# US 8,541,752 B2 · Apparatus and method for the locally resolved measurement of a radiation distribution produced using a lithography mask > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,541,752 B2 - Document ID: US8541752B2 - Status: Granted - Kind: B2 - Application number: 13/719,021 - Filed: 2012-12-18 - Published: 2013-05-02 - Granted: 2013-09-24 - Earliest claimed: 2011-06-15 - Assignees: Carl Zeiss SMT GmbH - Applicants: Carl Zeiss SMT GmbH - Inventors: Rolf Freimann - Web page: https://patentgrep.com/patent/US8541752B2 ## CPC - G01N 21/9515: {Objects of complex shape, e.g. examined with use of a surface follower device (measuring contours and curvatures G01B11/24)} - G01T 1/16: Measuring radiation intensity (G01T1/29 takes precedence {; self-powered detectors G01T3/006; using an ionisation chamber filled with a liquid or solid, e.g. frozen liquid, dielectric G01T3/008}) - G01T 1/2006: {using a combination of a scintillator and photodetector which measures the means radiation intensity} - G03F 7/70591: {Testing optical components} - G03F 7/70666: {Aerial image, i.e. measuring the image of the patterned exposure light at the image plane of the projection system} - G03F 7/7085: {Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00) - 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 method for locally resolved measurement of a radiation distribution (24) produced using a lithography mask (16) comprises providing a radiation converter (31, 131) having an at least two-dimensional arrangement of converter elements (32, 132) which can respectively be put in an active and a passive state, and are configured to convert incoming radiation in respect of its wavelength in the active state. The method further includes: manipulating the radiation converter (31, 131) several times such that respectively only a fraction of the converter elements (32, 132) adopts the active state, irradiating the radiation converter (31, 131) with the radiation distribution (24) after every manipulation of the radiation converter (31, 131) so that the active converter elements (32, 132) emit wavelength-converted measuring radiation (34), recording respective places of origin (54) of the measuring radiation at every irradiation with the radiation distribution (24). ## Claims ### Claim 1 A method for the locally resolved measurement of a radiation distribution produced using a lithography mask comprising: providing a radiation converter having an at least two-dimensional arrangement of converter elements which have alternatively an active and a passive state, and are configured to convert incoming radiation with respect to its wavelength in the active state, manipulating the radiation converter plural times such that respectively only a fraction of the converter elements adopts the active state, irradiating the radiation converter with the radiation distribution after every said manipulation of the radiation converter thereby causing the active converter elements to emit wavelength-converted measuring radiation, and recording respective places of origin of the measuring radiation at every irradiation with the radiation distribution, and determining the radiation distribution produced by the lithography mask from the places of origin recorded with said respective irradiations. ### Claim 2 (depends on 1) The method according to claim 1, wherein the radiation distribution is produced by imaging the lithography mask with a projection exposure tool for microlithography. ### Claim 3 (depends on 1) The method according to claim 1, wherein the radiation distribution is produced by imaging the lithography mask with a mask inspection device. ### Claim 4 (depends on 1) The method according to claim 1, further comprising placing the converter elements in the passive state after said irradiation with the radiation distribution. ### Claim 5 (depends on 1) The method according to claim 1, wherein the converter elements are photoactivatable, and the radiation converter is manipulated by irradiating an activation radiation of such an intensity that only a fraction of the converter elements adopts the active state. ### Claim 6 (depends on 5) The method according to claim 5, further comprising interrupting said irradiation of the radiation distribution in order to irradiate the activation radiation onto the radiation converter. ### Claim 7 (depends on 1) The method according to claim 1, wherein the converter elements are configured such that directly after emitting the wavelength-converted measuring radiation the converter elements pass temporarily into the passive state in which the converter elements do not convert incoming radiation with respect to their wavelength, said manipulation of the radiation converter is implemented by the radiation converter initially being irradiated with radiation of such an intensity that substantially all of the converter elements are stimulated to emit the wavelength-converted measuring radiation, and are thereby temporarily put in the passive state, and the radiation distribution is irradiated onto the radiation converter at a time when only a fraction of the converter elements has returned to the active state. ### Claim 8 (depends on 1) The method according to claim 1, wherein the radiation converter further comprises scintillator elements which upon irradiation with exposure radiation produced by the projection exposure tool emit intermediate radiation with an intermediate wavelength, and the active converter elements convert the intermediate radiation into the measuring radiation. ### Claim 9 (depends on 1) The method according to claim 1, wherein the converter elements are formed by fluorescent elements. ### Claim 10 (depends on 1) The method according to claim 1, wherein the wavelength of the determined radiation distribution is within the extreme-ultraviolet wavelength range. ### Claim 11 (depends on 1) The method according to claim 1, wherein the wavelength of the determined radiation distribution is within the ultraviolet wavelength range. ### Claim 12 (depends on 1) The method according to claim 1, wherein in order to record the respective places of origin of the measuring radiation the places of origin are imaged onto a detector with a microscope objective, and the positions of the images of the places of origin on the detector are determined with an accuracy which is at least one order of magnitude below an extension of the images caused by diffraction. ### Claim 13 (depends on 1) The method according to claim 1, wherein in order to determine the respective places of origin of the measuring radiation the places of origin are imaged onto a detector with an astigmatic microscope objective, and from the shape of the images on the detector an axial position coordinate of the place of origin in relation to the propagation direction of the radiation distribution is determined. ### Claim 14 (depends on 1) The method according to claim 1, wherein the radiation converter comprises a container which contains the converter elements in a liquid solution. ### Claim 15 (depends on 14) The method according to claim 14, wherein the container is permeable to the radiation distribution from one side and permeable to the wavelength-converted radiation from another side. ### Claim 16 (depends on 1) The method according to claim 1, wherein the converter elements are arranged at least two-dimensionally substantially uniformly distributed within the radiation converter. ### Claim 17 (depends on 1) The method according to claim 1, wherein the radiation converter has a membrane on which the converter elements are arranged evenly distributed. ### Claim 18 (depends on 1) The method according to claim 1, wherein the radiation converter is introduced into the image plane of the projection exposure tool for irradiation with the radiation distribution. ### Claim 19 A projection exposure tool for microlithography, comprising: a radiation converter having an at least two-dimensional arrangement of converter elements which have alternatively an active state and a passive state, and are configured to convert exposure radiation of the projection exposure tool into a wavelength-converted measuring radiation only in the active state, an image detection device configured to detect a place of origin of the measuring radiation, and a further component configured to manipulate the radiation converter such that only a fraction of the converter elements adopts the active state at any given time. ### Claim 20 A mask inspection device for inspecting a lithography mask, comprising: imaging optics arranged to image mask structures into an image plane using inspection radiation, a radiation converter disposed in the image plane having an at least two-dimensional arrangement of converter elements which have alternatively an active state and a passive state, and are configured to convert inspection radiation of the mask inspection device with respect to its wavelength only in the active state, an image detection device configured to detect a place of origin of the wavelength-converted radiation, and a further component configured to manipulate the radiation converter such that only a fraction of the converter elements adopts the active state at any given time. ### Claim 21 (depends on 20) The mask inspection device according to claim 20, wherein the imaging optics have a numerical aperture of at least 0.8 on the image side.