WO2001000907A1 - Polishing of fluoride crystal optical lenses and preforms using cerium oxide for microlithography - Google Patents
Polishing of fluoride crystal optical lenses and preforms using cerium oxide for microlithography Download PDFInfo
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- WO2001000907A1 WO2001000907A1 PCT/US2000/015575 US0015575W WO0100907A1 WO 2001000907 A1 WO2001000907 A1 WO 2001000907A1 US 0015575 W US0015575 W US 0015575W WO 0100907 A1 WO0100907 A1 WO 0100907A1
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- polishing
- cerium
- polish
- fluoride crystal
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- 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
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70216—Mask projection systems
- G03F7/70233—Optical aspects of catoptric systems, i.e. comprising only reflective elements, e.g. extreme ultraviolet [EUV] projection systems
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/005—Control means for lapping machines or devices
- B24B37/0056—Control means for lapping machines or devices taking regard of the pH-value of lapping agents
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B13/00—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor
- B24B13/06—Machines or devices designed for grinding or polishing optical surfaces on lenses or surfaces of similar shape on other work; Accessories therefor grinding of lenses, the tool or work being controlled by information-carrying means, e.g. patterns, punched tapes, magnetic tapes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B37/00—Lapping machines or devices; Accessories
- B24B37/04—Lapping machines or devices; Accessories designed for working plane surfaces
- B24B37/042—Lapping machines or devices; Accessories designed for working plane surfaces operating processes therefor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
- B24B49/00—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation
- B24B49/16—Measuring or gauging equipment for controlling the feed movement of the grinding tool or work; Arrangements of indicating or measuring equipment, e.g. for indicating the start of the grinding operation taking regard of the load
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/12—Halides
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B33/00—After-treatment of single crystals or homogeneous polycrystalline material with defined structure
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- 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
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70008—Production of exposure light, i.e. light sources
- G03F7/70041—Production of exposure light, i.e. light sources by pulsed sources, e.g. multiplexing, pulse duration, interval control or intensity control
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- 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
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70216—Mask projection systems
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- 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
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70216—Mask projection systems
- G03F7/70241—Optical aspects of refractive lens systems, i.e. comprising only refractive elements
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- 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
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/70858—Environment aspects, e.g. pressure of beam-path gas, temperature
- G03F7/709—Vibration, e.g. vibration detection, compensation, suppression or isolation
Definitions
- the present invention relates generally to optical lithography, and particularly to optical microlithography crystals for use in optical photolithography systems utilizing vacuum ultraviolet light (VUV) wavelengths below 200 nm, preferably below 193 nm, preferably below 175nm, more preferably below 164 nm, such as VUV projection lithography systems utilizing wavelengths in the 157 nm region.
- VUV vacuum ultraviolet light
- Projection optical photolithography systems that utilize the vacuum ultraviolet wavelengths of light below 200 nm provide benefits in terms of achieving smaller feature dimensions. Such systems that utilize vacuum ultraviolet wavelengths in the 157 nm wavelength region have the potential of improving integrated circuits with smaller feature sizes.
- Current optical lithography systems used by the semiconductor industry in the manufacture of integrated circuits have progressed towards shorter wavelengths of light, such as the popular 248 nm wavelengths, but the commercial use and adoption of vacuum ultraviolet wavelengths below 200 nm, such as 193 and 157 nm has been hindered by the transmission nature of such vacuum ultraviolet wavelengths in these VUV excimer laser regions through optical materials - and the surfaces of the optical materials.
- Cerium polishing of fluorite optical lithogaphy fluoride crystal surfaces has been avoided by the prior art due to cerium oxide contamination concerns that any cerium molecules/atoms/ions incorporated into the optical lithography fluoride crystal surface by polishing and then exposed to the highly energetic high fluence levels produced by 157 nm and 193 nm excimer lasers and used in optical lithography systems will strongly absorb the VUV light with the VUV absorbing cerium then damaging and corrupting the fluoride crystal structure and producing further detrimental VUV absorptions.
- the present invention overcomes problems in the prior art and provides a polished finished optical lithography fluoride crystal surface that can be used to improve the lithographic manufacturing of integrated circuits with VUV wavelengths.
