Measurement apparatus, measurement method, lithography apparatus and article manufacturing method
A measurement apparatus including an illumination system configured to illuminate a target with light including light of a first wavelength and light of a second wavelength, a wavefront changing unit configured to change a wavefront aberration in light from the target, and a control unit configured to control the wavefront changing unit, wherein the wavefront changing unit includes a first region where the light of the first wavelength enters, and a second region where the light of the second wavelength enters, and the control unit controls the wavefront changing unit such that a first correction wavefront for correcting a first wavefront aberration in the light of the first wavelength is generated in the first region, and a second correction wavefront for correcting a second wavefront aberration in the light of the second wavelength is generated in the second region.
1 . A measurement apparatus for measuring a position of a target, comprising:
an illumination system configured to illuminate the target with light including light of a first wavelength and light of a second wavelength different from the first wavelength;
a wavefront changing unit configured to change a wavefront aberration in light from the target; and
a control unit configured to control the wavefront changing unit,
wherein the wavefront changing unit includes a first region where the light of the first wavelength enters, and a second region, different from the first region, where the light of the second wavelength enters,
wherein the control unit controls the wavefront changing unit such that a first correction wavefront for correcting a first wavefront aberration in the light of the first wavelength is generated in the first region, and a second correction wavefront for correcting a second wavefront aberration in the light of the second wavelength is generated in the second region, and
wherein the first region and the second region are spatially separated regions on the wavefront changing unit, and light of the first wavelength and light of the second wavelength simultaneously enter the first region and the second region, respectively.
2 . The apparatus according to claim 1 , further comprising
a wavefront detection unit configured to detect the first wavefront aberration in the light of the first wavelength and the second wavefront aberration in the light of the second wavelength,
wherein the control unit controls the wavefront changing unit such that the first correction wavefront is generated in the first region based on the first wavefront aberration detected by the wavefront detection unit, and the second correction wavefront is generated in the second region based on the second wavefront aberration detected by the wavefront detection unit.
3 . The apparatus according to claim 2 , wherein
the wavefront detection unit detects the first wavefront aberration and the second wavefront aberration based on the light including the light of the first wavelength and the light of the second wavelength entering via the wavefront changing unit.
4 . The apparatus according to claim 1 , wherein
the control unit obtains a correction wavefront for correcting the first wavefront aberration and the second wavefront aberration from a third wavefront aberration obtained by connecting the first wavefront aberration and the second wavefront aberration so as to correspond to the first region and the second region, and
controls the wavefront changing unit based on the correction wavefront such that the first correction wavefront is generated in the first region and the second correction wavefront is generated in the second region.
5 . The apparatus according to claim 4 , wherein
the control unit obtains the third wavefront aberration by connecting the first wavefront aberration and the second wavefront aberration in a radial direction on a pupil plane.
6 . The apparatus according to claim 1 , wherein
the control unit
obtains a correction wavefront for correcting the first wavefront aberration and the second wavefront aberration by connecting the first correction wavefront and the second correction wavefront so as to correspond to the first region and the second region, and
controls the wavefront changing unit based on the correction wavefront such that the first correction wavefront is generated in the first region and the second correction wavefront is generated in the second region.
7 . The apparatus according to claim 6 , wherein
the control unit obtains the correction wavefront by connecting the first correction wavefront and the second correction wavefront in a radial direction on a pupil plane.
8 . The apparatus according to claim 1 , wherein
the wavefront changing unit includes a shape deformable mirror including a reflective film forming a reflective surface which reflects the light from the target, and an actuator configured to deform a shape of the reflective film.
9 . The apparatus according to claim 1 , wherein
the control unit
obtains, based on the first wavefront aberration and the second wavefront aberration, a correction wavefront for correcting a wavefront aberration asymmetric with respect to an optical axis, and
controls the wavefront changing unit based on the correction wavefront.
10 . The apparatus according to claim 1 , wherein
the control unit
obtains, based on the first wavefront aberration and the second wavefront aberration, a correction wavefront that sets the first correction wavefront and the second correction wavefront at predetermined focal positions, respectively, and
controls the wavefront changing unit based on the correction wavefront.
11 . The apparatus according to claim 1 , wherein
the control unit
obtains, based on the first wavefront aberration, the second wavefront aberration, and information indicating a relationship between a wavefront aberration in the light from the target and a measurement error of a position of the target, a correction wavefront for correcting the first wavefront aberration and the second wavefront aberration, and
controls the wavefront changing unit based on the correction wavefront.
12 . The apparatus according to claim 1 , wherein
the control unit
obtains, based on the first wavefront aberration and information indicating a relationship between a wavefront aberration in the light from the target and a measurement value of a position of the target, a correction wavefront that makes the measurement value of the position of the target reach a target value, and
controls, based on the correction wavefront, the wavefront changing unit such that the first correction wavefront is generated in the first region and the second correction wavefront is generated in the second region.
13 . The apparatus according to claim 1 , further comprising
a detection unit configured to detect the light from the target via the wavefront changing unit,
wherein the control unit obtains the position of the target based on the light from the target detected by the detection unit.
14 . The apparatus according to claim 13 , further comprising
an objective optical system arranged between the detection unit and the target,
wherein the wavefront changing unit is arranged on a pupil plane of the objective optical system.
15 . The apparatus according to claim 13 , wherein
each of the first wavefront aberration and the second wavefront aberration includes a wavefront aberration in the detection unit.
16 . The apparatus according to claim 13 , wherein
the target includes a first pattern and a second pattern, and
the control unit obtains a relative position between the first pattern and the second pattern.
17 . A lithography apparatus for forming a pattern on a substrate, the apparatus comprising:
a measurement apparatus defined in claim 1 , configured to measure a position of a target while using, as the target, a mark provided on the substrate; and
a stage configured to position the substrate based on the position of the target measured by the measurement apparatus.
18 . An apparatus according to claim 17 , further comprising
a projection optical system configured to project a pattern of a reticle onto the substrate.
19 . A measurement method of measuring a position of a target using a measurement apparatus that comprises an illumination system configured to illuminate the target with light including light of a first wavelength and light of a second wavelength different from the first wavelength, and a wavefront changing unit configured to change a wavefront aberration in light from the target, wherein
the wavefront changing unit includes a first region where the light of the first wavelength enters, and a second region, different from the first region, where the light of the second wavelength enters, and
the method comprises:
acquiring a first wavefront aberration in the light of the first wavelength and a second wavefront aberration in the light of the second wavelength, and
controlling the wavefront changing unit such that a first correction wavefront for correcting the first wavefront aberration is generated in the first region, and a second correction wavefront for correcting the second wavefront aberration is generated in the second region,
wherein the first region and the second region are spatially separated regions on the wavefront changing unit, and light of the first wavelength and light of the second wavelength simultaneously enter the first region and the second region, respectively.
20 . An article manufacturing method comprising:
measuring, using a measurement method defined in claim 17 , a position of a target while using, as the target, a mark provided on a substrate;
positioning the substrate based on the position of the target measured in the measuring;
forming a pattern on the substrate positioned in the positioning; and
manufacturing an article from the substrate with the pattern formed thereon in the forming.