Patent ID: 6649923
Filing Date: 2003-11-18
Classification: G03F

Abstract:
A method of detecting a relative positional deviation between a first object and a second object, opposed to each other, with respect to a predetermined direction by use of a first alignment mark provided on the first object and a second alignment mark provided on the second object, said method comprising:a first step for providing the first alignment mark by use of a first grating lens, a fifth grating lens, a second grating lens having a mirror image of the first grating lens, and a sixth grating lens having a mirror image of the fifth grating lens; a second step for providing the second alignment mark by use of a third grating lens, a seventh grating lens, a fourth grating lens having a mirror image of the third grating lens, and an eighth grating lens having a mirror image of the seventh grating lens; a third step for detecting an incidence position of first light coming via the first grating lens and the third grating lens and incident upon a first predetermined plane; a fourth step for detecting an incidence position of second light coming via the second grating lens and the fourth grating lens and incident upon a second predetermined plane; a fifth step for detecting an incidence position of third light coming via the fifth grating lens and the seventh grating lens and incident upon a third predetermined plane; a sixth step for detecting an incidence position of fourth light coming via the sixth grating lens and the eighth grating lens and incident upon a fourth predetermined plane; and a seventh step for detecting a relative positional deviation dx between the first and second objects in the predetermined direction, on the basis of a spacing d1 between the first and third lights and a spacing d2 between the second and fourth lights, and in accordance with an equation dx=(d1-d2)/M, wherein M is the magnification of the spot spacing to the first-to-second object deviation.