- the invention includes a method of making a below 200 nm vacuum ultraviolet optical microlithography lens element.
- the method includes providing a fluoride crystal, providing a cerium oxide polish, and polishing the fluoride crystal with said cerium oxide polish to provide an optical microlithography element.
- the invention includes a method of making a below 200 nm optical microlithography element preform.
- the method of making a below 200 nm optical microlithography element preform includes providing a fluoride crystal, providing a cerium polish, and polishing the fluoride crystal with the cerium polish to provide a microlithography element polished preform.
- the invention includes a method of making a below 170 nm optical microlithography preform.
- the method of making the below 170 nm optical microlithography preform includes providing a calcium fluoride crystal having a 157 nm internal transmission greater than 95%/cm and providing a cerium polish.
- the cerium polish includes cerium oxide particles in an acidic polishing environment.
- the method includes polishing the calcium fluoride crystal with the cerium polish to provide a VUV microlithography polished preform surface.
- the invention includes a method of making a 157 VUV optical element preform. The method includes providing a calcium fluoride crystal with a 157 nm internal transmission > 95%/cm.
- the method includes providing a cerium means for polishing the crystal into a 157 nm VUV optical element preform with a polished preform surface roughness less than 5 angstroms.
- the method includes polishing the calcium fluoride crystal with the cerium polishing means to a surface roughness less than five angstroms.
- the invention includes a method of making a below 200 nm optical microlithography element preform.
- the method of making a below 200 nm optical microlithography element preform includes providing a fluoride crystal, providing an aqueous polish, and polishing the fluoride crystal with the aqueous polish to provide a microlithography element polished preform.
- FIG. 1 is a side cross section view of an embodiment of the invention.
- FIG. 2 shows an embodiment of the invention.
- FIG. 3 shows an embodiment of the invention.
- FIG. 4 shows a method of the invention.
- FIGS. 6-9 illustrate a method of the invention.
- FIG. 10 shows a method of the invention.
- AFM atomic force photomicrograph
- FIG. 12 shows a method of the invention.
- FIG. 13 shows a method of the invention.
- the invention includes a method of making a below 200 nm VUV optical microlithography lens element.
- the optical microlithography lens element is a 193 nm lens element.
- the optical microlithography lens element is a 157 nm lens element.
- the method includes providing a fluoride crystal and a cerium oxide polish, and polishing the fluoride crystal with the cerium oxide polish to provide a VUV optical microlithography element with a surface roughness less than five angstroms, particularly surface roughness RMS (Root Mean Square Roughness) and Ra (Average Roughness) below five angstroms.
- the cerium oxide polish is an aqueous polish.
- FIG. 1 shows a below 200 nm VUV optical microlithography lens element 20 with a polished lens element surface 22.
- optical microlithography element 42 with finished polished optical surfaces 26 form the optical train of a below 200 nm VUV optical microlithography system, which preferably includes a below 200 nm VUV laser radiation source, a lithography illumination optics system, a lithography mask stage, a lithography projection optics system, and a wafer stage.
- FIG. 2 shows a 193 nm VUV optical microlithography system which utilizes 193 nm optical microlithography elements 42 to manipulate 193 nm optical microlithography radiation produced by a 193 nm ArF excimer laser to form microlithography patterns on a wafer in the wafer stage.
- FIG. 1 shows a 193 nm VUV optical microlithography system which utilizes 193 nm optical microlithography elements 42 to manipulate 193 nm optical microlithography radiation produced by a 193 nm ArF excimer laser to form microlithography patterns on a wafer in the wafer stage.
- FIG. 3 shows a 157 nm VUV optical microlithography system which utilizes 157 nm optical microlithography elements 42 to manipulate 157 nm optical microlithography radiation produced by a 157 nm fluorine excimer laser to form microlithography patterns.
- the method of making a VUV optical microlithography element includes providing a fluoride crystal, providing a cerium oxide polish, preferably an aqueous polish, and polishing the fluoride crystal with the polish to provide a VUV optical microlithography element with a surface roughness less than five angstroms.
- fluoride crystal 28 is polished with cerium oxide polish 30 which includes cerium oxide abrasive particles 32. Polishing fluoride crystal 28 with cerium oxide polish 30 efficiently provides a means for forming a VUV optical microlithography element with a surface roughness less than five angstroms.
