WO2022004754A1 - 窒化ケイ素焼結体の連続製造方法 - Google Patents

窒化ケイ素焼結体の連続製造方法 Download PDF

Info

Publication number
WO2022004754A1
WO2022004754A1 PCT/JP2021/024642 JP2021024642W WO2022004754A1 WO 2022004754 A1 WO2022004754 A1 WO 2022004754A1 JP 2021024642 W JP2021024642 W JP 2021024642W WO 2022004754 A1 WO2022004754 A1 WO 2022004754A1
Authority
WO
WIPO (PCT)
Prior art keywords
silicon nitride
firing
jig
container
sintered body
Prior art date
Application number
PCT/JP2021/024642
Other languages
English (en)
French (fr)
Inventor
大 草野
Original Assignee
株式会社トクヤマ
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 株式会社トクヤマ filed Critical 株式会社トクヤマ
Priority to KR1020227041851A priority Critical patent/KR20230031202A/ko
Priority to JP2022534063A priority patent/JPWO2022004754A1/ja
Priority to CN202180043686.0A priority patent/CN115715278A/zh
Priority to US18/011,865 priority patent/US20230357087A1/en
Priority to EP21833521.4A priority patent/EP4174425A1/en
Publication of WO2022004754A1 publication Critical patent/WO2022004754A1/ja

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/584—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
    • C04B35/593—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride obtained by pressure sintering
    • C04B35/5935—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride obtained by pressure sintering obtained by gas pressure sintering
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/584—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/584—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride
    • C04B35/593—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on silicon nitride obtained by pressure sintering
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/638—Removal thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/64—Burning or sintering processes
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B37/00—Joining burned ceramic articles with other burned ceramic articles or other articles by heating
    • C04B37/001—Joining burned ceramic articles with other burned ceramic articles or other articles by heating directly with other burned ceramic articles
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/04—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity adapted for treating the charge in vacuum or special atmosphere
    • F27B9/045—Furnaces with controlled atmosphere
    • F27B9/047—Furnaces with controlled atmosphere the atmosphere consisting of protective gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B9/00—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity
    • F27B9/14—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment
    • F27B9/20—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace
    • F27B9/26—Furnaces through which the charge is moved mechanically, e.g. of tunnel type; Similar furnaces in which the charge moves by gravity characterised by the path of the charge during treatment; characterised by the means by which the charge is moved during treatment the charge moving in a substantially straight path tunnel furnace on or in trucks, sleds, or containers
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3206—Magnesium oxides or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
    • C04B2235/3225—Yttrium oxide or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
    • C04B2235/3229—Cerium oxides or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/38—Non-oxide ceramic constituents or additives
    • C04B2235/3852—Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
    • C04B2235/3856—Carbonitrides, e.g. titanium carbonitride, zirconium carbonitride
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/38—Non-oxide ceramic constituents or additives
    • C04B2235/3852—Nitrides, e.g. oxynitrides, carbonitrides, oxycarbonitrides, lithium nitride, magnesium nitride
    • C04B2235/3873—Silicon nitrides, e.g. silicon carbonitride, silicon oxynitride
    • C04B2235/3882—Beta silicon nitrides
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5409—Particle size related information expressed by specific surface values
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5436—Particle size related information expressed by the size of the particles or aggregates thereof micrometer sized, i.e. from 1 to 100 micron
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5463—Particle size distributions
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
    • C04B2235/6562—Heating rate
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
    • C04B2235/6565—Cooling rate
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
    • C04B2235/6567—Treatment time
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/658—Atmosphere during thermal treatment
    • C04B2235/6581—Total pressure below 1 atmosphere, e.g. vacuum
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/72—Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/72—Products characterised by the absence or the low content of specific components, e.g. alkali metal free alumina ceramics
    • C04B2235/723—Oxygen content
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/77—Density
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9607—Thermal properties, e.g. thermal expansion coefficient
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/963—Surface properties, e.g. surface roughness
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2237/00—Aspects relating to ceramic laminates or to joining of ceramic articles with other articles by heating
    • C04B2237/30—Composition of layers of ceramic laminates or of ceramic or metallic articles to be joined by heating, e.g. Si substrates
    • C04B2237/32—Ceramic
    • C04B2237/36—Non-oxidic
    • C04B2237/368—Silicon nitride

