Metrology target, method and apparatus, computer program and lithographic system
US9977344B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 22, 2016 |
| Grant date | May 22, 2018 |
| Priority date | — |
| Expiry date | Nov 22, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7026
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Disclosed is a substrate comprising a combined target for measurement of overlay and focus. The target comprises: a first layer comprising a first periodic structure; and a second layer comprising a second periodic structure overlaying the first periodic structure. The target has structural asymmetry which comprises a structural asymmetry component resultant from unintentional mismatch between the first periodic structure and the second periodic structure, a structural asymmetry component resultant from an intentional positional offset between the first periodic structure and the second periodic structure and a focus dependent structural asymmetry component which is dependent upon a focus setting during exposure of said combined target on said substrate. Also disclosed is a method for forming such a target, and associated lithographic and metrology apparatuses.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.