- the cerium oxide polish has a pH in the range of 2 to 12, more preferably 3 to 7, and more preferably about 4 to 6, and most preferably about 5.
- the solubility of the cerium oxide in the polish solution is less than 1.0 ppm.
- providing fluoride crystal 28 comprises providing a calcium fluoride crystal.
- the provided calcium fluoride crystal preferably has a 157 nm internal transmission greater than 95%/cm and more preferably > 99%/cm.
- providing the calcium fluoride crystal includes providing a calcium fluoride crystal that consists essentially of Ca and F.
- the calcium fluoride crystal has a cerium impurity level of less than 0.5 ppm Ce by weight.
- the calcium fluoride crystal has an impurity level of less than 1 ppm Pb by weight, less than 2 ppm Na by weight, and less than 2 ppm K by weight.
- providing a fluoride crystal 28 includes providing a barium fluoride crystal.
- the provided barium fluoride crystal consists essentially of Ba and F.
- the method preferably includes exposing the VUV optical microlithography element to below 200 nm VUV optical lithography radiation.
- exposing the element comprises exposing the VUV optical microlithography element to 157 nm optical lithography radiation, such as produced by a fluorine excimer laser radiation source.
- exposing the element comprises exposing the VUV optical microlithography element to 193 nm optical lithography radiation, such as produced by a ArF excimer laser radiation source.
- polishing the fluoride crystal includes an additional polishing with a decontaminating colloidal silica polish, preferably an aqueous polish, after polishing the fluoride crystal with the cerium oxide polish.
- the fluoride crystal is first cerium polished with a hard polishing pad with a hardness H, and then cerium polished with a soft polishing pad with a hardness S wherein H > S, most preferably with the polishing pads being polyurethane polishing pads.
- a first cerium oxide polish with large size cerium oxide particles is used with the hard polishing pad, then a second cerium oxide polish with small size cerium oxide particles is used with the soft polishing pad with the small size particle size less than the size of the large size particles (small size ⁇ large size).
- polishing the fluoride crystal includes polishing the fluoride crystal with the cerium oxide polish to provide a microlithography element polished preform which has a preform surface roughness less than five angstroms and then forming the polished preform into the VUV optical microlithography element.
- forming the polished preform into the microlithography element comprises shaping the preform into a lens which operates on below 200 nm optical lithography light.
- the invention includes a method of making a below 200 nm
- VUV optical microlithography element preform preferably a 157 nm optical microlithography element preform.
- the method of making a below 200 nm optical microlithography element preform includes providing a fluoride crystal, providing a cerium polish, and polishing the fluoride crystal with the cerium polish to provide a VUV microlithography element polished preform with a surface roughness less than five angstroms.
- the cerium polish is an aqueous polish.
- providing a fluoride crystal includes providing a calcium fluoride crystal, most preferably which consists essentially of Ca and F.
- providing a fluoride crystal includes providing a barium fluoride crystal, most preferably which consists essentially of Ba and F.
- the invention includes providing fluoride crystal 28.
- Fluoride crystal 28 has unfinished top and bottom surfaces 29.
- the unfinished fluoride crystal surfaces have roughness greater than five angstroms, preferably greater than twenty angstroms, more preferably greater than fifty angstroms, most preferably greater than 100 angstroms. Even with such greater than 100 angstrom rough unfinished starting surfaces, the invention can achieve below 5 angstrom roughness surfaces with low processing times, preferably overall polishing times less than 2.5 hours.
- the invention includes providing a cerium polish 30 and polishing fluoride crystal 28.
- Polishing fluoride crystal 28 with the cerium polish provides a microlithography element polished preform 34 with polished preform surfaces 36.
- the cerium polish results in polished preform surfaces 36 which have surface roughness less than five angstroms.
- the polished surface roughness RMS (Root Mean Square Roughness) and Ra (Average Roughness) are polished to below 5 angstroms.
- polishing fluoride crystal 28 with aqueous cerium polish 30 includes cerium polishing the unfinished surfaces 29 into polished preform surfaces 36 with a surface finish which has a RMS less than two angstroms and a Ra less than two angstroms.