Definitions

  • the present invention relates to a method for continuously producing a silicon nitride sintered body, for example, a silicon nitride sintered substrate using ⁇ -type silicon nitride powder.
  • the silicon nitride sintered body obtained by adding various sintering aids to silicon nitride powder and sintering at high temperature is light, has strong mechanical strength, has high chemical resistance, and is electric. It has features such as high insulation, and is used as a wear-resistant member such as a ball bearing and a member for a high-temperature structure.
  • the silicon nitride sintered substrate should be used as a thin and strong heat dissipation substrate material. It has become.
  • Non-Patent Document 1 ⁇ -type silicon nitride powder is dissolved in a sintering aid during the sintering process and reprecipitated as ⁇ -type, resulting in dense sintering with high thermal conductivity. It is widely used today because it gives you a body.
  • Non-Patent Document 2 when manufacturing ⁇ -type silicon nitride powder, the manufacturing process tends to be complicated. For example, in the direct nitriding method, it is necessary to nitrid at a low temperature for a long time so that ⁇ type is not generated, so that the manufacturing cost is high (Non-Patent Document 2).
  • Patent Document 1 describes inventions relating to high thermal conductivity silicon nitride ceramics and a method for producing the same.
  • ⁇ -type silicon nitride powder having an average particle size of 0.5 ⁇ m, itterbium oxide and magnesium nitride silicon nitride are described. It has been shown that a silicon nitride sintered body is obtained by sintering a molded body (a body to be fired) containing a sintering aid made of powder at 1900 ° C. for 2 to 24 hours in pressurized nitrogen at 10 atm. ing.
  • the sintered body of ⁇ -type silicon nitride powder is produced in pressurized nitrogen at 10 atm.
  • firing under pressure makes it easier to suppress the decomposition of the raw material silicon nitride, which makes it possible to fire at a high temperature of over 1800 ° C.
  • the amount of impurity oxygen solidly dissolved inside the silicon nitride particles which is one of the factors that tend to densify the generated sintered body and lower the thermal conductivity, is determined. It is known that it can be reduced and it is easy to obtain a sintered body having high thermal conductivity.
  • firing under pressure it is necessary to use a pressure-resistant container at the time of manufacture.
  • the manufacturing method has equipment restrictions, and can only be performed by a batch method, and there is a problem that the manufacturing cost increases due to the need to repeatedly raise and cool the temperature for each batch.
  • the thermal conductivity under the condition of normal pressure (atmospheric pressure) or substantially normal pressure (pressure near atmospheric pressure) using ⁇ -type silicon nitride powder and not requiring the use of a pressure-resistant container No description or suggestion has been made as to how to obtain a high-quality sintered body.
  • the present invention has been made in view of the above-mentioned conventional problems, and by adopting a condition that a silicon nitride powder having a high ⁇ conversion rate is used as a raw material and the silicon nitride powder is sintered at normal pressure or substantially normal pressure. It is an object of the present invention to provide a method capable of producing a silicon nitride sintered body with high productivity by making it possible to use a continuous firing furnace having a structure in which the sintering raw material is sequentially supplied to and taken out from the firing furnace.
  • the present inventors have conducted extensive research to achieve the above object. As a result, a so-called ⁇ -type silicon nitride powder having a high ⁇ -formation rate is used, and the silicon nitride powder having a specific surface area in a specific range and a sintering aid are contained, and the total content of aluminum elements is specified.
  • a body to be fired in the range it can be fired under normal pressure or a pressure close to normal pressure, which enables the continuous firing furnace to be used and has high quality silicon nitride firing.
  • a silicon nitride powder having a ⁇ conversion rate of 80% or more and a specific surface area of 7 to 20 m 2 / g and a sintering aid are contained, and the total content of aluminum elements is 800 ppm or less.
  • a firing jig containing the adjusted fired body is placed on the outer periphery of the body of the firing container, which is a closed-type firing container having an opening / closing door for supplying the firing jig and an opening / closing door for discharging at the ends.
  • a series of silicon nitride sintered bodies characterized in that silicon nitride is sintered by heating to a temperature of 1200 to 1800 ° C. under an inert gas atmosphere and a pressure of 0 MPa ⁇ G or more and less than 0.1 MPa ⁇ G.
  • a manufacturing method is provided.
  • the molding composition for forming the object to be fired is composed of an aqueous system containing silicon nitride powder, a sintering aid, and water to prepare a molding composition using an organic solvent. Compared to the above, it is preferable because problems such as ignition and explosion in the continuous firing furnace can be solved.
  • the fired body is in the shape of a plate, and a plurality of sheets are stacked and housed in a firing jig to supply and discharge to a continuous firing furnace.
  • the present invention has a firing jig containing a silicon nitride powder and a calcined body containing a sintering aid, and an opening / closing door for supplying and an opening / closing door for discharging the firing jig at its ends.
  • a continuous firing furnace for sintering silicon nitride is used, which comprises a gas supply mechanism for supplying.
  • the present invention it is possible to continuously produce a silicon nitride sintered body having excellent quality with good productivity while using a silicon nitride powder having a high ⁇ -formation rate.
  • the schematic diagram which shows one aspect of the continuous firing furnace used for performing the continuous firing of this invention.
  • the chart which shows an example of the temperature profile in the continuous firing furnace of this invention.
  • the method for producing a silicon nitride sintered body of the present invention contains silicon nitride powder having a ⁇ conversion rate of 80% or more and a specific surface area of 7 to 20 m 2 / g, and a sintering aid, and is made of aluminum.
  • a closed firing container which has a firing jig containing a fired body whose total element content is adjusted to 800 ppm or less, at the opening / closing door for supply, the opening / closing door for discharging, and the end of the firing jig.
  • a heating mechanism provided on the outer periphery of the body of the firing container, a transport mechanism for supplying and discharging the firing jig into the firing container, and a gas supply mechanism for supplying an inert gas into the firing container. It is supplied to a continuous firing furnace provided, and the pressure is 0 MPa ⁇ G or more and less than 0.1 MPa ⁇ G under an inert gas atmosphere (hereinafter, it may be referred to as "normal pressure" including the range of such fine pressurization).
  • normal pressure including the range of such fine pressurization
  • the body to be fired is a molded body containing the specific silicon nitride powder and the sintering aid described below, and as described later, the molded body and the organic binder obtained by molding the above composition without using an organic binder. It contains a degreased body obtained by molding using the above and removing the organic binder from the obtained molded body by degreasing.
  • the ⁇ conversion rate of the silicon nitride powder contained in the calcined body is 80% or more. Since the silicon nitride powder having a ⁇ conversion rate of 80% or more can be obtained without setting strict production conditions, it can be produced at a relatively low cost. Therefore, by using the silicon nitride powder having a high ⁇ -formation rate, it is possible to suppress the overall production cost of the silicon nitride sintered body. Further, by setting the ⁇ conversion rate high, there is an advantage that the amount of oxygen taken in when the ⁇ -type silicon nitride particles undergo transformation into the ⁇ -type silicon nitride particles during firing can be further suppressed.
  • the ⁇ conversion rate of the silicon nitride powder is preferably 85% or more, more preferably 90% or more.
  • the ⁇ conversion rate of the silicon nitride powder is the ratio of the peak intensity of the ⁇ phase to the total of the ⁇ phase and the ⁇ phase in the silicon nitride powder [100 ⁇ (peak intensity of the ⁇ phase) / (peak intensity of the ⁇ phase + ⁇ phase). Peak intensity)], which is determined by powder X-ray diffraction (XRD) measurement using CuK ⁇ rays. More specifically, C.I. P. Gazzara and D. R. Messier: Am. Ceram. Soc. Bull. , 56 (1977), 777-780, by calculating the weight ratio of the ⁇ phase and the ⁇ phase of the silicon nitride powder.
  • the amount of solid solution oxygen dissolved in the silicon nitride powder is not particularly limited, but is preferably 0.2% by mass or less in order to obtain a silicon nitride sintered body having high thermal conductivity.
  • the amount of solid solution oxygen of the silicon nitride powder is preferably 0.1% by mass or less.
  • the amount of solid-dissolved oxygen means oxygen solid-dissolved inside the particles of the silicon nitride powder (hereinafter, also referred to as internal oxygen), and an oxide such as SiO 2 inevitably present on the surface of the particles.
  • Derived oxygen hereinafter also referred to as external oxygen
  • the amount of solid solution oxygen can be measured by the method described in Examples.
  • the method for adjusting the amount of dissolved oxygen in the silicon nitride powder is not particularly limited, but for example, when producing the silicon nitride powder, it is preferable to use a high-purity raw material.
  • silicon nitride powder is produced by the direct nitriding method, it is preferable to use silicon powder as a raw material to be used, which does not have a factor of dissolving oxygen inside, and specifically, it is derived from semiconductor grade silicon.
  • silicon powder typified by cutting powder generated when the silicon is processed such as by cutting.
  • the semiconductor grade silicon is typically polycrystalline silicon obtained by the so-called "Ziemens method" in which high-purity trichlorosilane is reacted with hydrogen in a Belger type reaction vessel.
  • the specific surface area of the silicon nitride powder is 7 to 20 m 2 / g.
  • the specific surface area of the silicon nitride powder is less than 7 m 2 / g, it becomes difficult to obtain a high-density and high-strength silicon nitride sintered body by firing under a pressure near normal pressure, and the continuous firing furnace described later can be applied. It will be difficult.
  • the specific surface area exceeds 20 m 2 / g, the amount of solidified oxygen tends to increase, and the thermal conductivity of the obtained silicon nitride sintered body decreases.
  • the specific surface area of the silicon nitride powder is preferably 12 to 15 m 2 / g.
  • the specific surface area means the BET specific surface area measured by using the BET one-point method by adsorbing nitrogen gas.
  • the average particle size D50 of the silicon nitride powder is preferably 0.5 to 3 ⁇ m, more preferably 0.7 to 1.7 ⁇ m. When silicon nitride powder having such an average particle size is used, sintering at normal pressure is more likely to proceed.
  • the average particle size D50 is a value on a 50% volume basis measured by a laser diffraction / scattering method.
  • the proportion of particles having a particle size of 0.5 ⁇ m or less in the silicon nitride powder is preferably 20 to 50% by mass, more preferably 20 to 40% by mass.
  • the proportion of particles having a particle size of 1 ⁇ m or more in the silicon nitride powder is preferably 20 to 50% by mass, more preferably 20 to 40% by mass.
  • a silicon nitride powder having such a particle size distribution it becomes easy to obtain a dense silicon nitride sintered body having high thermal conductivity by firing at normal pressure. The reason for this is not clear, but unlike ⁇ -type silicon nitride particles, ⁇ -type silicon nitride particles are less likely to undergo dissolution and reprecipitation during firing, and fine particles and coarse particles are balanced in a certain manner at the initial stage of firing. It is considered that it will be possible to obtain a more precise sintered body by preparing it.
  • the total oxygen content of the silicon nitride powder is not particularly limited, but is preferably 1% by mass or more.
  • the total oxygen amount is the sum of the above-mentioned solid solution oxygen (internal oxygen) amount and the external oxygen amount. When the total amount of oxygen is at least these lower limit values, for example, silicon oxide on the surface of the particles tends to promote sintering.
  • the total oxygen content of the silicon nitride powder is preferably 10% by mass or less. Even if the total oxygen content of the silicon nitride powder is 1% by mass or more, the thermal conductivity of the sintered body can be increased as long as the solid oxygen content is not more than a certain value as described above. Is.
  • the total oxygen content of the silicon nitride powder can be measured by the method described in Examples.
  • the method for producing the silicon nitride powder is not particularly limited as long as it is a method for obtaining the silicon nitride powder having the above-mentioned characteristics.
  • Examples of the method for producing silicon nitride powder include a reduction nitriding method in which silica powder is used as a raw material and nitrogen gas is circulated to generate silicon nitride in the presence of carbon powder, and direct nitriding in which the silicon powder and nitrogen are reacted at a high temperature.
  • a method, an imide decomposition method in which silicon halide is reacted with ammonia, or the like can be applied, but the direct nitriding method is preferable from the viewpoint of easy production of silicon nitride powder having the above-mentioned characteristics, and the direct nitriding method using the self-combustion method is particularly preferable.
  • the method (combustion synthesis method) is more preferable.
