Lift-off process for terminal metals
US4861425A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 22, 1988 |
| Grant date | Aug 29, 1989 |
| Priority date | — |
| Expiry date | Aug 22, 2008 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/951
- WIPO fieldSemiconductors
- WIPO sectorElectrical engineering
Abstract
A process is described for selective removal of unwanted metallization from the surface of a semiconductor device. The process comprises the usual deposition of a configurable image defining layer on the surface of the device upon which a suitable pad limiting metallurgy (PLM) has already been deposited. The layer is then opened over the pad limiting metallurgy using standard techniques and coated with a layer of the terminal metal. The coated device is then heated to just above the melting point of the terminal metal causing the melted metal, through surface tension to form a ball of metal on the PLM and to form small globules of metal on the surface of the layer and then permitted to cool. When cooled the layer is removed using the usual techniques. Because the coating of terminal metal is no longer a continuous layer on the surface of the mask, removal of the polymer mask can be accomplished in about one-tenth of the time required when compared to a deposited terminal metal layer that is not melted. Also because of the effects of surface tension the metal coating need only be one-half the thickness required under the prior art techniques.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.