Method for producing a mirror substrate blank of titanium-doped silica glass for EUV lithography, and system for determining the position of defects in a blank
US10016872B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 2, 2014 |
| Grant date | Jul 10, 2018 |
| Priority date | — |
| Expiry date | Jul 2, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/06113
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method for producing a mirror substrate blank made from titanium-doped silica glass for EUV lithography, having a thickness of at least 40 millimeters, includes steps of face grinding the surface of the blank and identifying data on defects in a surface layer of the blank. Light penetrates the blank at a predetermined angle of incidence α of less than 90° at a location on the flat surface of the blank. The light scatters on a defect in the blank, and the scattered light is detected at a distance x from the penetration location on the surface of the blank by a light detection element arranged perpendicularly thereabove. The method further includes steps of determining the position of the defect in the surface layer based on the obtained data, and partial or complete removal of the surface layer in consideration of the position determination and forming the mirror substrate blank.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.