Deviation measuring device including a mask having a grating pat

Details Deviation measuring device including a mask having a grating pat Deviation measuring device including a mask having a grating pat

1991-01-22

1993-03-23

Nelms, David C.

Radiant energy

Photocells; circuits and apparatus

Photocell controls its own optical systems

356400, G01V 904

Patent

active

051967111

ABSTRACT:
A device for detecting relative positional deviation between a mask and a wafer is disclosed, wherein the mask has a first grating pattern and a zone plate pattern and the wafer has a second grating pattern. The device includes a directing system for directing a radiation beam to the first grating pattern of the mask, such that the first grating pattern produces a first transmitted beam which is then inputted to the wafer substantially perpendicularly and a second transmitted beam which is obliquely inputted to the wafer and such that the first grating pattern also produces a first reflected beam; and a detecting system for detecting (i) the first reflected beam and also for detecting (ii) a second reflected beam resulting from reflective diffraction of the first transmitted beam by the second diffraction pattern of the wafer, the third reflected beam being displaceable with any inclination of a surface of the wafer and (iii) a third reflected beam resulting from reflection of the second transmitted beam by the wafer surface and from diffraction of the same by the zone plate pattern of the mask and being displaceable with any inclination of the wafer surface and an interval between the mask and the wafer.

REFERENCES:
patent: 4311389 (1982-01-01), Fay et al.
patent: 4779001 (1988-10-01), Makosch
patent: 4815854 (1989-03-01), Tanaka et al.
patent: 4870289 (1989-09-01), Sato et al.
patent: 4948983 (1990-08-01), Maruyama et al.
patent: 4999487 (1991-03-01), Maruyama et al.
patent: 5028797 (1991-07-01), Abe et al.

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