  • the combustion synthesis method is a method in which silicon powder is used as a raw material, a part of the raw material powder is forcibly ignited in a nitrogen atmosphere, and silicon nitride is synthesized by self-heating of the raw material compound.
  • the combustion synthesis method is a known method, and for example, Japanese Patent Application Laid-Open No. 2000-264608, International Publication No. 2019/167879, and the like can be referred to.
  • the sintering aid used in the present invention is not particularly limited as long as it is used for sintering silicon nitride powder, but a sintering aid containing a compound having no oxygen bond is particularly preferably used. By using such a sintering aid, it is possible to further prevent a decrease in the thermal conductivity of the obtained silicon nitride sintered body even when firing under a pressure near normal pressure.
  • the compound having no oxygen bond include a carbonitride-based compound containing a rare earth element or a magnesium element (hereinafter, also referred to as a specific carbonitride-based compound) and a nitride-based compound (hereinafter, a specific nitride).
  • a system compound is preferable.
  • a specific carbonitride-based compound and a specific nitride-based compound it becomes easier to obtain a silicon nitride sintered body having a higher thermal conductivity more effectively. That is, the specific carbonitride-based compound functions as a getter agent for adsorbing oxygen contained in the silicon nitride powder, and in the specific nitride-based compound, the total oxygen content of the silicon nitride sintered body is reduced. As a result, it is considered that a silicon nitride sintered body having high thermal conductivity can be obtained.
  • the rare earth elements are preferably Y (yttrium), La (lanthanum), Sm (samarium), Ce (cerium), ytterbium (Yb) and the like.
  • Examples of carbonitride-based compounds containing rare earth elements include Y 2 Si 4 N 6 C, Yb 2 Si 4 N 6 C, Ce 2 Si 4 N 6 C, and the like, among which thermal conductivity is used. From the viewpoint of facilitating the acquisition of a silicon nitride sintered body having a high rate, Y 2 Si 4 N 6 C and Yb 2 Si 4 N 6 C are preferable.
  • Examples of the carbonitride-based compound containing a magnesium element include MgSi 4 N 6 C and the like. Further, as a specific nitride compound containing a magnesium element, MgSiN 2 and the like can be mentioned. These specific carbonitride-based compounds and specific nitride-based compounds may be used alone or in combination of two or more.
  • Y 2 Si 4 N 6 C a MgSi 4 N 6 C, MgSiN 2 .
  • the sintering aid may further contain a metal oxide in addition to the above-mentioned compound having no oxygen bond.
  • a metal oxide for example, yttria (Y 2 O 3), magnesia (MgO), and the like ceria (CeO). Of these, itria is preferred.
  • One type of metal oxide may be used alone, or two or more types may be used in combination.
  • the mass ratio (oxygen-free compound / metal oxide) of the oxygen-free compound represented by the specific carbonitride-based compound and the metal oxide contained in the sintering aid is preferably 0. It is .2 to 4, more preferably 0.6 to 2. Within such a range, it becomes easy to obtain a silicon nitride sintered body that is dense and has high thermal conductivity.
  • the content of the sintering aid in the object to be fired is preferably 5 to 20 parts by mass, and more preferably 7 to 10 parts by mass with respect to 100 parts by mass of the silicon nitride powder.
  • the calcined body can be produced by using an organic binder.
  • a molded product can be obtained by using an organic binder and then degreasing to obtain a molded product.
  • the organic binder is not particularly limited, and examples thereof include polyvinyl alcohol, polyvinyl butyral, methyl cellulose, alginic acid, polyethylene glycol, carboxymethyl cellulose, ethyl cellulose, and acrylic resin.
  • the content of the organic binder in the molding composition used for producing the calcined body is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the silicon nitride powder, and the ratio thereof is appropriately determined according to the molding method. do it.
  • the total oxygen content of the calcined body is preferably 1 to 15% by mass.
  • the fired body means a state to be subjected to sintering, and the organic binder, solvent, etc. used in the production of the fired body are before being subjected to sintering. Those that are not included in those that are removed by treatment such as degreasing. If the total amount of oxygen in the fired body exceeds 15% by mass, the thermal conductivity of the obtained silicon nitride sintered body may decrease due to the influence of oxygen.
  • the total amount of oxygen is less than 1% by mass, sintering is difficult to proceed, a dense silicon nitride sintered body cannot be obtained, and the thermal conductivity and strength may decrease.
  • the total oxygen content of the calcined body is preferably 2 to 10% by mass, more preferably 3 to 5% by mass.
  • the total oxygen amount can be set in a desired range by appropriately adjusting the total oxygen amount of the silicon nitride used, the type of the sintering aid, the molding method, and the like.
  • the total content (mass) of the aluminum element of the object to be fired is preferably 800 ppm or less. That is, it is preferable that the amount of the aluminum element to be fired used in the present invention is very small in order to obtain a silicon nitride sintered body having high thermal conductivity.
  • the total content of the aluminum element in the object to be fired is preferably 700 ppm or less, more preferably 500 ppm or less.
  • the method for producing the object to be fired used in the present invention is not particularly limited, and examples thereof include a method for molding a molding composition containing at least silicon nitride powder and a sintering aid by a known molding means.
  • known molding means include a press molding method, an extrusion molding method, an injection molding method, a sheet molding method (doctor blade method), and the like.
  • an organic binder may be further added to the molding composition.
  • the types of the organic binder are as described above.
  • the molding composition may contain a solvent from the viewpoint of ease of handling and molding.
  • the solvent is not particularly limited, and examples thereof include organic solvents such as alcohols and hydrocarbons, water and the like, but in the present invention, it is preferable to use water. That is, it is preferable to form a molding composition containing silicon nitride powder, a sintering aid, and water to obtain an object to be fired.
  • water is used as the solvent, the environmental load is reduced as compared with the case where an organic solvent is used, which is preferable.
  • the merit that the risk of explosion due to evaporation of the residual solvent in the firing furnace can be avoided is extremely great in terms of safety management in industrial implementation.
  • solvent degreasing when an organic binder is used for forming the object to be fired, it is common to remove an organic component such as an organic binder from the molded product by providing a degreasing step.
  • the degreasing conditions are not particularly limited, but for example, the molded product molded using an organic binder may be heated to 450 to 650 ° C. in the air or in an inert atmosphere such as nitrogen or argon.
  • the degreasing furnace used in the above degreasing step may be either a batch method or a continuous method, but it is preferable to adopt the continuous method in combination with the continuous firing furnace described later.
  • a molded body mounted on a degreasing jig is transferred to a degreasing chamber adjusted to the gas atmosphere by a known transport mechanism, which is provided with a heating mechanism capable of heating the room to the temperature. There is a method of passing through continuously.
  • the molded body is a plate-shaped body for the purpose of manufacturing a sintered substrate
  • a plurality of molded bodies coated with a release material such as boron nitride powder are laminated and placed on the degreasing jig. , It is common to use for degreasing.
  • the degreasing jig As the degreasing jig, a plate-shaped jig without a peripheral wall is suitable for efficient degreasing. Further, the degreasing jig is used as a firing jig by attaching a member to be a peripheral wall in order to prevent damage when the degreased body to be fired is replaced with the firing jig in firing described later. It is preferable to configure it so that it can be done. For example, after using it as a degreasing jig in a plate-like state, there is an embodiment in which a tubular member forming a side wall is attached and used as a firing jig.
  • the material of the degreasing jig and the firing jig a known heat-resistant material that is stable in degreasing and firing, if necessary, is used without particular limitation. Specifically, a carbon member is preferably used.
  • FIG. 1 is a schematic view showing one aspect of a continuous firing furnace used for performing continuous firing of the present invention.
  • a closed firing container 5 having a firing jig 2 accommodating a fired body 1 at an opening / closing door 3 for supplying the firing jig, an opening / closing door 4 for discharging, and an end thereof.
  • a heating mechanism 6 provided on the outer periphery of the body of the firing container, a transport mechanism for supplying and discharging the firing jig into the firing container, and a gas supply mechanism for supplying an inert gas into the firing container.
  • the silicon nitride sintered body is manufactured by supplying the fired body to a continuous firing furnace equipped with the above.
  • the above-mentioned firing method will be described in a plate-like manner in which a sintered body from which the shape of the fired body 1 is obtained is used as a substrate of a semiconductor device. It is efficient to stack a plurality of plate-shaped bodies to be fired, accommodate them in a firing jig, and supply and discharge them to a continuous firing furnace. When molding the body to be fired using an organic binder, it is preferable to stack and handle the molded body before degreasing as described above. Further, in the above-mentioned lamination, it is preferable to interpose a boron nitride powder as a release material between the layers. Further, as the firing jig 2, as shown in the enlarged view of FIG. 1, a box-shaped container having a side wall is preferably used. Further, although not shown, it is preferable to dispose, for example, a plate-shaped sintered body of silicon nitride at the upper and lower ends of the laminated body to be fired.
  • the firing container 5 for firing in an inert gas atmosphere may have a structure sufficient to withstand the normal pressure, and does not require a highly pressure-resistant structure.
  • a casing made of stainless steel or the like, preferably lined with a heat-resistant member, specifically, a carbon member is preferable.
  • the above-mentioned inert gas atmosphere is formed by supplying, for example, an inert gas such as nitrogen gas or argon gas (hereinafter, nitrogen is described as an example) to the firing container 5.
  • the pressure in the firing vessel is preferably adjusted to 0 MPa ⁇ G or more and less than 0.1 MPa ⁇ G.
  • the pressure is more preferably 0 MPa ⁇ G or more and 0.05 MPa ⁇ G or less.
  • the G at the end of MPa and G in the pressure unit means the gauge pressure.
  • the body to be fired is heated to a temperature of 1200 to 1800 ° C. and fired. If the temperature for firing is less than 1200 ° C., the sintering of silicon nitride is difficult to proceed, and if it exceeds 1800 ° C., the silicon nitride is easily decomposed. From this point of view, the heating temperature for firing is preferably 1600 to 1800 ° C.
  • the body of the firing container 5 is provided with a heating mechanism 6 for adjusting the inside of the container to the temperature for firing.
  • a heating mechanism 6 for adjusting the inside of the container to the temperature for firing.
  • the heating mechanism 6 a carbon heater is generally used. Further, the heating mechanism 6 adjusts the temperature rise rate to the temperature for firing in the firing container 5, the maintenance of the temperature, and the temperature profile leading to cooling from the temperature, so that the heating mechanism 6 moves in the traveling direction of the object to be fired.
  • the zone is divided into a plurality of zones so that the temperature can be controlled independently. In the drawing, the heating mechanism 6 is divided into three parts, but in order to set a finer temperature, the heating mechanism 6 is divided into four parts or more, and each heating temperature can be adjusted independently. be able to.
  • the ratio of the heating time in each of the above zones can be changed by adjusting the ratio of the division of the heating mechanism 6.
  • FIG. 1 shows a pusher-type transfer mechanism that sequentially pushes the firing jig 2 from the inlet side of the firing container 5 in the firing container 5.
  • the guide plate 8 for sliding the firing jig 2 pushed in from the inlet side to move the inside of the furnace, and the firing jig 2 independently near the outlet of the firing container 5.
  • a roller 9 having a drive unit (not shown) for taking out from the furnace is provided.
  • the firing time at the heating temperature is not particularly limited, but is preferably about 3 to 20 hours at the firing temperature, and the time required is adjusted by adjusting the transport speed by the transport means, the length of the firing container, and the like. It is set by doing.
  • Carrying in and out of the firing container 5 into and out of the firing container 5 of the continuous firing furnace is performed by providing an opening / closing door 3 for supply and an opening / closing door 4 for discharging, which can be opened and closed at the inlet and outlet, respectively.
  • the supply opening / closing door 3 and the discharging opening / closing door 4 open / close in conjunction with the operation of the transport mechanism when supplying or taking out the firing jig 2 into the firing container 5.
  • the supply opening / closing door 3 and the discharging opening / closing door 4 those having a known structure capable of ensuring the airtightness in the firing container are used without particular limitation.
  • the continuous firing furnace used in the present invention is provided with a supply chamber 11 on the inlet side of the firing vessel 5 which is separated from the firing vessel 5 by a supply opening / closing door 3 and is provided with equipment for replacing nitrogen in the internal space. ..
