Optical micrometer for measuring thickness of transparent wafers
US5754294A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 3, 1996 |
| Grant date | May 19, 1998 |
| Priority date | — |
| Expiry date | May 3, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Techniques and systems for measuring absolute thickness, the total thickness variation, and electric resistivity of a semiconductor wafer in a nondestructive optical fashion. Optical absorption is used to measure the absolute thickness of a semiconductor wafer with a light source and a phototransceiver. The thickness is determined by comparing the amount of absorption to a calibrated amount. Coherent light interference is used to measure the total thickness variation of a substrate. Alternatively, both the absolute thickness and total thickness variation of the substrate can be measured based on light absorption using a CCD imaging device. The resistivity of a wafer sample can also be measured by using an alternating electrical signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.