Method for correlating a structural parameter of a plurality of gratings and method for determining a structural parameter value of an unknown grating using the same
US7433060B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Jun 19, 2006 |
| Grant date | Oct 7, 2008 |
| Priority date | — |
| Expiry date | Apr 8, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/24
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for correlating a structural parameter of a plurality of gratings acquires images from a plurality of gratings, which have different structural parameters. A focus metrics algorithm is then performed to find the off-focus offset of the orders of each grating from the intensity variation of these images, and the variation ratio of the off-focus offset to the order for each grating is calculated later. Consequently, the structural parameters of these gratings can be correlated based on the variation ratio of the off-focus offset to the order. The present method acquires images from an unknown grating at different off-focus offsets, and performs a focus metrics algorithm to find the off-focus offset of the orders of the unknown grating. The variation ratio is calculated and the structural parameter of the unknown grating is determined based on the variation ratio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.