- the VUV microlithography element preform is provided by cerium polishing the fluoride crystal to a surface finish with roughness RMS ⁇ 5 angstroms and Ra ⁇ 5 angstroms, and more preferably RMS ⁇ 2 angstroms and Ra ⁇ 2 angstroms, most preferably with fluoride crystal 28 comprising a calcium fluoride crystal.
- the cerium polish 30 has a pH from 2-12, more preferably from 3 to 7, preferably from 4 to 6, and most preferably a pH of about 5 (5 ⁇ .5).
- Providing cerium polish 30 preferably includes providing cerium oxide abrasive particles 32 in polishing environment 31, preferably an acidic aqueous polishing environment.
- polishing includes polishing with a synthetic polymer polyurethane polishing pad 38.
- polishing includes polishing with a low polishing pad pressure less than 2 PSI, more preferably a polishing pressure in the range from about 1 to 1.5 PSI.
- polishing includes polishing for a total polishing time of less than five hours, more preferably less than 3 hours, and most preferably with an overall total polishing time less than 2.5 hours, such as about 135 minutes.
- cerium polishing crystal 28 includes polishing with a hard polishing pad 38 having a hardness H and then polishing with a soft polishing pad 38 having a hardness S wherein H > S.
- hard polishing pad 38 hardness H is greater than 25 shore D hardness, more preferably > 30, and hardness S is less than 25 shore D hardness.
- the hard polishing pad shore D hardness is about 50 (50 ⁇ 25, more preferably 50 ⁇ 20).
- cerium polishing includes polishing with a first cerium polish with large cerium abrasive particles having a particle size of about LPS, and then polishing with a second cerium polish with small cerium abrasive particles having a particle size of about LPS, and then polishing with a second cerium polish with small cerium abrasive particles having a particle size of about SPS wherein LPS > SPS.
- the method includes following the cerium polishing with a polishing of colloidal non-cerium abrasive particle silica polish.
- the colloidal silica polish has a pH>7, preferably with a pH in the range of about 10 to 12.
- the method of making the below 200 nm VUV optical microlithography element preform includes exposing the polished crystal below 5 angstrom finished surfaces to 157 nm laser radiation. Such exposing preferably includes measuring the crystalline optical properties, such as the 157 nm transmission.
- the invention further includes a method of making a below 170 nm VUV optical microlithography preform.
- the method of making the below 170 nm VUV optical microlithography preform includes providing a calcium fluoride crystal.
- the provided calcium fluoride crystal has a 157 nm internal transmission greater than 95%/cm.
- the method further includes providing a cerium polish.
- the cerium polish has a pH from 2-12, more preferably 3 to 7, and more preferably 4 to 6 and most preferably about 5.
- the cerium oxide solubility in the polishing environment solution is less than 1 ppm.
- the provided cerium polish includes a plurality of cerium oxide particles in an acidic polishing environment.
- the method includes polishing the calcium fluoride crystal with the cerium polish to provide a VUV microlithography polished preform. As shown in FIG. 6-7, the method includes providing calcium fluoride crystal
- Calcium fluoride crystal 44 preferably has a 157 nm internal transmission greater than 95%/cm, more preferably > 99%/cm. 157 nm internal transmitting calcium fluoride crystal 44 preferably consists essentially of Ca and F. Calcium fluoride crystal 44 preferably has a cerium impurity level of less than .5 ppm Ce by weight. Preferably calcium fluoride crystal 44 has an impurity level of less than 1 ppm Pb by weight, less than 2 ppm Na by weight, and less than 2 ppm K by weight.
- the method includes providing a cerium polish 30.
- cerium polish 30 includes cerium oxide particles 32.
- cerium oxide particles 32 are in an aqueous polishing environment 31.
- the provided cerium polish is acidic.
- the method includes polishing calcium fluoride crystal 44 with the cerium polish 30 to provide a calcium fluoride VUV microlithography polished preform 46 with polished preform surface 48. Polishing the unfinished surfaces of calcium fluoride crystal 44 with cerium polish 30 provides a below 170 nm, preferably a 157 nm VUV microlithography element polished preform surface with a surface roughness less than 5 angstroms, preferably ⁇ 2 angstroms.
