Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C4/00—Compositions for glass with special properties
  • C03C4/0085—Compositions for glass with special properties for UV-transmitting glass
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B19/00—Other methods of shaping glass
  • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
  • C03B19/1415—Reactant delivery systems
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B19/00—Other methods of shaping glass
  • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
  • C03B19/1453—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B19/00—Other methods of shaping glass
  • C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
  • C03B19/1484—Means for supporting, rotating or translating the article being formed
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/06—Glass compositions containing silica with more than 90% silica by weight, e.g. quartz
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C3/00—Glass compositions
  • C03C3/04—Glass compositions containing silica
  • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2201/00—Type of glass produced
  • C03B2201/06—Doped silica-based glasses
  • C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
  • C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2201/00—Type of glass produced
  • C03B2201/06—Doped silica-based glasses
  • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
  • C03B2201/40—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
  • C03B2201/42—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn doped with titanium
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2207/00—Glass deposition burners
  • C03B2207/30—For glass precursor of non-standard type, e.g. solid SiH3F
  • C03B2207/32—Non-halide
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2207/00—Glass deposition burners
  • C03B2207/60—Relationship between burner and deposit, e.g. position
  • C03B2207/62—Distance
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
  • C03B2207/00—Glass deposition burners
  • C03B2207/70—Control measures
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2201/00—Glass compositions
  • C03C2201/06—Doped silica-based glasses
  • C03C2201/08—Doped silica-based glasses containing boron or halide
  • C03C2201/12—Doped silica-based glasses containing boron or halide containing fluorine
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2201/00—Glass compositions
  • C03C2201/06—Doped silica-based glasses
  • C03C2201/30—Doped silica-based glasses containing metals
  • C03C2201/40—Doped silica-based glasses containing metals containing transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn
  • C03C2201/42—Doped silica-based glasses containing metals containing transition metals other than rare earth metals, e.g. Zr, Nb, Ta or Zn containing titanium
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2203/00—Production processes
  • C03C2203/40—Gas-phase processes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P40/00—Technologies relating to the processing of minerals
  • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
  • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

• the invention relates generally to a method for forming an EUV(Extreme UltraViolet) lithography glass substrate. More specifically, the invention relates to a method for producing an extreme ultraviolet (EUV) lithography glass titania-doped fused silica substrate and an extreme ultraviolet (EUV) lithography glass titania- doped fused silica glass substrate having low water content.
• EUV extreme ultraviolet
• EUV extreme ultraviolet
• EUV lithography is emerging as one of the next- generation lithography techniques that will allow high-volume production of integrated circuits with sub-100-nm features.
• EUV lithography as currently contemplated involves producing electromagnetic radiation at around 13 nm.
• the EUV radiation may be produced, for example, using a 1064-nm neodymium-YAG laser which produces a xenon gas plasma or from a synchrotron source.
• a condenser collects the EUV radiation and projects it onto a mask containing a pattern to be replicated on a silicon wafer.
• the mask reflects the EUV radiation into an imaging system, which then projects an image onto a resist-coated silicon wafer.
• the pattern is later transferred to the silicon wafer by etching.
• the mask structure consists of a substrate ("mask blank"), a reflective multilayer stack formed on the mask blank, and an absorber formed on the multilayer stack.
• the multilayer stack includes alternating layers of Mo and Si or Mo and Be.
• the absorber defines the pattern to be replicated on the silicon wafer.
• the mask blank may be made of silicon or glass or other suitable material. It is important that the mask blank has a low thermal expansion so that it does not distort under exposure to the EUV radiation. Titania-doped fused silica (Si ⁇ 2 -TiO 2 ) is a preferred glass that can be made to have a very low thermal expansion, i.e. , lower than pure fused silica with the potential for a coefficient of thermal expansion that approximates zero. The coefficient of thermal expansion of the SiO 2 -TiO 2 glass can be controlled by adjusting the percent weight content of TiO 2 in the glass.
