Differential interferometer system and lithographic step-and-scan apparatus provided with such a system
US6046792A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 6, 1997 |
| Grant date | Apr 4, 2000 |
| Priority date | — |
| Expiry date | Mar 6, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/70
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A differential interferometer system for measuring the mutual positions and movements of a first object (WH) and a second object (MH). The system comprises a first interferometer unit (1, 2, 3, 4) having a first measuring reflector (RW) and a second interferometer unit (5, 6, 7, 8) having a second measuring reflector (RM). Since a measuring beam (b.sub.m) passes through both the first and the second interferometer unit and is reflected by both the first and the second measuring reflector, and since the measuring beam and the reference beam (b.sub.r) traverse the same path at least between the two interferometer units, accurate measurements can be preformed very rapidly. The interferometer system may be used to great advantage in a step-and-scan-lithographic projection apparatus.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.