Interconnect bump for flip-chip integrated circuit including integral standoff and hourglass shaped solder coating
US5872404A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 6, 1997 |
| Grant date | Feb 16, 1999 |
| Priority date | — |
| Expiry date | Feb 6, 2017 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY02P70/50
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
An interconnect bump is formed on a substrate structure of a flip-chip microelectronic integrated circuit by sputtering a metal base layer on the substrate, and then forming a copper standoff on the base layer. A solder cap is formed on the standoff having a peripheral portion that extends laterally external of the standoff. The peripheral portion of the cap is used as a self-aligned mask for a photolithographic step that results in removing the metal base layer except under the standoff and the cap. The cap has a lower melting point than the standoff. Heat is applied that is sufficient to cause the cap to melt over and coat the standoff and insufficient to cause the standoff to melt. The peripheral portions of the cap and the base layer that extend laterally external of the standoff cause the melted solder to form into a generally hourglass shape over the standoff due to surface tension.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.