  • the carry-in door (not shown) is opened to carry in the firing jig, the internal space is replaced with nitrogen, the pressure is adjusted with the inside of the firing container 5, and then the opening / closing door 3 for firing is opened for firing.
  • An operation of pushing the jig 2 into the firing container to supply the jig 2 is performed.
  • the above operation can be performed by providing the piston cylinder 10 in the supply chamber 11.
  • the supply chamber 11 is provided with a guide plate 7 having the same height as the transport surface of the firing container.
  • an take-out chamber 13 which is separated from the firing container 5 by a discharge opening / closing door 4 and is provided with a facility for replacing nitrogen in the internal space.
  • the firing jig is taken out from the firing container 5
  • the internal space of the take-out chamber 13 is replaced with nitrogen
  • the pressure is adjusted with the inside of the firing container 5
  • the discharge opening / closing door 4 is opened
  • the firing jig 2 is taken out.
  • the operation of taking out to the room 13 is performed.
  • the discharge opening / closing door 4 is closed, the take-out door 12 is opened, and the silicon nitride sintered body is taken out from the take-out chamber 13 together with the firing jig.
  • the supply and discharge of the firing jig 2 to the firing container 5 are performed in conjunction with each other so that the number of firing jigs 2 in the firing container is constant.
  • the silicon nitride sintered body can be continuously fired by the continuous firing furnace.
  • the degreasing step and the processing step after firing can also be continuously performed by connecting to the continuous firing furnace.
  • the silicon nitride sintered body obtained by the continuous manufacturing method of the present invention can produce an excellent silicon nitride sintered body that is not inferior to the case where the conventional batch method is adopted.
  • higher thermal conductivity can be exhibited.
  • the dielectric breakdown voltage can be 11 kV or more, particularly 13 kV or more.
  • a silicon nitride sintered body having such a dielectric breakdown voltage is less likely to undergo dielectric breakdown and is excellent in reliability when used as a substrate for a semiconductor.
  • the thermal conductivity, dielectric breakdown voltage, etc. are measured after the surface of the silicon nitride sintered body is blasted to remove deposits such as a mold release material adhering to the sintered body during sintering. Is.
  • the ⁇ -conversion rate of silicon nitride powder was determined by powder X-ray diffraction (XRD) measurement using CuK ⁇ rays. Specifically, C.I. P. Gazzara and D. R. Messier: Am. Ceram. Soc. Bull. , 56 (1977), 777-780, the weight ratio of the ⁇ phase and the ⁇ phase of the silicon nitride powder was calculated, and the ⁇ conversion rate was determined.
  • XRD powder X-ray diffraction
  • the specific surface area of silicon nitride powder was measured using a BET specific surface area measuring device (Macsorb HMmodel-1201) manufactured by Mountech Co., Ltd. using a BET one-point method by adsorbing nitrogen gas. .. Before performing the above-mentioned specific surface area measurement, the silicon nitride powder to be measured was previously heat-treated in air at 600 ° C. for 30 minutes to remove organic substances adsorbed on the powder surface.
  • Solid Oxygen Amount and Total Oxygen Amount of Silicon Nitride Powder The solid oxygen content of silicon nitride powder was measured by an inert gas melting-infrared absorption method. The measurement was performed by an oxygen / nitrogen analyzer (“EMGA-920” manufactured by HORIBA). As a sample, 25 mg of the silicon nitride powder used in each Example and Comparative Example was encapsulated in a tin capsule (the tin capsule uses TinCupusule manufactured by LECO), introduced into a graphite crucible, heated at 5.5 kW for 20 seconds, and adsorbed gas.
  • EMGA-920 oxygen / nitrogen analyzer
  • the temperature was raised at 0.8 kW for 10 seconds and from 0.8 kW to 4 kW over 350 seconds, and the amount of carbon dioxide generated during that period was measured and converted into an oxygen content.
  • the oxygen generated at the initial stage is oxygen derived from oxides (external oxygen) existing on the surface of the silicon nitride particles, and the oxygen generated later is solid-dissolved in the silicon nitride crystal. Since it corresponds to oxygen (internal oxygen), a perpendicular line was drawn from the portion corresponding to the valley of these two measurement peaks after subtracting the background measured in advance, and the two peaks were separated.
  • the amount of solid solution oxygen (internal oxygen) and the amount of external oxygen were calculated by proportionally distributing each peak area.
  • the particle size distribution of the obtained dispersion of the silicon nitride powder was measured using a laser diffraction / scattering method particle size distribution measuring device (Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd.).
  • a laser diffraction / scattering method particle size distribution measuring device Microtrac MT3300EXII manufactured by Microtrac Bell Co., Ltd.
  • water refractive index 1.33
  • the particle characteristics were selected as the refractive index 2.01
  • the particle permeability was selected as transparent
  • the particle shape was selected as non-spherical.
  • the particle size at which the cumulative curve of the particle size distribution measured by the above particle size distribution measurement is 50% is defined as the average particle size (average particle size D50).
  • Total oxygen content of the fired body was measured by the Infrared gas melting-infrared absorption method. The measurement was performed by an oxygen / nitrogen analyzer (“EMGA-920” manufactured by HORIBA). As a sample, 15 mg of the object to be calcined is encapsulated in a tin capsule (the tin capsule uses Tin Cupsule made by LECO), introduced into a graphite crucible, heated at 5.5 kW for 20 seconds, and further heated at 5.0 kW for 20 seconds to obtain the adsorbed gas. After degassing, the mixture was heated at 5.0 kW for 75 seconds, and the amount of carbon dioxide generated during that period was measured and converted into an oxygen content.
  • EMGA-920 oxygen / nitrogen analyzer
  • Density of the object to be fired The density of each object to be fired is measured using an automatic hydrometer (manufactured by Shinko Denshi Co., Ltd .: DMA-220H type), and the average value of 15 pieces is the density of the body to be fired. And said.
  • Total content of aluminum elements in the body to be fired was measured using an inductively coupled plasma emission spectrophotometer (“iCAP6500DUO” manufactured by Thermo Fisher Scientific Co., Ltd.). ..
  • Thermal Conductivity of Silicon Nitride Sintered Body The thermal conductivity of the silicon nitride sintered body was measured by a laser flash method using LFA-502 manufactured by Kyoto Electronics Industry. The thermal conductivity is obtained by multiplying the thermal diffusivity, the sintered body density, and the sintered body specific heat. The specific heat of the silicon nitride sintered body was 0.68 (J / g ⁇ K). The sintered body density was measured using an automatic hydrometer (manufactured by Shinko Denshi Co., Ltd .: DMA-220H type). The thermal conductivity was measured after the surface of the silicon nitride sintered body was blasted and then the surface was coated with Au and carbon.
  • Dielectric breakdown voltage of silicon nitride sintered body The dielectric breakdown voltage was measured according to JISC2110. Specifically, a voltage was applied to the silicon nitride sintered body using an insulation withstand voltage measuring device (“TK-O-20K” manufactured by Measurement Technology Research Institute), and the voltage when dielectric breakdown occurred was measured. ..
  • Ra (10) Ra (arithmetic mean roughness) of silicon nitride sintered body Ra of the silicon nitride sintered body is measured by scanning the needle with a surface roughness measuring instrument (manufactured by Tokyo Seimitsu Co., Ltd., "Surfcom 480A") at an evaluation length of 2.5 mm and a measurement degree of 0.3 mm / s. , Ra was measured.
  • a silicon nitride sintered body was used in which the surface was blasted to remove the release material and the like.
  • Silicon powder (semiconductor grade, average particle size 5 [mu] m) and, by mixing the silicon nitride powder (average particle size 1.5 [mu] m) is a diluent, the raw material powder (Si: 80 wt%, Si 3 N 4: 20 wt% ) was obtained.
  • the raw material powder was filled in a reaction vessel to form a raw material powder layer.
  • the reaction vessel was installed in a pressure-resistant closed reactor having an ignition device and a gas supply / discharge mechanism, the inside of the reactor was depressurized and degassed, and then nitrogen gas was supplied to replace the nitrogen. Then, nitrogen gas was gradually supplied, and the pressure was increased to 0.7 MPa.
  • the bulk density of the raw material powder at the time when the predetermined pressure was reached (at the time of ignition) was 0.5 g / cm 3 . Then, the end portion of the raw material powder in the reaction vessel was ignited and a combustion synthesis reaction was carried out to obtain a massive product made of silicon nitride. The obtained lumpy products were crushed by rubbing against each other, and then an appropriate amount was put into a vibration mill to perform fine pulverization for 6 hours.
  • the pulverizer and pulverization method use conventional equipment and methods, but as a measure to prevent heavy metal contamination, urethane lining is applied to the inside of the pulverizer, and a ball containing silicon nitride as the main component is used as the pulverizing medium. used. Immediately before the start of pulverization, 1% by mass of ethanol was added as a pulverizing aid, and the pulverizer was closed to perform pulverization to obtain a silicon nitride powder having the following characteristics.
  • Beta conversion rate 99% ⁇ Amount of solid solution oxygen 0.06% by mass ⁇ Specific surface area 13.5m 2 / g ⁇ Total oxygen content 1.84% by mass -Average particle size: D50 1.2 ⁇ m ⁇ Percentage of particles of 0.5 ⁇ m or less 25% by mass -Ratio of particles of 1.0 ⁇ m or more 32% by mass ⁇ Sintering aid>
  • ittoria manufactured by Shin-Etsu Chemical Co., Ltd.
  • silicon nitride powder manufactured by the company described above
  • carbon powder manufactured by Mitsubishi Chemical Co., Ltd.
  • Example 1 Silicon nitride powder A 100 parts by mass, compound containing no oxygen bond Y 2 Si 4 N 6 C: 2 parts by mass, MgSiN 2 : 5 parts by mass, Itria: 3 parts by mass, weighed, and nitrided with a resin pot using water as a dispersion medium. Using silicon balls, pulverization and mixing were carried out in a ball mill for 24 hours. The water was weighed in advance so that the concentration of the slurry was 60% by mass, and the water was put into the resin pot. After pulverization and mixing, 22 parts by mass of polyvinyl alcohol resin was added and further mixed for 12 hours to obtain a slurry-shaped molding composition.
  • the viscosity of the molding composition was adjusted using a vacuum defoaming machine (manufactured by Sayama Riken) to prepare a slurry for coating. Then, the viscosity-adjusted molding composition was sheet-molded by the doctor blade method to obtain a sheet-molded article having a width of 75 cm and a thickness of 0.42 mmt.
  • Ten sheet molded bodies obtained as described above are coated with a mold release material made of boron nitride powder, placed on a plate-shaped jig, set in a degreasing furnace, degreased, and subjected to degreasing treatment. A fired body was obtained.
  • the degreasing treatment was carried out in batch at 550 ° C. in dry air.
  • the total content of the aluminum element in the obtained body to be fired was 500 ppm.
  • a carbon square cylinder was attached to the carbon plate-shaped jig on which the fired body was placed, and the carbon square cylinder was set so as to surround the carbon plate-shaped jig as shown in the enlarged view of FIG.
  • the continuous firing furnace uses a firing container 5 equipped with a heating mechanism 6 divided into four parts, and the temperature setting for each zone is programmed according to the transfer speed so as to have the firing profile shown in FIG. rice field. Nitrogen was supplied into the firing vessel 5 and the pressure was adjusted to 0.02 MPa ⁇ G. On the other hand, the body to be fired is carried into the supply chamber by opening the carry-in door (not shown) of the supply chamber 11 in a state of being placed on the firing jig 2, and after closing the carry-in door, the internal space is reached. Was replaced with nitrogen, and after the pressure was adjusted to the inside of the firing container 5, the opening / closing door 3 for supply was opened and the firing jig 2 was pushed into the firing container 5 by the piston cylinder 10 to supply.
  • the firing jig sequentially advances in the firing container 5 by repeating the above operation, and during that time, the length of the firing container 5, the number of divisions of the heating mechanism 6, and the length of each zone are set, and the temperature of each zone is set. Was heated so as to have the temperature profile shown in FIG. 2 (total required time 24 hours).
  • the internal space of the taking-out chamber 13 is replaced with nitrogen, the pressure is adjusted with the inside of the firing container 5, the discharge opening / closing door 4 is opened, and the firing jig 2 is taken out. I took it out to 13. After that, the discharge opening / closing door 4 was closed, the take-out door 12 was opened, and the silicon nitride sintered body was taken out from the take-out chamber 13 together with the firing jig.
  • the physical properties of the obtained silicon nitride sintered body are the average of the values measured by extracting an arbitrary 100 sheets out of 1000 sheets continuously produced, and have a relative density of 99%, a thermal conductivity of 108 W / mK, and a surface roughness. It has been found that Ra is 0.57 ⁇ m and the insulation breakdown voltage is 16 kV, so that a silicon nitride sintered body that can sufficiently withstand practical use can be continuously produced.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Inorganic Chemistry (AREA)
  • Ceramic Products (AREA)
  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)

