Measuring method and apparatus

Claim 2

A method according to Claim 1, wherein the first and second patterns comprise regular-pitch grating patterns of the same pitch.

Claim 3

A method according to Claim 1, wherein the relative positional deviation is detected in accordance with phase difference detection based on a heterodyne method.

Claim 4

A method according to Claim 3, wherein, in said third step, coherent light of a first frequency is projected to the first grating pattern while coherent light of a second frequency is projected to the second grating pattern and first interference light produced as a result of interference of diffraction lights from the first and second patterns is detected, and wherein the relative positional deviation is detected on the basis of detection of a phase difference between the first interference light and second interference light which is produced by causing the first and second coherence lights to interfere with each other without being projected to the first and second patterns.

Claim 5

A method according to Claim 3, wherein, in said third step, coherent light having first and second frequencies is projected to the first and second grating patterns and first interference light produced as a result of interference of diffraction lights of the first and second frequencies emitted from the first grating pattern and second interference light produced as a result of interference of diffraction lights of the first and second frequencies emitted from the second grating pattern are detected, and wherein the relative positional deviation is detected on the basis of detection of a phase difference between the first and second interference lights.

Claim 6

A method according to Claim 3, wherein, in one of said first and second steps, a third grating pattern is formed on the object together with the first or second pattern, wherein in said third step coherent light of a first frequency is projected to the first grating pattern while coherent light of a second frequency is projected to the second grating pattern and first interference light produced as a result of interference of diffraction lights from the first and second diffraction patterns is detected, wherein coherent light of first and second frequencies is projected to the third grating pattern and second interference light produced as a result of interference of diffraction lights of the first and the second frequencies from the third pattern is detected, and wherein the relative positional deviation is detected on the basis of detection of a phase difference between the first and second interference lights.

Claim 7

A method according to Claim 1, wherein the object has a photosensitive material and wherein the first and second grating patterns are defined by latent images formed on the photosensitive material.

Claim 8

A method according to Claim 1, wherein the object has a photosensitive material, wherein said fist step is carried out by printing a pattern of a reticle, having the first grating pattern, upon the photosensitive material, and wherein said second step is carried out by printing a second reticle having the second grating pattern upon the photosensitive material.

Claim 9

A method according to Claim 1, wherein, in said second step, the position of the object having the first grating pattern formed thereon is adjusted before the formation of the second grating pattern.

Claim 10

A measuring apparatus, characterized by: means for projecting coherent light to first and second patterns provided on the same plane; and means for detecting, on the basis of interference of diffraction lights from the first pattern and/or the second pattern, a relative positional deviation of the first and second patterns.

Claim 11

An apparatus according to Claim 10, wherein the relative positional deviation is detected in accordance with phase difference detection based on a heterodyne method.

Claim 12

An apparatus according to Claim 10, wherein coherent light of a first frequency is projected to the first grating pattern while coherent light of a second frequency is projected to the second grating pattern and first interference light produced as a result of interference of diffraction lights from the first and second patterns is detected, and wherein the relative positional deviation is detected on the basis of detection of a phase difference between the first interference light and second interference light which is produced by causing the first and second coherent lights to interfere with each other without being projected to the first and second patterns.

Claim 13

An apparatus according to Claim 10, wherein coherent light having first and second frequencies is projected to the first and second grating patterns so that first interference light is produced as a result of interference of diffraction lights of the first and second frequencies emitted from the first grating pattern while second interference light is produced as a result of interference of diffraction lights of the first and second frequencies emitted from the second grating pattern, and wherein the relative positional deviation is detected on the basis of detection of a phase difference between the first and second interference lights.

Claim 14

An apparatus according to Claim 10, wherein coherent light of a first frequency is projected to the first grating pattern while coherent light of a second frequency is projected to the second grating pattern and first interference light produced as a result of interference of diffraction lights from the first and second diffraction patterns is detected, wherein coherent light of first and second frequencies is projected to a third grating pattern, having been formed on said plane together with the first or second grating pattern, and second interference light produced as a result of interference of diffraction lights of the first and the second frequencies from the third pattern is detected, and wherein the relative positional deviation is detected on the basis of detection of a phase difference between the first and second interference lights.

Claim 15

A measuring method, characterized by: a first step for forming at least a first grating pattern on an object; a second step for forming at least a second grating pattern on the object; a third step for producing first, second, third and fourth lights; a fourth step for projecting the first light to the first grating pattern on the object and projecting the second light to the second grating pattern on the object; a fifth step for receiving, through a first light receiving region, two of the third light, the fourth light, the first light as diffracted by the first grating pattern and the second light as diffracted by the second grating pattern, and for receiving the remaining two lights through a second light receiving region; and a sixth step for comparing optical interference outputs, corresponding to the lights received by the first and second light receiving regions, respectively, with each other to determine a relative positional deviation of the first and second patterns on the object.

Claim 16

A method according to Claim 15, wherein the first and second lights have a small difference in wavelength, wherein the first light receiving region receives the first and second lights as a beat signal, wherein the third and fourth lights have wavelengths equal to those of the first and second lights, respectively, and wherein the second light receiving region receives the third and fourth lights as a beat signal.

Claim 17

A method according to Claim 15, wherein the first and third lights have a small difference in wavelength, wherein the first light receiving region receives the first and third lights as a beat signal, wherein the third and fourth lights have wavelengths equal to those of the second and first lights, respectively, and wherein the second light receiving region receives the second and fourth lights as a beat signal.

Claim 18

A method according to Claim 17, wherein the third and fourth lights are produced as a result of diffraction by the first and second grating patterns, respectively.

Claim 19

A method according to Claim 15, wherein the first and second lights have the same wavelength and wherein the third and fourth lights have the same wavelength which is slightly different from that of the first and second lights.

Claim 20

A method according to Claim 15, wherein the first, the second, the third and the fourth lights have the same wavelength and wherein a difference in optical path length between the first and third lights and a difference in optical path length between the second and fourth lights are changeable slightly.

Claim 21

A measuring apparatus, characterized by: means for forming at least first and second grating patterns on an object; means for producing first, second, third and fourth lights; means for projecting the first light to the first grating pattern on the object and projecting the second light to the second grating pattern on the object; means for receiving, through a first light receiving region, two of the third light, the fourth light, the first light as diffracted by the first grating pattern and the second light as diffracted by the second grating pattern, and for receiving the remaining two lights through a second light receiving region; and means for comparing optical interference outputs, corresponding to the lights received by the first and second light receiving regions, respectively, with each other to determine a relative positional deviation of the first and second patterns on the object.