Method and apparatus for detecting a mark position

Details Method and apparatus for detecting a mark position Method and apparatus for detecting a mark position

1983-09-27

1986-04-01

Evans, F. L.

Optics: measuring and testing

By polarized light examination

With light attenuation

250548, 356401, G01B 1114

Patent

active

045794537

ABSTRACT:
A method of aligning a mask and a wafer for manufacturing semiconductor integrated circuits. The mask and wafer have respective alignment marks which are scanned by a laser beam to detect the misalignment therebetween. The relative position between the mask and wafer is changed in response to the detected misalignment. The marks are formed by bar-like mark elements. The width of the mark element, measured along the line of the beam scan, is 2 to 3 times the diameter of the scanning beam so that the light scattered by the leading edge of the mark element and the trailing edge of the mark element is separately detected by a photoelectric transducer, which produces a first signal in response to the leading edge and a second signal in response to the trailing edge. The position of the mark element is determined on the basis of the falling portion of the first signal and the rising portion of the second signal.

REFERENCES:
patent: 4266876 (1981-05-01), Nakazawa et al.
patent: 4301363 (1981-11-01), Suzuki et al.

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