Abstract

β化率の高い窒化ケイ素粉末を用いた焼結による窒化ケイ素焼結体の製造を連続的に行うことができる窒化ケイ素焼結体の連続製造方法を提供する。　β化率が８０％以上、比表面積が７～２０ｍ２／ｇの窒化ケイ素粉末と、焼結助剤とを含有し、アルミニウム元素の総含有量が８００ｐｐｍ以下に調整された被焼成体１を収容した焼成用治具２を、上記焼成用治具の供給用開閉扉３と排出用開閉扉４とを端部に有する密閉式の焼成容器５、上記焼成容器５の胴部外周に設けられた加熱機構６、前記焼成用治具を焼成容器内に給排出するための搬送機構、及び、焼成容器内に不活性ガスを供給するためのガス供給機構を備えた連続焼成炉に供給し、不活性ガス雰囲気下及び０ＭＰａ・Ｇ以上０．１ＭＰａ・Ｇ未満の圧力下、１２００～１８００℃の温度に加熱して窒化ケイ素を焼結する。

Description

窒化ケイ素焼結体の連続製造方法
　本発明は、β型の窒化ケイ素粉末を使用して、窒化ケイ素焼結体、例えば、窒化ケイ素焼結基板を連続して製造する方法に関する。
　窒化ケイ素粉末に各種の焼結助剤を添加し、高温で焼結させた窒化ケイ素焼結体は、各種セラミックス焼結体の中でも、軽い、機械的強度が強い、耐薬品性が高い、電気絶縁性が高い、等の特徴があり、ボールベアリング等の耐摩耗用部材、高温構造用部材として用いられている。また助剤の種類や焼結条件を工夫することにより、熱伝導性も高めることが可能であるため、窒化ケイ素焼結基板は、薄くて強度の高い放熱用基板材料としても使用されるようになってきた。
　窒化ケイ素粉末の結晶形態としては、α型とβ型とが存在することが知られている。例えば非特許文献１に示すように、α型の窒化ケイ素粉末は、焼結過程で焼結助剤に溶解してβ型として再析出し、この結果として、緻密で熱伝導率の高い焼結体を得ることができるため、現在広く使用されている。
　しかしながら、α型の窒化ケイ素粉末を製造する場合は、その製造プロセスが複雑となりやすい。例えば、直接窒化法では、β型が生成しないように、低温で長時間かけて窒化する必要があるため、製造コストが高くなる（非特許文献２）。
　このような背景から、比較的低コストで製造されるβ型窒化ケイ素粉末を用いて、焼結体を製造する技術が注目されつつある。特許文献１には、高熱伝導窒化ケイ素セラミックス並びにその製造方法に関する発明が記載されており、その実施例では、平均粒径０．５μｍであるβ型の窒化ケイ素粉末と、酸化イッテルビウム及び窒化ケイ素マグネシウム粉末からなる焼結助剤とを含む成形体（被焼成体）を、１０気圧の加圧窒素中、１９００℃で２～２４時間焼結を行い、窒化ケイ素焼結体を得ることが示されている。
特開２００２－１２８５６９号公報
日本舶用機関学会誌、１９９３年９月、第２８巻、第９号、ｐ５４８－５５６ Ｊｏｕｒｎａｌ　ｏｆ　ｔｈｅ　Ｃｅｒａｍｉｃ　Ｓｏｃｉｅｔｙ　ｏｆ　Ｊａｐａｎ　１００［１１］１３６６－１３７０（１９９２）
　前記したように、β型窒化ケイ素粉末の焼結体は１０気圧の加圧窒素中で製造されている。一般に、加圧下で焼成すると原料の窒化ケイ素の分解を抑制しやすくなり、そのため１８００℃超の高温で焼成することが可能となる。このような高温高圧下において焼成する場合は、生成する焼結体が緻密化されやすく、また熱伝導率を低下させる要因の一つである窒化ケイ素粒子内部に固溶している不純物酸素量を低減することが可能であり、熱伝導率の高い焼結体が得やすいことが知られている。しかしながら、加圧下で焼成を行う場合は、製造時に耐圧容器を用いる必要がある。そのため、製造方法は設備的な制約があり、バッチ方式により行うことしかできず、バッチ毎の昇温・冷却を繰り返す必要があることなどにより、製造コストが高くなるという問題がある。また、前記特許文献には、β型窒化ケイ素粉末を使用し、かつ耐圧容器を用いる必要のない常圧（大気圧）又は略常圧（大気圧近傍の圧力）の条件下で、熱伝導率の高い焼結体を得る方法について何ら記載も示唆もされていない。
　本発明は、上記従来の課題に鑑みてなされたものであって、β化率の高い窒化ケイ素粉末を原料として用い、しかもこれを常圧又は略常圧で焼結させる条件を採用することにより、焼成炉への焼結原料の供給、取り出しを逐次行う構造の連続焼成炉の使用を可能とし、生産性良く窒化ケイ素焼結体を製造することができる方法を提供することを課題とする。
　本発明者らは、前記目的を達成するために鋭意研究を重ねた。その結果、β化率が高い、所謂β型の窒化ケイ素粉末を使用し、比表面積が特定の範囲にある窒化ケイ素粉末と焼結助剤とを含有し、かつアルミニウム元素の総含有量を特定範囲とした被焼成体を用いることにより、これを常圧又は常圧に近い圧力下で焼成することができることを見出し、これにより前記連続焼成炉の使用を可能とし、高い品質を有する窒化ケイ素焼結体を連続して製造できる方法を完成させ、本発明を提案するに至った。
　即ち、本発明によれば、β化率が８０％以上、比表面積が７～２０ｍ２／ｇの窒化ケイ素粉末と、焼結助剤とを含有し、アルミニウム元素の総含有量が８００ｐｐｍ以下に調整された被焼成体を収容した焼成用治具を、上記焼成用治具の供給用開閉扉と排出用開閉扉とを端部に有する密閉式の焼成容器、上記焼成容器の胴部外周に設けられた加熱機構、前記焼成用治具を焼成容器内に給排出するための搬送機構、及び、焼成容器内に不活性ガスを供給するためのガス供給機構を備えた連続焼成炉に供給し、不活性ガス雰囲気下及び０ＭＰａ・Ｇ以上０．１ＭＰａ・Ｇ未満の圧力下、１２００～１８００℃の温度に加熱して窒化ケイ素を焼結することを特徴とする、窒化ケイ素焼結体の連続製造方法が提供される。
　上記方法において、加熱機構が焼成用容器の搬送方向に対して複数に分割され、それぞれの加熱温度が独立して調整可能とした連続焼成炉を使用することにより、前記焼成温度範囲内で最適な焼結を進行させることが可能となり好ましい。
　また、前記被焼成体を形成するための成形用組成物を窒化ケイ素粉末、焼結助剤、及び水を含む水系で構成することにより、有機溶媒を使用して成形用組成物を調製する場合に比較して、連続焼成炉内での引火や、爆発等の問題を解消することができ好ましい。
　更に、前記被焼成体が板状であり、複数枚を積層して焼成用治具に収容して連続焼成炉に対して供給、排出を行うようにすることが効率的である。
　本発明には、窒化ケイ素粉末と、焼結助剤とを含有する被焼成体を収容した焼成用治具、前記焼成用治具の供給用開閉扉と排出用開閉扉とを端部に有する密閉式の焼成容器、前記焼成容器の胴部外周に設けられた加熱機構、前記焼成用治具を前記焼成容器内に給排出するための搬送機構、及び、前記焼成容器内に不活性ガスを供給するためのガス供給機構を備えることを特徴とする、窒化ケイ素焼結用連続焼成炉が用いられる。
　本発明によれば、β化率の高い窒化ケイ素粉末を用いながら、優れた品質を有する窒化ケイ素焼結体を連続的に、生産性良く製造することができる。
本発明の連続焼成を行うために使用される連続焼成炉の一態様を示す概略図。 本発明の連続焼成炉における温度プロファイルの一例を示すチャート。
［窒化ケイ素焼結体の製造方法］
　本発明の窒化ケイ素焼結体の製造方法は、前記のとおり、β化率が８０％以上、比表面積が７～２０ｍ２／ｇの窒化ケイ素粉末と、焼結助剤とを含有し、アルミニウム元素の総含有量が８００ｐｐｍ以下に調整された被焼成体を収容した焼成用治具を、上記焼成用治具の供給用開閉扉と排出用開閉扉と端部に有する密閉式の焼成容器、上記焼成容器の胴部外周に設けられた加熱機構、前記焼成用治具を焼成容器内に給排出するための搬送機構、及び、焼成容器内に不活性ガスを供給するためのガス供給機構を備えた連続焼成炉に供給し、不活性ガス雰囲気下及び０ＭＰａ・Ｇ以上０．１ＭＰａ・Ｇ未満の圧力（以下、かかる微加圧の範囲を含めて「常圧」と称することもある。）下、１２００～１８００℃の温度に加熱して窒化ケイ素を焼結する。
〔被焼成体〕
　本発明の窒化ケイ素焼結体の製造方法において、焼成に供される被焼成体について説明する。被焼成体は、以下に説明する特定の窒化ケイ素粉末及び焼結助剤を含有する成形体であり、後述するように、上記組成を、有機バインダーを使用せずに成形した成形体、有機バインダーを使用して成形し、得られた成形体から有機バインダーを脱脂により除去した脱脂体を含むものである。
＜窒化ケイ素粉末＞
（β化率）
　被焼成体に含まれる窒化ケイ素粉末のβ化率は８０％以上である。β化率が８０％以上の窒化ケイ素粉末は、厳密な製造条件を設定しなくても得ることができるため、比較的低コストで製造することができる。したがって、β化率の高い窒化ケイ素粉末を使用することで、窒化ケイ素焼結体の全体の製造コストを抑制することができる。また、β化率を高く設定することで、α型の窒化ケイ素粒子が焼成時にβ型の窒化ケイ素粒子に変態を起こす際に取り込む酸素量をさらに少なく抑えることが出来るというメリットもある。ここで窒化ケイ素粉末のβ化率は、好ましくは８５％以上、より好ましくは９０％以上である。
　なお、窒化ケイ素粉末のβ化率とは、窒化ケイ素粉末におけるα相とβ相の合計に対するβ相のピーク強度割合［１００×（β相のピーク強度）／（α相のピーク強度＋β相のピーク強度）］を意味し、ＣｕＫα線を用いた粉末Ｘ線回折（ＸＲＤ）測定により求められる。より詳細には、Ｃ．Ｐ．Ｇａｚｚａｒａ　ａｎｄ　Ｄ．Ｒ．Ｍｅｓｓｉｅｒ：Ａｍ．　Ｃｅｒａｍ．　Ｓｏｃ．　Ｂｕｌｌ．，５６（１９７７），７７７－７８０に記載された方法により、窒化ケイ素粉末のα相とβ相の重量割合を算出することで求められる。
（固溶酸素量）
　本発明において、窒化ケイ素粉末の固溶酸素量は、特に制限されるものではないが、０．２質量％以下であることが高熱伝導率の窒化ケイ素焼結体を得るために好ましい。窒化ケイ素粉末の固溶酸素量は、好ましくは０．１質量％以下である。ここで、固溶酸素量とは、窒化ケイ素粉末の粒子内部に固溶された酸素（以下、内部酸素ともいう）のことを意味し、粒子表面に不可避的に存在するＳｉＯ２などの酸化物由来の酸素（以下、外部酸素ともいう）は含まない。なお、固溶酸素量は、実施例に記載の方法で測定することができる。
　窒化ケイ素粉末の固溶酸素量の調整方法は、特に限定されないが、例えば、窒化ケイ素粉末を製造する際に、高純度の原料を用いるとよい。例えば、直接窒化法で窒化ケイ素粉末を製造する場合は、使用する原料として、内部に酸素が固溶する要因が無いシリコン粉末を使用することが好ましく、具体的には、半導体グレードのシリコン由来、例えば、上記シリコンを切断等の加工する際に発生する切削粉を代表とするシリコン粉末を使用することが好ましい。上記半導体グレードのシリコンは、ベルジャー式反応容器内で、高純度のトリクロロシランと水素とを反応させる、いわゆる「ジーメンス法」により得られる多結晶シリコンが代表的である。
（比表面積）
　窒化ケイ素粉末の比表面積は７～２０ｍ２／ｇである。窒化ケイ素粉末の比表面積が７ｍ２／ｇ未満の場合、常圧付近の圧力下での焼成により、高密度で強度が高い窒化ケイ素焼結体が得にくくなり、後述の連続焼成炉の適用が困難となる。また、比表面積が２０ｍ２／ｇを超えると、固溶酸素量が増加する傾向があり、得られる窒化ケイ素焼結体の熱伝導率が低下する。窒化ケイ素粉末の比表面積は、好ましくは１２～１５ｍ２／ｇである。なお、本発明において比表面積は、窒素ガス吸着によるＢＥＴ１点法を用いて測定したＢＥＴ比表面積を意味する。
（平均粒径）
　窒化ケイ素粉末の平均粒径Ｄ５０は、０．５～３μｍであることが好ましく、０．７～１．７μｍであることがより好ましい。このような平均粒径の窒化ケイ素粉末を用いると、常圧での焼結が一層進行し易くなる。平均粒径Ｄ５０は、レーザー回折散乱法により測定した５０％体積基準での値である。また、窒化ケイ素粉末において粒径０．５μｍ以下の粒子の割合は、好ましくは２０～５０質量％であり、より好ましくは２０～４０質量％であることが好ましい。さらに、窒化ケイ素粉末における粒径１μｍ以上の粒子の割合は、好ましくは２０～５０質量％であり、より好ましくは２０～４０質量％である。このような粒度分布を有する窒化ケイ素粉末を用いると、常圧での焼成で、緻密で熱伝導率が高い窒化ケイ素焼結体を得やすくなる。この理由は、定かではないが、β型の窒化ケイ素粒子は、α型の窒化ケイ素粒子とは異なり焼成中の溶解再析出は起こりにくく焼成初期の段階で微細粒子と粗大粒子を一定のバランスに整えておくことでより緻密な焼結体を得ることが可能となるものと考えられる。
（全酸素量）
　前記窒化ケイ素粉末の全酸素量は、特に限定されないが１質量％以上であることが好ましい。全酸素量とは、上記した固溶酸素（内部酸素）量と、外部酸素量との合計である。全酸素量がこれら下限値以上であると、例えば、粒子表面の酸化ケイ素などにより焼結が促進されやすくなるという効果が発揮される。また、窒化ケイ素粉末の全酸素量は、１０質量％以下であることが好ましい。なお、窒化ケイ素粉末の全酸素量が１質量％以上であったとしても、固溶酸素量が上記したように一定値以下である限りは、焼結体の熱伝導性を高くすることが可能である。窒化ケイ素粉末の全酸素量は、実施例に記載の方法で測定することができる。
＜窒化ケイ素粉末の製造＞
　前記窒化ケイ素粉末の製造方法は、上述した特性を有する窒化ケイ素粉末を得られる方法であれば特に限定されない。窒化ケイ素粉末の製造方法としては、例えば、シリカ粉末を原料として、炭素粉末存在下において、窒素ガスを流通させて窒化ケイ素を生成させる還元窒化法、シリコン粉末と窒素とを高温で反応させる直接窒化法、ハロゲン化ケイ素とアンモニアとを反応させるイミド分解法などを適用できるが、上述した特性を有する窒化ケイ素粉末を製造しやすい観点から、直接窒化法が好ましく、中でも自己燃焼法を利用する直接窒化法（燃焼合成法）がより好ましい。燃焼合成法は、シリコン粉末を原料として使用し、窒素雰囲気下で原料粉末の一部を強制着火し、原料化合物の自己発熱により窒化ケイ素を合成する方法である。燃焼合成法は、公知の方法であり、例えば、特開２０００－２６４６０８号公報、国際公開第２０１９／１６７８７９号などを参照することができる。
