Moire overlay target
US6275621A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 25, 1999 |
| Grant date | Aug 14, 2001 |
| Priority date | — |
| Expiry date | Feb 25, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and system of measuring misalignment between two levels wherein there is provided a first grating pattern (19, 21, 23, 25, 3, 5, 7, 9) on a first layer (1) and a second grating pattern (19', 21', 23', 25', 3', 5', 7', 9') on a second layer (41) capable of providing Moire fringes when disposed over the first grating pattern and which is disposed over the first grating pattern whereby the first and second grating patterns are capable of providing Moire fringes. Misalignment of the first layer relative to the second layer is measured from the position of the Moire fringe provided by the first and second grating patterns either visually or by optical instrumentation. The second layer is preferably transparent. The first grating pattern comprises a first group of plural sets of lines (3, 5, 7, 9) , each of the lines of each of the sets being parallel to each other and extending across first imaginary straight lines, a second group of plural sets of lines (19, 21, 23, 25) each of the lines of each set of lines of the second group being parallel to each other and each extending across a second imaginary straight line, each second imaginary line being parallel to a different one o…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.