# US 8,786,827 B2 · Method and apparatus for measurement of exit pupil transmittance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,827 B2 - Document ID: US8786827B2 - Status: Granted - Kind: B2 - Application number: 12/703,100 - Filed: 2010-02-09 - Published: 2011-01-13 - Granted: 2014-07-22 - Earliest claimed: 2004-04-14 - Assignees: Litel Instruments - Applicants: Adlai H. Smith; Robert O. Hunter, Jr. - Inventors: Adlai H. Smith; Robert O. Hunter, Jr. - Web page: https://patentgrep.com/patent/US8786827B2 ## CPC - G03F 7/70941: {Stray fields and charges, e.g. stray light, scattered light, flare, transmission loss} - G02B 27/0927: {Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat} - G02B 27/0944: {Diffractive optical elements, e.g. gratings, holograms (gratings per se G02B5/18; holograms used as optical elements per se G02B5/32)} - G03F 7/70091: {Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]} - G03F 7/70158: {Diffractive optical elements} - G03F 7/70566: {Polarisation control} - G03F 7/70591: {Testing optical components} - 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) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A method and apparatus for determining the state of the lens transmittance of an optical projection system are described. A lens or imaging objective transmission is determined as a function of exit pupil transverse direction cosine (nx,ny) at multiple field points thereby providing a more complete analysis and correction of a photolithographic exposure system. The entrance pupil of a projection imaging system is uniformly illuminated and the angular dependence of transmission through the imaging system as a function of exit pupil direction cosines is determined. The illumination source includes a light conditioner with an in-situ illumination structure (ISIS), which is an optical structure that can provide uniform illumination of the system's entrance pupil. ## Claims ### Claim 1 A light conditioner comprising: a reticle having a reticle top surface and a reticle bottom surface; a lens and means for mounting the lens to the reticle; and an aperture plate and means for mounting the aperture plate to the reticle, wherein the lens is mounted above the reticle top surface and substantially focuses on the aperture plate, the aperture plate being attached to the reticle top surface. ### Claim 2 (depends on 1) The light conditioner as defined in claim 1, wherein the lens is a ball lens. ### Claim 3 A light conditioner comprising: a reticle having a reticle top surface and a reticle bottom surface; a lens and means for mounting the lens to the reticle; and an aperture plate and means for mounting the aperture plate to the reticle, wherein the lens is mounted below the reticle bottom surface and substantially focuses on the aperture plate, the aperture plate being attached to the reticle bottom surface. ### Claim 4 (depends on 3) A light conditioner as defined in claim 3, wherein said lens is a ball lens. ### Claim 5 A method of determining a reticle side telecentricity of a projection imaging system, the method comprising: providing an illumination source with a substantially uniform illumination with an angular extent that is greater than an angular size of an entrance pupil of the projection imaging system; exposing a recording media with illumination from the illumination source that is emitted from an exit pupil of the projection imaging system; reconstructing a transmission function of the projection imaging system as a function of field position from the exposed recording media; determining a difference between a center of a reference frame and a center of the exposed exit pupil for each of a plurality of field points in the exit pupil; and calculating individual components of reticle side telecentricity. ### Claim 6 (depends on 5) A method as defined in claim 5, further comprising fitting the components to a polynomial function. ### Claim 7 (depends on 5) A method as defined in claim 5, wherein the projection imaging system comprises a stepper, a scanner, a scanner configured for immersion lithography, or a stepper configured for immersion lithography. ### Claim 8 (depends on 5) A method as defined in claim 5, wherein the recording media comprises a photoresist, an electronic device, or a CCD structure. ### Claim 9 (depends on 5) A method as defined in claim 5, wherein exposing comprises multiple sub-exposures. ### Claim 10 A light conditioner for a projection imaging system, the light conditioner comprising: an optical input; an optical output, wherein the light conditioner receives light at the optical input from a light source and outputs a substantially uniform illumination light with an angular extent that is greater than an angular size of an entrance pupil of the projection imaging system; a reticle having a reticle top surface and a reticle bottom surface; a lens and means for mounting the lens to the reticle; and an aperture plate and means for mounting the aperture plate to the reticle, wherein the lens is mounted above the reticle top surface and substantially focuses on the aperture plate, the aperture plate being attached to the reticle top surface. ### Claim 11 (depends on 10) The light conditioner as defined in claim 10, wherein the lens is a ball lens. ### Claim 12 A light conditioner for a projection imaging system, the light conditioner comprising: an optical input; an optical output, wherein the light conditioner receives light at the optical input from a light source and outputs a substantially uniform illumination light with an angular extent that is greater than an angular size of an entrance pupil of the projection imaging system; a reticle having a reticle top surface and a reticle bottom surface; a lens and means for mounting the lens to the reticle; and an aperture plate and means for mounting the aperture plate to the reticle, wherein the lens is mounted below the reticle bottom surface and substantially focuses on the aperture plate, the aperture plate being attached to the reticle bottom surface. ### Claim 13 (depends on 12) The light conditioner of claim 12, wherein said lens is a ball lens.