Method and apparatus for overlay measurement
US6463184B1 · kind B1 · utility
11Cited by
7References
15Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jun 17, 1999 |
| Grant date | Oct 8, 2002 |
| Priority date | — |
| Expiry date | Jun 17, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70633
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A process for measuring the alignment of different layers on a semiconductor wafer (33) includes forming repetitive alignment marks (14, 24) having substantially the same period on the different layers on the wafer (33). The images of the overlay alignment marks (14, 24) are converted from space domain to frequency domain through Fourier transformations. The alignment measurements are performed by calculating the phase difference between the images corresponding to the repetitive patterns (14, 24) on different layers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.