Correction of optical metrology for focus offset
US7450225B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 13, 2007 |
| Grant date | Nov 11, 2008 |
| Priority date | — |
| Expiry date | May 30, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/0625
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A metrology system performs optical metrology while holding a sample with an unknown focus offset. The measurements are corrected by fitting for the focus offset in a model regression analysis. Focus calibration is used to determine the optical response of the metrology device to the focus offset. The modeled data is adjusted based on the optical response to the focus offset and the model regression analysis fits for the focus offset as a variable parameter along with the sample characteristics that are to be measured. Once an adequate fit is determined, the values of the sample characteristics to be measured are reported. The adjusted modeled data may be stored in a library, or alternatively, modeled data may be adjusted in real-time.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.