Wafer alignment sensor
US5576831A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 20, 1994 |
| Grant date | Nov 19, 1996 |
| Priority date | — |
| Expiry date | Jun 20, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A surface height detection and positioning device for use in a surface inspection system. An incident beam of light impinges obliquely upon the surface, and a position detector is disposed to receive light reflected from the surface. The position detector has a sensitivity characteristic graded along a direction transverse to the surface, so that the output of the position detector is used to determine a height of the surface. The device can be incorporated into a particle detection system that scans patterned wafers with obliquely incident light to search for particles with a particle detector positioned to receive scattered light. In one embodiment, the position detector can have a width that is graded along the direction transverse to the surface, so that a scan line on the surface that is focused upon the position detector crosses the width of that detector in a time that varies as a function of the height of the surface. This time can be measured as an electrical pulse from the position detector that can be used for various purposes, including adjusting the height of the surface during scanning. In another embodiment, the position detector can have a periodic variance in light…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.