JP2013012623A - Led light-emitting element holding substrate and manufacturing method thereof and led light-emitting element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED light-emitting element holding substrate whose difference in linear thermal expansion coefficient with group III-V semiconductor crystal constituting an LED is small and which excels in thermal conductivity and further excels in chemical resistance against acid and alkali solutions used in manufacturing, making it suitable for a high output LED.SOLUTION: The LED light-emitting element holding substrate is covered with aluminum or aluminum alloy in thickness of 0.1 to 2.0 mm on the outer periphery thereof, and has aluminum or aluminum alloy formed in thickness of 0.05 to 2 μm on both sides of the substrate having a metal impregnated ceramic composite body exposed to both principal planes thereof. After being heated at 460 to 650°C for one minute or more in a nitrogen, argon, hydrogen, helium or vacuum atmosphere, the substrate has a Ni plated layer in thickness of 0.5 to 5 μm and a gold plated layer in thickness of 0.05 to 2 μm formed in order over the whole surface thereof.

Description

  The present invention relates to an LED light-emitting element holding substrate, a manufacturing method thereof, and an LED light-emitting element.

  An LED (light emitting diode) is an element that emits light when a forward current flows through a pn junction of a semiconductor, and is manufactured using a III-V group semiconductor crystal such as GaAs or GaN. For example, a method has been proposed in which a buffer layer such as GaN is formed on a single crystal growth substrate such as a sapphire substrate, and GaN is epitaxially grown thereon (Patent Document 1). However, in this method, due to the difference in coefficient of linear expansion between the sapphire substrate and GaN, the sapphire substrate after epitaxial growth may be warped and the substrate may be cracked. Furthermore, since the single crystal sapphire constituting the sapphire substrate has a thermal conductivity of about 40 W / mK, the heat generated in the III-V group semiconductor element such as GaN cannot be sufficiently dissipated. For this reason, in the high-power LED in which a large current flows, the temperature of the element rises, resulting in a decrease in luminous efficiency and element life.

  In order to improve heat dissipation, there is a method in which a III-V group semiconductor crystal is epitaxially grown on a single crystal growth substrate, then a high thermal conductivity substrate is joined through a metal layer, and then the single crystal growth substrate is removed. Although it has been proposed (Patent Document 2), the difference in linear expansion coefficient from the III-V group semiconductor crystal is large, which is not satisfactory for high-power LEDs.

Japanese Patent Publication No. 5-73252 JP 2006-128710 A

  An object of the present invention is to provide an LED light-emitting element holding substrate that has a small difference in linear expansion coefficient from an LED (hereinafter also simply referred to as an LED) composed of a group III-V semiconductor crystal and excellent thermal conductivity. And providing an LED light emitting device.

  Furthermore, the problem to be solved by the present invention is to provide a holding substrate for an LED light-emitting element that is excellent in chemical resistance against an acid and an alkali solution used at the time of manufacturing the LED light-emitting element and that is suitable for a high-power LED. It is.

The outer peripheral portion is covered with aluminum or aluminum alloy having a thickness of 0.1 to 2.0 mm, and the aluminum or aluminum alloy layer has a thickness of 0.0 on both main surfaces of the substrate where the metal-impregnated ceramic composite is exposed on both main surfaces. After being heat-treated at 460-650 ° C. for 1 minute or more in nitrogen, argon, hydrogen, helium or a vacuum atmosphere, a Ni plating layer having a thickness of 0.5-5 μm and a thickness of 0.05- This is a holding substrate for an LED light emitting element in which a 2 μm gold plating layer is sequentially formed.

Furthermore, the metal-impregnated ceramic composite of the present invention is obtained by impregnating a porous body made of silicon carbide having a porosity of 10 to 50% by volume with metal, and the metal-impregnated ceramic composite has a three-point bending strength. 50 MPa or more, thermal conductivity at a temperature of 25 ° C. is 150 to 300 W / mK, linear thermal expansion coefficient at a temperature of 25 ° C. to 150 ° C. is 4 × 10 ^{−6 to} 9 × 10 ⁻⁶ / K, and volume resistivity is 10 ^−9. 10 ^-5 Ω · m, a plate thickness of 0.05 to 1.0 mm, and a surface roughness (Ra) of 0.01 to 0.5 μm.

