Topographic phase control for overlay measurement
US10520832B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 2016 |
| Grant date | Dec 31, 2019 |
| Priority date | — |
| Expiry date | Sep 28, 2036 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/673
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Metrology tools and methods are provided, which estimate the effect of topographic phases corresponding to different diffraction orders, which result from light scattering on periodic targets, and adjust the measurement conditions to improve measurement accuracy. In imaging, overlay error magnification may be reduced by choosing appropriate measurement conditions based on analysis of contrast function behavior, changing illumination conditions (reducing spectrum width and illumination NA), using polarizing targets and/or optical systems, using multiple defocusing positions etc. On-the-fly calibration of measurement results may be carried out in imaging or scatterometry using additional measurements or additional target cells.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.