• Si ⁇ 2-TiO 2 glass Commercial processes for producing Si ⁇ 2-TiO 2 glass involve transporting a mixture of a silica precursor and a titania precursor to a reaction site, thermally decomposing the mixture of precursors (usually via flame hydrolysis) into SiO 2 -TiO 2 particles ("soot"), and depositing the soot on a support.
• the soot is captured in a cup of a refractory furnace at consolidation temperatures (typically 1200 to 1900°C) so as to allow the soot to immediately consolidate into a solid body ("boule").
• consolidation temperatures typically 1200 to 1900°C
• These high consolidation temperatures may result in compositional variations within the glass, which would result in the glass having non-uniform thermal expansion properties. Therefore, a production method which favors homogeneity in the SiO 2 -TiO 2 glass is desirable.
• SiO 2 -Ti ⁇ 2 glass For environmental reasons, commercial processes for producing SiO 2 -Ti ⁇ 2 glass use a chloride-free material such as octamethylcyclotetrasiloxane (OMCTS), a siloxane, as a silica precursor.
• OCTS octamethylcyclotetrasiloxane
• SiO 2 -TiO 2 glass containing more OH (often referred to as water) than can be tolerated by infrared transmission applications or deep-UV applications such as at 157 run.
• OH has some absorption at these wavelengths. Therefore, a production method which favors dehydration of the SiO 2 - iO 2 glass is also desirable.
• the invention relates to a method for producing a EUV lithography glass substrate.
• the method comprises synthesizing particles of silica and titania by delivering a mixture of a silica precursor and a titania precursor to a burner, growing a porous preform by successively depositing the particles on a deposition surface while rotating and translating the deposition surface relative to the burner, consolidating the porous preform into a dense glass.
• Figure 1 is a schematic of a system for producing SiO 2 -TiO 2 EUV lithography glass in accordance with an embodiment of the invention.
• Figure 2 is a top view of an EUV lithography mask blank.
• Figure 3 is a side view of the EUV lithography mask blank shown in Figure 2.
• the invention includes making thermally stable EUV lithography glass substrates such as optical mirror element and mask substrates.
• PCT patent publication WOO 108163 Al EUV SOFT X-RAY PROJECTION LITHOGRAPHIC METHOD SYSTEM AND LITHOGRAPHY ELEMENTS of CORNING INCORPORATED by Davis et al.
• Patent Application No. US0018798 US, Filed 20000710, Al Published 20010201 and WO0107967 Al
• EUV SOFT X-RAY PROJECTION LITHOGRAPHIC METHOD AND MASK DEVICES of CORNING INCORPORATED by Davis et al. Application No.
• Embodiments of the invention provide a method for producing EUV lithography SiO 2 -TiO 2 glass substrates with low variations in CTE within the substrate, preferably with the EUV lithography substrate having a very low variation in coefficient of thermal expansion (CTE) within the substrate, preferably a homogeneous CTE with a variation of 0 ⁇ 5 ppb/°C.
• the method involves transporting silica and titania precursors in vapor form to deposition burners. The precursors exit the deposition burners where they react to form fine SiO2-TiO2 particles ("soot").
• the soot collect on a deposition surface to form a porous preform.
• the method further includes consolidating the porous preform to give a dense EUV lithography SiO 2 -TiO 2 glass in a separate step. Consolidating the glass in a separate step eliminates the need to capture the soot at consolidation temperatures. This allows the soot to be deposited at lower temperatures (typically, 200°C to 500°C lower) than possible with the conventional boule process.
• Si ⁇ 2 -TiO 2 glass having low OH content can be produced by exposing the preform to a dehydrating agent, such as chlorine or fluorine, prior to consolidation. Chlorine and/or fluorine treatment would also remove impurities from the glass which could result in seeds.
• production of EUV lithography Si ⁇ 2 - ⁇ O2 glass utilizes a vapor-axial deposition (VAD) process with two delivery systems used to provide entrained vapors of titania precursor and silica precursor.
• the two separate vapor trains feed into a manifold where they are mixed together.
• the mixture is then carried through fume lines to deposition burners where it reacts to form soot.
• the soot is deposited on a bait which is rotated and moved axially within an enclosure.
• the porous preform formed by the soot is thermally consolidated into dense glass in a later separate step.
• An intermediate chlorine and/or fluorine treatment step may be used to remove impurities or adsorbed water from the glass.
• Relatively large and homogeneous SiO 2 -TiO2 EUV lithography glass substrates e.g., 6" x 6" x 0.25" substrates and larger, can be made using this process.
• FIG 2 is a schematic of a system, generally designated by the numeral 2, for use in practicing the present invention.
• the system 2 includes source 4 of a silica precursor 6.
• a silica precursor such as OMCTS (Si O (CH ) 8 ), halogen-based precursors such as silicon tetrachloride (SiCl 4 ), silane (SiH 4 ), and other silicon-containing compounds.
• halogen- free precursors are preferred because they are more environmentally friendly.
• Silane exists in vapor form at room temperature and does not need a vaporization step prior to mixing with the titania precursor.
• the silica precursor 6 is pumped into the source 4 at a predetermined rate.
• the source 4 which may be a vaporizer or evaporator tank or similar equipment, converts the silica precursor 6 into vapor form if the silica precursor 6 is not already in vapor form.
• the system 2 further includes a source 16 of the titania precursor 18, e.g., a titanium alkoxide such as titanium isopropoxide (Ti(OPri) ).
• the titania precursor 18 is pumped into the source 16 at a predetermined rate.
• the source 16 converts the titania precursor 18 into vapor form if the titania precursor 18 is not already in vapor form.
• a stream of inert gas 22, e.g., nitrogen, can be brought into contact with the vaporous titania precursor to prevent saturation of the vapors.
• An inert carrier gas 20 e.g., nitrogen, entrains the titania precursor 18 vapors and carries the vapors through a distribution system 24 to manifold 14, where they are mixed with the silica precursor 6 vapors.
• the mixture of vaporous precursors passes through heated fume lines 26 to deposition burners 28 positioned below a multi-chambered hood 32.
• the temperatures of the fume lines 26 are preferably controlled to prevent reaction prior to reaching the deposition burners 28.
• a bait 34 Prior to injecting the mixture into the deposition burners 28, a bait 34 is disposed in the center chamber 33 of the multi-chambered hood 32.
• the bait 34 is made of fused quartz.
• the bait 34 may also be made of other bait materials such as alumina or graphite.
• the bait 34 may be shaped like a rod, as shown in the drawing, or may have other desired shape.
• the bait 34 may be shaped like a ball or a plate.
• the upper end of the bait 34 is connected to a spindle 36, for example, by pin 35.
• the spindle 36 is in turn connected to a drive motor 38.
• the spindle 36 and the bait 34 rotate in unison and ascend within the chamber 33 at predetermined speeds.
• the speed at which the bait 34 ascends is critical to the temperature profile and shape of the porous preform 40 formed on the bait 34.
• a typical bait speed is 0.3 to 0.5 mm/min.
• Burner placement is fixed and bait speed is adjusted to maintain a constant burner-to-soot preform distance during deposition.
• two deposition burners 28 are shown, it should be clear that one or more than two deposition burners can be used. In general, the number of deposition burners will depend on the size of porous preform to be made.
• the deposition burners 28 are typically inclined at an angle with respect to the translation axis of the bait 34.
• Auxiliary heat burners 29 may also be provided to promote the thermal environment needed to form the SiO2-TiO2 particles. Improper placements of the deposition burners 28 and the auxiliary heat burners 29 could result in both excessively hot and cold regions on the preform.
• the mixture of vaporous precursors are injected into the deposition burners 28, as previously described.
• the vaporous precursors exit the deposition burners 28 where they react to form SiO2-TiO2 soot.
