Projection optical system, method of manufacturing projection optical system, exposure apparatus, and exposure method
First Claim
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1. A projection optical system provided with at least one of optical members made of a calcium fluoride single crystal,wherein each of the optical members satisfies at least any one of the following conditions of (i) to (iii):
- (i) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 50 periods inclusive, out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm, is equal to or below 0.35 nm/cm;
(ii) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 100 periods inclusive, out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm, is equal to or below 0.45 nm/cm; and
(iii) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 150 periods inclusive, out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm, is equal to or below 0.50 nm/cm.
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Abstract
A projection optical system provided with at least one of optical members made of a calcium fluoride single crystal,
- wherein each of the optical members satisfies at least any one of the following conditions of (i) to (iii):
- (i) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 50 periods inclusive out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm is equal to or below 0.35 nm/cm;
- (ii) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 100 periods inclusive out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm is equal to or below 0.45 nm/cm; and
- (iii) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 150 periods inclusive out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm is equal to or below 0.50 nm/cm.
18 Citations
13 Claims
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1. A projection optical system provided with at least one of optical members made of a calcium fluoride single crystal,
wherein each of the optical members satisfies at least any one of the following conditions of (i) to (iii): -
(i) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 50 periods inclusive, out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm, is equal to or below 0.35 nm/cm; (ii) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 100 periods inclusive, out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm, is equal to or below 0.45 nm/cm; and (iii) an RMS value of a spatial frequency component having a number of periods fPD in partial diameter in a range from 10 periods to 150 periods inclusive, out of fluctuation of a transmission wavefront relative to light having a wavelength of 633 nm, is equal to or below 0.50 nm/cm. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of manufacturing a projection optical system comprising the steps of:
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measuring transmission wavefronts of calcium fluoride single crystals and finding two-dimensional distribution of wavefront aberrations; Fourier transforming the two-dimensional distribution and calculating two-dimensional power spectra of fluctuations of the transmission wavefronts; calculating an Average Radial PSD value for each spatial frequency in the two-dimensional power spectra; calculating an RMS value by integrating the Average Radial PSD values in a predetermined spatial frequency range; selecting the calcium fluoride single crystal having the RMS value equal to or below a predetermined upper limit; manufacturing an optical member by processing the selected calcium fluoride single crystal; and manufacturing a projection optical system including at least one of the optical member made of the calcium fluoride single crystal. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification