| 摘要 |
A projection exposure apparatus is able to monitor changes in transmissivity of the projection optical system so as to provide a high degree of control over the exposure illuminance to produce precision printing of circuit patterns on a substrate. A referencing member, having reference marks and a window section for determining the illuminance of the transmitting exposure beam, is provided on the sample stage for the substrate. During scanning/exposure process, any positional deviation of projection optical system is checked by the alignment system by comparing reticle marks on the reticle with reference marks on the sample stage illuminated with alignment beams. Simultaneously, illuminance of exposure light passing through the projection optical system is checked to determine if there is any change in the transmission coefficient of the optical system, and illumination power is adjusted to provide near real-time compensation for any change in transmissivity in the optical system.
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