• the soot is formed by hydrolysis or thermal oxidation reaction of the precursors with a methane-oxygen flame. Alternatively, an oxyhydrogen flame could be used to form the soot.
• the soot is deposited on the lower end of the bait 34 to form a columnar porous preform 40.
• the lower end of the bait 34 on which the preform is formed is generally spherical in shape but could be planar or have other shape.
• the perform 40 grows as more soot is deposited and the bait 34 ascends.
• Spurious soot is generated at the time of deposition and is removed through the exhaust chambers 42.
• the chamber 33 in which the spindle 36 and bait 34 travel is provided with a stream of clean air 44 that is directed towards the emerging preform 40.
• This stream of air 44 directs the spurious soot outward and away from the preform 40 into the exhaust chambers 42 which carry it away. This is a critical step in the reduction of physical defects on the preform 40.
• the process is shut-down and the preform 40 is removed to an environmentally controlled storage area (not shown) where it will await consolidation process and, if needed, an intermediate chlorine treatment step.
• the consolidation of the porous preform 40 into a dense EUV lithography glass involves heating the preform to consolidation temperatures, typically 1200 to 1900°C with preferred values in a range from 1300 to 1700°C, in vacuum or at atmospheric pressure.
• Chlorine treatment involves heating the porous preform 40 in chlorine gas, usually in the presence of an inert gas such as helium. Chlorine treatment is generally best at temperatures just prior to consolidation of the preform 40, typically 900 to 1100°C. The high temperatures allow reaction of metal impurities to form volatile metal chlorides which are removed. Additionally, the chlorine removes OH from the glass structure. Dehydration of the porous preform prior to consolidation can also be accomplished by exposing the porous preform to a fluorinating gas, such as CF or SiF , usually in the presence of an inert gas such as helium.
• a fluorinating gas such as CF or SiF
• the low thermal expansion EUV lithography Si ⁇ 2-TiO 2 glass formed by the process above has TiO 2 content in a range from 2 to 12% by weight.
• the weight percent of TiO 2 in the glass can be adjusted by changing the amount of titanium precursor 18 delivered to the deposition burners 28.
• the consolidated preform made by the process above is formed into a finished mask blank for EUV lithography.
• Forming into a finished EUV lithography mask blank includes cutting the consolidated dense glass preform into a desired shape, polishing the surface of the preform, and cleaning the preform.
• Figures 2 and 3 show a EUV lithography mask blank 46 having a planar top surface 48 and a planar bottom surface 50.
• a consolidated preform produced by the process above can be cut as necessary to form the mask blank 46.
• a mask for EUV lithography can be formed by depositing alternating layers of reflective coating, i.e., Mo/Si or Mo/Be, on the glass substrate and depositing an absorber, e.g., Al or Si, on the multilayer reflective coating.
• Dry SiU 2 -Ti ⁇ 2 glass can be used in fabricating optical elements for infrared transmission in the 700 to 1600 nm wavelength range, and more specifically in the 1200 to 1600 nm wavelength range. Dry SiO 2 -Ti ⁇ 2 glass can also be used in fabricating optical elements for deep-UV applications such as at 157 nm.

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• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
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• Life Sciences & Earth Sciences (AREA)
• Manufacturing & Machinery (AREA)
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• Thermal Sciences (AREA)
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• Preparing Plates And Mask In Photomechanical Process (AREA)
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• 2001
  • 2001-04-27 US US09/844,947 patent/US8047023B2/en not_active Expired - Lifetime
• 2002
  • 2002-03-25 EP EP02723639.7A patent/EP1390309B1/en not_active Expired - Lifetime
  • 2002-03-25 JP JP2002585343A patent/JP2005507353A/ja active Pending
  • 2002-03-25 WO PCT/US2002/009461 patent/WO2002088036A1/en not_active Ceased
  • 2002-04-29 TW TW091109108A patent/TW568889B/zh not_active IP Right Cessation

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