Structure and method for determining an overlay accuracy
US7666559B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Apr 11, 2008 |
| Grant date | Feb 23, 2010 |
| Priority date | — |
| Expiry date | Apr 11, 2028 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S438/975
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An enhanced technique for determination of an alignment accuracy involves an overlay target assembly which comprises at least two targets, each target having a first sub-structure of a first layer and a second sub-structure of a second layer, wherein, when the first layer and the second layer are correctly aligned, the first sub-structure and the second sub-structure of at least one of the targets are offset with respect to each other by a programmed offset and the overlay target assembly is invariant to at least one geometric transformation. If the offset vectors which describe the offset between the first sub-structure and the second sub-structure all have the same norm, the overlay error may be determined without calibration. Redundancy may be increased by providing each target with two or more programmed offsets between elements of the first sub-structure and elements of the second sub-structure.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.