摘要 |
A projection exposure apparatus for projecting, onto a semiconductor wafer through a projection lens, an integrated circuit pattern formed on a mask or reticle. An alignment beam having a wavelength different from that for the exposure is used to achieve alignment between the mask and the wafer. A parallel flat plate is detachably disposed between the projection lens and the mask and/or the wafer to prevent a magnification error and/or a focus error of the projection lens which would otherwise be caused upon alignment due to the difference in wavelength.
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