- the method of making the below 170 nm microlithography preform includes decontaminating the polished preform surface which has been polished with the cerium polish, preferably with the cerium polish cerium oxide solubility less than 1 ppm in solution.
- Decontaminating the cerium polished preform surface preferably includes removing contaminant particles from the cerium polished preform surface, and more preferably removing any residual contaminant cerium particles left on the polished preform surface.
- decontaminating the cerium polished preform surface includes removing reaction products from the cerium polished preform surface, and more preferably removing any cerium polish reaction products from the polished preform surface.
- Decontaminating preferably includes finishing preform surface 48 with cerium-free non-reactive abrasives such as with cerium-free particles 50, preferably colloidal abrasive particles.
- finishing preform surface 48 preferably includes using decontaminating finishing colloid 52 to clean finish and decontaminate the cerium polished preform surface so that cerium related contaminants are removed and washed away.
- colloidal silicon dioxide (SiO 2 ) silica is used as the decontaminating colloid.
- Finishing the cerium polished preform surface 48 preferably includes using an aqueous >7pH colloidal silica solution preferably with a pH of about 10 to 12.
- a virgin clean unused finishing polyurethane soft polishing pad is used with an appropriate flow of the colloidal silica to clean the preform surface.
- a finishing polishing load pressure less than 2 PSI is used with the polyurethane pad and colloidal silica, with the finishing time in the range of about 15 ⁇ 10 minutes.
- An alternative decontaminating finishing colloid 52 is a colloidal alumina (aluminum oxide) (Al 2 O 3 ).
- a further alternative decontaminating colloid 52 is colloidal diamond.
- a further decontaminating colloid colloidal abrasive particle is colloidal zirconium dioxide (ZrO 2 ).
- a further decontaminating colloidal abrasive particle is titanium dioxide (TiO 2 ).
- An alternative decontaminating finishing with cerium-free particles includes finishing with a fixed abrasive pad 70.
- FIGS. 12 and 13 show decontaminating finishing with a fixed abrasive pad 70 which includes abrasive particles 72 fixed in solid binding material 74 such as resin or wax.
- a particle-free solvent fixed abrasive liquid 152 such as water, is used with fixed abrasive pad 70.
- Decontaminating finishing with a fixed abrasive pad includes finishing with a diamond containing pad, an aluminum oxide containing pad, a silicon dioxide containing pad, a zirconium dioxide containing pad, or a titanium dioxide containing pad.
- the decontaminating finishing step does not significantly degrade the surface quality of the polished preform surface, and preferably improves the surface quality, preferably with the cerium-free abrasive particles being non-reactive abrasives which do not chemically react with the fluoride crystal.
- the cerium-free abrasive decontaminating particles can be precipitated particles, flame hydrolyzed particles or metal oxide sintered and milled particles.
- the cerium-free abrasive decontaminating particles have a particle size less than 500 nm, and more preferably less than about 100 nm.
- Providing the decontaminated microlithography fluoride crystal ⁇ 5 angstrom surfaces preferably includes cleansing the polished surfaces while the polish surfaces are still wetted by the polish process.
- the cerium polish is cleansed from the surface after termination of a polishing segment before the cerium polish is allowed to dry on the surface.
- a preffered decontaminated and cleansed surface is achieved by cleansing in a segragated cleaning work station that is seperated from the polishing work stations.
- cleansing quickly follows termination of polishing to ensure the wet polished surface are cleansed of the polish before the surface are allowed to dry.
- Cleansing preferably includes washing with a mixture of deionized water and cleaning solution such as Micro-90 brand Concentrated Cleaning Solution for Critical Cleaning, Catalog #9031 from International Products Corp., PO Box 70, Burlington, NJ 08016-0070, wiping with a virgin cleanroom cleaning sponge, and rinsing with distilled water.
- Micro-90 brand Concentrated Cleaning Solution for Critical Cleaning includes water, glycine, ethanediylbis tetrasodium salt, benzenesulfonic acid, dimethy-ammonium salt, and nitrilotris(ethanol). Preferably all polishing is immediately followed with cleansing of the polished surface. In a particularly preferred embodiment the invention includes polishing with using a multitude of short polishing segments (preferably time length of about 15 minutes
- providing the cerium polish includes utilizing cerium polish 30 with a pH in the range of about 2 to 12, more preferably 3 to 7 pH, more preferably a pH from 4 to 6, and most preferably a pH of about 5 (5 ⁇ .5).