＜焼結助剤＞
　本発明において使用する焼結助剤は、窒化ケイ素粉末の焼結に使用されるものであれば特に制限されないが、酸素結合を持たない化合物を含む焼結助剤が特に好適に使用される。このような焼結助剤を用いることにより、常圧付近の圧力下での焼成においても、得られる窒化ケイ素焼結体の熱伝導率の低下をより防止することができる。上記酸素結合を持たない化合物としては、希土類元素又はマグネシウム元素を含む炭窒化物系の化合物（以下、特定の炭窒化物系の化合物ともいう）および窒化物系の化合物（以下、特定の窒化物系の化合物ともいう）が好ましい。このような、特定の炭窒化物系の化合物および特定の窒化物系の化合物を用いることで、より効果的に熱伝導率が高い窒化ケイ素焼結体を得やすくなる。即ち、上記特定の炭窒化物系の化合物が、窒化ケイ素粉末に含まれる酸素を吸着するゲッター剤として機能、特定の窒化物系の化合物においては、窒化ケイ素焼結体の全酸素量を低下させ、結果として熱伝導率が高い窒化ケイ素焼結体が得られるものと考えられる。
　希土類元素を含む炭窒化物系の化合物において、希土類元素としては、Ｙ（イットリウム）、Ｌａ（ランタン）、Ｓｍ（サマリウム）、Ｃｅ（セリウム）、イッテルビウム（Ｙｂ）などが好ましい。
　希土類元素を含む炭窒化物系の化合物としては、例えば、Ｙ２Ｓｉ４Ｎ６Ｃ、Ｙｂ２Ｓｉ４Ｎ６Ｃ、Ｃｅ２Ｓｉ４Ｎ６Ｃ、などが挙げられ、これらの中でも、熱伝導率が高い窒化ケイ素焼結体を得やすくする観点から、Ｙ２Ｓｉ４Ｎ６Ｃ、Ｙｂ２Ｓｉ４Ｎ６Ｃが好ましい。マグネシウム元素を含む炭窒化物系の化合物としては、例えば、ＭｇＳｉ４Ｎ６Ｃなどが挙げられる。またマグネシウム元素を含む特定の窒化物系の化合物としては、ＭｇＳｉＮ２などが挙げられる。これら特定の炭窒化物系の化合物および特定の窒化物系の化合物は、１種を単独で用いてもよいし、２種以上を併用してもよい。
　上記した希土類元素又はマグネシウム元素を含む炭窒化物系の化合物および特定の窒化物系の化合物の中でも、特に好ましい化合物は、Ｙ２Ｓｉ４Ｎ６Ｃ、ＭｇＳｉ４Ｎ６Ｃ、ＭｇＳｉＮ２である。
　また、焼結助剤は、上記酸素結合を持たない化合物に加えて、さらに金属酸化物を含むことができる。焼結助剤が、金属酸化物を含有することで、窒化ケイ素粉末の焼結が進行しやすくなり、より緻密で強度が高い焼結体を得やすくなる。金属酸化物としては、例えば、イットリア（Ｙ２Ｏ３）、マグネシア（ＭｇＯ）、セリア（ＣｅＯ）などが挙げられる。これらの中でも、イットリアが好ましい。金属酸化物は１種を単独で用いてもよいし、２種以上を併用してもよい。
　焼結助剤に含まれる、前記特定の炭窒化物系の化合物を代表とする酸素を持たない化合物と金属酸化物との質量比（酸素を持たない化合物／金属酸化物）は、好ましくは０．２～４であり、より好ましくは０．６～２である。このような範囲であると、緻密で、熱伝導率が高い窒化ケイ素焼結体を得やすくなる。
　また、被焼成体における焼結助剤の含有量は、窒化ケイ素粉末１００質量部に対して、好ましくは５～２０質量部であり、より好ましくは７～１０質量部である。
＜有機バインダー＞
　本発明において、被焼成体は、有機バインダーを使用して製造することができる。具体的には、有機バインダーを使用して成形体を得た後、脱脂を行うことにより被焼成体を得ることができる。上記有機バインダーとしては、特に限定されないが、ポリビニルアルコール、ポリビニルブチラール、メチルセルロース、アルギン酸、ポリエチレングリコール、カルボキシメチルセルロース、エチルセルロース、アクリル樹脂などが挙げられる。
　被焼成体の製造に用いる成形用組成物中の有機バインダーの含有量は、窒化ケイ素粉末１００質量部に対して、好ましくは１～３０質量部であり、成形方法に応じて適宜その割合を決定すればよい。
＜総酸素量＞
　本発明において、被焼成体の総酸素量は、１～１５質量％であることが好ましい。ここで、上記被焼成体は、前記説明からも理解されるように、焼結に供する状態のものをいい、前記被焼成体の製造に使用した有機バインダー、溶媒等、焼結に供する前の脱脂等の処理により除去されるものは含まない状態のものをいう。かかる被焼成体の総酸素量が１５質量％を超えると、酸素の影響により、得られる窒化ケイ素焼結体の熱伝導率が低下する場合がある。また、総酸素量が１質量％未満であると、焼結が進行し難く、緻密な窒化ケイ素焼結体が得られず、熱伝導率及び強度が低下することがある。被焼成体の総酸素量は、好ましくは２～１０質量％であり、より好ましくは３～５質量％である。総酸素量は、使用する窒化ケイ素の全酸素量、及び焼結助剤の種類、並びに成形方法などを適宜調節することにより所望の範囲とすることができる。
＜アルミニウム元素の総含有量＞
　被焼成体のアルミニウム元素の総含有量（質量）は８００ｐｐｍ以下であることが好ましい。即ち、本発明において使用する被焼成体は、アルミニウム元素の量を非常に少なくすることが高い熱伝導率を有する窒化ケイ素焼結体を得るために好ましい。被焼成体におけるアルミニウム元素の総含有量は、好ましくは７００ｐｐｍ以下であり、より好ましくは５００ｐｐｍ以下である。
〔被焼成体の製造〕
　本発明において使用する被焼成体の製造方法は特に限定されず、例えば、窒化ケイ素粉末、及び焼結助剤を少なくとも含有する成形用組成物を、公知の成形手段によって成形する方法が挙げられる。公知の成形手段としては、例えば、プレス成形法、押出し成形法、射出成形法、シート成形法（ドクターブレード法）などが挙げられる。
　成形しやすさの観点から、前記成形用組成物にさらに、有機バインダーを配合してもよい。なお、有機バインダーの種類は前記したとおりである。
　また、成形用組成物には、取り扱い易さや、成形のし易さなどの観点から、溶剤を含有させてもよい。溶剤としては、特に限定されず、アルコール類、炭化水素類などの有機溶剤、水などを挙げることができるが、本発明においては、水を用いることが好ましい。即ち、窒化ケイ素粉末、焼結助剤、及び水を含む成形用組成物を成形して、被焼成体を得ることが好ましい。溶剤として水を用いる場合は、有機溶剤を用いる場合と比較して、環境負荷が低減され好ましい。特に、焼成炉内での残留溶媒の蒸発による爆発の危険性も回避することができるというメリットは、工業的に実施における安全管理上、極めて大きい。
　一般的には、成形用組成物に含まれる溶剤として水を用いると、得られる窒化ケイ素焼結体の内部に水由来の酸素が残存しやすく、そのため、熱伝導率が低下しやすい。これに対して、本発明では、前記固溶酸素量が一定値以下の窒化ケイ素粉末を用いることなどにより溶剤として水を用いて総酸素量が増加したとしても、前記総酸素量を制御することで熱伝導率の高い焼結体を得ることができる。
〔脱脂〕
　本発明において、前記被焼成体の形成に有機バインダーを使用する場合、成形体からの有機バインダーなどの有機成分の除去は、脱脂工程を設けて行うのが一般的である。脱脂条件は、特に限定されないが、例えば、有機バインダーを使用して成形された成形体を空気中又は窒素、アルゴン等の不活性雰囲気下で４５０～６５０℃に加熱することにより行えばよい。
　上記脱脂工程に使用する脱脂炉は、バッチ方式、連続方式のいずれでもよいが、後述の連続焼成炉との組み合わせにおいて、連続方式を採用することが好ましい。連続方式を具体的に例示すれば、前記温度に室内を加熱し得る加熱機構を備え、前記ガス雰囲気に調整された脱脂室に、脱脂用治具に載置した成形体を公知の搬送機構により連続的に通過させる方法が挙げられる。
　上記成形体が、焼結基板の製造を目的とした板状体である場合、脱脂用治具には、窒化ホウ素粉末などの離型材を塗布した複数枚の成形体を積層して載置し、脱脂に供するのが一般的である。
　上記脱脂用治具としては、脱脂を効率的に行うため、周壁の無い板状の治具が好適である。また、上記脱脂用治具は、後述する焼成において、脱脂体である被焼成体を焼成用治具に載せ替える際の破損を防止するため、周壁となる部材を取り付けて焼成用治具として使用できるように構成することが好ましい。例えば、板状の状態で脱脂用治具として使用した後、側壁を形成する筒状の部材を取り付けて焼成用治具として使用する態様が挙げられる。
　尚、上記脱脂用治具、焼成用治具の材質は、脱脂、さらに必要に応じて焼成において安定な公知の耐熱性材料が特に制限なく使用される。具体的には、カーボン部材が好適に使用される。
〔焼結方法〕
　本発明の窒化ケイ素焼結体の製造方法においては、前記常圧での焼結に適した特定の原料を選択することにより、常圧付近の圧力で、窒化ケイ素を焼成できるため、圧力容器（耐圧容器）内で製造する必要がなく前記被焼成体を、連続焼成炉を使用して連続的に焼成して窒化ケイ素焼結体を製造することを最大の特徴とする。かかる連続焼成炉の使用により、バッチ毎に炉の温度を常温から焼成温度まで昇温する必要が無く、極めて低エネルギーで焼結を行うことが可能となる。
　図１は、本発明の連続焼成を行うために使用される連続焼成炉の一態様を示す概略図である。
　図１に示すように、被焼成体１を収容した焼成用治具２を、上記焼成用治具の供給用開閉扉３と排出用開閉扉４と端部に有する密閉式の焼成容器５、上記焼成容器の胴部外周に設けられた加熱機構６、前記焼成用治具を焼成容器内に給排出するための搬送機構、及び、焼成容器内に不活性ガスを供給するためのガス供給機構を備えた連続焼成炉に供給して被焼成体の焼成を行い、窒化ケイ素焼結体を製造する。
　以下、上記焼成方法を、被焼成体１の形状が得られる焼結体を半導体装置の基板として使用される板状である態様について説明する。板状の被焼成体は、複数枚を積層して焼成用治具に収容して連続焼成炉に対して供給、排出を行うようにすることが効率的である。尚、被焼成体の成形を、有機バインダーを使用して行う場合、前記したように、脱脂を行う前から積層して扱うことが好ましい。また、上記積層は、層間に離型材として窒化ホウ素粉末を介在させることが好ましい。また、焼成用治具２は、図１の拡大図に示すように、側壁を有する箱形の容器が好適に使用される。また、図示されていないが、積層した被焼成体の上下端には、例えば、窒化ケイ素の板状焼結体を配することが好ましい。
　前記連続焼成炉において、不活性ガス雰囲気下で焼成を行うための焼成容器５は、前記常圧の圧力に耐えられる程度の構造を有していればよく、高度な耐圧構造は必要としない。
　例えば、ステンレス鋼等のケーシングに、耐熱性部材、具体的には、カーボン部材を内張したものが好適である。
　上記不活性ガス雰囲気下は、例えば、窒素ガスやアルゴンガスなどの不活性ガス（以下、窒素を例として記載する。）を焼成容器５に供給して形成される。上記焼成容器内の圧力は、０ＭＰａ・Ｇ以上０．１ＭＰａ・Ｇ未満に調整されることが好ましい。圧力は、好ましくは０ＭＰａ・Ｇ以上０．０５ＭＰａ・Ｇ以下であることが更に好ましい。ここで、圧力単位のＭＰａ・Ｇの末尾のＧはゲージ圧力を意味する。
　一般に、このような常圧又は略常圧領域の圧力であると、窒化ケイ素が分解し易いため、焼成のための温度を例えば１８００℃を超えて設定することができず、そのため、緻密化され、熱伝導率の高い窒化ケイ素焼結体を得ることが難しかった。これに対して、本発明の製造方法では、上記のように特定の原料を使用した被焼成体を用いているため、上記圧力範囲で窒化ケイ素の分解を防止し得る温度で焼成することができ、熱伝導率の高い窒化ケイ素焼結体を得ることができる。
　被焼成体は、１２００～１８００℃の温度に加熱して焼成させる。焼成のための温度が１２００℃未満であると窒化ケイ素の焼結が進行し難くなり、１８００℃を超えると窒化ケイ素が分解しやすくなる。このような観点から、焼成のための加熱温度は、１６００～１８００℃が好ましい。
　前記焼成容器５の胴部には、容器内を前記焼成のための温度に調整するための加熱機構６が設けられる。加熱機構６としては、カーボンヒーターが一般的である。更に、加熱機構６は、焼成容器５内の焼成のための温度までの昇温速度、上記温度の維持、上記温度からの冷却に至る温度プロファイルを調整するため、被焼成体の進行方向に、複数のゾーンに分割され、独立して温度制御可能とすることが好ましい。図面では、加熱機構６は３分割した態様が示されているが、より細かい温度設定を行うために、４分割、或いはそれ以上に分割し、それぞれの加熱温度を独立して調整できるように設けることができる。上記各ゾーンにおける加熱時間の比率は、加熱機構６の分割の比率を調整することによって変更することができる。
　また、前記連続焼成炉において、被焼成体１を収容した焼成用治具２を搬送するための搬送機構は、公知の連続加熱炉で採用されている構造が特に制限なく採用される。図１には、焼成容器５内において、焼成用治具２を焼成容器５の入口側から順次押し進める、プッシャー式の搬送機構を示すものである。具体的には、入口側から押し込まれた焼成用治具２を摺動させて炉内を移動させるための案内板８と、焼成容器５の出口付近において、焼成用治具２を独立して炉から取り出すための、駆動部を有する（図示せず）ローラー９を備える。
　前記加熱温度における焼成の時間は、特に限定されないが、前記焼成のための温度で３～２０時間程度とすることが好ましく、かかる時間は上記搬送手段による搬送速度、焼成容器の長さなどを調整することにより設定される。
