WO2016125519A1 - Semiconductor element and method for manufacturing same - Google Patents

Semiconductor element and method for manufacturing same Download PDF

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Publication number
WO2016125519A1
WO2016125519A1 PCT/JP2016/050204 JP2016050204W WO2016125519A1 WO 2016125519 A1 WO2016125519 A1 WO 2016125519A1 JP 2016050204 W JP2016050204 W JP 2016050204W WO 2016125519 A1 WO2016125519 A1 WO 2016125519A1
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ceramic
semiconductor element
particles
sintered body
internal electrode
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PCT/JP2016/050204
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French (fr)
Japanese (ja)
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渉 青戸
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株式会社村田製作所
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    • 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
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
    • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
    • C04B35/465—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates
    • C04B35/468—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
    • H01C7/02—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material having positive temperature coefficient

Definitions

  • the present invention relates to a semiconductor element and a manufacturing method thereof, and more particularly to a barium titanate-based semiconductor element and a manufacturing method thereof.
  • barium titanate-based semiconductor ceramics have a positive temperature characteristic, they are widely used in semiconductor elements such as a positive temperature coefficient thermistor (PTC thermistor).
  • PTC thermistor positive temperature coefficient thermistor
  • Patent Document 1 discloses a semiconductor porcelain characterized in that, in a BaTiO 3 -based semiconductor ceramic subjected to reduction firing reoxidation, the sintered density is 85 to 90% relative density. . Patent Document 1 describes that sufficient PTC characteristics can be obtained by appropriately reducing the sintered density, and that the particle size of the semiconductor ceramic is preferably 0.5 to 2 ⁇ m.
  • Patent Document 2 discloses a barium titanate semiconductor ceramic having an average ceramic particle size of 0.9 ⁇ m or less. Patent Document 2 describes that a barium titanate-based semiconductor ceramic having an average ceramic particle size in the above range has a small specific resistance at room temperature and an excellent withstand voltage strength. Patent Document 2 discloses that the above-described barium titanate-based semiconductor ceramic has a particle size of 0.1 ⁇ m or less, a crystal structure of cubic, a lattice constant of 4.020 angstroms or more, and a small amount of semiconductor. It is described that a barium titanate powder in which an agent is solid-solved or a product obtained by calcining the barium titanate powder is used as a raw material powder and is fired.
  • PTC thermistors are used in a wide variety of electronic devices to protect against overcurrent. With the recent increase in functionality of electronic devices, a PTC thermistor capable of handling particularly a large current has been demanded, and a PTC thermistor element having high withstand voltage characteristics has been developed. In order to improve the withstand voltage characteristics of the PTC thermistor, semiconductor ceramics constituting the PTC thermistor are made fine (Patent Document 2). However, as a result of repeated studies by the present inventor, it has been found that there is a problem that the operating temperature of the PTC thermistor decreases due to the formation of fine particles.
  • An object of the present invention is to provide a semiconductor device having high withstand voltage characteristics and a high operating temperature, and a method for manufacturing the same.
  • the present inventor reduced the Curie point of the ceramic sintered body particles by making the ceramic sintered body particles contained in the ceramic body constituting the PTC thermistor fine, and as a result, the operating temperature of the PTC thermistor decreased. I paid attention to it.
  • perovskite-type barium titanate compound particles with high tetragonal properties as raw materials, even if the ceramic sintered particles are made fine particles to improve the withstand voltage characteristics, It has been found that the reduction of the point can be suppressed and a high operating temperature can be achieved, and the present invention has been completed.
  • a ceramic body including ceramic sintered body particles; A first external electrode disposed on a first end face of the ceramic body, A semiconductor element including a second external electrode disposed on a second end face of the ceramic body, Ceramic sintered body particles are perovskite type compounds containing at least Ba and Ti, The average particle size of the ceramic sintered body particles is 1.0 ⁇ m or less, A semiconductor element is provided in which the ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles is 1.007 or more.
  • the average particle diameter of the ceramic sintered body particles described above is preferably 0.6 ⁇ m or more and 0.9 ⁇ m or less. Further, the ratio (tetragonal) c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles described above is preferably 1.008 or more and 1.010 or less.
  • the Curie point of the ceramic sintered body particles described above can be 100 ° C. or higher.
  • the semiconductor element described above may be a stacked semiconductor element in which one or more first internal electrodes and one or more second internal electrodes are arranged inside a ceramic body.
  • the first internal electrode is electrically connected to the first external electrode at the first end face of the ceramic body
  • the second internal electrode is connected to the second end face of the ceramic base body at the second end face. Electrically connected to the external electrode.
  • the first internal electrode and the second internal electrode may be Ni electrodes.
  • a method for manufacturing a semiconductor element Preparing perovskite-type compound particles containing at least Ba and Ti; Forming a green chip containing perovskite-type compound particles; Obtaining a ceramic body by firing a green chip; Forming a semiconductor element by forming external electrodes on both end faces of the ceramic body,
  • the specific surface area of the perovskite type compound particles is 2.9 m 2 / g or more and 13.0 m 2 / g or less,
  • a method is provided wherein the ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the perovskite type compound particles is not less than 1.006 and not more than 1.010.
  • the step of forming the green chip containing the perovskite type compound particles Producing a ceramic green sheet containing perovskite type compound particles; Applying a conductive paste for internal electrodes on the main surface of the ceramic green sheet; A step of obtaining a laminate by laminating a plurality of the ceramic green sheets coated with the internal electrode conductive paste; And placing a ceramic green sheet not coated with the internal electrode conductive paste on the upper and lower sides of the laminate and pressing the ceramic green sheet, and cutting to a predetermined size to obtain a green chip.
  • the above-mentioned internal electrode conductive paste may contain Ni metal powder as the conductive powder.
  • the semiconductor element according to the present invention has a high withstand voltage characteristic and a high operating temperature by having the above configuration. Moreover, the manufacturing method of the semiconductor element which concerns on this invention can manufacture the semiconductor element which has a high withstand voltage characteristic and high operating temperature by having the said structure.
  • FIG. 1 is a schematic cross-sectional view of a semiconductor device according to an embodiment of the present invention.
  • FIG. 2 is a schematic cross-sectional view of a modification of the semiconductor device according to one embodiment of the present invention.
  • FIG. 3 is a schematic cross-sectional view of another modification of the semiconductor device according to one embodiment of the present invention.
  • FIG. 1 is a schematic cross-sectional view of a semiconductor element 1 according to this embodiment.
  • the semiconductor element 1 according to this embodiment is a PTC thermistor.
  • a semiconductor element 1 shown in FIG. 1 is disposed on a ceramic body 2, a first external electrode 31 disposed on a first end surface 21 of the ceramic body 2, and a second end surface 22 of the ceramic body 2.
  • Second external electrode 32 is disposed on a ceramic body 2, a first external electrode 31 disposed on a first end surface 21 of the ceramic body 2, and a second end surface 22 of the ceramic body 2.
  • the ceramic body 2 includes ceramic sintered body particles.
  • the sintered ceramic particles are made of a ceramic material in which a donor element is added to barium titanate.
  • the ceramic sintered body particles are a perovskite type compound containing at least Ba and Ti.
  • the perovskite-type compound includes, in addition to Ba and Ti, at least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu and / or a group consisting of Nb, W, Sb and Ta. It may contain at least one element selected.
  • At least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu is at least one element selected from the group consisting of “element ⁇ ”, Nb, W, Sb and Ta Is also referred to as “element ⁇ ”.
  • the elements ⁇ and ⁇ are donors (semiconductor agents) for imparting PTC characteristics to the ceramic body 2.
  • the ceramic sintered body particles may include only one of the above-described element ⁇ and element ⁇ , or may include both elements ⁇ and ⁇ .
  • the ceramic body 2 preferably contains 99.5 mol parts or more and 100.5 mol parts or less of Ba when the total mol portion of Ti and ⁇ is 100 mol parts.
  • the ceramic body 2 may contain the above-described element ⁇ and / or element ⁇ in addition to Ba and Ti.
  • the ceramic body 2 contains the element ⁇ and / or the element ⁇ in such an amount that the total content of the elements ⁇ and ⁇ in the ceramic body 2 is 0.020 mol part or more and 0.500 mol part or less. Is preferred.
  • the ceramic body 2 may contain Zr that may be inevitably mixed in the manufacturing process. Zr may occur due to the use of zirconia balls as a grinding and dispersion medium when preparing a ceramic slurry described later.
  • the ceramic body 2 may include 0.010 mol part or more and 0.600 mol part or less of Zr.
  • the average particle diameter of the ceramic sintered body particles contained in the ceramic body 2 is 1.0 ⁇ m or less.
  • the semiconductor device 1 can achieve high withstand voltage characteristics.
  • the average particle diameter of the ceramic sintered body particles is preferably 0.6 ⁇ m or more and 0.9 ⁇ m or less.
  • the average particle size is 0.6 ⁇ m or more, the specific resistance of the ceramic body can be reduced, and consequently the resistance value of the semiconductor element can be reduced.
  • the average particle size is 0.9 ⁇ m or less, the withstand voltage characteristics of the semiconductor element 1 can be further improved.
  • the average particle diameter of the sintered ceramic particles can be calculated by observing a cross section of the semiconductor element with a scanning electron microscope (SEM) and performing image analysis.
  • the ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles contained in the ceramic body 2 is 1.007 or more.
  • c / a is 1.007 or more, a high Curie point can be maintained even when the average particle size of the ceramic sintered body particles is small, and as a result, a semiconductor element 1 having a high operating temperature is obtained. be able to.
  • the ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles is preferably 1.008 or more and 1.010 or less.
  • the Curie point of the ceramic sintered body particles can be further increased.
  • the ceramic body 2 is composed of a barium titanate material
  • c / a is generally 1.010 or less.
  • the c / a of the sintered ceramic particles can be calculated by performing a qualitative analysis using a powder X-ray diffractometer and performing a Rietveld analysis. In the present specification, it may be considered that the c / a measurement value of the ceramic sintered body particles is substantially the same as the c / a measurement value of the ceramic body 2.
  • the Curie point of the ceramic sintered body particles contained in the ceramic body 2 can be 100 ° C. or higher.
  • the semiconductor element 1 can be used in an operating temperature range of 85 ° C., which is generally required in the market of in-vehicle thermistors, even when variation in the Curie point of each product is taken into consideration. Can be suitably used.
  • the Curie point of ceramic sintered body particles can be determined by differential scanning calorimetry (DSC). In the present specification, the measured value of the Curie temperature of the ceramic sintered body particles may be considered to be substantially the same as the measured value of the Curie temperature of the ceramic body 2.
  • the dimensions of the ceramic body 2 are not particularly limited, and can be set as appropriate according to the application.
  • the dimension of the ceramic body 2 may be, for example, L dimension 2.0 mm ⁇ W dimension 1.2 mm ⁇ T dimension 1.0 mm.
  • the direction from the first end face 21 to the second end face 22 of the ceramic body 2 is the “L direction”, and the direction perpendicular to the L direction in the horizontal plane. Is called the “W direction”, and the direction perpendicular to the L direction and the W direction is called the “T direction”.
  • the dimension of the ceramic body 2 in the L direction is referred to as “L dimension”, the dimension in the W direction as “W dimension”, and the dimension in the T direction as “T dimension”.
  • the semiconductor element 1 is a stacked semiconductor in which one or more first internal electrodes 41 and one or more second internal electrodes 42 are arranged inside a ceramic body 2. It may be an element.
  • the first internal electrode 41 and the second internal electrode 42 may be collectively referred to as “internal electrodes”.
  • the first internal electrode 41 is electrically connected to the first external electrode 31 at the first end face 21 of the ceramic body 2, and the second internal electrode 42 is the second end face 22 of the ceramic body 2. And electrically connected to the second external electrode 32.
  • the first internal electrode 41 extends from the first end face 21 of the ceramic body 2 toward the second end face 22, and the second internal electrode 42 extends from the second end face 22 of the ceramic body 2.
  • the first internal electrodes 41 and the second internal electrodes 42 are alternately arranged so as to face each other inside the ceramic body 2.
  • the number of internal electrodes (the total of the first internal electrode 41 and the second internal electrode 42) may be, for example, about 2 or more and 50 or less.
  • the distance between the adjacent first internal electrode 41 and second internal electrode 42 is not particularly limited, and can be appropriately set according to a desired application.
  • the distance between the adjacent first internal electrode 41 and second internal electrode 42 may be, for example, about 10 ⁇ m to 200 ⁇ m.
  • the composition of the internal electrode is not particularly limited, and may be set as appropriate according to the application.
  • the first internal electrode 41 and the second internal electrode 42 may be, for example, Ni electrodes that exhibit good ohmic properties with respect to a barium titanate-based semiconductor.
  • a glass layer 5 may be formed on the surface of the ceramic body 2 as shown in FIG.
  • the glass layer 5 has a function of improving environmental resistance and element strength.
  • the composition and thickness of the glass layer 5 are not particularly limited, and may be set as appropriate according to the application.
  • the first internal electrode 41 and the second internal electrode 42 are disposed inside the ceramic body 2, but the semiconductor element 1 according to the present embodiment is limited to this configuration. However, the configuration may be such that no internal electrode is provided.
  • plating layers 61 and 62 (described later) are formed on the surfaces of the first external electrode 31 and the second external electrode 32.
  • the semiconductor element 1 according to the present embodiment is It is not limited to this structure, The structure which does not have a plating layer may be sufficient.
  • the semiconductor element 1 includes a first external electrode 31 disposed on the first end surface 21 of the ceramic body 2 and a second external surface disposed on the second end surface 22 of the ceramic body 2. Electrode 32.
