Polarimetric scatterometer for critical dimension measurements of periodic structures
US6778273B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 2002 |
| Grant date | Aug 17, 2004 |
| Priority date | — |
| Expiry date | Mar 29, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/213
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical measurement system for evaluating a sample has a azimuthally rotatable measurement head. A motor-driven rotating mechanism is coupled to the measurement head to allow the optics to rotate with respect to the sample. In particular, a preferred embodiment is a polarimetric scatterometer (FIG. 1) for measuring optical properties of a periodic structure on a wafer sample (12). This scatterometer has optics (30) directing a polarized illumination beam at non-normal incidence onto the periodic structure. In addition to a polarizer (8), the illumination path can also be provided with an E-O modulator for modulating the polarization. The measurement head optics also collect light reflected from the periodic structure and feed that light to a spectrometer (17) for measurement. A polarization beamsplitter (18) is provided in the collection path so that both S and P polarization from the sample can be separately measured. The entire measurement head can be mounted for rotation of the plane of incidence to different azimuthal directions relative to the periodic structures on the wafer. The instrument can be integrated within a wafer process tool in which wafers may be provided at ar…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.