摘要 |
Disclosed is an exposure method, an exposure apparatus and a device manufacturing method, in which transmission factors of almost all optical systems, including a projection optical system, can be measured during an exposure process, and in which the exposure amount is controlled on the basis of it. The exposure apparatus includes an illumination optical system for illuminating a pattern of a reticle with a laser beam from an excimer laser, and a projection lens system for projecting the pattern illuminated by the illumination optical system onto a wafer, to thereby expose the wafer with the reticle pattern, wherein reflection light or ghost light produced at a surface of a lens of the projection lens system is received by a sensor and, on the basis of the an output of the sensor, the transmission factor of the projection lens system is measured. The exposure amount is then controlled on the basis of the measurement.
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