  • the first external electrode 31 and the second external electrode 32 may be formed so as to extend to a part of the side surface of the ceramic body 2 as shown in FIG.
  • the “side surface” of the ceramic body 2 refers to a surface other than the first end surface 21 and the second end surface 22 of the ceramic body 2.
  • the first external electrode 31 and the second external electrode 32 may be collectively referred to as “external electrode”.
  • the composition and configuration of the external electrode can be appropriately set according to the type of the ceramic body 2 or the internal electrodes (the first internal electrode 41 and the second internal electrode 42) when present.
  • the first external electrode 31 and the second external electrode 32 may have, for example, a multilayer structure in which Cr, NiCu alloy, and Ag are sequentially stacked.
  • plating layers 61 and 62 may be formed on the surfaces of the first external electrode 31 and the second external electrode 32 as shown in FIG.
  • the plating layers 61 and 62 have a function of improving solder wettability and heat resistance during mounting.
  • the composition of the plating layers 61 and 62 can be appropriately selected according to the composition of the external electrode, and may be, for example, a Sn plating layer, a Ni plating layer, or a combination of two or more thereof.
  • the first internal electrode 41 and the second internal electrode 42 are disposed inside the ceramic body 2, but the semiconductor element 1 according to the present embodiment is limited to this configuration. However, the configuration may be such that no internal electrode is provided.
  • the glass layer 5 is formed on the surface of the ceramic body 2, but the semiconductor element 1 according to the present embodiment is not limited to this configuration. The structure which does not have may be sufficient.
  • the method for manufacturing a semiconductor device includes a step of preparing perovskite type compound particles, a step of forming a green chip containing perovskite type compound particles, and a step of obtaining a ceramic body by firing the green chip. And forming a semiconductor element by forming external electrodes on both end faces of the ceramic body.
  • a method for manufacturing a stacked PTC thermistor having an internal electrode will be mainly described.
  • perovskite compound particles containing at least Ba and Ti are prepared as raw materials for the ceramic body constituting the semiconductor element.
  • the perovskite type compound particles as the raw material may contain at least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu and / or Nb, W, Sb and Ta in addition to Ba and Ti. It may contain at least one element selected from the group consisting of:
  • Each raw material of the perovskite type compound particles is weighed so that the composition of the ceramic sintered body particles contained in the ceramic body constituting the finally obtained semiconductor element becomes the target composition.
  • the composition of the target ceramic sintered body particles is as follows.
  • ICP-AES Inductively-Coupled-Plasma-Atomic-Emission-Spectrometry
  • It may be a composition represented by the formula (1).
  • ⁇ is at least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu, and ⁇ is at least one selected from the group consisting of Nb, W, Sb and Ta Elements.
  • m Ba is 99.50 ⁇ m Ba ⁇ 100.5
  • the range of m ( ⁇ + ⁇ ) is 0.020 ⁇ m ( ⁇ + ⁇ ) ⁇ 0.500
  • m is 0.995.
  • the ceramic sintered body particles contained in the ceramic body constituting the finally obtained semiconductor element contain the elements ⁇ and / or ⁇ as donors (semiconductor agents).
  • the raw material perovskite type compound particles may contain neither element ⁇ nor element ⁇ , or the total amount of element ⁇ and / or element ⁇ necessary for obtaining ceramic sintered particles having a desired composition may be included. It does not have to be included.
  • the amount of element ⁇ and / or ⁇ chloride, hydroxide, oxide, carbonate, alkoxide, ionized aqueous solution, etc. necessary for preparation of the ceramic slurry described later can be adjusted to the desired composition. it can.
  • the method for preparing the raw material perovskite type compound particles is not particularly limited, and a solid-phase synthesis method or a hydrothermal synthesis method such as a hydrothermal synthesis method or an oxalic acid method is appropriately used depending on the desired specific surface area and c / a. You can choose.
  • the raw material perovskite type compound particles may be prepared, for example, by the procedure described below. Each of the above-mentioned raw materials weighed is put into a ball mill together with PSZ (partially stabilized zirconia) balls and pure water, sufficiently mixed and pulverized in a wet manner, and dried to obtain a mixed powder.
  • PSZ partially stabilized zirconia
  • raw material perovskite type compound particles are obtained.
  • the calcination temperature can be appropriately set according to the specific surface area of the target perovskite type compound particles and the value of c / a.
  • the specific surface area of the raw material perovskite compound particles is preferably 2.9 m 2 / g or more and 13.0 m 2 / g or less.
  • the specific surface area is 2.9 m 2 / g or more, the ceramic sintered body particles in the ceramic body constituting the semiconductor element to be obtained can be reduced to an average particle size of 0.9 ⁇ m or less.
  • a high withstand voltage characteristic of 1000 V / mm or more can be obtained.
  • the specific surface area is 13.0 m 2 / g or less, the Curie point of the ceramic sintered body particles in the ceramic body constituting the obtained semiconductor element can be set to 100 ° C. or higher.
  • the specific surface area of the perovskite compound particles is more preferably 2.9 m 2 / g or more and 7.8 m 2 / g or less. When the specific surface area is 7.8 m 2 / g or less, a high Curie temperature of 110 ° C. or more is obtained.
  • the specific surface area of the perovskite compound particles can be measured by a gas adsorption method such as a BET method.
  • Raw material perovskite type compound particles have a highly tetragonal crystal structure.
  • the ceramic sintered body particles in the ceramic body constituting the obtained semiconductor element have a tetragonal structure.
  • the ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the raw material perovskite compound particles is preferably from 1.006 to 1.010.
  • the c / a of the ceramic sintered body particles in the ceramic body constituting the obtained semiconductor element can be made 1.007 or more.
  • the Curie point of the body particles can be set to 100 ° C. or higher.
  • c / a is generally 1.010 or less.
  • c / a is more preferably 1.007 or more and 1.010 or less.
  • the Curie point of the ceramic sintered body particles can be 110 ° C. or more.
  • the c / a of the raw material perovskite compound particles can be calculated by conducting a qualitative analysis using a powder X-ray diffractometer and performing a Rietveld analysis.
  • a green chip containing raw material perovskite type compound particles is formed.
  • a step of forming a green chip containing perovskite compound particles includes a step of producing a ceramic green sheet containing perovskite compound particles, and a main part of the ceramic green sheet.
  • a step of applying a conductive paste for internal electrodes on a surface a step of obtaining a laminate by laminating a plurality of ceramic green sheets coated with a conductive paste for internal electrodes, and a conductivity for internal electrodes above and below the laminate. And placing a ceramic green sheet to which a paste has not been applied, press-bonding, and cutting to a predetermined size to obtain a green chip.
  • a ceramic green sheet containing perovskite type compound particles is prepared according to the following procedure.
  • An organic binder, a dispersant and water are added to the raw material perovskite type compound particles and mixed with zirconia balls for several hours to obtain a ceramic slurry.
  • the raw material perovskite type compound particles do not contain both element ⁇ and element ⁇ , or the total amount of element ⁇ and / or element ⁇ necessary for obtaining ceramic sintered particles having a desired composition
  • a predetermined amount of chloride, hydroxide, oxide, carbonate, alkoxide, ionized aqueous solution, or the like of the element ⁇ and / or ⁇ may be added as a donor during the preparation of the ceramic slurry.
  • the above-mentioned ceramic slurry is formed into a sheet by the doctor blade method and dried to produce a ceramic green sheet.
  • the thickness of the ceramic green sheet is preferably 20 ⁇ m or more and 40 ⁇ m or less.
  • a conductive paste for internal electrodes is applied on the main surface of the ceramic green sheet.
  • conductive powder such as metal powder and an organic binder are dispersed in an organic solvent to prepare a conductive paste for internal electrodes.
  • metal powder such as Ni metal powder can be appropriately used.
  • this internal electrode conductive paste on the main surface of the ceramic green sheet.
  • the coating thickness of the internal electrode conductive paste is set so that the thickness of the internal electrode in the finally obtained semiconductor element is 0.5 ⁇ m or more and 2 ⁇ m or less.
  • the conductive paste for internal electrodes may be applied by a method such as screen printing.
  • a plurality of ceramic green sheets coated with the internal electrode conductive paste are laminated to obtain a laminate.
  • the number of laminated ceramic green sheets coated with the internal electrode conductive paste may be set according to the number of internal electrodes that the finally obtained semiconductor element should have.
  • ceramic green sheets not coated with the internal electrode conductive paste are placed on the top and bottom of the laminate, for example, 5 sheets each, and pressed, and predetermined dimensions are set so that the dimensions after firing become a desired value. Cut to get green chips.
  • the size of the ceramic body obtained by firing the green chip may be, for example, L size 2.0 mm ⁇ W size 1.2 mm ⁇ T size 1.0 mm.
  • a plurality of ceramic green sheets not coated with the internal electrode conductive paste are stacked, pressed, and cut to a predetermined size to produce a green chip. It's okay.
  • the ceramic body is obtained by firing the green chip.
  • the green chip is degreased at a temperature of 250 ° C. to 350 ° C. for 10 hours to 15 hours in an air atmosphere.
  • the green chip after the degreasing treatment is 0.5 hours to 3 hours at a temperature of 1050 ° C. or higher and 1240 ° C. or lower in a reducing atmosphere such as N 2 / H 2 , Ar / H 2 , N 2 / H 2 / H 2 O
  • firing is performed to obtain a ceramic body.
  • the obtained ceramic body is glass-coated and heat-treated at a temperature of 600 ° C. or higher and 900 ° C. or lower in an air atmosphere to form a glass layer on the surface of the ceramic body, and at the same time, recycle the ceramic body. Oxidation may be performed.
  • external electrodes are formed on both end faces of the ceramic body.
  • the ceramic body is barrel-polished.
  • External electrodes are formed on both end faces of the ceramic body after barrel polishing.
  • the composition and formation method of the external electrode are not particularly limited, and can be appropriately selected according to the purpose.
  • the external electrode can be formed by sputtering Cr, NiCu alloy and Ag in this order on both end faces of the ceramic body.
  • the external electrode may be formed by applying a paste containing a resin component and a metal (Ag or the like) and baking it at an appropriate temperature.
  • a plating layer may be formed on the surface of the formed external electrode by a method such as electrolytic plating.
  • the composition of the plating layer can be appropriately selected according to the composition of the external electrode, and may be, for example, a Sn plating layer, a Ni plating layer, or a combination of two or more thereof. In this way, the semiconductor element according to this embodiment is obtained.
  • the semiconductor elements of Examples 1 to 19 were fabricated by the following procedure.
  • the semiconductor elements of Examples 1 to 19 are stacked PTC thermistors.
  • perovskite type compound particles were prepared as raw materials.
  • the obtained perovskite compound particles had a specific surface area of 2.1 m 2 / g and c / a of 1.010.
  • the specific surface area of the raw material perovskite type compound particles was measured using a Macsorb (registered trademark) manufactured by Mountec Co., Ltd. under a degassing temperature of 250 ° C.
  • the c / a of the raw material perovskite type compound particles was determined by conducting a qualitative analysis using a powder X-ray diffraction apparatus (RINT2500 manufactured by Rigaku Corporation) and performing a Rietveld analysis.
  • An organic binder, a dispersant and water were added to the obtained raw material perovskite type compound particles and mixed with zirconia balls for several hours to obtain a ceramic slurry.
  • This ceramic slurry was formed into a sheet by a doctor blade method and dried to prepare a ceramic green sheet having a thickness of 30 ⁇ m.
  • Ni metal powder and an organic binder were dispersed in an organic solvent to prepare a conductive paste for internal electrodes.
  • This internal electrode conductive paste was applied on the main surface of the ceramic green sheet by screen printing.
  • the coating thickness of the internal electrode conductive paste was adjusted so that the thickness of the internal electrode in the finally obtained semiconductor element was 0.5 ⁇ m or more and 2 ⁇ m or less.
  • coated the conductive paste for internal electrodes was laminated
  • This green chip was degreased at 300 ° C. for 12 hours in an air atmosphere.
  • the green chip after the degreasing treatment was fired for 2 hours at a temperature of 1050 ° C. or higher and 1240 ° C. or lower in a reducing atmosphere of N 2 / H 2 to obtain a ceramic body.
  • the obtained ceramic body was glass-coated and heat-treated at 800 ° C. in an air atmosphere to form a glass layer on the surface of the ceramic body and simultaneously re-oxidize the ceramic body.
  • the ceramic body on which the glass layer was formed was barrel polished. External electrodes were formed by sputtering Cr, NiCu alloy and Ag in this order on both end faces of the ceramic body after barrel polishing. An Sn plating layer was formed on the surface of the formed external electrode by electrolytic plating. Thus, the semiconductor element of Example 1 was obtained.
  • Example 2 to 19 Semiconductor devices of Examples 2 to 19 were produced in the same procedure as Example 1 except that perovskite type compound particles having specific surface areas and c / a values shown in Table 1 described later were used as raw materials.
  • the average particle diameter, c / a, and Curie point of the ceramic sintered body particles were measured.
  • the average particle size of the sintered ceramic particles was measured by the following procedure. First, the semiconductor element is polished to about 1/2 W point (about half the W dimension of the semiconductor element) in the direction of the LT plane (plane perpendicular to the W direction), and the semiconductor element cross section parallel to the LT plane is exposed. I let you. This cross section was observed using a scanning electron microscope (JSM-7500FA manufactured by JEOL Ltd.) under the conditions of an acceleration voltage of 5 kV and a magnification of 10,000 times to obtain an SEM image.
