Small spot ellipsometer
US6515744B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 8, 2001 |
| Grant date | Feb 4, 2003 |
| Priority date | — |
| Expiry date | Feb 8, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J4/00
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An ellipsometer capable of generating a small beam spot is disclosed. The ellipsometer includes a light source for generating a narrow bandwidth probe beam. An analyzer is provided for determining the change in polarization state of the probe beam after interaction with the sample. A lens is provided having a numerical aperture and focal length sufficient to focus the beam to a diameter of less than 20 microns on the sample surface. The lens is formed from a graded index glass wherein the index of refraction varies along its optical axis. The lens is held in a relatively stress free mount to reduce stress birefringence created in the lens due to changes in ambient temperature. The ellipsometer is capable of measuring features on semiconductors having a dimensions as small as 50×50 microns.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.