Methods and patterning devices and apparatuses for measuring focus performance of a lithographic apparatus, device manufacturing method
US10895811B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 11, 2019 |
| Grant date | Jan 19, 2021 |
| Priority date | — |
| Expiry date | Oct 11, 2039 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/7085
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A lithographic apparatus prints a focus metrology pattern (T) on a substrate, the printed pattern including at least a first array of features (800). Features at any location within the array define a pattern that repeats at in at least a first direction of periodicity (X), while geometric parameters of the repeating pattern (w1, w3) vary over the array. A focus measurement is derived from measurements of the array at a selected subset of locations (ROI). As a result, the geometric parameters upon which the measurement of focus performance is based can be optimized by selection of locations within the array. The need to optimize geometric parameters of a target design on a reticle (MA) is reduced or eliminated. The measured property may be asymmetry, for example, and/or diffraction efficiency. The measured property for all locations may be captured by dark-field imaging, and a subset of locations selected after capture.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.