  • JSM-7500FA manufactured by JEOL Ltd.
  • the SEM image was subjected to image analysis using an analyzer (IP-1000 manufactured by Asahi Engineering Co., Ltd.), and the area of the ceramic sintered body particles in the SEM image was determined.
  • An equivalent area equivalent circle diameter (Heywood diameter) calculated based on the obtained area was defined as the particle diameter of the ceramic sintered body particles.
  • the average value of the particle diameters of the ceramic sintered body particles completely contained in the field of view of the observed SEM image (about 18 ⁇ m square or more and about 20 ⁇ m square or less) was defined as the average particle diameter of the ceramic sintered body particles.
  • the average particle diameter of the ceramic sintered body particles was obtained in the above-mentioned semiconductor element cross section, but the same result can be obtained even when the average particle diameter is obtained in other semiconductor element cross sections. You can think of it.
  • the c / a of the ceramic sintered body particles was determined by performing a qualitative analysis using a powder X-ray diffraction apparatus (RINT2500 manufactured by Rigaku Corporation) and performing a Rietveld analysis.
  • the Curie point of the sintered ceramic particles was determined by DSC measurement using a differential scanning calorimeter (model DSC2920) manufactured by TA Instruments.
  • the DSC measurement was performed under the conditions that the measurement atmosphere was an air atmosphere, the rate of temperature increase was 10 ° C./min, the start temperature was 25 ° C., and the end temperature was 250 ° C.
  • the peak temperature of the endothermic peak in the obtained differential heat-temperature curve was taken as the Curie point.
  • the withstand voltage characteristics were measured by the following procedure. After mounting the semiconductor element on the substrate, a voltage of 680 V / mm was applied to the semiconductor element for 3 minutes, and the current value at that time was measured. Next, when the semiconductor element was not destroyed at a voltage of 680 V / mm, the measurement was repeated by increasing the voltage in steps of 20 V / mm and applying it for 3 minutes. The voltage value immediately before the semiconductor element was destroyed was defined as a withstand voltage characteristic. The above measurement results are shown in Table 1.
  • the semiconductor elements of Examples 13, 16, 18 and 19 in which c / a of the ceramic sintered body particles was less than 1.007 the Curie point of the ceramic sintered body particles was less than 100 ° C. Therefore, it can be seen that the semiconductor elements of Examples 18 and 19 had a low operating temperature of less than 100 ° C.
  • the semiconductor elements of Examples 1 and 2 in which the average particle diameter of the ceramic sintered body particles was larger than 1.0 ⁇ m exhibited low withstand voltage characteristics of less than 1000 V / mm.
  • the semiconductor element according to the present invention has both a high withstand voltage characteristic and a high operating temperature, and can be suitably used in an operating temperature range of 85 ° C. generally required in the in-vehicle thermistor market.

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Abstract

A semiconductor element which comprises: a ceramic element that contains sintered ceramic particles; a first external electrode that is arranged on a first end face of the ceramic element; and a second external electrode that is arranged on a second end face of the ceramic element. The sintered ceramic particles are composed of a perovskite compound that contains at least Ba and Ti, and have an average particle diameter of 1.0 μm or less. The ratio of the c-axis length to the a-axis length of the crystal lattice of the sintered ceramic particles, namely c/a is 1.007 or more.

Description

半導体素子およびその製造方法Semiconductor device and manufacturing method thereof
　本発明は、半導体素子およびその製造方法に関し、特にチタン酸バリウム系半導体素子およびその製造方法に関する。 The present invention relates to a semiconductor element and a manufacturing method thereof, and more particularly to a barium titanate-based semiconductor element and a manufacturing method thereof.
　チタン酸バリウム系半導体磁器は正の温度特性を有するため、正特性サーミスタ（ＰＴＣサーミスタ）等の半導体素子に広く用いられている。 Since barium titanate-based semiconductor ceramics have a positive temperature characteristic, they are widely used in semiconductor elements such as a positive temperature coefficient thermistor (PTC thermistor).
　例えば、特許文献１には、還元焼成再酸化処理を行ったＢａＴｉＯ３系の半導体磁器において、焼結密度は相対密度が８５～９０％であることを特徴とする、半導体磁器が開示されている。特許文献１には、焼結密度を適度に低下させることにより十分なＰＴＣ特性を得ることができること、および半導体磁器の粒径は０．５～２μｍであることが好ましいことが記載されている。 For example, Patent Document 1 discloses a semiconductor porcelain characterized in that, in a BaTiO 3 -based semiconductor ceramic subjected to reduction firing reoxidation, the sintered density is 85 to 90% relative density. . Patent Document 1 describes that sufficient PTC characteristics can be obtained by appropriately reducing the sintered density, and that the particle size of the semiconductor ceramic is preferably 0.5 to 2 μm.
　特許文献２には、平均磁器粒径が０．９μｍ以下であるチタン酸バリウム系半導体磁器が開示されている。特許文献２には、平均磁器粒径が上記範囲にあるチタン酸バリウム系半導体磁器は室温において比抵抗が小さく、かつ優れた耐電圧強度を有することが記載されている。また、特許文献２には、上述のチタン酸バリウム系半導体磁器は、粒子径が０．１μｍ以下であり、結晶構造が立方晶であり、格子定数が４．０２０オングストローム以上であり、微量の半導体化剤が固溶しているチタン酸バリウム粉末、または該チタン酸バリウム粉末を仮焼したものを原料粉末とし、これを焼成することによって得られることが記載されている。 Patent Document 2 discloses a barium titanate semiconductor ceramic having an average ceramic particle size of 0.9 μm or less. Patent Document 2 describes that a barium titanate-based semiconductor ceramic having an average ceramic particle size in the above range has a small specific resistance at room temperature and an excellent withstand voltage strength. Patent Document 2 discloses that the above-described barium titanate-based semiconductor ceramic has a particle size of 0.1 μm or less, a crystal structure of cubic, a lattice constant of 4.020 angstroms or more, and a small amount of semiconductor. It is described that a barium titanate powder in which an agent is solid-solved or a product obtained by calcining the barium titanate powder is used as a raw material powder and is fired.
特開２００１－１３０９５７号公報JP 2001-130957 A 特開平１１－１１６３２７号公報JP-A-11-116327
　ＰＴＣサーミスタは過電流に対する保護のために幅広い種類の電子機器に用いられている。近年の電子機器の高機能化に伴い、特に大電流に対応可能なＰＴＣサーミスタが求められており、高い耐電圧特性を有するＰＴＣサーミスタ素子の開発が行われている。ＰＴＣサーミスタの耐電圧特性を向上させるため、ＰＴＣサーミスタを構成する半導体磁器の微粒子化が行われている（特許文献２）。しかし、本発明者が検討を重ねた結果、微粒子化によりＰＴＣサーミスタの動作温度が低下してしまうという問題があることが明らかになった。 PTC thermistors are used in a wide variety of electronic devices to protect against overcurrent. With the recent increase in functionality of electronic devices, a PTC thermistor capable of handling particularly a large current has been demanded, and a PTC thermistor element having high withstand voltage characteristics has been developed. In order to improve the withstand voltage characteristics of the PTC thermistor, semiconductor ceramics constituting the PTC thermistor are made fine (Patent Document 2). However, as a result of repeated studies by the present inventor, it has been found that there is a problem that the operating temperature of the PTC thermistor decreases due to the formation of fine particles.
　本発明は、高い耐電圧特性を有し且つ高い動作温度を有する半導体素子およびその製造方法を提供することを目的とする。 An object of the present invention is to provide a semiconductor device having high withstand voltage characteristics and a high operating temperature, and a method for manufacturing the same.
　本発明者は、ＰＴＣサーミスタを構成するセラミックス素体に含まれるセラミックス焼結体粒子を微粒子化することにより、セラミックス焼結体粒子のキュリー点が低下し、その結果、ＰＴＣサーミスタの動作温度が低下してしまうことに着目した。そして、正方晶性の高いペロブスカイト型チタン酸バリウム化合物粒子を原料として用いることにより、耐電圧特性向上のためにセラミックス焼結体粒子を微粒子化した場合であっても、セラミックス焼結体粒子のキュリー点の低下を抑制することができ、高い動作温度を達成することができることを見出し、本発明を完成させるに至った。 The present inventor reduced the Curie point of the ceramic sintered body particles by making the ceramic sintered body particles contained in the ceramic body constituting the PTC thermistor fine, and as a result, the operating temperature of the PTC thermistor decreased. I paid attention to it. By using perovskite-type barium titanate compound particles with high tetragonal properties as raw materials, even if the ceramic sintered particles are made fine particles to improve the withstand voltage characteristics, It has been found that the reduction of the point can be suppressed and a high operating temperature can be achieved, and the present invention has been completed.
　本発明の第１の要旨によれば、セラミックス焼結体粒子を含むセラミックス素体と、
　セラミックス素体の第１の端面に配置される第１の外部電極と、
　セラミックス素体の第２の端面に配置される第２の外部電極と
を含む半導体素子であって、
　セラミックス焼結体粒子は、ＢａおよびＴｉを少なくとも含むペロブスカイト型化合物であり、
　セラミックス焼結体粒子の平均粒径が１．０μｍ以下であり、
　セラミックス焼結体粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａが１．００７以上である、半導体素子が提供される。 According to a first aspect of the present invention, a ceramic body including ceramic sintered body particles;
A first external electrode disposed on a first end face of the ceramic body,
A semiconductor element including a second external electrode disposed on a second end face of the ceramic body,
Ceramic sintered body particles are perovskite type compounds containing at least Ba and Ti,
The average particle size of the ceramic sintered body particles is 1.0 μm or less,
A semiconductor element is provided in which the ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles is 1.007 or more.
　上述のセラミックス焼結体粒子の平均粒径は、０．６μｍ以上０．９μｍ以下であることが好ましい。また、上述のセラミックス焼結体粒子の結晶格子のａ軸長に対するｃ軸長の比（正方晶性）ｃ／ａは、１．００８以上１．０１０以下であることが好ましい。上述のセラミックス焼結体粒子のキュリー点は、１００℃以上であり得る。 The average particle diameter of the ceramic sintered body particles described above is preferably 0.6 μm or more and 0.9 μm or less. Further, the ratio (tetragonal) c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles described above is preferably 1.008 or more and 1.010 or less. The Curie point of the ceramic sintered body particles described above can be 100 ° C. or higher.
　上述の半導体素子は、セラミックス素体の内部に１以上の第１の内部電極および１以上の第２の内部電極が配置された積層型半導体素子であってよい。このとき、第１の内部電極は、セラミックス素体の第１の端面において第１の外部電極と電気的に接続し、第２の内部電極は、セラミックス素体の第２の端面において第２の外部電極と電気的に接続する。第１の内部電極および第２の内部電極は、Ｎｉ電極であってよい。 The semiconductor element described above may be a stacked semiconductor element in which one or more first internal electrodes and one or more second internal electrodes are arranged inside a ceramic body. At this time, the first internal electrode is electrically connected to the first external electrode at the first end face of the ceramic body, and the second internal electrode is connected to the second end face of the ceramic base body at the second end face. Electrically connected to the external electrode. The first internal electrode and the second internal electrode may be Ni electrodes.
　本発明の第２の要旨によれば、半導体素子の製造方法であって、
　ＢａおよびＴｉを少なくとも含むペロブスカイト型化合物粒子を調製する工程と、
　ペロブスカイト型化合物粒子を含むグリーンチップを形成する工程と、
　グリーンチップを焼成することによりセラミックス素体を得る工程と、
　セラミックス素体の両端面に外部電極を形成することにより半導体素子を得る工程と
を含み、
　ペロブスカイト型化合物粒子の比表面積が２．９ｍ２／ｇ以上１３．０ｍ２／ｇ以下であり、
　ペロブスカイト型化合物粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａが１．００６以上１．０１０以下である、方法が提供される。 According to a second aspect of the present invention, there is provided a method for manufacturing a semiconductor element,
Preparing perovskite-type compound particles containing at least Ba and Ti;
Forming a green chip containing perovskite-type compound particles;
Obtaining a ceramic body by firing a green chip;
Forming a semiconductor element by forming external electrodes on both end faces of the ceramic body,
The specific surface area of the perovskite type compound particles is 2.9 m 2 / g or more and 13.0 m 2 / g or less,
A method is provided wherein the ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the perovskite type compound particles is not less than 1.006 and not more than 1.010.
　上述の方法において、ペロブスカイト型化合物粒子を含むグリーンチップを形成する工程は、
　ペロブスカイト型化合物粒子を含むセラミックスグリーンシートを作製する工程と、
　セラミックスグリーンシートの主面上に内部電極用導電性ペーストを塗布する工程と、
　内部電極用導電性ペーストを塗布した前記セラミックスグリーンシートを複数枚積層して積層体を得る工程と、
　積層体の上下に内部電極用導電性ペーストを塗布していないセラミックスグリーンシートを配置して圧着し、所定の寸法に切断してグリーンチップを得る工程と
を含んでよい。このような方法により、セラミックス素体の内部に内部電極が配置された積層型の半導体素子を製造することができる。上述の内部電極用導電性ペーストは、導電性粉末としてＮｉ金属粉末を含んでよい。 In the above method, the step of forming the green chip containing the perovskite type compound particles,
Producing a ceramic green sheet containing perovskite type compound particles;
Applying a conductive paste for internal electrodes on the main surface of the ceramic green sheet;
A step of obtaining a laminate by laminating a plurality of the ceramic green sheets coated with the internal electrode conductive paste;
And placing a ceramic green sheet not coated with the internal electrode conductive paste on the upper and lower sides of the laminate and pressing the ceramic green sheet, and cutting to a predetermined size to obtain a green chip. By such a method, it is possible to manufacture a stacked semiconductor element in which internal electrodes are arranged inside a ceramic body. The above-mentioned internal electrode conductive paste may contain Ni metal powder as the conductive powder.
