Surface examining apparatus and method
US4547073A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 11, 1982 |
| Grant date | Oct 15, 1985 |
| Priority date | — |
| Expiry date | Feb 11, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/8803
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The surface of a polished semiconductor wafer is examined by an apparatus comprising a light source, a first optical means for converging the light to a parallel light and projecting it onto the surface to be examined and a second optical means for converging the light reflected by the surface and projecting it onto a light receiving screen. If the surface has a defect, such as a crystal imperfection, the surface forms a very slight recess or wave, for example, having a sub-micron depth and having an opening diameter of several mm. When such surface is examined by the above-mentioned apparatus, specific shading patterns, lines, stripes or dots are projected on the light-receiving screen, thereby making detection of wafer defects easy and even subject to automation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.