Metrology method and apparatus, and device manufacturing method
US9158194B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 27, 2012 |
| Grant date | Oct 13, 2015 |
| Priority date | — |
| Expiry date | Feb 10, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7088
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An approach is used to estimate and correct the overlay variation as function of offset for each measurement. A target formed on a substrate includes periodic gratings. The substrate is illuminated with a circular spot on the substrate with a size larger than each grating. Radiation scattered by each grating is detected in a dark-field scatterometer to obtain measurement signals. The measurement signals are used to calculate overlay. The dependence (slope) of the overlay as a function of position in the illumination spot is determined. An estimated value of the overlay at a nominal position such as the illumination spot's center can be calculated, correcting for variation in the overlay as a function of the target's position in the illumination spot. This compensates for the effect of the position error in the wafer stage movement, and the resulting non-centered position of the target in the illumination spot.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.