# US 8,570,488 B2 · Transmitting optical element and objective for a microlithographic projection exposure apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,570,488 B2 - Document ID: US8570488B2 - Status: Granted - Kind: B2 - Application number: 11/718,146 - Filed: 2005-12-08 - Published: 2009-08-13 - Granted: 2013-10-29 - Earliest claimed: 2004-12-09 - Assignees: Carl Zeiss SMT GmbH - Applicants: Wilfried Clauss; Michael Totzeck; Gisela Rissmann - Inventors: Wilfried Clauss; Michael Totzeck; Werner Mueller-Rissmann - Web page: https://patentgrep.com/patent/US8570488B2 ## CPC - C04B 35/443: Magnesium aluminate spinel - C04B 35/053: Fine ceramics - C04B 35/44: based on aluminates - C04B 35/6455: {Hot isostatic pressing} - G02B 1/02: made of crystals, e.g. rock-salt, semi-conductors (G02B1/08 takes precedence) - G03F 7/70341: {Details of immersion lithography aspects, e.g. exposure media or control of immersion liquid supply (chemical composition of immersion liquids G03F7/2041)} - G03F 7/70941: {Stray fields and charges, e.g. stray light, scattered light, flare, transmission loss} - G03F 7/70958: {Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties} - C04B 2235/3225: Yttrium oxide or oxide-forming salts thereof - C04B 2235/72: Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics - C04B 2235/762: Cubic symmetry, e.g. beta-SiC - C04B 2235/77: Density - C04B 2235/786: Micrometer sized grains, i.e. from 1 to 100 micron - C04B 2235/9646: Optical properties - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract A transmitting optical element adapted for use in an objective for a microlithographic projection exposure apparatus is composed of a polycrystalline material, with the polycrystalline material having crystallites with a cubic crystal structure, and with the mean crystallite size of these crystallites being at least micrometers, and at most micrometers. ## Claims ### Claim 1 A system, comprising: a housing; an objective in the housing, the objective comprising a plurality of optical elements comprising a transmitting optical element composed of polycrystalline material having a refractive index of more than 1.7 for a wavelength of less than 200 nm; and an immersion liquid in the housing, wherein the transmitting optical element composed of polycrystalline material is closest to an image plane of the objective. ### Claim 2 (depends on 1) The system according to claim 1, wherein the transmitting optical element comprises at least two sub-elements made of polycrystalline material. ### Claim 3 (depends on 2) The system according to claim 2, wherein the sub-elements are connected by optical contacting, fusion bonding or low temperature bonding. ### Claim 4 (depends on 2) The system according to claim 2, wherein between the sub-elements an intermediate space is provided, wherein the intermediate space is filled with gas or a liquid having a refractive index higher than 1.4. ### Claim 5 (depends on 2) The system according to claim 2, wherein a contact surface between at least two sub-elements or between at least one of the sub-elements and the intermediate space is of spherical shape. ### Claim 6 (depends on 2) The system according to claim 2, wherein the sub-elements are made of different materials. ### Claim 7 (depends on 1) The system according to claim 1, wherein the plurality of optical elements comprises a second optical element composed of polycrystalline material, and the second optical element is arranged in the area of a pupil plane of the objective. ### Claim 8 (depends on 1) The system according to claim 1, wherein the objective has a numerical aperture (NA) of more than 1.2. ### Claim 9 (depends on 1) The system according to claim 1, wherein the transmitting optical element is connected optically seamlessly to a further optical element. ### Claim 10 (depends on 9) The system according to claim 9, wherein a contact surface between the transmitting optical element and the further optical element is of spherical shape. ### Claim 11 (depends on 9) The system according to claim 9, wherein the transmitting optical element is connected to the further optical element by optical contacting, fusion bonding or low temperature bonding. ### Claim 12 (depends on 9) The system according to claim 9, wherein the further optical element is composed of the same material as the transmitting optical element. ### Claim 13 (depends on 9) The system according to claim 9, wherein the further optical element is composed of a different material than the transmitting optical element. ### Claim 14 (depends on 9) The objective according to claim 9, wherein the further optical element is composed of quartz glass. ### Claim 15 (depends on 9) The objective according to claim 9, wherein the further optical element is composed of calcium fluoride. ### Claim 16 (depends on 1) The system according to claim 1, wherein the objective is designed for an operating wavelength of less than 250 nm. ### Claim 17 (depends on 1) The system according to claim 1, wherein the immersion liquid is in direct contact with the transmitting optical element. ### Claim 18 (depends on 17) The system according to claim 17, wherein the immersion liquid comprises water. ### Claim 19 (depends on 1) The system according to claim 1, wherein the immersion liquid comprises water. ### Claim 20 An apparatus, comprising: an illumination system; a device to hold a movable mask; and an objective comprising a transmitting optical element composed of polycrystalline material, wherein the polycrystalline material has a refractive index of more than 1.7 for a wavelength of less than 200 nm, and the apparatus is a microlithography projection exposure apparatus. ### Claim 21 (depends on 20) The projection exposure apparatus of claim 20, further comprising an immersion liquid between the transmitting optical element and a light-sensitive substrate. ### Claim 22 (depends on 21) The projection exposure apparatus according to claim 21, wherein the transmitting optical element is provided with a coating. ### Claim 23 (depends on 21) The projection exposure apparatus according to claim 21, wherein the polycrystalline material is selected from the group consisting of polycrystalline MgAl2O4, polycrystalline MgO, and polycrystalline yttrium aluminum garnet Y3Al5O12. ### Claim 24 (depends on 21) The projection exposure apparatus according to claim 21, wherein the polycrystalline material is formed from crystallites with the chemical composition (M1)3(M2)5O12, where M1 is a metal which is selected from the group consisting of yttrium, lanthanum, gadolinium, terbium, erbium, scandium and lutetium, and M2 is a metal selected from the group consisting of aluminum, gallium, indium, and thallium. ### Claim 25 (depends on 21) The projection exposure apparatus according to claim 21, wherein the polycrystalline material is a mixed crystal with the formula MgO×m Al2O3, wherein m is a value between 0.9 and 4. ### Claim 26 (depends on 21) The projection exposure apparatus according to claim 21, wherein the polycrystalline material has a refractive index of more than 1.8 for a wavelength of less than 200 nm. ### Claim 27 (depends on 21) The projection exposure apparatus of claim 21, wherein the immersion liquid contacts the optical element. ### Claim 28 (depends on 20) The projection exposure apparatus according to claim 20, wherein the projection exposure apparatus is adapted to be operated at a wavelength of less than 250 nm. ### Claim 29 (depends on 20) The projection exposure apparatus according to claim 20, wherein the polycrystalline material is selected from the group consisting of polycrystalline MgAl2O4, polycrystalline MgO, and polycrystalline yttrium aluminum garnet Y3Al5O12. ### Claim 30 (depends on 20) The projection exposure apparatus according to claim 20, wherein the polycrystalline material is formed from crystallites with the chemical composition (M1)3(M2)5O12, where M1 is a metal which is selected from the group consisting of yttrium, lanthanum, gadolinium, terbium, erbium, scandium and lutetium, and M2 is a metal selected from the group consisting of aluminum, gallium, indium, and thallium. ### Claim 31 (depends on 20) The projection exposure apparatus according to claim 20, wherein the polycrystalline material is a mixed crystal with the formula MgO×m Al2O3, wherein m is a value between 0.9 and 4. ### Claim 32 (depends on 20) The projection exposure apparatus according to claim 20, wherein the transmitting optical element is provided with a coating. ### Claim 33 (depends on 20) The projection exposure apparatus according to claim 20, wherein the transmitting optical element comprises at least two sub-elements made of polycrystalline material. ### Claim 34 (depends on 20) The projection exposure apparatus according to claim 20, wherein the polycrystalline material has a refractive index of more than 1.8 for a wavelength of less than 200 nm. ### Claim 35 (depends on 20) The projection exposure apparatus according to claim 20, wherein the polycrystalline material has a refractive index of more than 1.9 for a wavelength of less than 200 nm.