Scanning overlay metrology using overlay targets having multiple spatial frequencies
US11796925B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 30, 2022 |
| Grant date | Oct 24, 2023 |
| Priority date | — |
| Expiry date | May 5, 2042 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/706843
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An overlay metrology system may include an illumination source and illumination optics to illuminate an overlay target on a sample with illumination from the illumination source as the sample is in motion with respect to the illumination from the illumination source in accordance with a measurement recipe. The overlay target may include one or more cells, where a single cell is suitable for measurement along a particular direction. Such a cell may include two or more gratings with different pitches. Further, the system may include two or more photodetectors, each configured to capture three diffraction lobes from the two or more grating structures. The system may further include a controller to determine an overlay measurement associated with each cell of the overlay target.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.