Radiant energy – Photocells; circuits and apparatus – Photocell controls its own optical systems
Patent
1988-02-12
1989-03-21
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controls its own optical systems
356401, 355 8, G01N 2186
Patent
active
048146250
ABSTRACT:
An exposure apparatus having a movable stage for carrying thereon a workpiece such as a semiconductor wafer and a laser interferometer system for measuring the position of the stage with respect to X and Y directions, is disclosed. The movement of the stage is controlled on the basis of the position measurement by use of the laser interferometer system, so that a pattern of a mask or reticle is transferred onto different portions of the workpiece in a step-and-repeat manner. One or more air-conditioning devices are provided to supply currents of air, being controlled at the same temperature, toward the stage and along the measuring paths of the laser interferometer system which are in the X and Y directions. This is effective to avoid spatial temperature irregularities, particularly along the measuring paths, with the result that the measuring accuracy of the laser interferometer system can be improved remarkably. Thus, the step-and-repeat exposures can be made with higher correctness.
REFERENCES:
patent: 3904290 (1975-09-01), Kidd et al.
patent: 4503335 (1985-03-01), Takahashi
patent: 4530592 (1985-07-01), Green et al.
patent: 4720732 (1988-01-01), Tsutsui
Allen Stephone B.
Canon Kabushiki Kaisha
Nelms David C.
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