- the method includes using a cerium polish acidic polishing environment which includes a non- water liquid. The non- water liquid component of the polishing environment slows down the chemical activity of the aqueous polish by lowering the water content of the polish.
- a polishing environment such as about 50% water and 50% ethylene glycol provides for slowing of the cerium polish chemical reactivity by lowering its water content.
- polishing includes polishing with synthetic polyurethane polishing pads 38.
- polishing includes polishing with a first hard polishing pad having a hardness H and then polishing with a second soft polishing pad having a hardness S with H > S.
- the hard polishing pad of the invention has a hardness H > 25 shore D hardness and the soft pad has a hardness S ⁇ 25 shore D hardness.
- the first polishing pad has a shore D hardness > 30, and more preferably in the range of about 30 to 75.
- the methods of the invention provide means for generating ⁇ 5 angstrom surface on calcium fluoride using cerium oxide abrasives in conjunction with polyurethane polishing pads under low pressure and in slightly acidic environments. Resulting less than five angstroms high quality 157nm lithography surfaces have a total polishing time of less than 2.5 hours.
- the present invention provides polishing of calcium fluoride (CaF2) using a combination of cerium oxide abrasives and polyurethane pads. The process includes a first stage in which surface and subsurface damage remnant from lapping is removed using a hard pad, followed by a second stage in which a softer pad is used to improve the surface.
- Both steps incorporate cerium oxide abrasive in slightly acidic environments (pH ⁇ 5) and low pressures (-1-1.5 PSI), and result in a final surface quality of Ra and RMS ⁇ 2 angstroms.
- This invention preferably utilizes cerium oxide abrasives on a combination of hard and soft polyurethane pads at pH -5.0 to generate surface finishes between 1.5- 2.0 angstrom (Ra and RMS values). Further processing using high pH (-10) colloidal silica solutions further improve the surface finish to a Ra ⁇ 1.3 A. Overall polishing time is less than 2.5 hours.
- Ground and lapped calcium fluoride (CaF 2 ) was polished using high purity cerium oxide abrasives dispersed to pH ⁇ 5.0 on polyurethane pads.
- the first step was to use a cerium oxide (Product Name Opaline, from Rhodia Rare Earths, La Rochelle, France) with a relatively large particle size of 2.76 ⁇ m on a polyurethane pad with a Shore D hardness of 38 (Product Code MHC-14B, from Rodel Incorporated, Newark, DE 19713). Polishing was performed on a single-sided machine with load set at 1.2 PSI and wheel speed at 50 RPM. Surface analysis was performed every 15 minutes using a scanning white light interferometer, observing improvement in surface finish. Surface analysis was preceded by cleansing of the polished surface.
- the second polishing step incorporated a different abrasive and pad from the first.
- the cerium oxide abrasive was also dispersed at pH ⁇ 5.0, but had a lower particle size of 1.6 ⁇ m (Product Name Hastelite 919 from James H. Rhodes & Co. Division of Universal Photonics, Hicksville, NY 11801).
- the polishing pad was a soft, polyurethane polishing pad (Product Code 204, from Rodel Incorporated, Newark, DE 19713). Polishing time for the second step was limited to 30 total minutes.
- the third polishing stage consisted of using an unused pad identical to that used in the second polishing stage, with the abrasive being a colloidal silica dispersed at pH ⁇ 10 (Product Code A2095, from Cab- O-Sil Division of Cabot Corporation, Tuscola, IL 61953). Polishing time was 15 minutes under the same polishing conditions as for stages 1 and 2 (first and second polishing steps).
- Results for Surface analysis performed every 15 minutes using scanning white light interferometry are shown in Table 1.
- FIG. 11 is a AFM photomicrograph of a section of the finished calcium fluoride surface with the side dimension scales of the section in ⁇ m (micrometer).
- the invention provides a super polished surface suitable 157nm microlithography with the use of cerium oxide abrasives with polyurethane pads. The acidic nature of the cerium polish and the high pH of the colloidal silica abrasives are particularly preferred.
