Undercut-free BLM process for Pb-free and Pb-reduced C4
US7825511B2 · kind B2 · utility
31Cited by
8References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jan 22, 2009 |
| Grant date | Nov 2, 2010 |
| Priority date | — |
| Expiry date | Apr 30, 2029 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L2924/04953
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A system and method for eliminating undercut when forming a C4 solder bump for BLM (Ball Limiting Metallurgy) and improving the C4 pitch. In the process, a barrier layer metal stack is deposited above a metal pad layer. A top layer of the barrier layer metals (e.g., Cu) is patterned by CMP with a bottom conductive layer of the barrier metal stack removed by etching. The diffusion barrier and C4 solder bump may be formed by electroless plating, in one embodiment, using a maskless technique, or by an electroplating techniques using a patterned mask. This allows the pitch of the C4 solder bumps to be reduced.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.