Multilayer mirror, method for manufacturing the same, and exposure equipment
First Claim
1. A multilayer mirror comprising a reflective multilayer in which a high refractive-index film and a low refractive-index film are laminated on a substrate by turns under a condition that a Bragg'"'"'s reflection condition holds that reflected light from a plurality of boundary surfaces of the high refractive-index film and low-refractive index film for EUV ray is put in phase, comprising:
- an interposed layer having a thickness of half or more of a center wavelength of the EUV ray, whereina band of EUV ray wavelength or a range of incidence angle both having a relatively high EUV ray reflectivity is widened, andeach layer is laminated while the film thickness thereof is varied arbitrarily so the reflectivity for light having a wavelength of 13.1 nm to 13.9 nm is set to 45% or more.
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Abstract
A multilayer mirror aims to reduce incidence angle dependence of reflectivity. A substrate is made of low thermal polished expansion glass with 0.2 nm RMS or less roughness of the surface. On the surface thereof formed is a Ru/Si multilayer having a wide full-width half maximum of peak reflectivity, and on the Ru/Si multilayer formed is a Mo/Si multilayer having a high peak reflectivity value. This enables higher reflectivity than when Ru/Si alone provided and a reflectivity peak having a wider full-width half maximum than when the Mo/Si multilayer alone provided. Since Ru absorbs EUV ray more than Mo does, higher reflectivity is obtainable than that of a structure having the Ru/Si multilayer formed on the Mo/Si multilayer. The multilayer with a wide full-width half maximum has small incidence angle dependence of reflectivity in spectral reflectivity, thereby achieving high imaging performance in projection optical system.
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Citations
4 Claims
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1. A multilayer mirror comprising a reflective multilayer in which a high refractive-index film and a low refractive-index film are laminated on a substrate by turns under a condition that a Bragg'"'"'s reflection condition holds that reflected light from a plurality of boundary surfaces of the high refractive-index film and low-refractive index film for EUV ray is put in phase, comprising:
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an interposed layer having a thickness of half or more of a center wavelength of the EUV ray, wherein a band of EUV ray wavelength or a range of incidence angle both having a relatively high EUV ray reflectivity is widened, and each layer is laminated while the film thickness thereof is varied arbitrarily so the reflectivity for light having a wavelength of 13.1 nm to 13.9 nm is set to 45% or more. - View Dependent Claims (2, 3, 4)
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Specification