Measuring apparatus, exposure apparatus and method, and device manufacturing method
A measuring apparatus includes a pinhole mask, located on an object plane of an optical system to be measured, and having a plurality of pinholes for generating a spherical wave from a measuring light beam, and a diffraction grating for splitting the measuring light beam that has passed the pinhole mask and the optical system, in which Lg=m·Pg 2 /λ is met, where Pg is a grating pitch of the diffraction grating, λ is a wavelength of the measuring light beam, m is an integer other than zero, and Lg is a distance between the diffraction grating and an image plane of the optical system. The measuring apparatus detects an interferogram formed by interference between a plurality of the measuring light beams split by the diffraction grating. The plurality of measuring light beams includes an aberration of the optical system.
1. A measuring apparatus comprising:
a pinhole mask, located on an object plane of an optical system to be measured, and having a plurality of pinholes for generating a spherical wave from a measuring light beam; and
a diffraction grating for splitting the measuring light beam that has passed said pinhole mask and the optical system,
wherein Lg=m·Pg 2 /λ is met, where Pg is a grating pitch of the diffraction grating, λ is a wavelength of the measuring light beam, m is an integer other than zero, and Lg is a distance between the diffraction grating and an image plane of the optical system, and
wherein said measuring apparatus detects an interferogram formed by interference between a plurality of the measuring light beams split by said diffraction grating, the plurality of measuring light beams including an aberration of the optical system.
2. A measuring apparatus according to claim 1 , wherein the plurality of pinholes are located two-dimensionally.
3. A measuring apparatus according to claim 1 , wherein said pinhole mask is a reflection pinhole mask.
4. A measuring apparatus according to claim 1 , wherein said pinhole mask is a transmission pinhole mask.
5. A measuring apparatus according to claim 1 , wherein said diffraction grating is a two-dimensional diffraction grating.
6. A measuring apparatus according to claim 1 , wherein Pp=(Pg/β)·(Lc/(Lg+Lc)) is met, where Pp is an interval among the plurality of pinholes, Lc is a distance between the image plane of the optical system and an observing section for observing the interferogram, and β is a magnification of the optical system.
7. A measuring apparatus according to claim 1 , wherein Pp=Pg/β is met, where β is a magnification of the optical system, and Pp is an interval among the plurality of pinholes.
8. A measuring apparatus according to claim 1 , wherein said pinhole mask comprises a plurality of pinhole units, each having a plurality of pinholes, and
wherein Pp=(Pg/β)·(Lc/(Lg+Lc)) or Pp=Pg/β Pp is met, where Pp is an interval between central positions of the pinhole units, Lc is a distance between the image plane of the optical system and an observing section for observing the interferogram, and β is a magnification of the optical system.
9. A measuring apparatus according to claim 8 , wherein an interval of the pinholes in each pinhole unit sets a coherence factor of the light to zero.
10. An exposure apparatus for exposing a pattern of a reticle onto a plate using light from a light source, said exposure apparatus comprising:
a projection optical system for projecting the pattern onto the plate;
a measuring apparatus according to claim; and
a controller configured to calculate a wavefront aberration of said projection optical system using a result of the interferogram detected by said measuring apparatus.
11. An exposure method comprising the steps of:
calculating a wavefront aberration of the projection optical system using a result of the interferogram detected by the measuring apparatus according to claim 1 ;
adjusting the projection optical system based on the calculated wavefront aberration of the projection optical system; and
exposing a plate by using the projection optical system adjusted in said adjusting step.
12. A device manufacturing method comprising the steps of:
(a) exposing a plate using an exposure apparatus; and
(b) developing the plate exposed in said exposing step,
wherein the exposure apparatus exposes a pattern of a reticle onto the plate using light from a light source, and includes:
(i) a projection optical system for projecting the pattern onto the plate;
(ii) a measuring apparatus according to claim 1 ; and
(iii) a controller configured to calculate a wavefront aberration of the projection optical system using a result of the interferogram detected by the measuring apparatus.