Method of removing smear from via holes
US6766811B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 7, 2002 |
| Grant date | Jul 27, 2004 |
| Priority date | — |
| Expiry date | Aug 7, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/0796
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An aqueous solution containing sulfuric acid and hydrogen peroxide is used for a soft etchant in a soft etching step in a smear removing process performed prior to a catalyst applying process for chemical copper plating after formation of via holes through an insulating layer of a multi-layer substrate by irradiation of laser. The concentration of sulfuric acid is 2.4 times or less than the concentration of hydrogen peroxide. Preferably, the concentration of sulfuric acid is in a range of 9 to 90 g/l, and the concentration of sulfuric acid is lower than the concentration of hydrogen peroxide. More preferably, the concentration of sulfuric acid is in a range of 9 to 18 g/l, and the concentration of hydrogen peroxide is in a range of 33 to 38.5 g/l. As a result, smear can be certainly removed without excessively etching a conductive layer in the smear removing process.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.