Apparatus and method for detecting optimal focal plane of lithographic projection objective lens
US10976670B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 27, 2019 |
| Grant date | Apr 13, 2021 |
| Priority date | — |
| Expiry date | Dec 27, 2039 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B27/10
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An apparatus and a method for detecting an optimal focal plane of a lithographic projection objective lens, the apparatus including: an illumination device, a beam splitting device, a lens array, a mask plate, a reflecting device, a photoelectric detector and a controller. The illumination device generates a collimated beam, which is transmitted through the beam splitting device, focused by the lens array to the mask plate for spatial-filtering, and delivered to the lithographic projection objective lens. The reflecting device reflects a focused beam passing through the lithographic projection objective lens to generate a reflected beam. The photoelectric detector detects an intensity of the reflected beam from the reflecting device after being spatial-filtered via the mask plate and generates a beam intensity signal. The controller controls a movement of a workpiece table and/or collects the beam intensity signal generated by the photoelectric detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.