Optical apparatus for measuring profiles of a wafer
US5995226A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jun 8, 1998 |
| Grant date | Nov 30, 1999 |
| Priority date | — |
| Expiry date | Jun 8, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A pair of optical profile measuring systems 10, 20 are provided at positions faced to both sides of a wafer 1 vertically supported at its edge. Each system 10, 20 includes a light emitter 11, 21 for discharging a measuring light beam 12, 22, a collimator lens 14, 24 for rectifying the light beam 12, 22 into a collimated beam, an optical flat 15, 25 for transmitting the collimated light beam 12, 22, a light detector 16, 26 receiving the light beams 12, 22 reflected on a surface of the wafer 1 and on a referential plane of the optical flat 15, 25 through the collimator lens 14, 24 and a computer 17, 27 for processing interference fringes which occur between the surface of the wafer 1 and the referential plane of the optical flat 15, 25. Profiles of main and back surfaces of the wafer as well as its thickness variation are easily measured utilizing light interference fringes corresponding to both sides of a wafer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.