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020017016599A KR20020036789A (en) | 1999-06-25 | 2000-06-06 | Polishing of fluoride crystal optical lenses and preforms using cerium oxide for microlithography |
DE60038806T DE60038806D1 (en) | 1999-06-25 | 2000-06-06 | POLISHING OF OPTICAL LENSES AND FORMS OF FLUORIDE CRYSTALS USING CERIUM OXIDE FOR MICROLITHOGRAPHY |
JP2001506306A JP2003503223A (en) | 1999-06-25 | 2000-06-06 | Polishing of fluoride crystal optical lens and preform for microlithography using cerium oxide |
EP00941240A EP1216316B1 (en) | 1999-06-25 | 2000-06-06 | Polishing of fluoride crystal optical lenses and preforms using cerium oxide for microlithography |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14114099P | 1999-06-25 | 1999-06-25 | |
US60/141,140 | 1999-06-25 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2001000907A1 true WO2001000907A1 (en) | 2001-01-04 |
Family
ID=22494340
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2000/015575 WO2001000907A1 (en) | 1999-06-25 | 2000-06-06 | Polishing of fluoride crystal optical lenses and preforms using cerium oxide for microlithography |
Country Status (6)
Country | Link |
---|---|
US (1) | US6375551B1 (en) |
EP (1) | EP1216316B1 (en) |
JP (1) | JP2003503223A (en) |
KR (1) | KR20020036789A (en) |
DE (1) | DE60038806D1 (en) |
WO (1) | WO2001000907A1 (en) |
Cited By (4)
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---|---|---|---|---|
EP1338911A2 (en) * | 2002-02-22 | 2003-08-27 | Nikon Corporation | Device and methods for holding an optical element with reduced stress inside and outside an optical column |
WO2004015461A1 (en) * | 2002-08-07 | 2004-02-19 | Corning Incorporated | Scatter-free uv optical fluoride crystal elements for < 200 nm laser lithography and methods |
CN105269412A (en) * | 2015-09-17 | 2016-01-27 | 中国科学院光电技术研究所 | Combined technology method suitable for efficient processing of calcium fluoride convex cone mirror |
CN106826409A (en) * | 2017-02-09 | 2017-06-13 | 同济大学 | A kind of calcium fluoride mono crystal polishing method based on aluminium salt complex compound |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6595834B2 (en) * | 1999-06-25 | 2003-07-22 | Corning Incorporated | Method of making <200nm light transmitting optical fluoride crystals for transmitting less than 200nm light |
US6984334B2 (en) * | 2000-06-08 | 2006-01-10 | Canon Kabushiki Kaisha | Method of manufacturing optical element |
FR2822853B1 (en) | 2001-03-29 | 2003-06-27 | Corning Inc | PREPARATION OF (MONO) CRYSTALS |
RU2001111056A (en) * | 2001-04-16 | 2003-04-10 | Репкина Тать на Александровна | METHOD FOR GROWING CALCIUM FLUORIDE SINGLE CRYSTALS |
RU2001111055A (en) * | 2001-04-16 | 2003-04-10 | Репкина Тать на Александровна | MULTI-SECTION CONTAINER FOR GROWING CALCIUM FLUORIDE SINGLE CRYSTALS |
DE10124423A1 (en) * | 2001-05-18 | 2003-01-02 | Schott Glas | Growing oriented single crystals with reusable crystal seeds |
JP2004020710A (en) * | 2002-06-13 | 2004-01-22 | Canon Inc | Method for manufacturing optical element |
DE60304579T2 (en) * | 2003-10-23 | 2007-05-10 | Société Européenne de Systèmes Optiques S.E.S.O. | Process for final polishing |
US7014703B2 (en) * | 2003-12-30 | 2006-03-21 | Corning Incorporated | Method for annealing group IIA metal fluoride crystals |
US20050159088A1 (en) * | 2004-01-15 | 2005-07-21 | Ecolab Inc. | Method for polishing hard surfaces |
JP2006176631A (en) * | 2004-12-22 | 2006-07-06 | Topcon Corp | Polishing slurry for ionic bond material, method for selecting dispersing agent to be used therein, method for setting compounded concentration of selected dispersing agent and method for polishing with polishing slurry |
US9254544B2 (en) * | 2008-08-28 | 2016-02-09 | Corning Incorporated | Colloidal silica finishing of metal fluoride optical components |