　本発明に係る半導体素子は、上記構成を有することにより、高い耐電圧特性を有し且つ高い動作温度を有する。また、本発明に係る半導体素子の製造方法は、上記構成を有することにより、高い耐電圧特性および高い動作温度を有する半導体素子を製造することができる。 The semiconductor element according to the present invention has a high withstand voltage characteristic and a high operating temperature by having the above configuration. Moreover, the manufacturing method of the semiconductor element which concerns on this invention can manufacture the semiconductor element which has a high withstand voltage characteristic and high operating temperature by having the said structure.
図１は、本発明の一の実施形態に係る半導体素子の概略断面図である。FIG. 1 is a schematic cross-sectional view of a semiconductor device according to an embodiment of the present invention. 図２は、本発明の一の実施形態に係る半導体素子の一の変形例の概略断面図である。FIG. 2 is a schematic cross-sectional view of a modification of the semiconductor device according to one embodiment of the present invention. 図３は、本発明の一の実施形態に係る半導体素子のもう１つの変形例の概略断面図である。FIG. 3 is a schematic cross-sectional view of another modification of the semiconductor device according to one embodiment of the present invention.
　以下、図面を参照して、本発明の一の実施形態に係る半導体素子について説明する。但し、以下に示す実施形態は例示を目的とするものであり、本発明は以下の実施形態に限定されるものではない。以下に説明する構成要素の寸法、材質、形状、相対的配置等は、特定的な記載がない限りは本発明の範囲をそれのみに限定する趣旨ではなく、単なる説明例にすぎない。また、各図面が示す構成要素の大きさ、形状、位置関係等は説明を明確にするため誇張していることがある。各部材の寸法は、以下に示す値を必ずしも正確に示すものではなく、公差を有するものとする。 Hereinafter, a semiconductor device according to an embodiment of the present invention will be described with reference to the drawings. However, the embodiment shown below is for the purpose of illustration, and the present invention is not limited to the following embodiment. The dimensions, materials, shapes, relative arrangements, and the like of the constituent elements described below are not merely intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. In addition, the size, shape, positional relationship, and the like of components illustrated in each drawing may be exaggerated for clarity of explanation. The dimension of each member does not necessarily indicate the following values accurately, but has tolerances.
　［半導体素子］
　図１に、本実施形態に係る半導体素子１の概略断面図を示す。本実施形態に係る半導体素子１はＰＴＣサーミスタである。図１に示す半導体素子１は、セラミックス素体２と、セラミックス素体２の第１の端面２１に配置される第１の外部電極３１と、セラミックス素体２の第２の端面２２に配置される第２の外部電極３２とを含む。 [Semiconductor element]
FIG. 1 is a schematic cross-sectional view of a semiconductor element 1 according to this embodiment. The semiconductor element 1 according to this embodiment is a PTC thermistor. A semiconductor element 1 shown in FIG. 1 is disposed on a ceramic body 2, a first external electrode 31 disposed on a first end surface 21 of the ceramic body 2, and a second end surface 22 of the ceramic body 2. Second external electrode 32.
　（セラミックス素体）
　セラミックス素体２は、セラミックス焼結体粒子を含む。セラミックス焼結体粒子は、チタン酸バリウムにドナー元素が添加されたセラミックス材料で構成される。セラミックス焼結体粒子は、ＢａおよびＴｉを少なくとも含むペロブスカイト型化合物である。ペロブスカイト型化合物は、ＢａおよびＴｉに加えて、更にＰｍ、Ｔｍ、ＹｂおよびＬｕを除く希土類元素からなる群から選択される少なくとも１種の元素ならびに／またはＮｂ、Ｗ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素を含み得る。以下、Ｐｍ、Ｔｍ、ＹｂおよびＬｕを除く希土類元素からなる群から選択される少なくとも１種の元素を「元素α」、Ｎｂ、Ｗ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素を「元素β」ともよぶ。元素αおよび元素βは、セラミックス素体２にＰＴＣ特性を付与するためのドナー（半導体化剤）である。セラミックス焼結体粒子は、上述の元素αまたは元素βのいずれか一方のみを含んでよく、元素αおよびβの両方を含んでもよい。 (Ceramic body)
The ceramic body 2 includes ceramic sintered body particles. The sintered ceramic particles are made of a ceramic material in which a donor element is added to barium titanate. The ceramic sintered body particles are a perovskite type compound containing at least Ba and Ti. The perovskite-type compound includes, in addition to Ba and Ti, at least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu and / or a group consisting of Nb, W, Sb and Ta. It may contain at least one element selected. Hereinafter, at least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu is at least one element selected from the group consisting of “element α”, Nb, W, Sb and Ta Is also referred to as “element β”. The elements α and β are donors (semiconductor agents) for imparting PTC characteristics to the ceramic body 2. The ceramic sintered body particles may include only one of the above-described element α and element β, or may include both elements α and β.
　セラミックス素体２は、Ｔｉおよびβの合計モル部を１００モル部とした場合に、９９．５モル部以上１００．５モル部以下のＢａを含むことが好ましい。Ｂａの含有量が９９．５モル部以上１００．５モル部以下であると、セラミックス素体の室温比抵抗が低くなり、高い耐電圧特性を得ることができる。セラミックス素体２は、ＢａおよびＴｉに加えて上述の元素αおよび／または元素βを含んでよい。セラミックス素体２は、セラミックス素体２における元素αおよび元素βの含有量の合計が０．０２０モル部以上０．５００モル部以下となるような量の元素αおよび／または元素βを含むことが好ましい。元素αおよび元素βの含有量の合計が０．０２０モル部以上であると、セラミックス素体２に好適なＰＴＣ（正温度係数）特性を付与することができる。元素αおよび元素βの含有量の合計が０．５００モル部以下であると、セラミックス素体２のキュリー点を高くすることができる。 The ceramic body 2 preferably contains 99.5 mol parts or more and 100.5 mol parts or less of Ba when the total mol portion of Ti and β is 100 mol parts. When the content of Ba is 99.5 mol parts or more and 100.5 mol parts or less, the room temperature specific resistance of the ceramic body is lowered, and high withstand voltage characteristics can be obtained. The ceramic body 2 may contain the above-described element α and / or element β in addition to Ba and Ti. The ceramic body 2 contains the element α and / or the element β in such an amount that the total content of the elements α and β in the ceramic body 2 is 0.020 mol part or more and 0.500 mol part or less. Is preferred. When the total content of the element α and the element β is 0.020 mol part or more, suitable PTC (positive temperature coefficient) characteristics can be imparted to the ceramic body 2. When the total content of the elements α and β is 0.500 mol part or less, the Curie point of the ceramic body 2 can be increased.
　セラミックス素体２は、製造工程において不可避に混入し得るＺｒを含み得る。Ｚｒの混入は、後述のセラミックススラリー調製時に粉砕および分散用メディアとしてジルコニアボールを使用することに起因して起こり得る。セラミックス素体２は、０．０１０モル部以上０．６００モル部以下のＺｒを含み得る。 The ceramic body 2 may contain Zr that may be inevitably mixed in the manufacturing process. Zr may occur due to the use of zirconia balls as a grinding and dispersion medium when preparing a ceramic slurry described later. The ceramic body 2 may include 0.010 mol part or more and 0.600 mol part or less of Zr.
　セラミックス素体２に含まれるセラミックス焼結体粒子の平均粒径は１．０μｍ以下である。平均粒径が１．０μｍ以下であると、半導体素子１において高い耐電圧特性を達成することができる。セラミックス焼結体粒子の平均粒径は、好ましくは０．６μｍ以上０．９μｍ以下である。平均粒径が０．６μｍ以上であると、セラミックス素体の比抵抗を低減することができ、ひいては半導体素子の抵抗値を低減することができる。平均粒径が０．９μｍ以下であると、半導体素子１の耐電圧特性がより一層向上し得る。セラミックス焼結体粒子の平均粒径は、半導体素子断面を走査型電子顕微鏡（ＳＥＭ）で観察し、画像解析を行うことにより算出することができる。 The average particle diameter of the ceramic sintered body particles contained in the ceramic body 2 is 1.0 μm or less. When the average particle size is 1.0 μm or less, the semiconductor device 1 can achieve high withstand voltage characteristics. The average particle diameter of the ceramic sintered body particles is preferably 0.6 μm or more and 0.9 μm or less. When the average particle size is 0.6 μm or more, the specific resistance of the ceramic body can be reduced, and consequently the resistance value of the semiconductor element can be reduced. When the average particle size is 0.9 μm or less, the withstand voltage characteristics of the semiconductor element 1 can be further improved. The average particle diameter of the sintered ceramic particles can be calculated by observing a cross section of the semiconductor element with a scanning electron microscope (SEM) and performing image analysis.
　セラミックス素体２に含まれるセラミックス焼結体粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａは、１．００７以上である。ｃ／ａが１．００７以上であると、セラミックス焼結体粒子の平均粒径が小さい場合であっても高いキュリー点を維持することができ、その結果、動作温度の高い半導体素子１を得ることができる。セラミックス焼結体粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａは、好ましくは１．００８以上１．０１０以下である。ｃ／ａが１．００８以上であると、セラミックス焼結体粒子のキュリー点をより一層高くすることができる。セラミックス素体２がチタン酸バリウム系材料で構成される場合、ｃ／ａは一般に１．０１０以下である。セラミックス焼結体粒子のｃ／ａは、粉末Ｘ線回折装置を用いて定性分析を行い、リートベルト解析することにより算出することができる。なお、本明細書において、セラミックス焼結体粒子のｃ／ａの測定値は、セラミックス素体２のｃ／ａの測定値と実質的に同じであると考えて差し支えない。 The ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles contained in the ceramic body 2 is 1.007 or more. When c / a is 1.007 or more, a high Curie point can be maintained even when the average particle size of the ceramic sintered body particles is small, and as a result, a semiconductor element 1 having a high operating temperature is obtained. be able to. The ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the ceramic sintered body particles is preferably 1.008 or more and 1.010 or less. When the c / a is 1.008 or more, the Curie point of the ceramic sintered body particles can be further increased. When the ceramic body 2 is composed of a barium titanate material, c / a is generally 1.010 or less. The c / a of the sintered ceramic particles can be calculated by performing a qualitative analysis using a powder X-ray diffractometer and performing a Rietveld analysis. In the present specification, it may be considered that the c / a measurement value of the ceramic sintered body particles is substantially the same as the c / a measurement value of the ceramic body 2.
　セラミックス素体２に含まれるセラミックス焼結体粒子のキュリー点は１００℃以上であり得る。セラミックス焼結体粒子のキュリー点が１００℃以上であると、製品ごとのキュリー点のばらつきを考慮しても、車載用サーミスタの市場において一般的に求められる８５℃の使用温度範囲において半導体素子１を好適に用いることができる。セラミックス焼結体粒子のキュリー点は、示差走査熱量測定（ＤＳＣ）により求めることができる。なお、本明細書において、セラミックス焼結体粒子のキュリー温度の測定値は、セラミックス素体２のキュリー温度の測定値と実質的に同じであると考えて差し支えない。 The Curie point of the ceramic sintered body particles contained in the ceramic body 2 can be 100 ° C. or higher. When the Curie point of the ceramic sintered body particles is 100 ° C. or higher, the semiconductor element 1 can be used in an operating temperature range of 85 ° C., which is generally required in the market of in-vehicle thermistors, even when variation in the Curie point of each product is taken into consideration. Can be suitably used. The Curie point of ceramic sintered body particles can be determined by differential scanning calorimetry (DSC). In the present specification, the measured value of the Curie temperature of the ceramic sintered body particles may be considered to be substantially the same as the measured value of the Curie temperature of the ceramic body 2.
　セラミックス素体２の寸法は特に限定されるものではなく、用途に応じて適宜設定することができる。セラミックス素体２の寸法は、例えばＬ寸２．０ｍｍ×Ｗ寸１．２ｍｍ×Ｔ寸１．０ｍｍであってよい。なお、本明細書において、図１に示すように、セラミックス素体２の第１の端面２１から第２の端面２２に向かう方向を「Ｌ方向」、水平面内においてＬ方向に対して垂直な方向を「Ｗ方向」、Ｌ方向およびＷ方向に対して垂直な方向を「Ｔ方向」とよぶ。また、セラミックス素体２のＬ方向の寸法を「Ｌ寸」、Ｗ方向の寸法を「Ｗ寸」、Ｔ方向の寸法を「Ｔ寸」とよぶ。 The dimensions of the ceramic body 2 are not particularly limited, and can be set as appropriate according to the application. The dimension of the ceramic body 2 may be, for example, L dimension 2.0 mm × W dimension 1.2 mm × T dimension 1.0 mm. In the present specification, as shown in FIG. 1, the direction from the first end face 21 to the second end face 22 of the ceramic body 2 is the “L direction”, and the direction perpendicular to the L direction in the horizontal plane. Is called the “W direction”, and the direction perpendicular to the L direction and the W direction is called the “T direction”. The dimension of the ceramic body 2 in the L direction is referred to as “L dimension”, the dimension in the W direction as “W dimension”, and the dimension in the T direction as “T dimension”.
