Semiconductor wafer scanning system
US4689491A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 19, 1985 |
| Grant date | Aug 25, 1987 |
| Priority date | — |
| Expiry date | Apr 19, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/103
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A semiconductor wafer scanning system includes a confocal optical imaging system with a laser beam being focused on a small spot on the wafer surface to be scanned. The optics include an objective lens located closest to the wafer with means being provided to vary the spacing of the lens from the wafer over small distances to thus change the focal plane of the system. The wafer may be independently driven in two orthogonal directions in a plane generally perpendicular to the imaging system to bring selected portions thereof into view of the optics. During scanning, the wafer is rapidly vibrated in one of the directions while it is slowly moved in the other direction with a series of digital output signals being provided by the light reflected back from the laser spot on the moving wafer to provide precise information for constructing a three dimensional representation of the surface pattern of the wafer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.