Optical metrology with reduced sensitivity to grating anomalies
US9470639B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 3, 2016 |
| Grant date | Oct 18, 2016 |
| Priority date | — |
| Expiry date | Feb 3, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Methods and systems for performing broadband spectroscopic metrology with reduced sensitivity to grating anomalies are presented herein. A reduction in sensitivity to grating anomalies is achieved by selecting a subset of available system parameter values for measurement analysis. The reduction in sensitivity to grating anomalies enables an optimization of any combination of precision, sensitivity, accuracy, system matching, and computational effort. These benefits are particularly evident in optical metrology systems having large ranges of available azimuth angle, angle of incidence, illumination wavelength, and illumination polarization. Predictions of grating anomalies are determined based on a measurement model that accurately represents the interaction between the measurement system and the periodic metrology target under measurement. A subset of available system parameter values is selected to reduce the impact of grating anomalies on measurement results. The selected subset of available system parameters is implemented on a configurable spectroscopic metrology system performing measurements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.