Method of determining a focus of a projection system, device manufacturing method, and apparatus for determining a focus of a projection system
US11415899B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 5, 2018 |
| Grant date | Aug 16, 2022 |
| Priority date | — |
| Expiry date | Apr 5, 2038 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70625
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Methods and apparatus for determining a focus of a projection system are disclosed. In one arrangement, a method includes obtaining first data derived from a first measurement of one or more selected properties of a target pattern formed on a substrate by exposing the substrate using the projection system. The first measurement is performed before the substrate is etched based on the target pattern. The method further includes obtaining second data derived from a second measurement of the one or more selected properties of the target pattern. The second measurement is performed after the substrate is etched based on the target pattern. The method further includes determining the focus of the projection system using the first data and the second data.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.