Methods for monitoring source symmetry of photolithography systems
US9316925B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 13, 2013 |
| Grant date | Apr 19, 2016 |
| Priority date | — |
| Expiry date | Jun 5, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70133
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method for monitoring the source symmetry of a photolithography system is provided. The method includes providing a first reticle; and providing a second reticle. The method also includes forming first bottom overlay alignment marks on a first wafer using the first reticle; and forming first top overlay alignment marks on the first bottom overlay alignment marks using the second reticle. Further, the method includes forming second bottom overlay alignment marks on a second wafer using the first reticle; and forming second top overlay alignment marks on the second bottom overlay alignment marks using the second reticle. Further, the method also include measuring a first overlay shift; measuring a second overlay shift; and obtaining an overlay shift caused by the source asymmetry based on the first overlay shift and the second overlay shift.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.