　連続焼成炉の焼成容器５への焼成容器５の搬入搬出には、入口と出口にそれぞれ開閉が可能な供給用開閉扉３と排出用開閉扉４を設けて行われる。上記供給用開閉扉３と排出用開閉扉４は、焼成容器５内に焼成用治具２を供給する際、或いは、取り出す際の搬送機構の動作と連動して開閉する。上記供給用開閉扉３と排出用開閉扉４としては、焼成容器内の気密性を確保できる公知の構造のものが特に制限なく使用される。
　本発明で使用する連続焼成炉は、前記焼成容器５の入口側に、供給用開閉扉３により焼成容器５と仕切られ、内部空間の窒素置換を行う設備が設けられた供給室１１が設けられる。供給室においては、搬入扉（図示せず）を開いて焼成用治具を搬入し、内部空間を窒素置換し、焼成容器５内と圧力を合わせた後、供給用開閉扉３を開放し焼成用治具２を焼成容器内に押し込んで供給する操作が行われる。上記操作には、供給室１１にピストンシリンダー１０を設けて行うことができる。尚、供給室１１には、焼成容器５の搬送手段への供給をスムースに行うため、焼成容器の搬送面と高さを揃えた案内板７を備えることが好ましい。
　一方、前記焼成容器５の出口側には、排出用開閉扉４により焼成容器５と仕切られ、内部空間の窒素置換を行う設備が設けられた取出室１３が設けられる。焼成容器５より焼成用治具を取り出す際、取出室１３の内部空間を窒素置換し、焼成容器５内と圧力を合わせた後、排出用開閉扉４を開放し、焼成用治具２を取出室１３に取り出す操作が行われる。その後、排出用開閉扉４を閉とし、取出用扉１２を開いて取出室１３から窒化ケイ素焼結体を焼成用治具ごと取り出す。上記焼成用治具２の焼成容器５への供給、排出は、焼成容器内の焼成用治具２が一定数となるように、連動して実施されることが好ましい。
　かくして、連続焼成炉により、窒化ケイ素焼結体を連続して焼成することができる。
　本発明の方法において、前記脱脂工程、焼成後の処理工程も、前記連続焼成炉に接続して、連続で行うことも可能である。
［窒化ケイ素焼結体の物性］
　本発明の連続製造方法で得られる窒化ケイ素焼結体は、従来のバッチ式を採用した場合に劣らない優れた窒化ケイ素焼結体を製造することが可能である。前記好ましい条件を採用することにより、より高い熱伝導率を発揮することができる。例えば、熱伝導率が、８０Ｗ／ｍＫ以上、特に、１００Ｗ／ｍＫ以上の窒化ケイ素焼結体を得ることが可能である。また、絶縁破壊電圧は、１１ｋＶ以上、特に１３ｋＶ以上とすることが可能である。このような絶縁破壊電圧を備える窒化ケイ素焼結体は、絶縁破壊が生じ難く、半導体用の基板として使用する場合の信頼性に優れる。
　尚、前記熱伝導率、絶縁破壊電圧等の測定は、窒化ケイ素焼結体の表面をブラスト処理して、焼結時に焼結体に付着した離型材等の付着物を除去した後に測定した値である。
　以下、本発明をさらに具体的に説明するため実施例を示すが、本発明はこれらの実施例に限定されるものではない。なお、実施例において、各種物性の測定は以下の方法によって行ったものである。
（１）窒化ケイ素粉末のβ化率
　窒化ケイ素粉末のβ化率は、ＣｕＫα線を用いた粉末Ｘ線回折（ＸＲＤ）測定により求めた。具体的には、Ｃ．Ｐ．Ｇａｚｚａｒａ　ａｎｄ　Ｄ．Ｒ．Ｍｅｓｓｉｅｒ：Ａｍ．　Ｃｅｒａｍ．　Ｓｏｃ．　Ｂｕｌｌ．，５６（１９７７），７７７－７８０に記載された方法により、窒化ケイ素粉末のα相とβ相の重量割合を算出し、β化率を求めた。
（２）窒化ケイ素粉末の比表面積
　窒化ケイ素粉末の比表面積は、（株）マウンテック製のＢＥＴ法比表面積測定装置（ＭａｃｓｏｒｂＨＭｍｏｄｅｌ－１２０１）を用いて、窒素ガス吸着によるＢＥＴ１点法を用いて測定した。なお、上述した比表面積測定を行う前に、測定する窒化ケイ素粉末は事前に空気中で６００℃、３０分熱処理を行い、粉末表面に吸着している有機物を除去した。
（３）窒化ケイ素粉末の固溶酸素量及び全酸素量
　窒化ケイ素粉末の固溶酸素量は、不活性ガス融解－赤外線吸収法により測定した。測定は、酸素・窒素分析装置（ＨＯＲＩＢＡ社製「ＥＭＧＡ－９２０」）により行った。試料として各実施例、比較例で使用した窒化ケイ素粉末２５ｍｇをスズカプセルに封入（スズカプセルはＬＥＣＯ製のＴｉｎＣｕｐｓｕｌｅを使用）しグラファイト坩堝に導入し、５．５ｋＷで２０秒間加熱し、吸着ガスの脱ガスを行った後、０．８ｋＷで１０秒、０．８ｋＷから４ｋＷまで３５０秒かけて昇温しその間に発生した二酸化炭素の量を測定し、酸素含有量に換算した。３５０秒の昇温中、初期に発生する酸素が、窒化ケイ素粒子の表面に存在する酸化物由来の酸素（外部酸素）であり、遅れて発生する酸素が窒化ケイ素の結晶に固溶する固溶酸素（内部酸素）に相当することから、予め測定したバックグランドを差し引いたこれら２つの測定ピークの谷に相当する部分から垂線を引き、２つのピークを分離した。それぞれのピーク面積を比例配分することより、固溶酸素（内部酸素）量と、外部酸素量とを算出した。
（４）窒化ケイ素粉末の粒子径
　（ｉ）試料の前処理試料の窒化ケイ素粉末の前処理として、窒化ケイ素粉末を空気中で約５００℃の温度で２時間焼成処理を行った。上記焼成処理を行うことによって窒化ケイ素粉末に親水性を付与し、水溶媒に分散しやすくなって再現性の高い粒子径測定が可能となる。この際、空気中で焼成しても測定される粒子径にはほとんど影響がないことを確認している。
　（ｉｉ）粒子径の測定最大１００ｍＬの標線を持つビーカー（内径６０ｍｍφ、高さ７０ｍｍ）に、９０ｍＬの水と濃度５質量％のピロリン酸ナトリウム５ｍＬを入れてよく撹拌した後、耳かき一杯程度の試料の窒化ケイ素粉末を投入し、超音波ホモイナイザー（（株）日本精機製作所製ＵＳ－３００Ｅ、チップ径２６ｍｍ）によってＡＭＰＬＩＴＵＤＥ（振幅）５０％（約２アンペア）で２分間、窒化ケイ素粉末を分散させた。なお、上記チップは、その先端がビーカーの２０ｍＬの標線の位置まで挿入して分散を行った。次いで、得られた窒化ケイ素粉末の分散液について、レーザー回折・散乱法粒度分布測定装置（マイクロトラック・ベル（株）製マイクロトラックＭＴ３３００ＥＸＩＩ）を用いて粒度分布を測定した。測定条件は、溶媒は水（屈折率１．３３）を選択し、粒子特性は屈折率２．０１、粒子透過性は透過、粒子形状は非球形を選択した。上記の粒子径分布測定で測定された粒子径分布の累積カーブが５０％になる粒子径を平均粒子径（平均粒径Ｄ５０）とする。
（５）被焼成体の総酸素量
　被焼成体の総酸素量は、不活性ガス融解－赤外線吸収法により測定した。測定は、酸素・窒素分析装置（ＨＯＲＩＢＡ社製「ＥＭＧＡ－９２０」）により行った。試料として被焼成体１５ｍｇをスズカプセルに封入（スズカプセルはＬＥＣＯ製のＴｉｎＣｕｐｓｕｌｅを使用）しグラファイト坩堝に導入し、５．５ｋＷで２０秒間加熱し、さらに５．０ｋＷで２０秒間加熱し吸着ガスの脱ガスを行った後、５．０ｋＷで７５秒加熱しその間に発生した二酸化炭素の量を測定し、酸素含有量に換算した。
（６）被焼成体の密度
　自動比重計（新光電子（株）製：ＤＭＡ－２２０Ｈ型）を使用してそれぞれの被焼成体について密度を測定し、１５ピースの平均値を被焼成体の密度とした。
（７）被焼成体のアルミニウム元素の総含有量
　被焼成体中のアルミニウム元素の総含有量は、誘導結合プラズマ発光分光分析装置（サーモフィッシャーサイエンティフック社製「ｉＣＡＰ６５００ＤＵＯ」）を用いて測定した。
（８）窒化ケイ素焼結体の熱伝導率
　窒化ケイ素焼結体の熱伝導率は、京都電子工業製ＬＦＡ－５０２を用いてレーザーフラッシュ法により測定した。熱伝導率は、熱拡散率と焼結体密度と焼結体比熱の掛け算によって求められる。尚、窒化ケイ素焼結体の比熱は０．６８（Ｊ／ｇ・Ｋ）の値を採用した。焼結体密度は、自動比重計（新光電子（株）製：ＤＭＡ－２２０Ｈ型）を用いて測定した。なお、熱伝導率の測定は、窒化ケイ素焼結体の表面をブラスト処理した後、表面にＡｕコート及びカーボンコートをした後に行った。
（９）窒化ケイ素焼結体の絶縁破壊電圧
　ＪＩＳＣ２１１０に準じて、絶縁破壊電圧を測定した。具体的には、絶縁耐圧測定装置装置（計測技術研究所社製「ＴＫ－Ｏ－２０Ｋ」）を用いて、窒化ケイ素焼結体に電圧を加え、絶縁破壊が生じたときの電圧を測定した。
（１０）窒化ケイ素焼結体のＲａ（算術平均粗さ）
　窒化ケイ素焼結体のＲａは、表面粗さ測定器（東京精密株式会社製、「サーフコム４８０Ａ」）を用いて、評価長さ２．５ｍｍ、測定度０．３ｍｍ／ｓで針を走査させて、Ｒａを測定した。なお、窒化ケイ素焼結体は、表面をブラスト処理して離型材等を除去したものを用いた。
＜窒化ケイ素粉末＞
　シリコン粉末（半導体グレード、平均粒径５μｍ）と、希釈剤である窒化ケイ素粉末（平均粒径１．５μｍ）とを混合し、原料粉末（Ｓｉ：８０質量％、Ｓｉ３Ｎ４：２０質量％）を得た。該原料粉末を反応容器に充填し、原料粉末層を形成させた。次いで、該反応容器を着火装置とガスの給排機構を有する耐圧性の密閉式反応器内に設置し、反応器内を減圧して脱気後、窒素ガスを供給して窒素置換した。その後、窒素ガスを除々に供給し、０．７ＭＰａまで上昇せしめた。所定の圧力に達した時点（着火時）での原料粉末の嵩密度は０．５ｇ／ｃｍ３であった。その後、反応容器内の原料粉末の端部に着火し、燃焼合成反応を行い、窒化ケイ素よりなる塊状生成物を得た。得られた塊状生成物を、お互いに擦り合わせることで解砕した後、振動ミルに適量を投入して６時間の微粉砕を行った。なお、微粉砕機及び微粉砕方法は、常法の装置及び方法を用いているが、重金属汚染防止対策として粉砕機の内部はウレタンライニングを施し、粉砕メディアには窒化ケイ素を主剤としたボールを使用した。また微粉砕開始直前に粉砕助剤としてエタノールを１質量％添加し、粉砕機を密閉状態として微粉砕を行い、以下の特性を有する窒化ケイ素粉末を得た。
　・β化率　９９％
　・固溶酸素量　０．０６質量％
　・比表面積　１３．５ｍ２／ｇ
　・全酸素量　１．８４質量％
　・平均粒径：Ｄ５０　１．２μｍ
　・０．５μｍ以下の粒子の割合　２５質量％
　・１．０μｍ以上の粒子の割合　３２質量％
＜焼結助剤＞
　酸素結合を持たない化合物Ｙ２Ｓｉ４Ｎ６Ｃ粉末については、イットリア（信越化学工業株式会社製）、窒化ケイ素粉末（上記記載の自社製粉末）および炭素粉末（三菱化学製）を、下記反応式を用い加熱合成を行い作製した。
　８Ｓｉ３Ｎ４＋６Ｙ２Ｏ３＋１５Ｃ＋２Ｎ２　→　６Ｙ２Ｓｉ４Ｎ６Ｃ＋９ＣＯ２
　また酸素結合を持たない化合物ＭｇＳｉＮ２粉末については、マグネシウム粉末（山石金属株式会社）、窒化ケイ素粉末（上記記載の自社製粉末）および金属ケイ素粉末（自社保有）を、下記反応式に示す加熱合成を行って作製した。
　　　Ｓｉ３Ｎ４＋Ｓｉ＋４Ｍｇ＋２Ｎ２　→　４ＭｇＳｉＮ２
＜有機バインダー＞
　有機バインダーとして、ポリビニルアルコール樹脂（日本酢ビ・ポバール株式会社）を用いた。
［実施例１］
　窒化ケイ素粉末Ａ１００質量部、酸素結合を含まない化合物Ｙ２Ｓｉ４Ｎ６Ｃ：２質量部、ＭｇＳｉＮ２：５質量部、イットリア：３質量部、秤量し、水を分散媒として樹脂ポットと窒化ケイ素ボールを用いて、２４時間ボールミルで粉砕混合を行った。なお、水はスラリーの濃度が６０質量％となるように予め秤量し、樹脂ポット内に投入した。粉砕混合後、ポリビニルアルコール樹脂を２２質量部添加し、さらに１２時間混合を行いスラリー状の成形用組成物を得た。次いで、該成形用組成物を、真空脱泡機（サヤマ理研製）を用いて粘度調整を行い、塗工用スラリーを作製した。その後、この粘度調整した成形用組成物をドクターブレード法によりシート成形を行い、幅７５ｃｍ、厚さ０．４２ｍｍｔのシート成形体を得た。上記の通り得られたシート成形体１０枚を、窒化ホウ素粉末よりなる離型材を塗布して板状の治具に重ねて載置し、これを脱脂炉にセットして脱脂処理を行い、被焼成体を得た。尚、脱脂処理は、バッチで、乾燥空気中５５０℃で行った。
　得られた被焼成体のアルミニウム元素の総含有量は５００ｐｐｍであった。次いで、被焼成体を載置した前記カーボン製の板状の治具に、カーボン製の四角い筒状体を取り付けて、図１の拡大図に示すようにその周囲を囲うようにセットした。
　上記被焼成体が収容された治具を順次製造し、これを図１に示す連続焼成炉に供給して連続焼成を実施した。
　連続焼成炉は、焼成容器５の胴部に４分割された加熱機構６を備えたものを使用し、図２に示す焼成プロファイルとなるよう、搬送速度に合わせてゾーン毎の温度設定をプログラムされた。焼成容器５内に窒素を供給し、圧力を０．０２ＭＰａ・Ｇに調整した。一方、被焼成体は焼成用治具２に載置された状態で、前記供給室１１の搬入扉（図示せず）を開いて供給室に搬入し、搬入扉を閉とした後、内部空間を窒素置換し、焼成容器５内と圧力を合わせた後、供給用開閉扉３を開放し焼成用治具２を焼成容器５内にピストンシリンダー１０により押し込むことにより供給した。
　焼成用治具は、上記操作の繰り返しにより、焼成容器５内を順次進み、その間、焼成容器５の長さ、加熱機構６の分割数、各ゾーンの長さを設定すると共に、各ゾーンの温度を制御することにより、図２に示す温度プロファイル（全所要時間２４時間）となるように加熱した。
　焼成が完了した焼成用治具２は、取出室１３の内部空間を窒素置換し、焼成容器５内と圧力を合わせた後、排出用開閉扉４を開とし、焼成用治具２を取出室１３に取り出した。その後、排出用開閉扉４を閉とし、取出用扉１２を開いて取出室１３から窒化ケイ素焼結体を焼成用治具ごと取り出した。
　得られた窒化ケイ素焼結体の物性は、連続生産された１０００枚のうち、任意の１００枚を抜き出して測定した値の平均で、相対密度９９％、熱伝導率１０８Ｗ／ｍＫ、表面粗さＲａが０．５７μｍ、絶縁破壊電圧が１６ｋＶであり、十分に実用に耐える窒化ケイ素焼結体を連続して製造できることが判明した。
　１　被焼成体
　２　焼成用治具
　３　供給用開閉扉
　４　排出用開閉扉
　５　焼成容器
　６　加熱機構
　７　案内板
　８　案内板
　９　ローラー
１０　ピストンシリンダー
１１　供給室
１２　取出用扉
１３　取出室

