Computationally efficient X-ray based overlay measurement
US10545104B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 28, 2016 |
| Grant date | Jan 28, 2020 |
| Priority date | — |
| Expiry date | Dec 12, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG21K1/062
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Methods and systems for performing overlay and edge placement errors of device structures based on x-ray diffraction measurement data are presented. Overlay error between different layers of a metrology target is estimated based on the intensity variation within each x-ray diffraction order measured at multiple, different angles of incidence and azimuth angles. The estimation of overlay involves a parameterization of the intensity modulations of common orders such that a low frequency shape modulation is described by a set of basis functions and a high frequency overlay modulation is described by an affine-circular function including a parameter indicative of overlay. In addition to overlay, a shape parameter of the metrology target is estimated based on a fitting analysis of a measurement model to the intensities of the measured diffraction orders. In some examples, the estimation of overlay and the estimation of one or more shape parameter values are performed simultaneously.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.