Position detector employing a sector fresnel zone plate

Claim 2

(2) A position detector according to Claim 1 in which said first object body (14) is a mask and said second object body (15) is a wafer.

Claim 3

(3) A position detector according to Claim 1 in which said first sigle SFZP (16) is disposed between a pair of said second SFZPs (17).

Claim 4

(4) A position detector according to Claim 1 in which said single SFZP (17) is disposed between a pair of said first SFZPs (16).

Claim 5

(5) A position detector according to Claim 1 in which said first single SFZP (16) is disposed over said second single SFZP (17).

Claim 6

(6) A position detector according to any one of Claims 1 and 3 to 5 in which said first SFZP (16) is provid with a transparent window zone (22) through which a ray of incidence upon and of diffraction by said second SFZP (17) pass.

Claim 7

(7) A position detector according to Claim 1 in which said ray of a single wavelength is a coherent ray of bright line with a reduced half width such as a laser ray of He-Ne of a wavelength of 633nm, Ar of a wavelength of 488nm and green He-Ne of a wavelength of 543.5nm.

Claim 8

(8) A position detector according to Claim 1 in which said illumination means (5) and detection means (12) are arranged such that an illumination optical axia angle of said illumination means whose optical axis makes with the surface of the alignment mark is equal to a detection optical axis angle of said detection means whose optical makes with the surface of the alignment mark at the opposite sides of the normal of the surface.

Claim 9

(9) A position detector according to Claim 8 in which said illumination angle is in a range of 45 ° to 80° .

Claim 10

(10) A position detector according to Claim 1 in which said detection means (12) a general magnifying optical system comprising an objective lens (9) and a relay lens (8).

Claim 11

(11) A position detector according to Claim 10 in which said objective lens (9) is the one of an apochromatic or a chromatic system in which an aberration is properly compensated.

Claim 12

(12) A position detector according to Claim 1 in which said transducer means (6) is a one dimensional solid-state camera such as a CCD and a MOS type LSI.

Claim 13

(13) A position detector according to Claim 1 in which said signal handling means (30) employs a similar patternmatching method.

Claim 14

(14) A position detector for use in an X ray exposure apparatus for detecting a relative position between first and second object bodies minutely spaced in the direction of the normal of the surfaces of said bodies, in the direction perpendicular to said normal; characterized by first and second Fresnel's zone plate (SFZP) (16) (17) on which respective alignment marks are formed and which are disposed respectively on said first and second object bodies (14)(15); illumination means (5) disposed at an angle with respect to said normal for simultaneously illuminating said first and second SFZPs (16)(17) with rays of a plurality of wavelengths from the same direction; said first and second SFZPs being constructed such that a principal focal plane formed by Fresnel diffraction on said first SFZP (16) which plane lies at a different position to each of said rays of said plurality of wavelengths agrees with a principal focal plane formed by Fresnel diffraction on said second SFZP (17) which plane lies at a different position to each of said rays of said rays of said plurality of wavelengths, with respect to a ray of at least one of said plurality of wavelengths; detection means (12) disposed on the opposite side of said illumination means (5) at the same angle with respect to said normal and including an objective lens having such an axial chromatic aberration that its focal planes to said rays of said plurality of wavelengths agree with respective principal focal planes formed by Fresnel diffraction on said second SFZP (17) which planes lie at different positions to said rays of said pluraity of wavelengths, for detecting Fresnel diffraction images formed by said alignment marks to said rays of said plurality of wavelengths; transducer means (5) disposed on an image forming plane of said detection means for converting a Fresnel diffraction image in a straight line formed by said first and second SFZPs (16)(17) into an electric signal by linearly scanning said Fresnel diffraction image in the direction perpendicular to the image; and signal handling means (30) for handling said electrical signal obtained by said transducer means (6) to detect a relative position between said alignment marks in the direction perpendicular to said normal.

Claim 15

(15) A position detector according to Claim 14in which said first object body (14) is a mask and said second object body (15) is a wafer.

Claim 16

(16) A position detector according to Claim 14 in which said first single SFZP (16) is disposed between a pair ofsaid second SFZPs (17).

Claim 17

(17) A position detector according to Claim 14 in which said second single SFZP (17) is disposed between a pair of said first SFZPs (16).

Claim 18

(18) A position detector according to Claim 14 in which said first single SFZP (16) is disposed over said second single SFZP (17).

Claim 19

(19) A position detector according to any one of Claim 14 and 16 to 18 in which said first SFZP (16) is providedwith a transparent window zone (22) through which a ray of indence upon and of diffraction by said second SFZP pass.

Claim 20

(20) A position detector according to Claim 14 in which said illumination means (5) employs a coherent ray of bright line with a reduced half wihdow such as a laser ray.

Claim 21

(21) A position detector according to Claim 14 in which said illumination means (5) and detection means (12) are arranged such that an illumination optical axis anble of said illumination means whose optical axis makes with the surface of the alignment mark is equal to a detection optical axis angle of said detection means whose optical axis makes with the surface of the alignment mark at the opposite sides of the normal of the surface.

Claim 22

(22) A position detector according to Claim 19 in which said illumination-angle is in a range of 45 ° to 80° .

Claim 23

(23) A position detector according to Claim 14 in which said detection means (12) comprises an objective lens (9) having an axial chromatic aberration and relay lens (8).

Claim 24

(24) A position detector according to Claim 14 in which said transducer means (8) is a one dimensional solid-stage camera such as a CCD and a MOS type LSI.

Claim 25

(25) A position detector according to Claim 14 in which said signal handling means (30) employs a similar pattern matching method.

Claim 26

(26) A position detector according to Claim 14 in which said rays of said plurality of wavelengths include a single wavelength ray and a band ray both of which are after passing through respective band-pass filters, thereby dispensing with the use of a pattern barrior filter for eliminating blurring of an image due to an axial chromatic aberration.

Claim 27

(27) A position detector according to Claim 26 in which said single wavelength ray is a g ray of wavelenghth of 436nm, for example and said band ray includes e ray andd ray of wavelength zone 520nm to 600nm, for example.