# US 5,705,298 A · Holographic method for generating three dimensional conformal photo lithographic masks > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,298 A - Document ID: US5705298A - Status: Granted - Kind: A - Application number: 08/622,797 - Filed: 1996-03-27 - Granted: 1998-01-06 - Earliest claimed: 1994-12-23 - Assignees: Lucent Technologies Inc. - Inventors: George Knoedl, Jr. - Web page: https://patentgrep.com/patent/US5705298A ## CPC - G03H 1/16: using Fourier transform ({G03H1/10}, G03H1/12, G03H1/14 take precedence; analogue computers G06G, e.g. G06G7/19) - G03F 1/50: Mask blanks not covered by G03F1/20 - G03F1/34; Preparation thereof - G03H 1/00: Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto - G03H 1/20: Copying holograms by holographic {, i.e. optical} means - G03H 1/22: Processes or apparatus for obtaining an optical image from holograms (G03H1/26 - G03H1/34 take precedence) - H05K 3/0002: {for manufacturing artworks for printed circuits} - G03F 7/001: {Phase modulating patterns, e.g. refractive index patterns} - H05K 1/0284: {Details of three-dimensional rigid printed circuit boards (H05K1/119 takes precedence; shaping of the substrate H05K3/0014)} - H05K 2203/056: Using an artwork, i.e. a photomask for exposing photosensitive layers - G03H: HOLOGRAPHIC PROCESSES OR APPARATUS (holograms, e.g. point holograms, used as ordinary optical elements G02B5/32; producing stereoscopic or other three-dimensional effects G02B30/00; diffraction-grating systems G02B27/44; systems using moiré fringes G02B27/60; optical logic elements G02F3/00; stereo-photography G03B35/00; photosensitive materials or processes for photographic purposes G03C; {stereo-photographic or similar processes G03C9/00}; apparatus for processing exposed photographic materials G03D; analogue computers performing mathematical operations with the aid of optical elements G06E3/00; authentication by radiation, of concealed information carried by holograms or diffraction gratings G06K19/16; holographic storage G11B7/0065, G11C13/04; {stereoscopic or other three dimensional effects in television systems H04N13/00}) - 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) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract A three-dimensional photo mask is formed from a substrate having a first side and a three-dimensional side. A holograph is provided on the first side of the substrate. The three-dimensional side of the substrate has a photosensitive resist material provided thereon. The holograph includes information that defines features to be imaged onto the photosensitive resist material. A method and a system are disclosed for producing the three-dimensional mask. ## Claims ### Claim 1 A method of forming a mask, comprising the steps of: providing a transparent substrate having a first, planar side and an opposing, three-dimensional side, the three-dimensional side conforming to a shape of a workpiece; providing a hologram at the planar side of said substrate, said hologram is a Fourier or Fresnell transform of a desired three-dimensional lithographic pattern; providing a photosensitive masking material on the three-dimensional side of the substrate; placing the substrate having the photosensitive masking material thereon in an index matching liquid; irradiating light through the first side of the substrate in a pattern according to said hologram to expose the photosensitive masking material to the desired three-dimensional lithographic pattern, the index matched liquid mitigating internal reflections within the substrate; and removing undesired portions of the photosensitive masking material from the three-dimensional side of the substrate to form said mask having said lithographic pattern. ### Claim 2 (depends on 1) The method of claim 1, wherein said step of providing a hologram at the planar side of said substrate comprises providing said hologram directly on said planar side. ### Claim 3 (depends on 1) The method of claim 1, wherein said step of providing a hologram at the planar side of said substrate comprises providing directly on said planar side, a layer of material containing said hologram. ### Claim 4 (depends on 1) The method of claim 1, wherein said step of providing a hologram comprises providing a mating planar plate bearing said hologram in direct proximity with said planar side. ### Claim 5 (depends on 1) The method of claim 1, further comprising providing a container having optically black walls, said index matching liquid being contained within said container. ### Claim 6 (depends on 1) The method of claim 1, wherein said index matching liquid contains a light absorbing material. ### Claim 7 A method of forming a mask, comprising the steps of: providing a transparent substrate having a planar side and an opposing three-dimensional side, the three-dimensional side conforming to a shape of a workpiece; providing a hologram at the planar side of said substrate, said hologram is a Fourier or Fresnell transform of a desired three-dimensional lithographic pattern; providing a photosensitive masking material on the three-dimensional side of the substrate; irradiating light through the planar side of the substrate in a pattern according to said hologram to expose the photosensitive masking material to the desired three-dimensional lithographic pattern; and removing undesired portions of the photosensitive masking material from the three-dimensional side of the substrate to form said mask having said lithographic pattern. ### Claim 8 (depends on 7) The method of claim 7, wherein said step of providing a hologram at the planar side of said substrate comprises providing said hologram on said planar side. ### Claim 9 (depends on 7) The method of claim 7, wherein said step of providing a hologram at the planar side of said substrate comprises providing directly on said planar side, a layer of material containing said hologram. ### Claim 10 (depends on 7) The method of claim 7, wherein said step of providing a hologram comprises providing a mating planar plate bearing said hologram in direct proximity with said planar side.