Measuring overlay and profile asymmetry using symmetric and anti-symmetric scatterometry signals
US7277172B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 4, 2006 |
| Grant date | Oct 2, 2007 |
| Priority date | — |
| Expiry date | Jan 4, 2026 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/956
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Systems and methods are disclosed for using ellipsometer configurations to measure the partial Mueller matrix and the complete Jones matrix of a system that may be isotropic or anisotropic. In one embodiment two or more signals, which do not necessarily satisfy any symmetry assumptions individually, are combined into a composite signal which satisfies a symmetry assumption. The individual signals are collected at two or more analyzer angles. Symmetry properties of the composite signals allow easy extraction of overlay information for any relative orientation of the incident light beam with respect to a 1D grating target, as well as for targets comprising general 2D gratings. Signals of a certain symmetry property also allow measurement of profile asymmetry in a very efficient manner. In another embodiment a measurement methodology is defined to measure only signals which satisfy a symmetry assumption. An optional embodiment comprises a single polarization element serving as polarizer and analyzer. Another optional embodiment uses an analyzing prism to simultaneously collect two polarization components of reflected light.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.