulting solution is heated to remove fluorides of silicon as reaction products of hydrogen fluoride with silicon compounds which have been contained in the etching solution together with vaporized water.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.