Single cell scatterometry overlay targets
US10837919B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 24, 2018 |
| Grant date | Nov 17, 2020 |
| Priority date | — |
| Expiry date | Sep 24, 2038 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70633
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Scatterometry overlay (SCOL) single cell targets are provided, along with target design methods and measurement methods which employ the single cell SCOL targets for in-die metrology measurements, utilizing the small size of the target along with maintained optical performance due to the design of the target. Disclosed single cell targets comprise a lattice of elements at two or more layers which is periodic two or more measurement directions. Elements in different layers are offset with respect to each other and may have the same pitch along the measurement directions. Measurement algorithms are also provided to derive metrology measurements such as overlays from the single cell targets, possibly simultaneously in both (or more) measurement directions, reducing measurement time and enhancing the metrology throughput. Positioning the small targets in-die provides more accurate metrology results which are less sensitive to process variation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.