Array of encoders for alignment measurement
US10078269B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 3, 2016 |
| Grant date | Sep 18, 2018 |
| Priority date | — |
| Expiry date | Oct 3, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F9/7088
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
System and method for accurately measuring alignment of every exposure field on a pre-patterned wafer without reducing wafer-exposure throughput. Diffraction grating disposed in scribe-lines of such wafer, used as alignment marks, and array of encoder-heads (each of which is configured to define positional phase(s) of at least one such alignment mark) are used. Determination of trajectory of a wafer-stage scanning during the wafer-exposure in the exposure tool employs determining in-plane coordinates of such spatially-periodic alignment marks by simultaneously measuring position-dependent phases of signals produced by these marks as a result of recombination of light corresponding to different diffraction orders produced by these marks. Measurements may be performed simultaneously at all areas corresponding to at least most of the exposure fields of the wafer, and/or with use of a homodyne light source, and/or in a wavelength-independent fashion, and/or with a pre-registration process allowing for accommodation of wafers with differently-dimensioned exposure fields.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.