Claims (5)

  1. 　β化率が８０％以上、比表面積が７～２０ｍ２／ｇの窒化ケイ素粉末と、焼結助剤とを含有し、アルミニウム元素の総含有量が８００ｐｐｍ以下に調整された被焼成体を収容した焼成用治具を、上記焼成用治具の供給用開閉扉と排出用開閉扉とを端部に有する密閉式の焼成容器、上記焼成容器の胴部外周に設けられた加熱機構、前記焼成用治具を焼成容器内に給排出するための搬送機構、及び、焼成容器内に不活性ガスを供給するためのガス供給機構を備えた連続焼成炉に供給し、不活性ガス雰囲気下及び０ＭＰａ・Ｇ以上０．１ＭＰａ・Ｇ未満の圧力下に、１２００～１８００℃の温度に加熱して窒化ケイ素を焼結することを特徴とする、窒化ケイ素焼結体の連続製造方法。
  2. 　加熱機構が焼成用容器の搬送方向に対して複数に分割され、それぞれの加熱温度が独立して調整可能とした請求項１記載の窒化ケイ素焼結体の連続製造方法。
  3. 　前記被焼成体が、窒化ケイ素粉末、焼結助剤、及び水を含む成形用組成物を成形したものである請求項１又は２に記載の窒化ケイ素焼結体の連続製造方法。
  4. 　前記被焼成体が板状であり、複数枚を積層して焼成用治具に収容した、請求項１～３のいずれか１項に記載の窒化ケイ素焼結体の連続製造方法。
  5. 　窒化ケイ素粉末と、焼結助剤とを含有する被焼成体を収容した焼成用治具、前記焼成用治具の供給用開閉扉と排出用開閉扉とを端部に有する密閉式の焼成容器、前記焼成容器の胴部外周に設けられた加熱機構、前記焼成用治具を前記焼成容器内に給排出するための搬送機構、及び、前記焼成容器内に不活性ガスを供給するためのガス供給機構を備えることを特徴とする、窒化ケイ素焼結用連続焼成炉。
PCT/JP2021/024642 2020-06-30 2021-06-29 窒化ケイ素焼結体の連続製造方法 WO2022004754A1 (ja)

Priority Applications (5)

Application Number Priority Date Filing Date Title
KR1020227041851A KR20230031202A (ko) 2020-06-30 2021-06-29 질화규소 소결체의 연속 제조 방법
JP2022534063A JPWO2022004754A1 (ja) 2020-06-30 2021-06-29
CN202180043686.0A CN115715278A (zh) 2020-06-30 2021-06-29 氮化硅烧结体的连续制造方法
US18/011,865 US20230357087A1 (en) 2020-06-30 2021-06-29 Method for continuously producing silicon nitride sintered compact
EP21833521.4A EP4174425A1 (en) 2020-06-30 2021-06-29 Method for continuously producing silicon nitride sintered compact

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2020112366 2020-06-30
JP2020-112366 2020-06-30

Publications (1)

Publication Number Publication Date
WO2022004754A1 true WO2022004754A1 (ja) 2022-01-06

Family

ID=79316519

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2021/024642 WO2022004754A1 (ja) 2020-06-30 2021-06-29 窒化ケイ素焼結体の連続製造方法

Country Status (7)

Country Link
US (1) US20230357087A1 (ja)
EP (1) EP4174425A1 (ja)
JP (1) JPWO2022004754A1 (ja)
KR (1) KR20230031202A (ja)
CN (1) CN115715278A (ja)
TW (1) TW202204288A (ja)
WO (1) WO2022004754A1 (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7161638B1 (ja) 2022-03-30 2022-10-26 株式会社ノリタケカンパニーリミテド マッフル炉

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01252886A (ja) * 1988-03-31 1989-10-09 Central Glass Co Ltd 熱加工炉並びにそれによる熱処理方法
JP2000264608A (ja) 1999-03-23 2000-09-26 Osamu Yamada 燃焼合成反応によるＢＮ、ＡｌＮ又はＳｉ３Ｎ４の製造方法
JP2002128569A (ja) 2000-10-19 2002-05-09 National Institute Of Advanced Industrial & Technology 高熱伝導窒化ケイ素セラミックス並びにその製造方法
JP2008175517A (ja) * 2006-03-08 2008-07-31 Ibiden Co Ltd 焼成体用冷却機、焼成炉、セラミック焼成体の冷却方法、及び、ハニカム構造体の製造方法
WO2013105577A1 (ja) * 2012-01-12 2013-07-18 住友化学株式会社 トンネルキルン及びこれを用いた焼成体の製造方法
WO2019167879A1 (ja) 2018-02-28 2019-09-06 株式会社トクヤマ 窒化ケイ素粉末の製造方法

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5352395A (en) * 1992-07-17 1994-10-04 Phillips Petroleum Company Carbon and ceramic-containing layers for use in sintering of silicon nitride article
DE10165107B3 (de) * 2000-09-20 2015-06-18 Hitachi Metals, Ltd. Substrat mit Siliciumnitrid-Sinterkörper und Leiterplatte
KR20030041096A (ko) * 2001-11-16 2003-05-23 니혼도꾸슈도교 가부시키가이샤 질화규소질 소결체 및 질화규소질 공구
FR2865671B1 (fr) * 2004-01-30 2007-03-16 Commissariat Energie Atomique Nanopoudre ceramique apte au frittage et son procede de synthese
DE112013005817T5 (de) * 2012-12-05 2015-09-24 Dow Global Technologies Llc Poröse Mullitkörper mit verbesserter thermischer Beständigkeit
WO2015060274A1 (ja) * 2013-10-23 2015-04-30 株式会社東芝 窒化珪素基板およびそれを用いた窒化珪素回路基板
US9938444B2 (en) * 2014-03-31 2018-04-10 Japan Fine Ceramics Co., Ltd. Method for producing silicon nitride substrate
EP3281927B1 (en) * 2015-04-07 2020-02-19 Kabushiki Kaisha Toshiba Silicon nitride sintered body and high-temperature-resistant member using the same
TWI657043B (zh) * 2016-12-12 2019-04-21 日商宇部興產股份有限公司 氮化矽粉末及氮化矽燒結體之製造方法
CN107588662B (zh) * 2017-10-27 2024-01-09 宁波恒普技术股份有限公司 一种真空脱脂烧结炉

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01252886A (ja) * 1988-03-31 1989-10-09 Central Glass Co Ltd 熱加工炉並びにそれによる熱処理方法
JP2000264608A (ja) 1999-03-23 2000-09-26 Osamu Yamada 燃焼合成反応によるＢＮ、ＡｌＮ又はＳｉ３Ｎ４の製造方法
JP2002128569A (ja) 2000-10-19 2002-05-09 National Institute Of Advanced Industrial & Technology 高熱伝導窒化ケイ素セラミックス並びにその製造方法
JP2008175517A (ja) * 2006-03-08 2008-07-31 Ibiden Co Ltd 焼成体用冷却機、焼成炉、セラミック焼成体の冷却方法、及び、ハニカム構造体の製造方法
WO2013105577A1 (ja) * 2012-01-12 2013-07-18 住友化学株式会社 トンネルキルン及びこれを用いた焼成体の製造方法
WO2019167879A1 (ja) 2018-02-28 2019-09-06 株式会社トクヤマ 窒化ケイ素粉末の製造方法

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
C.P. GAZZARAD.R. MESSIER, AM. CERAM. SOC. BULL., vol. 56, 1977, pages 777 - 780
JOURNAL OF THE CERAMIC SOCIETY OF JAPAN, vol. 100, no. 11, 1992, pages 1366 - 1370
JOURNAL OF THE MARINE ENGINEERING SOCIETY IN JAPAN, vol. 28, September 1993 (1993-09-01), pages 548 - 556

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP7161638B1 (ja) 2022-03-30 2022-10-26 株式会社ノリタケカンパニーリミテド マッフル炉
JP2023148905A (ja) * 2022-03-30 2023-10-13 株式会社ノリタケカンパニーリミテド マッフル炉

Also Published As

Publication number Publication date
KR20230031202A (ko) 2023-03-07
EP4174425A1 (en) 2023-05-03
JPWO2022004754A1 (ja) 2022-01-06
TW202204288A (zh) 2022-02-01
CN115715278A (zh) 2023-02-24
US20230357087A1 (en) 2023-11-09

Similar Documents

Publication Publication Date Title
WO2021107021A1 (ja) 窒化ケイ素焼結体の製造方法
Medri et al. Comparison of ZrB2‐ZrC‐SiC composites fabricated by spark plasma sintering and hot‐pressing
TWI573757B (zh) A silicon nitride powder manufacturing method and a silicon nitride powder, and a silicon nitride sintered body and a circuit board using the same
JP5836522B2 (ja) 窒化ケイ素基板の製造方法
WO2022004755A1 (ja) 窒化ケイ素焼結基板
WO2019167879A1 (ja) 窒化ケイ素粉末の製造方法
KR20170021282A (ko) 질화규소 분말, 질화규소 소결체 및 회로 기판, 및 질화규소 분말의 제조 방법
Solodkyi et al. Synthesis of B6O powder and spark plasma sintering of B6O and B6O–B4C ceramics
Wang et al. Enhanced thermal conductivity in Si3N4 ceramics prepared by using ZrH2 as an oxygen getter
WO2022004754A1 (ja) 窒化ケイ素焼結体の連続製造方法
Nakashima et al. Effects of heating rate on microstructure and property of sintered reaction bonded silicon nitrides
Vlasova et al. Synthesis of composite AlN-AlON-Al2O3 powders and ceramics prepared by high-pressure sintering
Lee et al. Densification of ZrB2–SiC nanocomposites prepared using ZrSi2, B4C, and C additives
Bezdorozhev et al. Tough yttria-stabilized zirconia ceramic by low-temperature spark plasma sintering of long-term stored nanopowders
JP7337304B1 (ja) 窒化ケイ素粉末
WO2022210369A1 (ja) 窒化ケイ素焼結体の製造方法
WO2024195605A1 (ja) 窒化ケイ素仮焼体及びその製造方法、並びに、窒化ケイ素粉末の製造方法
WO2024095834A1 (ja) 窒化ケイ素焼結体
Lin et al. Properties and microstructure of AlN prepared using alumina crucible and MoSi2 heating element
Zhang et al. Synthesis of Novel Al2O3-Mullite-cBN Composites from a Mixture of Al2O3 with SiO2 Nanolayer Coated cBN by Rotary CVD and Spark Plasma Sintering
CN115819089A (zh) 一种抗非晶化且高硬度、高韧性碳化硼复相陶瓷的制备方法
EP4455078A1 (en) Silicon nitride powder
TW202434540A (zh) 氮化矽燒結體
Chung et al. Microwave Sintering of Combustion Synthesized AlN Powder towards High Thermal Conductivity Ceramics
PRESSING Encapsulation HIPing of laser synthesized nanosize silicon carbide

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21833521

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2022534063

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2021833521

Country of ref document: EP

Effective date: 20230130