Optical micrometer for measuring thickness of transparent substrates based on optical absorption
US5959731A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 29, 1997 |
| Grant date | Sep 28, 1999 |
| Priority date | — |
| Expiry date | Oct 29, 2017 |
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 substrate in a nondestructive optical fashion. Optical absorption is used to measure the absolute thickness of a semiconductor substrate with a light source and a photo transceiver. The thickness is determined by comparing the amount of absorption to a calibrated amount. Both the absolute thickness and total thickness variation of the substrate can be measured based on light absorption using an imaging device. The invention can be used to directly image and measure localized features formed on micro machined substrates. The resistivity of a substrate sample can also be measured by using an alternating electrical signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.