Dynamic alignment scheme for a photolithography system
US6528219B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 27, 2000 |
| Grant date | Mar 4, 2003 |
| Priority date | — |
| Expiry date | Dec 27, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7046
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Photolithography tools have alignment systems for aligning a level to be printed with a level already on the wafer. Commonly a photolithography tool has several alignment systems Also, wafers may have several alignment marks, and the various alignment systems may be capable of reading several of the alignment marks. The present invention provides a method of selecting the alignment system-alignment mark combination that gives the most accurate alignment to a previous level. The inventors found that residual errors provide a metric by which to evaluate alignment system-alignment mark combinations. The combination with the least residual error is selected. Alternatively data for actual overlay measurements is compared with alignment data for each alignment system-alignment mark combination, and the combination that has the best correlation to the overlay data is selected.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.