　本実施形態に係る半導体素子１は、図２に示すように、セラミックス素体２の内部に１以上の第１の内部電極４１および１以上の第２の内部電極４２が配置された積層型半導体素子であってよい。本明細書において、第１の内部電極４１および第２の内部電極４２をまとめて「内部電極」とよぶこともある。第１の内部電極４１は、セラミックス素体２の第１の端面２１において第１の外部電極３１と電気的に接続し、第２の内部電極４２は、セラミックス素体２の第２の端面２２において第２の外部電極３２と電気的に接続する。
第１の内部電極４１は、セラミックス素体２の第１の端面２１から第２の端面２２に向かって延在し、第２の内部電極４２は、セラミックス素体２の第２の端面２２から第１の端面２１に向かって延在する。第１の内部電極４１と第２の内部電極４２とは、セラミックス素体２の内部において互いに対向するように交互に配置される。図２に示す変形例において、セラミックス素体２の内部に第１の内部電極４１および第２の内部電極４２が２つずつ配置されているが、内部電極の数はこれに限定されるものではなく、所望の特性に応じて適宜設定することができる。内部電極の数（第１の内部電極４１および第２の内部電極４２の合計）は、例えば２以上５０以下程度であってよい。隣り合う第１の内部電極４１と第２の内部電極４２との間の距離は特に限定されるものではなく、所望の用途に応じて適宜設定することができる。隣り合う第１の内部電極４１と第２の内部電極４２との間の距離は、例えば１０μｍ以上２００μｍ以下程度であってよい。 As shown in FIG. 2, the semiconductor element 1 according to the present embodiment is a stacked semiconductor in which one or more first internal electrodes 41 and one or more second internal electrodes 42 are arranged inside a ceramic body 2. It may be an element. In the present specification, the first internal electrode 41 and the second internal electrode 42 may be collectively referred to as “internal electrodes”. The first internal electrode 41 is electrically connected to the first external electrode 31 at the first end face 21 of the ceramic body 2, and the second internal electrode 42 is the second end face 22 of the ceramic body 2. And electrically connected to the second external electrode 32.
The first internal electrode 41 extends from the first end face 21 of the ceramic body 2 toward the second end face 22, and the second internal electrode 42 extends from the second end face 22 of the ceramic body 2. It extends toward the first end face 21. The first internal electrodes 41 and the second internal electrodes 42 are alternately arranged so as to face each other inside the ceramic body 2. In the modification shown in FIG. 2, two first internal electrodes 41 and two second internal electrodes 42 are arranged inside the ceramic body 2, but the number of internal electrodes is not limited to this. And can be appropriately set according to desired characteristics. The number of internal electrodes (the total of the first internal electrode 41 and the second internal electrode 42) may be, for example, about 2 or more and 50 or less. The distance between the adjacent first internal electrode 41 and second internal electrode 42 is not particularly limited, and can be appropriately set according to a desired application. The distance between the adjacent first internal electrode 41 and second internal electrode 42 may be, for example, about 10 μm to 200 μm.
　内部電極の組成は特に限定されるものではなく、用途に応じて適宜設定してよい。第１の内部電極４１および第２の内部電極４２は、例えば、チタン酸バリウム系半導体に対して良好なオーミック性を示すＮｉ電極であってよい。 The composition of the internal electrode is not particularly limited, and may be set as appropriate according to the application. The first internal electrode 41 and the second internal electrode 42 may be, for example, Ni electrodes that exhibit good ohmic properties with respect to a barium titanate-based semiconductor.
　本実施形態に係る半導体素子１において、図３に示すように、セラミックス素体２の表面にガラス層５が形成されていてもよい。ガラス層５は、耐環境性能や素子強度を向上させる機能を有する。ガラス層５の組成および厚さは特に限定されるものではなく、用途に応じて適宜設定してよい。なお、図３に示す変形例において、セラミックス素体２の内部に第１の内部電極４１および第２の内部電極４２が配置されているが、本実施形態に係る半導体素子１はこの構成に限定されるものではなく、内部電極を有しない構成であってもよい。また、図３に示す変形例において、第１の外部電極３１および第２の外部電極３２の表面にめっき層６１および６２（後述）が形成されているが、本実施形態に係る半導体素子１はこの構成に限定されるものではなく、めっき層を有しない構成であってもよい。 In the semiconductor element 1 according to this embodiment, a glass layer 5 may be formed on the surface of the ceramic body 2 as shown in FIG. The glass layer 5 has a function of improving environmental resistance and element strength. The composition and thickness of the glass layer 5 are not particularly limited, and may be set as appropriate according to the application. In the modification shown in FIG. 3, the first internal electrode 41 and the second internal electrode 42 are disposed inside the ceramic body 2, but the semiconductor element 1 according to the present embodiment is limited to this configuration. However, the configuration may be such that no internal electrode is provided. In the modification shown in FIG. 3, plating layers 61 and 62 (described later) are formed on the surfaces of the first external electrode 31 and the second external electrode 32. The semiconductor element 1 according to the present embodiment is It is not limited to this structure, The structure which does not have a plating layer may be sufficient.
　（外部電極）
　本実施形態に係る半導体素子１は、セラミックス素体２の第１の端面２１に配置される第１の外部電極３１と、セラミックス素体２の第２の端面２２に配置される第２の外部電極３２とを含む。第１の外部電極３１および第２の外部電極３２は、図１に示すようにセラミックス素体２の側面の一部に延在するように形成されてよい。なお、本明細書において、セラミックス素体２の「側面」は、セラミックス素体２の第１の端面２１および第２の端面２２以外の面を指す。本明細書において、第１の外部電極３１および第２の外部電極３２をまとめて「外部電極」とよぶこともある。外部電極の組成および構成は、セラミックス素体２または存在する場合には内部電極（第１の内部電極４１および第２の内部電極４２）の種類に応じて適宜設定することができる。第１の外部電極３１および第２の外部電極３２は、例えば、Ｃｒ、ＮｉＣｕ合金およびＡｇを順番に積層した多層構造を有してよい。 (External electrode)
The semiconductor element 1 according to the present embodiment includes a first external electrode 31 disposed on the first end surface 21 of the ceramic body 2 and a second external surface disposed on the second end surface 22 of the ceramic body 2. Electrode 32. The first external electrode 31 and the second external electrode 32 may be formed so as to extend to a part of the side surface of the ceramic body 2 as shown in FIG. In the present specification, the “side surface” of the ceramic body 2 refers to a surface other than the first end surface 21 and the second end surface 22 of the ceramic body 2. In the present specification, the first external electrode 31 and the second external electrode 32 may be collectively referred to as “external electrode”. The composition and configuration of the external electrode can be appropriately set according to the type of the ceramic body 2 or the internal electrodes (the first internal electrode 41 and the second internal electrode 42) when present. The first external electrode 31 and the second external electrode 32 may have, for example, a multilayer structure in which Cr, NiCu alloy, and Ag are sequentially stacked.
　本実施形態に係る半導体素子１において、図３に示すように、第１の外部電極３１および第２の外部電極３２の表面にめっき層６１および６２が形成されていてもよい。めっき層６１および６２は、実装時のはんだ濡れ性や耐熱性を向上させる機能を有する。めっき層６１および６２の組成は外部電極の組成に応じて適宜選択することができ、例えば、Ｓｎめっき層、Ｎｉめっき層またはこれらの２以上の組み合わせであってよい。なお、図３に示す変形例において、セラミックス素体２の内部に第１の内部電極４１および第２の内部電極４２が配置されているが、本実施形態に係る半導体素子１はこの構成に限定されるものではなく、内部電極を有しない構成であってもよい。また、図３に示す変形例において、セラミックス素体２の表面にガラス層５が形成されているが、本実施形態に係る半導体素子１はこの構成に限定されるものではなく、ガラス層５を有しない構成であってもよい。 In the semiconductor element 1 according to the present embodiment, plating layers 61 and 62 may be formed on the surfaces of the first external electrode 31 and the second external electrode 32 as shown in FIG. The plating layers 61 and 62 have a function of improving solder wettability and heat resistance during mounting. The composition of the plating layers 61 and 62 can be appropriately selected according to the composition of the external electrode, and may be, for example, a Sn plating layer, a Ni plating layer, or a combination of two or more thereof. In the modification shown in FIG. 3, the first internal electrode 41 and the second internal electrode 42 are disposed inside the ceramic body 2, but the semiconductor element 1 according to the present embodiment is limited to this configuration. However, the configuration may be such that no internal electrode is provided. In the modification shown in FIG. 3, the glass layer 5 is formed on the surface of the ceramic body 2, but the semiconductor element 1 according to the present embodiment is not limited to this configuration. The structure which does not have may be sufficient.
　［半導体素子の製造方法］
　以下、本実施形態に係る半導体素子の製造方法の一例について以下に説明するが、本発明に係る半導体素子の製造方法は以下に示す方法に限定されるものではない。本実施形態に係る半導体素子の製造方法は、ペロブスカイト型化合物粒子を調製する工程と、ペロブスカイト型化合物粒子を含むグリーンチップを形成する工程と、グリーンチップを焼成することによりセラミックス素体を得る工程と、セラミックス素体の両端面に外部電極を形成することにより半導体素子を得る工程とを含む。なお、本実施形態においては、例示的に、内部電極を有する積層型ＰＴＣサーミスタの製造方法を主に説明する。 [Method for Manufacturing Semiconductor Device]
Hereinafter, although an example of the manufacturing method of the semiconductor element which concerns on this embodiment is demonstrated below, the manufacturing method of the semiconductor element which concerns on this invention is not limited to the method shown below. The method for manufacturing a semiconductor device according to the present embodiment includes a step of preparing perovskite type compound particles, a step of forming a green chip containing perovskite type compound particles, and a step of obtaining a ceramic body by firing the green chip. And forming a semiconductor element by forming external electrodes on both end faces of the ceramic body. In the present embodiment, for example, a method for manufacturing a stacked PTC thermistor having an internal electrode will be mainly described.
　まず、半導体素子を構成するセラミックス素体の原料として、ＢａおよびＴｉを少なくとも含むペロブスカイト型化合物粒子（以下、「原料のペロブスカイト型化合物粒子」ともよぶ）を調製する。原料のペロブスカイト型化合物粒子は、ＢａおよびＴｉに加えて、更にＰｍ、Ｔｍ、ＹｂおよびＬｕを除く希土類元素からなる群から選択される少なくとも１種の元素ならびに／またはＮｂ、Ｗ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素を含み得る。ペロブスカイト型化合物粒子の各原材料を、最終的に得られる半導体素子を構成するセラミックス素体に含まれるセラミックス焼結体粒子の組成が目的とする組成となるように秤量する。目的とするセラミックス焼結体粒子の組成は、内部電極を含むセラミック素子素体を溶解し、例えばＩＣＰ－ＡＥＳ（Inductively Coupled Plasma-Atomic Emission Spectrometry）により定量分析したときに各元素の含有比が下記の（１）式で表されるような組成であってよい。 First, perovskite compound particles containing at least Ba and Ti (hereinafter, also referred to as “raw perovskite compound particles”) are prepared as raw materials for the ceramic body constituting the semiconductor element. The perovskite type compound particles as the raw material may contain at least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu and / or Nb, W, Sb and Ta in addition to Ba and Ti. It may contain at least one element selected from the group consisting of: Each raw material of the perovskite type compound particles is weighed so that the composition of the ceramic sintered body particles contained in the ceramic body constituting the finally obtained semiconductor element becomes the target composition. The composition of the target ceramic sintered body particles is as follows. When the ceramic element body including the internal electrode is dissolved and quantitative analysis is performed by, for example, ICP-AES (Inductively-Coupled-Plasma-Atomic-Emission-Spectrometry), It may be a composition represented by the formula (1).
Figure JPOXMLDOC01-appb-C000001
 式中、αはＰｍ、Ｔｍ、ＹｂおよびＬｕを除く希土類元素からなる群から選択される少なくとも１種の元素であり、βはＮｂ、Ｗ、ＳｂおよびＴａからなる群から選択される少なくとも１種の元素である。Ｂａ、α、α＋β、Ｔｉ＋βの含有モル部を、ｍＢａ、ｍα、ｍ（α＋β）、ｍ（Ｔｉ＋β）とし、ｍ＝（ｍＢａ＋ｍ（α＋β））／ｍ（Ｔｉ＋β）をモル比と定義する。この定義の下で、ｍＢａは９９．５０≦ｍＢａ≦１００．５であり、ｍ（α＋β）の範囲は、０．０２０≦ｍ（α＋β）≦０．５００であり、ｍは０．９９５≦ｍ≦１．００５である。
Figure JPOXMLDOC01-appb-C000001
 In the formula, α is at least one element selected from the group consisting of rare earth elements excluding Pm, Tm, Yb and Lu, and β is at least one selected from the group consisting of Nb, W, Sb and Ta Elements. The content molar part of Ba, α, α + β, Ti + β is defined as m Ba , m α , m (α + β) , m (Ti + β), and m = (m Ba + m (α + β) ) / m (Ti + β) is defined as the molar ratio. To do. Under this definition, m Ba is 99.50 ≦ m Ba ≦ 100.5, the range of m (α + β) is 0.020 ≦ m (α + β) ≦ 0.500, and m is 0.995. ≦ m ≦ 1.005.
