Method for detecting focus plane based on Hartmann wavefront detection principle
US9400220B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 17, 2015 |
| Grant date | Jul 26, 2016 |
| Priority date | — |
| Expiry date | Sep 17, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70258
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The present disclosure relates to a method for detecting focus plane based on Hartmann wavefront detection principle, the function of which is to detect the position of a silicon wafer in a photolithograph machine in real time so as to accomplish adjustment of the leveling and focus of the silicon wafer. By utilizing microlens array to detect the wavefront carrying information about the position of the silicon wafer based on the Hartmann wavefront detection principle, the spherical wavefront is divided by the respective subunits of the microlens array and is imaged on the respective focus planes of the subunits. If the silicon wafer is located on the focal plane, the incident wavefront for the microlens array is a planar wavefront so that the diffraction light spots are on the focus of the respective subunits of the microlens array; and if the silicon wafer is defocused, the incident wavefront for the microlens array is a spherical wavefront so that the diffraction light spots are shifted on the focus plane of the microlens array. Based on Hartmann wavefront detection principle, the detection of the spherical wavefront may be implemented by the microlens array shifting the imaged l…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.