Purge gas flow control for high-precision film measurements using ellipsometry and reflectometry
US7755764B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 24, 2008 |
| Grant date | Jul 13, 2010 |
| Priority date | — |
| Expiry date | Jan 24, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/0233
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical method and system for measuring characteristics of a sample using a broadband metrology tool in a purge gas flow environment are disclosed. In the method a beam path for the metrology tool is purged with purge gas at a first flow rate. A surface of the sample is illuminated by a beam of source radiation having at least one wavelength component in a vacuum ultraviolet (VUV) range and/or at least one wavelength component in an ultraviolet-visible (UV-Vis) range. A flow rate of a purge gas is adjusted between the first flow rate for metrology measurements made when the source radiation is in the VUV spectral region and a second flow rate for metrology measurements made when the source radiation is in the UV-Vis spectral region. The system includes a light source, illumination optics, collection optics, detector, a purge gas source and a controller. The purge gas source is configured to supply a flow of purge gas to a beam path in the light source and/or illumination optics and/or sample and/or collection optics and/or detector. The controller is configured to control a flow rate of the purged gas flow in response to an output signal from the detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.