　ペロブスカイト型化合物粒子を調製するための原材料としては、Ｂａ、Ｔｉ、元素αおよびβの塩化物、水酸化物、酸化物、炭酸塩、アルコキシド等を適宜用いることができる。なお、上記式（１）に示すように、最終的に得られる半導体素子を構成するセラミックス素体に含まれるセラミックス焼結体粒子はドナー（半導体化剤）として元素αおよび／またはβを含むが、原料のペロブスカイト型化合物粒子は元素αおよび元素βをいずれも含まなくてよく、あるいは所望の組成を有するセラミックス焼結体粒子を得るのに必要な元素αおよび／または元素βの量の全量を含まなくてもよい。これらの場合、後述のセラミックススラリー調製時に必要な量の元素αおよび／またはβの塩化物、水酸化物、酸化物、炭酸塩、アルコキシド、イオン化水溶液等を添加することで所望の組成に調整ができる。 As raw materials for preparing perovskite type compound particles, Ba, Ti, chlorides of elements α and β, hydroxides, oxides, carbonates, alkoxides and the like can be used as appropriate. As shown in the above formula (1), the ceramic sintered body particles contained in the ceramic body constituting the finally obtained semiconductor element contain the elements α and / or β as donors (semiconductor agents). The raw material perovskite type compound particles may contain neither element α nor element β, or the total amount of element α and / or element β necessary for obtaining ceramic sintered particles having a desired composition may be included. It does not have to be included. In these cases, the amount of element α and / or β chloride, hydroxide, oxide, carbonate, alkoxide, ionized aqueous solution, etc. necessary for preparation of the ceramic slurry described later can be adjusted to the desired composition. it can.
　原料のペロブスカイト型化合物粒子の調製方法は特に限定されるものではなく、所望の比表面積およびｃ／ａに応じて固相合成法または水熱合成法およびシュウ酸法等の液中合成法を適宜選択することができる。原料のペロブスカイト型化合物粒子は、例えば以下に説明する手順で調製してよい。秤量した上述の各原材料をＰＳＺ（部分安定化ジルコニア）ボールおよび純水と共にボールミルに投入し、湿式で十分に混合粉砕し、乾燥させて混合粉体を得る。この混合粉体に８００℃～１１００℃の温度で仮焼処理（熱処理）を施すことにより、原料のペロブスカイト型化合物粒子を得る。仮焼処理温度は、目的とするペロブスカイト型化合物粒子の比表面積およびｃ／ａの値に応じて適宜設定することができる。 The method for preparing the raw material perovskite type compound particles is not particularly limited, and a solid-phase synthesis method or a hydrothermal synthesis method such as a hydrothermal synthesis method or an oxalic acid method is appropriately used depending on the desired specific surface area and c / a. You can choose. The raw material perovskite type compound particles may be prepared, for example, by the procedure described below. Each of the above-mentioned raw materials weighed is put into a ball mill together with PSZ (partially stabilized zirconia) balls and pure water, sufficiently mixed and pulverized in a wet manner, and dried to obtain a mixed powder. By subjecting this mixed powder to a calcining treatment (heat treatment) at a temperature of 800 ° C. to 1100 ° C., raw material perovskite type compound particles are obtained. The calcination temperature can be appropriately set according to the specific surface area of the target perovskite type compound particles and the value of c / a.
　原料のペロブスカイト型化合物粒子の比表面積は、２．９ｍ２／ｇ以上１３．０ｍ２／ｇ以下であることが好ましい。比表面積が２．９ｍ２／ｇ以上であると、得られる半導体素子を構成するセラミックス素体中のセラミックス焼結体粒子を平均粒径０．９μｍ以下の小粒径にすることができ、その結果、１０００Ｖ／ｍｍ以上の高い耐電圧特性を得ルことができる。比表面積が１３．０ｍ２／ｇ以下であると、得られる半導体素子を構成するセラミックス素体中のセラミックス焼結体粒子のキュリー点を１００℃以上にすることができる。ペロブスカイト型化合物粒子の比表面積は、より好ましくは２．９ｍ２／ｇ以上７．８ｍ２／ｇ以下である。比表面積が７．８ｍ２／ｇ以下であると、１１０℃以上の高いキュリー温度が得られる。ペロブスカイト型化合物粒子の比表面積は、例えばＢＥＴ法等の気体吸着法により測定することができる。 The specific surface area of the raw material perovskite compound particles is preferably 2.9 m 2 / g or more and 13.0 m 2 / g or less. When the specific surface area is 2.9 m 2 / g or more, the ceramic sintered body particles in the ceramic body constituting the semiconductor element to be obtained can be reduced to an average particle size of 0.9 μm or less. As a result, a high withstand voltage characteristic of 1000 V / mm or more can be obtained. When the specific surface area is 13.0 m 2 / g or less, the Curie point of the ceramic sintered body particles in the ceramic body constituting the obtained semiconductor element can be set to 100 ° C. or higher. The specific surface area of the perovskite compound particles is more preferably 2.9 m 2 / g or more and 7.8 m 2 / g or less. When the specific surface area is 7.8 m 2 / g or less, a high Curie temperature of 110 ° C. or more is obtained. The specific surface area of the perovskite compound particles can be measured by a gas adsorption method such as a BET method.
　原料のペロブスカイト型化合物粒子は正方晶性の高い結晶構造を有する。正方晶性の高い結晶構造を有するペロブスカイト型化合物粒子を原料として用いると、得られる半導体素子を構成するセラミックス素体中のセラミックス焼結体粒子は正方晶構造を有することになる。その結果、セラミックス焼結体粒子のキュリー点の低下を抑制することができ、半導体素子の動作温度の低下を抑制することができる。原料のペロブスカイト型化合物粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａは、１．００６以上１．０１０以下であることが好ましい。ｃ／ａが１．００６以上であると、得られる半導体素子を構成するセラミックス素体中のセラミックス焼結体粒子のｃ／ａを１．００７以上にすることができ、その結果、セラミックス焼結体粒子のキュリー点を１００℃以上にすることができる。セラミックス素体２がチタン酸バリウム系材料で構成される場合、ｃ／ａは一般に１．０１０以下である。ｃ／ａは、より好ましくは１．００７以上１．０１０以下である。ｃ／ａが１．００７以上であると、セラミックス焼結体粒子のキュリー点を１１０℃以上にすることができる。原料のペロブスカイト型化合物粒子のｃ／ａは、粉末Ｘ線回折装置を用いて定性分析を行い、リートベルト解析することにより算出することができる。 Raw material perovskite type compound particles have a highly tetragonal crystal structure. When perovskite type compound particles having a highly tetragonal crystal structure are used as raw materials, the ceramic sintered body particles in the ceramic body constituting the obtained semiconductor element have a tetragonal structure. As a result, a decrease in the Curie point of the ceramic sintered body particles can be suppressed, and a decrease in the operating temperature of the semiconductor element can be suppressed. The ratio c / a of the c-axis length to the a-axis length of the crystal lattice of the raw material perovskite compound particles is preferably from 1.006 to 1.010. When c / a is 1.006 or more, the c / a of the ceramic sintered body particles in the ceramic body constituting the obtained semiconductor element can be made 1.007 or more. The Curie point of the body particles can be set to 100 ° C. or higher. When the ceramic body 2 is composed of a barium titanate material, c / a is generally 1.010 or less. c / a is more preferably 1.007 or more and 1.010 or less. When the c / a is 1.007 or more, the Curie point of the ceramic sintered body particles can be 110 ° C. or more. The c / a of the raw material perovskite compound particles can be calculated by conducting a qualitative analysis using a powder X-ray diffractometer and performing a Rietveld analysis.
　次に、原料のペロブスカイト型化合物粒子を含むグリーンチップを形成する。半導体素子として内部電極を有する積層型ＰＴＣサーミスタを製造する場合、ペロブスカイト型化合物粒子を含むグリーンチップを形成する工程は、ペロブスカイト型化合物粒子を含むセラミックスグリーンシートを作製する工程と、セラミックスグリーンシートの主面上に内部電極用導電性ペーストを塗布する工程と、内部電極用導電性ペーストを塗布したセラミックスグリーンシートを複数枚積層して積層体を得る工程と、積層体の上下に内部電極用導電性ペーストを塗布していないセラミックスグリーンシートを配置して圧着し、所定の寸法に切断してグリーンチップを得る工程とを含む。 Next, a green chip containing raw material perovskite type compound particles is formed. When manufacturing a stacked PTC thermistor having an internal electrode as a semiconductor element, a step of forming a green chip containing perovskite compound particles includes a step of producing a ceramic green sheet containing perovskite compound particles, and a main part of the ceramic green sheet. A step of applying a conductive paste for internal electrodes on a surface, a step of obtaining a laminate by laminating a plurality of ceramic green sheets coated with a conductive paste for internal electrodes, and a conductivity for internal electrodes above and below the laminate. And placing a ceramic green sheet to which a paste has not been applied, press-bonding, and cutting to a predetermined size to obtain a green chip.
　まず、以下に示す手順でペロブスカイト型化合物粒子を含むセラミックスグリーンシートを作製する。原料のペロブスカイト型化合物粒子に有機バインダー、分散剤および水を加え、ジルコニアボールと共に数時間混合して、セラミックススラリーを得る。なお、原料のペロブスカイト型化合物粒子が元素αおよび元素βをいずれも含んでいない場合、あるいは所望の組成を有するセラミックス焼結体粒子を得るのに必要な元素αおよび／または元素βの量の全量を含んでいない場合、セラミックススラリーの調製時にドナーとして元素αおよび／またはβの塩化物、水酸化物、酸化物、炭酸塩、アルコキシド、イオン化水溶液等を所定量添加してよい。 First, a ceramic green sheet containing perovskite type compound particles is prepared according to the following procedure. An organic binder, a dispersant and water are added to the raw material perovskite type compound particles and mixed with zirconia balls for several hours to obtain a ceramic slurry. In addition, when the raw material perovskite type compound particles do not contain both element α and element β, or the total amount of element α and / or element β necessary for obtaining ceramic sintered particles having a desired composition When the ceramic slurry is not included, a predetermined amount of chloride, hydroxide, oxide, carbonate, alkoxide, ionized aqueous solution, or the like of the element α and / or β may be added as a donor during the preparation of the ceramic slurry.
　上述のセラミックススラリーを、ドクターブレード法によりシート状に成形し、乾燥させてセラミックスグリーンシートを作製する。セラミックスグリーンシートの厚さは２０μｍ以上４０μｍ以下であることが好ましい。 The above-mentioned ceramic slurry is formed into a sheet by the doctor blade method and dried to produce a ceramic green sheet. The thickness of the ceramic green sheet is preferably 20 μm or more and 40 μm or less.
　次に、セラミックスグリーンシートの主面上に内部電極用導電性ペーストを塗布する。まず、金属粉末等の導電性粉末および有機バインダーを有機溶媒に分散させて、内部電極用導電性ペーストを調製する。導電性粉末としては、例えばＮｉ金属粉末等の金属粉末等を適宜用いることができる。 Next, a conductive paste for internal electrodes is applied on the main surface of the ceramic green sheet. First, conductive powder such as metal powder and an organic binder are dispersed in an organic solvent to prepare a conductive paste for internal electrodes. As the conductive powder, for example, metal powder such as Ni metal powder can be appropriately used.
　この内部電極用導電性ペーストをセラミックスグリーンシートの主面上に塗布する。内部電極用導電性ペーストの塗布厚さは、最終的に得られる半導体素子における内部電極の厚さが０．５μｍ以上２μｍ以下となるように設定する。内部電極用導電性ペーストの塗布は、スクリーン印刷等の方法により行ってよい。 ¡Apply this internal electrode conductive paste on the main surface of the ceramic green sheet. The coating thickness of the internal electrode conductive paste is set so that the thickness of the internal electrode in the finally obtained semiconductor element is 0.5 μm or more and 2 μm or less. The conductive paste for internal electrodes may be applied by a method such as screen printing.
　次に、内部電極用導電性ペーストを塗布したセラミックスグリーンシートを複数枚積層して積層体を得る。内部電極用導電性ペーストを塗布したセラミックスグリーンシートの積層枚数は、最終的に得られる半導体素子が有するべき内部電極の数に応じて設定してよい。 Next, a plurality of ceramic green sheets coated with the internal electrode conductive paste are laminated to obtain a laminate. The number of laminated ceramic green sheets coated with the internal electrode conductive paste may be set according to the number of internal electrodes that the finally obtained semiconductor element should have.
　次に、積層体の上下に、内部電極用導電性ペーストを塗布していないセラミックスグリーンシートを、例えば５枚ずつ配置して圧着し、焼成後の寸法が所望の値となるように所定の寸法に切断してグリーンチップを得る。グリーンチップを焼成して得られるセラミックス素体の寸法は、例えばＬ寸２．０ｍｍ×Ｗ寸１．２ｍｍ×Ｔ寸１．０ｍｍであってよい。 Next, ceramic green sheets not coated with the internal electrode conductive paste are placed on the top and bottom of the laminate, for example, 5 sheets each, and pressed, and predetermined dimensions are set so that the dimensions after firing become a desired value. Cut to get green chips. The size of the ceramic body obtained by firing the green chip may be, for example, L size 2.0 mm × W size 1.2 mm × T size 1.0 mm.
　なお、内部電極を有しない半導体素子を製造する場合、内部電極用導電性ペーストを塗布していないセラミックスグリーンシートを複数枚積層し、圧着した後所定の寸法に切断することによりグリーンチップを作製してよい。 When manufacturing a semiconductor element having no internal electrode, a plurality of ceramic green sheets not coated with the internal electrode conductive paste are stacked, pressed, and cut to a predetermined size to produce a green chip. It's okay.
