Method for chemical etch control of noble metals in the presence of less noble metals
US6979647B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 2, 2003 |
| Grant date | Dec 27, 2005 |
| Priority date | — |
| Expiry date | Jan 20, 2024 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/3025
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A method for preparing a bonding pad on an integrated circuit wafer by the steps of depositing a conductive seed layer (104) on the bonding pad; depositing a metal layer (301, 302, and 303) over a portion of the conductive seed layer; and immersing the wafer in an etchant solution (501) to remove the portion of the seed layer not covered by the metal layer. The etchant solution contains a chelating agent that bonds ions from the seed layer. When the seed layer is copper or a refractory metal, and the metal layer is gold or palladium, the preferred chelating agent is selected from, but is not limited to, but is not limited to, the families of ethylenediaminetetraacetic acids (EDTA), 8-hydroxy-quinolines, including 8-hydroxy-quinoline-5-sulfonic acid, porphyrins, and phthalocyanines.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.