Inspection apparatus for lithography
US8792096B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 24, 2009 |
| Grant date | Jul 29, 2014 |
| Priority date | — |
| Expiry date | Jan 22, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/9501
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Four separately polarized beams are simultaneously measured upon diffraction from a substrate (W) to determine properties of the substrate. Linearly, circularly or elliptically polarized radiation is transmitted through a first beam splitter (N-PBS) and split into two polarized beams. These two beams are further split into two further beams using two further beam splitters, the further beam splitters (32,34) being rotated by 45° with respect to each other. The plurality of polarizing beam splitters enables the measurement of the intensity of all four beams and thus the measurement of the phase modulation and amplitude of the combined beams to give the features of the substrate. Algorithms are used to compare the four intensities of each of the polarized angles to give rise to the phase difference between the polarization directions and the ratio between the two main polarization direction amplitudes of the original polarized beam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.