　次に、グリーンチップを焼成することによりセラミックス素体を得る、まず、焼成に先立って、グリーンチップを大気雰囲気下にて２５０℃以上３５０以下の温度で１０時間以上１５時間以下脱脂処理する。脱脂処理後のグリーンチップを、Ｎ２／Ｈ２、Ａｒ／Ｈ２，Ｎ２／Ｈ２／Ｈ２Ｏ等の還元雰囲気の下１０５０℃以上１２４０℃以下の温度で０．５時間以上３時間以下焼成し、セラミックス素体を得る。 Next, the ceramic body is obtained by firing the green chip. First, prior to firing, the green chip is degreased at a temperature of 250 ° C. to 350 ° C. for 10 hours to 15 hours in an air atmosphere. The green chip after the degreasing treatment is 0.5 hours to 3 hours at a temperature of 1050 ° C. or higher and 1240 ° C. or lower in a reducing atmosphere such as N 2 / H 2 , Ar / H 2 , N 2 / H 2 / H 2 O Thereafter, firing is performed to obtain a ceramic body.
　場合により、得られたセラミックス素体をガラスコートし、大気雰囲気の下６００℃以上９００℃以下の温度で熱処理することにより、セラミックス素体の表面にガラス層を形成すると同時に、セラミックス素体の再酸化を行ってよい。 In some cases, the obtained ceramic body is glass-coated and heat-treated at a temperature of 600 ° C. or higher and 900 ° C. or lower in an air atmosphere to form a glass layer on the surface of the ceramic body, and at the same time, recycle the ceramic body. Oxidation may be performed.
　次いで、セラミックス素体の両端面に外部電極を形成する。まず、外部電極の形成に先立って、セラミックス素体をバレル研磨する。バレル研磨後のセラミックス素体の両端面に外部電極を形成する。外部電極の組成および形成方法は特に限定されるものではなく、目的に応じて適宜選択することができる。例えば、外部電極は、セラミックス素体の両端面にＣｒ、ＮｉＣｕ合金およびＡｇをこの順番にスパッタリングすることにより形成することができる。別法として、外部電極は、樹脂成分および金属（Ａｇ等）を含むペーストを塗布し、適当な温度で焼きつける事により形成してもよい。形成された外部電極の表面に、電解めっき等の方法によりめっき層を形成してよい。めっき層の組成は外部電極の組成に応じて適宜選択することができ、例えば、Ｓｎめっき層、Ｎｉめっき層またはこれらの２以上の組み合わせであってよい。このようにして、本実施形態に係る半導体素子が得られる。 Next, external electrodes are formed on both end faces of the ceramic body. First, prior to the formation of the external electrode, the ceramic body is barrel-polished. External electrodes are formed on both end faces of the ceramic body after barrel polishing. The composition and formation method of the external electrode are not particularly limited, and can be appropriately selected according to the purpose. For example, the external electrode can be formed by sputtering Cr, NiCu alloy and Ag in this order on both end faces of the ceramic body. Alternatively, the external electrode may be formed by applying a paste containing a resin component and a metal (Ag or the like) and baking it at an appropriate temperature. A plating layer may be formed on the surface of the formed external electrode by a method such as electrolytic plating. The composition of the plating layer can be appropriately selected according to the composition of the external electrode, and may be, for example, a Sn plating layer, a Ni plating layer, or a combination of two or more thereof. In this way, the semiconductor element according to this embodiment is obtained.
　以下に示す手順で例１～１９の半導体素子を作製した。なお、例１～１９の半導体素子は、積層型ＰＴＣサーミスタである。 The semiconductor elements of Examples 1 to 19 were fabricated by the following procedure. The semiconductor elements of Examples 1 to 19 are stacked PTC thermistors.
　［例１］
　まず、最終的に得られる半導体素子を構成するセラミックス素体に含まれるセラミックス焼結体粒子の組成が下記の（２）式で表される組成となるように、ＢａＣＯ３、ＴｉＯ２およびＬａ２Ｏ３を秤量した。例１において、α＝Ｌａであり、ｍＢａ＝１００、ｍα＝ｍＬａ＝０．１、ｍ＝０．９９９となるように各原料を秤量した。 [Example 1]
First, BaCO 3 , TiO 2, and La 2 so that the composition of the ceramic sintered body particles contained in the ceramic body constituting the finally obtained semiconductor element is a composition represented by the following formula (2). O 3 was weighed. In Example 1, each raw material was weighed so that α = La, m Ba = 100, m α = m La = 0.1, and m = 0.999.
Figure JPOXMLDOC01-appb-C000002
Figure JPOXMLDOC01-appb-C000002
　秤量した各原材料をＺｒＯ２ボールおよび純水と共にボールミルに投入し、湿式で十分に混合および粉砕した後、乾燥させた。このようにして得られた混合粉体を１１００℃の温度で仮焼処理（熱処理）することにより、原料のペロブスカイト型化合物粒子を調製した。得られた原料のペロブスカイト型化合物粒子の比表面積は２．１ｍ２／ｇ、ｃ／ａは１．０１０であった。原料のペロブスカイト型化合物粒子の比表面積は、株式会社マウンテック製のＭａｃｓｏｒｂ（登録商標）を用いて脱気温度２５０℃の条件下で測定した。原料のペロブスカイト型化合物粒子のｃ／ａは、粉末Ｘ線回折装置（リガク社製ＲＩＮＴ２５００）を用いて定性分析を行い、リートベルト解析することにより求めた。 Each weighed raw material was put into a ball mill together with ZrO 2 balls and pure water, thoroughly mixed and pulverized by a wet method, and then dried. The mixed powder thus obtained was calcined (heat treated) at a temperature of 1100 ° C. to prepare perovskite type compound particles as raw materials. The obtained perovskite compound particles had a specific surface area of 2.1 m 2 / g and c / a of 1.010. The specific surface area of the raw material perovskite type compound particles was measured using a Macsorb (registered trademark) manufactured by Mountec Co., Ltd. under a degassing temperature of 250 ° C. The c / a of the raw material perovskite type compound particles was determined by conducting a qualitative analysis using a powder X-ray diffraction apparatus (RINT2500 manufactured by Rigaku Corporation) and performing a Rietveld analysis.
　得られた原料のペロブスカイト型化合物粒子に有機バインダー、分散剤および水を加え、ジルコニアボールと共に数時間混合して、セラミックススラリーを得た。このセラミックススラリーを、ドクターブレード法によりシート状に成形し、乾燥させて、厚さ３０μｍのセラミックスグリーンシートを作製した。 An organic binder, a dispersant and water were added to the obtained raw material perovskite type compound particles and mixed with zirconia balls for several hours to obtain a ceramic slurry. This ceramic slurry was formed into a sheet by a doctor blade method and dried to prepare a ceramic green sheet having a thickness of 30 μm.
　次に、Ｎｉ金属粉末および有機バインダーを有機溶媒に分散させて、内部電極用導電性ペーストを調製した。この内部電極用導電性ペーストを、スクリーン印刷によりセラミックスグリーンシートの主面上に塗布した。内部電極用導電性ペーストの塗布厚さは、最終的に得られる半導体素子における内部電極の厚さが０．５μｍ以上２μｍ以下となるように調節した。このように内部電極用導電性ペーストを塗布したセラミックスグリーンシートを、内部電極が２４枚含まれ且つ内部電極間距離が３０μｍとなるように積層して積層体を得た。この積層体の上下に、内部電極用導電性ペーストを塗布していないセラミックスグリーンシートを５枚ずつ配置して圧着し、焼成後の寸法がＬ寸２．０ｍｍ×Ｗ寸１．２ｍｍ×Ｔ寸１．０ｍｍとなるように寸法に切断してグリーンチップを得た。 Next, Ni metal powder and an organic binder were dispersed in an organic solvent to prepare a conductive paste for internal electrodes. This internal electrode conductive paste was applied on the main surface of the ceramic green sheet by screen printing. The coating thickness of the internal electrode conductive paste was adjusted so that the thickness of the internal electrode in the finally obtained semiconductor element was 0.5 μm or more and 2 μm or less. Thus, the ceramic green sheet which apply | coated the conductive paste for internal electrodes was laminated | stacked so that 24 internal electrodes might be contained and the distance between internal electrodes might be set to 30 micrometers, and the laminated body was obtained. Five ceramic green sheets not coated with the internal electrode conductive paste are placed on the upper and lower sides of this laminate and pressed, and the dimensions after firing are L dimension 2.0 mm × W dimension 1.2 mm × T dimension. A green chip was obtained by cutting into a size of 1.0 mm.
　このグリーンチップを大気雰囲気下にて３００℃で１２時間脱脂処理した。脱脂処理後のグリーンチップを、Ｎ２／Ｈ２の還元雰囲気下にて１０５０℃以上１２４０℃以下の温度で２時間焼成し、セラミックス素体を得た。 This green chip was degreased at 300 ° C. for 12 hours in an air atmosphere. The green chip after the degreasing treatment was fired for 2 hours at a temperature of 1050 ° C. or higher and 1240 ° C. or lower in a reducing atmosphere of N 2 / H 2 to obtain a ceramic body.
　得られたセラミックス素体をガラスコートし、大気雰囲気下にて８００℃で熱処理することにより、セラミックス素体の表面にガラス層を形成すると同時に、セラミックス素体の再酸化を行った。 The obtained ceramic body was glass-coated and heat-treated at 800 ° C. in an air atmosphere to form a glass layer on the surface of the ceramic body and simultaneously re-oxidize the ceramic body.
　ガラス層が形成されたセラミックス素体をバレル研磨した。バレル研磨後のセラミックス素体の両端面にＣｒ、ＮｉＣｕ合金およびＡｇをこの順番にスパッタリングすることにより、外部電極を形成した。形成された外部電極の表面に、電解めっきによりＳｎめっき層を形成した。このようにして、例１の半導体素子を得た。 The ceramic body on which the glass layer was formed was barrel polished. External electrodes were formed by sputtering Cr, NiCu alloy and Ag in this order on both end faces of the ceramic body after barrel polishing. An Sn plating layer was formed on the surface of the formed external electrode by electrolytic plating. Thus, the semiconductor element of Example 1 was obtained.
　［例２～１９］
　後述の表１に示す比表面積およびｃ／ａの値を有するペロブスカイト型化合物粒子を原料として用いた以外は例１と同様の手順で例２～１９の半導体素子を製造した。 [Examples 2 to 19]
Semiconductor devices of Examples 2 to 19 were produced in the same procedure as Example 1 except that perovskite type compound particles having specific surface areas and c / a values shown in Table 1 described later were used as raw materials.
　例１～１９の半導体素子の各々について、セラミックス焼結体粒子の平均粒径、ｃ／ａおよびキュリー点を測定した。セラミックス焼結体粒子の平均粒径は以下の手順で測定した。まず、半導体素子をＬＴ面（Ｗ方向に対して垂直な面）方向に約１／２Ｗ地点（半導体素子のＷ寸の約半分の地点）まで研磨し、ＬＴ面に平行な半導体素子断面を露出させた。この断面を、走査型電子顕微鏡（日本電子製ＪＳＭ－７５００ＦＡ）を用いて加速電圧５ｋＶ、倍率１００００倍の条件で観察し、ＳＥＭ画像を得た。このＳＥＭ画像を、解析装置（旭エンジニアリング株式会社製ＩＰ－１０００）を用いて画像解析し、ＳＥＭ画像におけるセラミックス焼結体粒子の面積を求めた。求めた面積に基づいて算出した等面積円相当径（Ｈｅｙｗｏｏｄ径）をセラミックス焼結体粒子の粒径とした。観察したＳＥＭ画像の視野（約１８μｍ平方以上約２０μｍ平方以下）の中に完全に収まっているセラミックス焼結体粒子の粒径の平均値を、セラミックス焼結体粒子の平均粒径とした。なお、本実施例において、上述の半導体素子断面においてセラミックス焼結体粒子の平均粒径を求めたが、他の半導体素子断面において平均粒径を求めた場合であっても同様の結果が得られると考えて差し支えない。セラミックス焼結体粒子のｃ／ａは、粉末Ｘ線回折装置（リガク社製ＲＩＮＴ２５００）を用いて定性分析を行い、リートベルト解析することにより求めた。セラミックス焼結体粒子のキュリー点は、ＴＡインスツルメント社製の示差走査熱量計（型式ＤＳＣ２９２０）を用いたＤＳＣ測定により求めた。ＤＳＣ測定は、測定雰囲気が大気雰囲気、昇温速度が１０℃／分、開始温度が２５℃、終了温度が２５０℃の条件で行った。得られた示差熱－温度曲線における吸熱ピークのピーク温度をキュリー点とした。 For each of the semiconductor elements of Examples 1 to 19, the average particle diameter, c / a, and Curie point of the ceramic sintered body particles were measured. The average particle size of the sintered ceramic particles was measured by the following procedure. First, the semiconductor element is polished to about 1/2 W point (about half the W dimension of the semiconductor element) in the direction of the LT plane (plane perpendicular to the W direction), and the semiconductor element cross section parallel to the LT plane is exposed. I let you. This cross section was observed using a scanning electron microscope (JSM-7500FA manufactured by JEOL Ltd.) under the conditions of an acceleration voltage of 5 kV and a magnification of 10,000 times to obtain an SEM image. The SEM image was subjected to image analysis using an analyzer (IP-1000 manufactured by Asahi Engineering Co., Ltd.), and the area of the ceramic sintered body particles in the SEM image was determined. An equivalent area equivalent circle diameter (Heywood diameter) calculated based on the obtained area was defined as the particle diameter of the ceramic sintered body particles. The average value of the particle diameters of the ceramic sintered body particles completely contained in the field of view of the observed SEM image (about 18 μm square or more and about 20 μm square or less) was defined as the average particle diameter of the ceramic sintered body particles. In this example, the average particle diameter of the ceramic sintered body particles was obtained in the above-mentioned semiconductor element cross section, but the same result can be obtained even when the average particle diameter is obtained in other semiconductor element cross sections. You can think of it. The c / a of the ceramic sintered body particles was determined by performing a qualitative analysis using a powder X-ray diffraction apparatus (RINT2500 manufactured by Rigaku Corporation) and performing a Rietveld analysis. The Curie point of the sintered ceramic particles was determined by DSC measurement using a differential scanning calorimeter (model DSC2920) manufactured by TA Instruments. The DSC measurement was performed under the conditions that the measurement atmosphere was an air atmosphere, the rate of temperature increase was 10 ° C./min, the start temperature was 25 ° C., and the end temperature was 250 ° C. The peak temperature of the endothermic peak in the obtained differential heat-temperature curve was taken as the Curie point.