RU2521129C1 (en) * | 2012-12-27 | 2014-06-27 | Виталий Алексеевич САВЕНКОВ | Method for machining of cylindrical sapphire parts, sapphire plunger pair and metering pump built there around |
TW201543137A (en) | 2014-04-02 | 2015-11-16 | Zygo Corp | Photo-masks for lithography |
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JPH1187808A (en) * | 1997-07-07 | 1999-03-30 | Nikon Corp | Manufacture of optical element for arf excimer laser |
US6099389A (en) * | 1998-10-05 | 2000-08-08 | The United States Of America As Represented By The United States Department Of Energy | Fabrication of an optical component |
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JP3765329B2 (en) * | 1996-06-14 | 2006-04-12 | 株式会社ニコン | Calcium fluoride crystal, method for producing the same, and projection exposure apparatus using the same |
KR100521897B1 (en) | 1996-09-30 | 2005-12-29 | 가부시키가이샤 니콘 | Optical device manufacturing method |
JPH10230445A (en) * | 1996-12-16 | 1998-09-02 | Nikon Corp | Small loss grinding method |
JPH10330120A (en) * | 1997-04-01 | 1998-12-15 | Nikon Corp | Production of quartz glass with improved resistance to excimer laser and quartz glass material |
US5978070A (en) | 1998-02-19 | 1999-11-02 | Nikon Corporation | Projection exposure apparatus |
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2000
- 2000-06-06 EP EP00941240A patent/EP1216316B1/en not_active Expired - Lifetime
- 2000-06-06 KR KR1020017016599A patent/KR20020036789A/en not_active Application Discontinuation
- 2000-06-06 DE DE60038806T patent/DE60038806D1/en not_active Expired - Fee Related
- 2000-06-06 WO PCT/US2000/015575 patent/WO2001000907A1/en not_active Application Discontinuation
- 2000-06-06 US US09/587,830 patent/US6375551B1/en not_active Expired - Fee Related
- 2000-06-06 JP JP2001506306A patent/JP2003503223A/en active Pending
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US5876268A (en) * | 1997-01-03 | 1999-03-02 | Minnesota Mining And Manufacturing Company | Method and article for the production of optical quality surfaces on glass |
JPH1187808A (en) * | 1997-07-07 | 1999-03-30 | Nikon Corp | Manufacture of optical element for arf excimer laser |
US6099389A (en) * | 1998-10-05 | 2000-08-08 | The United States Of America As Represented By The United States Department Of Energy | Fabrication of an optical component |
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1338911A2 (en) * | 2002-02-22 | 2003-08-27 | Nikon Corporation | Device and methods for holding an optical element with reduced stress inside and outside an optical column |
EP1338911A3 (en) * | 2002-02-22 | 2005-06-15 | Nikon Corporation | Device and methods for holding an optical element with reduced stress inside and outside an optical column |
WO2004015461A1 (en) * | 2002-08-07 | 2004-02-19 | Corning Incorporated | Scatter-free uv optical fluoride crystal elements for < 200 nm laser lithography and methods |
CN105269412A (en) * | 2015-09-17 | 2016-01-27 | 中国科学院光电技术研究所 | Combined technology method suitable for efficient processing of calcium fluoride convex cone mirror |
CN106826409A (en) * | 2017-02-09 | 2017-06-13 | 同济大学 | A kind of calcium fluoride mono crystal polishing method based on aluminium salt complex compound |
CN106826409B (en) * | 2017-02-09 | 2018-05-08 | 同济大学 | A kind of calcium fluoride mono crystal polishing method based on aluminium salt complex compound |
Also Published As
Publication number | Publication date |
---|---|
EP1216316A1 (en) | 2002-06-26 |
US6375551B1 (en) | 2002-04-23 |
KR20020036789A (en) | 2002-05-16 |
EP1216316B1 (en) | 2008-05-07 |
DE60038806D1 (en) | 2008-06-19 |
JP2003503223A (en) | 2003-01-28 |
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