Furthermore, this invention is an LED light emitting element manufactured through the following processes in order.
(1) A step of epitaxially growing a group III-V semiconductor crystal on one main surface of a disk-like or flat plate-like single crystal growth substrate.
(2) The LED light-emitting element holding substrate according to claim 1, 2 or 3 is bonded to the III-V group semiconductor crystal surface via a metal layer, and is simply applied by any one of laser irradiation, etching, and grinding. Removing the crystal growth substrate;
(3) A step of cutting after performing surface processing of the III-V semiconductor crystal surface and electrode formation.

In addition, according to the present invention, an LED light emitting device or a single crystal growth substrate, wherein the single crystal growth substrate is selected from the group of single crystal sapphire, single crystal silicon carbide, single crystal GaAs, and single crystal Si. The LED light-emitting device is surface-coated with a material selected from the group consisting of AlN, SiC, GaN, and GaAs.

In addition, the present invention is an LED light emitting element characterized in that the group III-V semiconductor crystal is any one of GaN, GaAs, and GaP.

  A holding substrate for an LED light-emitting element having a small difference in linear thermal expansion coefficient from the group III-V semiconductor crystal constituting the LED is obtained. By using this LED light-emitting element holding substrate, it is possible to provide a high-output LED light-emitting element having excellent heat dissipation and reliability. Furthermore, the LED light-emitting element holding substrate of the present invention is excellent in chemical resistance against acid and alkali solutions used in the manufacture of LED light-emitting elements, is conductive, and has both sides of the III-V group semiconductor crystal constituting the LED. An electrode can be formed on the substrate. Therefore, it is possible to reduce the manufacturing process of the LED light emitting element and increase the light emission amount per unit area.

Explanatory drawing of the metal-impregnated ceramic composite of claim 1 Illustration of LED light-emitting element holding substrate The schematic sectional drawing of the LED light emitting element which shows one embodiment of this invention The schematic sectional drawing of the LED light emitting element which shows one embodiment of this invention The schematic sectional drawing of the LED light emitting element which shows one embodiment of this invention

  The single crystal growth substrate used in the present invention requires a material having a small difference in lattice constant from a group III-V semiconductor crystal to be epitaxially grown in a later step and having few defects. From the standpoints of crystallinity and uniformity, it is common to process and use a single crystal material. These single crystal growth substrates need to withstand the temperature and atmosphere in the process of epitaxially growing a III-V semiconductor crystal. Therefore, the material for the single crystal growth substrate used in the present invention is preferably selected from the group of single crystal sapphire, single crystal silicon carbide, single crystal GaAs, and single crystal Si. Furthermore, the single crystal growth substrate used in the present invention is preferably surface-coated with a material selected from the group consisting of AlN, SiC, GaN, and GaAs.

  The group III-V semiconductor crystal constituting the LED is preferably GaN, GaAs, or GaP from the viewpoint of conversion efficiency as the LED light emitting element. These III-V semiconductor crystals have high luminous efficiency and can be used properly according to the application. The III-V semiconductor crystal is selected according to the optimum emission wavelength for each application.

In the present invention, first, a III-V semiconductor crystal is grown on one main surface of these single crystal growth substrates by epitaxial growth. The epitaxial growth of the group III-V semiconductor crystal is preferably performed by metal organic vapor phase epitaxy (MOCVD method) or halide vapor phase epitaxy (HVPE method). The MOCVD method is suitable for growing a group III-V semiconductor crystal with good crystallinity, and the HVPE method has a high crystal growth rate and can grow a group III-V semiconductor crystal efficiently. These methods are publicly known, and implementation conditions can be set as appropriate. The epitaxial growth method is not limited to the above method as long as it can grow a group III-V semiconductor crystal.