　例１～１９の半導体素子の各々について、下記の手順で耐電圧特性を測定した。半導体素子を基板に実装した後、半導体素子に６８０Ｖ／ｍｍの電圧を３分間印加し、その時の電流値を測定した。次いで、６８０Ｖ／ｍｍの電圧において半導体素子が破壊しなかった場合には、電圧を２０Ｖ／ｍｍのステップで増大させて３分間印加するという測定を繰り返した。半導体素子が破壊した直前の電圧値を耐電圧特性とした。以上の測定結果を表１に示す。 With respect to each of the semiconductor elements of Examples 1 to 19, the withstand voltage characteristics were measured by the following procedure. After mounting the semiconductor element on the substrate, a voltage of 680 V / mm was applied to the semiconductor element for 3 minutes, and the current value at that time was measured. Next, when the semiconductor element was not destroyed at a voltage of 680 V / mm, the measurement was repeated by increasing the voltage in steps of 20 V / mm and applying it for 3 minutes. The voltage value immediately before the semiconductor element was destroyed was defined as a withstand voltage characteristic. The above measurement results are shown in Table 1.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表１より、原料のペロブスカイト型化合物粒子の比表面積が２．９ｍ２／ｇ以上１３．０ｍ２／ｇ以下であり且つｃ／ａが１．００６以上１．０１０以下であった例３～１２、１４、１５および１７において、得られた半導体素子に含まれるセラミックス焼結体粒子の平均粒径を１．０μｍ以下にすることができ、且つセラミックス焼結体粒子のｃ／ａを１．００７以上にすることができたことがわかる。一方、原料のペロブスカイト型化合物粒子の比表面積が２．９ｍ２／ｇ未満であった例１および２において、得られた半導体素子に含まれるセラミックス焼結体粒子の平均粒径は１．０μｍより大きかった。また、原料のペロブスカイト型化合物粒子の比表面積が１３．０ｍ２／ｇより大きく且つｃ／ａが１．００６未満であった例１８および１９において、得られた半導体素子に含まれるセラミックス焼結体粒子のｃ／ａは１．００７未満であった。原料のペロブスカイト型化合物粒子のｃ／ａが１．００６より小さかった例１３および１６においては、得られた半導体素子に含まれるセラミックス焼結体粒子のｃ／ａが１．００７未満であった。 From Table 1, Examples 3 to 12 in which the specific surface area of the raw material perovskite compound particles was 2.9 m 2 / g or more and 13.0 m 2 / g or less and c / a was 1.006 or more and 1.010 or less. , 14, 15 and 17, the average particle size of the ceramic sintered body particles contained in the obtained semiconductor element can be 1.0 μm or less, and the c / a of the ceramic sintered body particles is 1.007. It turns out that it was able to do it above. On the other hand, in Examples 1 and 2 in which the specific surface area of the raw material perovskite compound particles was less than 2.9 m 2 / g, the average particle size of the ceramic sintered body particles contained in the obtained semiconductor element was 1.0 μm or more. It was big. In addition, in Examples 18 and 19 in which the specific surface area of the raw material perovskite compound particles was greater than 13.0 m 2 / g and c / a was less than 1.006, the ceramic sintered body contained in the obtained semiconductor element The c / a of the particles was less than 1.007. In Examples 13 and 16, where c / a of the raw material perovskite compound particles was smaller than 1.006, the c / a of the ceramic sintered body particles contained in the obtained semiconductor element was less than 1.007.
　表１に示すように、セラミックス焼結体粒子の平均粒径が１．０μｍ以下であり且つｃ／ａが１．００７以上であった例３～１２、１４、１５および１７の半導体素子において、セラミックス焼結体粒子のキュリー点は１００℃以上であった。従って、例３～１２、１４、１５および１７の半導体素子は１００℃以上の高い動作温度を示したことがわかる。また、表１より、例３～１２、１４、１５および１７の半導体素子は１０００Ｖ／ｍｍ以上の高い耐電圧特性を有したことがわかる。一方、セラミックス焼結体粒子のｃ／ａが１．００７未満であった例１３、１６、１８および１９の半導体素子において、セラミックス焼結体粒子のキュリー点は１００℃未満であった。従って、例１８および１９の半導体素子は１００℃未満の低い動作温度を有したことがわかる。また、セラミックス焼結体粒子の平均粒径が１．０μｍより大きかった例１および２の半導体素子は、１０００Ｖ／ｍｍ未満の低い耐電圧特性を示した。 As shown in Table 1, in the semiconductor elements of Examples 3 to 12, 14, 15, and 17 in which the average particle diameter of the ceramic sintered body particles was 1.0 μm or less and c / a was 1.007 or more, The Curie point of the ceramic sintered body particles was 100 ° C. or higher. Therefore, it can be seen that the semiconductor elements of Examples 3 to 12, 14, 15, and 17 exhibited a high operating temperature of 100 ° C. or higher. Further, it can be seen from Table 1 that the semiconductor elements of Examples 3 to 12, 14, 15 and 17 had high withstand voltage characteristics of 1000 V / mm or more. On the other hand, in the semiconductor elements of Examples 13, 16, 18 and 19 in which c / a of the ceramic sintered body particles was less than 1.007, the Curie point of the ceramic sintered body particles was less than 100 ° C. Therefore, it can be seen that the semiconductor elements of Examples 18 and 19 had a low operating temperature of less than 100 ° C. In addition, the semiconductor elements of Examples 1 and 2 in which the average particle diameter of the ceramic sintered body particles was larger than 1.0 μm exhibited low withstand voltage characteristics of less than 1000 V / mm.
　本発明に係る半導体素子は、高い耐電圧特性と高い動作温度とを両立しており、車載用サーミスタの市場において一般的に求められる８５℃の使用温度範囲において好適に用いることができる。 The semiconductor element according to the present invention has both a high withstand voltage characteristic and a high operating temperature, and can be suitably used in an operating temperature range of 85 ° C. generally required in the in-vehicle thermistor market.
　１　半導体素子
　２　セラミックス素体
　２１　セラミックス素体の第１の端面
　２２　セラミックス素体の第２の端面
　３１　第１の外部電極
　３２　第２の外部電極
　４１　第１の内部電極
　４２　第２の内部電極
　５　ガラス層
　６１、６２　めっき層 DESCRIPTION OF SYMBOLS 1 Semiconductor element 2 Ceramic body 21 First end surface of ceramic body 22 Second end surface of ceramic body 31 First external electrode 32 Second external electrode 41 First internal electrode 42 Second internal electrode 5 Glass layer 61, 62 Plating layer

Claims (9)

  1. 　セラミックス焼結体粒子を含むセラミックス素体と、
    　前記セラミックス素体の第１の端面に配置される第１の外部電極と、
    　前記セラミックス素体の第２の端面に配置される第２の外部電極と
    を含む半導体素子であって、
    　前記セラミックス焼結体粒子は、ＢａおよびＴｉを少なくとも含むペロブスカイト型化合物であり、
    　前記セラミックス焼結体粒子の平均粒径が１．０μｍ以下であり、
    　前記セラミックス焼結体粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａが１．００７以上である、半導体素子。     A ceramic body including ceramic sintered body particles;
    A first external electrode disposed on a first end surface of the ceramic body,
    A semiconductor element including a second external electrode disposed on a second end face of the ceramic body,
    The ceramic sintered body particles are perovskite type compounds containing at least Ba and Ti,
    The ceramic sintered body particles have an average particle size of 1.0 μm or less,
    A semiconductor element, wherein a ratio c / a of c-axis length to a-axis length of a crystal lattice of the ceramic sintered body particles is 1.007 or more.
  2. 　前記セラミックス焼結体粒子の平均粒径が０．６μｍ以上０．９μｍ以下である、請求項１に記載の半導体素子。 The semiconductor element according to claim 1, wherein an average particle diameter of the ceramic sintered body particles is 0.6 μm or more and 0.9 μm or less.
  3. 　前記セラミックス焼結体粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａが１．００８以上１．０１０以下である、請求項１または２に記載の半導体素子。 The semiconductor element according to claim 1 or 2, wherein a ratio c / a of c-axis length to a-axis length of a crystal lattice of the ceramic sintered body particles is 1.008 or more and 1.010 or less.
  4. 　前記セラミックス焼結体粒子のキュリー点が１００℃以上である、請求項１～３のいずれか１項に記載の半導体素子。 4. The semiconductor element according to claim 1, wherein a Curie point of the ceramic sintered body particles is 100 ° C. or higher.
  5. 　前記半導体素子が、前記セラミックス素体の内部に１以上の第１の内部電極および１以上の第２の内部電極が配置された積層型半導体素子であり、
    　前記第１の内部電極は、前記セラミックス素体の前記第１の端面において前記第１の外部電極と電気的に接続し、
    　前記第２の内部電極は、前記セラミックス素体の前記第２の端面において前記第２の外部電極と電気的に接続する、請求項１～４のいずれか１項に記載の半導体素子。     The semiconductor element is a stacked semiconductor element in which one or more first internal electrodes and one or more second internal electrodes are disposed inside the ceramic body,
    The first internal electrode is electrically connected to the first external electrode at the first end face of the ceramic body;
    The semiconductor element according to any one of claims 1 to 4, wherein the second internal electrode is electrically connected to the second external electrode at the second end face of the ceramic body.
  6. 　前記第１の内部電極および前記第２の内部電極がＮｉ電極である、請求項５に記載の半導体素子。 The semiconductor element according to claim 5, wherein the first internal electrode and the second internal electrode are Ni electrodes.
  7. 　半導体素子の製造方法であって、
    　ＢａおよびＴｉを少なくとも含むペロブスカイト型化合物粒子を調製する工程と、
    　前記ペロブスカイト型化合物粒子を含むグリーンチップを形成する工程と、
    　前記グリーンチップを焼成することによりセラミックス素体を得る工程と、
    　前記セラミックス素体の両端面に外部電極を形成することにより半導体素子を得る工程と
    を含み、
    　前記ペロブスカイト型化合物粒子の比表面積が２．９ｍ２／ｇ以上１３．０ｍ２／ｇ以下であり、
    　前記ペロブスカイト型化合物粒子の結晶格子のａ軸長に対するｃ軸長の比ｃ／ａが１．００６以上１．０１０以下である、方法。     A method for manufacturing a semiconductor device, comprising:
    Preparing perovskite-type compound particles containing at least Ba and Ti;
    Forming a green chip containing the perovskite type compound particles;
    Obtaining a ceramic body by firing the green chip;
    Forming a semiconductor element by forming external electrodes on both end faces of the ceramic body,
    The perovskite compound particles have a specific surface area of 2.9 m 2 / g or more and 13.0 m 2 / g or less,
    A method in which a ratio c / a of a c-axis length to an a-axis length of a crystal lattice of the perovskite compound particles is 1.006 or more and 1.010 or less.
  8. 　前記ペロブスカイト型化合物粒子を含むグリーンチップを形成する工程が、
    　前記ペロブスカイト型化合物粒子を含むセラミックスグリーンシートを作製する工程と、
    　前記セラミックスグリーンシートの主面上に内部電極用導電性ペーストを塗布する工程と、
    　前記内部電極用導電性ペーストを塗布した前記セラミックスグリーンシートを複数枚積層して積層体を得る工程と、
    　前記積層体の上下に前記内部電極用導電性ペーストを塗布していないセラミックスグリーンシートを配置して圧着し、所定の寸法に切断してグリーンチップを得る工程と
    を含む、請求項７に記載の方法。     Forming a green chip containing the perovskite type compound particles,
    Producing a ceramic green sheet containing the perovskite type compound particles;
    Applying a conductive paste for internal electrodes on the main surface of the ceramic green sheet;
    Laminating a plurality of the ceramic green sheets coated with the internal electrode conductive paste to obtain a laminate; and
    A ceramic green sheet not coated with the internal electrode conductive paste is disposed above and below the laminated body and bonded, and cut to a predetermined size to obtain a green chip. Method.
  9. 　前記内部電極用導電性ペーストが、導電性粉末としてＮｉ金属粉末を含む、請求項８に記載の方法。 The method according to claim 8, wherein the internal electrode conductive paste contains Ni metal powder as the conductive powder.
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07220902A (en) * 1994-02-07 1995-08-18 Murata Mfg Co Ltd Barium titanate semiconductor ceramic
JP2001031471A (en) * 1999-05-20 2001-02-06 Murata Mfg Co Ltd Barium titanate-based semiconductor ceramic powder and lamination type semiconductor ceramic element

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07220902A (en) * 1994-02-07 1995-08-18 Murata Mfg Co Ltd Barium titanate semiconductor ceramic
JP2001031471A (en) * 1999-05-20 2001-02-06 Murata Mfg Co Ltd Barium titanate-based semiconductor ceramic powder and lamination type semiconductor ceramic element

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