Electricity: measuring and testing – Magnetic – Displacement
Patent
1988-05-27
1990-03-27
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
Displacement
324248, 505843, 505872, G01B 714, G01R 33035
Patent
active
049124080
ABSTRACT:
Disclosed is a distance measuring system suitably usable in a semiconductor microcircuit manufacturing lithographic apparatus such as an aligner or a stepper, for measuring the position or the distance of movement of a movable object such as a mask stage or a wafer stage. The system includes a magnetic field producing portion such as a magnet for producing a predetermined magnetic field, a superconducting quantum interference device coupled to the mask stage or the wafer stage. Further, there are provided a magnetic flux detecting portion for outputting signals corresponding to changes in the magnetic flux, in the magnetic field, passing through the superconducting quantum interference device and a signal processing unit for processing the output signals of the magnetic flux detecting portion to detect the position or the distance of movement of the mask stage or the wafer stage. Also, a shielding member is provided to shield at least the magnetic field producing portion and the magnetic flux detecting portion against an external magnetic field, by use of a superconductor. The distance measuring system of the present invention assures accurate measurement with a high resolution, for a wide movable range of the movable member such as a range not less than 100 mm.
REFERENCES:
patent: 3286161 (1966-11-01), Jones et al.
patent: 3777255 (1973-12-01), Young et al.
patent: 4315214 (1982-02-01), Kataoka
patent: 4489274 (1984-12-01), Berlincourt
patent: 4491795 (1985-01-01), Gelinas
Phys. Bull. 38, Michael Dickens, "Sensationally Sensitive SQUIDS", 1987, pp. 296-299.
Kuroda Ryo
Niwa Yukichi
Nose Noriyuki
Sawada Takeshi
Canon Kabushiki Kaisha
Strecker Gerard R.
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