Nec Corporation

Joji Iwata

Yoshiharu Tanaka

Eiichi Kouno

A method of alignment between a mask and a semiconductor wafer is disclosed. At least one linear Fresnel zone plate lens is provided on the mask, and first and second reflecting gratings are provided one the semiconductor wafer. The first reflecting grating includes a plurality of concaves or convexs arranged with a constant pitch P.sub.1, and the second reflecting grating includes a plurality of concaves of convexs arranged with a constant pitch P.sub.2 different from the pitch P.sub.1 in the first reflecting grating. A monochromatic radiation is irradiated on the mask and first and second reflected radiations from the first and second reflecting gratings are detected by first and second detectors, respectively. A difference value between the outputs of the first and second detectors is obtained, and the relative position between the mask and the semiconductor wafer is displaced in accordance with the difference value.

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Tokyo, Japan

Joji Iwata