Stable gold bump solder connections
US7939939B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 4, 2007 |
| Grant date | May 10, 2011 |
| Priority date | — |
| Expiry date | Oct 4, 2027 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/3025
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A metallic interconnect structure (200) for connecting a gold bump (205) and a copper pad (212), as used for example in semiconductor flip-chip assembly. A first region (207) of binary AuSn2 intermetallic is adjacent to the gold bump. A region (208) of binary AuSn4 intermetallic is adjacent to the first AuSn2 region. Then, a region (209) of binary gold-tin solid solution is adjacent to the AuSn4 region, and a second region (210) of binary AuSn2 intermetallic is adjacent to the solid solution region. The second AuSn2 region is adjacent to a nickel layer (213) (preferred thickness about 0.08 μm), which covers the copper pad. The nickel layer insures that the gold/tin intermetallics and solutions remain substantially free of copper and thus avoid ternary compounds, providing stabilized gold bump/solder connections.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.