  The epitaxially grown III-V group semiconductor crystal can be subjected to a surface treatment in order to further improve the light emission characteristics. In addition, in order to improve the uniformity of the crystal surface and the like, the surface may be etched or polished. In order to join the holding substrate, a metal layer is formed on the surface of the III-V group semiconductor crystal by a technique such as vapor deposition or sputtering. The metal layer is preferably indium, aluminum, gold, silver and alloys thereof. The thickness of the metal layer is not preferable because the linear thermal expansion coefficient of the metal is different from that of the group III-V semiconductor crystal, and if it is extremely thick, the adhesion is lowered. When the thermal conductivity of the metal layer is low, it is not preferable from the viewpoint of heat dissipation. For this reason, it is preferable that the thickness of a metal layer is 0.5-10 micrometers, More preferably, it is 0.5-2 micrometers.

  In order to bond to the III-V group semiconductor crystal, a metal layer is similarly formed on the surface of the holding substrate by vapor deposition or sputtering. The metal layer is preferably indium, aluminum, gold, silver and alloys thereof. The characteristics required for the holding substrate are (1) having a strength that can withstand bonding, and (2) that there are no inclusions such as voids and foreign substances on the bonding surface, and that the bonding surface is flat. In order to satisfy the condition (1), the three-point bending strength of the holding substrate is 50 MPa or more, preferably 200 MPa or more. In order to satisfy the condition (2), the surface roughness (Ra) of the holding substrate is 0.01 to 0.5 μm, preferably 0.01 to 0.2 μm.

  The joining of the III-V semiconductor crystal and the holding substrate is performed by heating in a state where the joining surfaces are combined while applying pressure as necessary. Although heating temperature changes with kinds of metal layer, generally it is 250 to 550 degreeC. The pressure for pressurization is generally 2 to 20 MPa.

Since the holding substrate is used while being bonded to a group III-V semiconductor crystal, it is important that the difference in linear thermal expansion coefficient between the two materials is small. For this reason, it is preferable that the linear thermal expansion coefficient at a temperature of 40 ° C. to 150 ° C. of the metal-impregnated ceramic composite used for the holding substrate is 4 × 10 ^{−6 to} 9 × 10 ⁻⁶ / K. More preferably ^{4 × 10 -6 ~7 × 10 -6} / K. Group III-V semiconductor crystal or growth substrate to be bonded when the linear thermal expansion coefficient at a temperature of 40 ° C. to 150 ° C. of the metal-impregnated ceramic composite is out of the range of 4 × 10 ^{−6 to} 9 × 10 ⁻⁶ / K The linear thermal expansion coefficient difference between the first and second layers is not preferable because warping may occur after bonding, peeling of the bonding layer may occur when used as an LED light-emitting element, or the III-V group semiconductor crystal may be broken.

  The holding substrate of the present invention serves as a base substrate of the LED light emitting element. Most of the heat generated in the III-V semiconductor device is radiated through the substrate, and the substrate is required to have high heat dissipation characteristics. For this reason, the thermal conductivity at a temperature of 25 ° C. of the metal-impregnated ceramic composite used for the holding substrate is preferably 100 to 300 W / mK, and more preferably 150 to 300 W / mK. If the thermal conductivity is less than 100 W / mK, the heat generated in the III-V group semiconductor device cannot be sufficiently dissipated, and particularly in a high-power LED that needs to pass a large current, the temperature of the device increases and the luminous efficiency And the accompanying decrease in device life are undesirable. On the other hand, the upper limit value of the thermal conductivity is not limited in terms of characteristics, but the substrate material becomes extremely expensive.

From the viewpoint of heat dissipation, it is preferable that the holding substrate is thin. On the other hand, a certain plate thickness is required because strength that can withstand the holding of the III-V group semiconductor element and the handling at the time of manufacturing the LED light emitting element is necessary. The thickness of the holding substrate is preferably 0.05 mm to 1 mm, more preferably 0.05 mm to 0.3 mm. If the thickness of the holding substrate exceeds 1 mm, the heat dissipation characteristics of the LED light-emitting element deteriorate, which is not preferable. The holding substrate of the present invention can be thinned by polishing or the like, if necessary, after joining with the III-V group semiconductor crystal.

In the present invention, the single crystal growth substrate is removed after the III-V semiconductor crystal and the holding substrate are bonded via the metal layer. In general, the single crystal growth substrate is removed by irradiating a laser from the substrate side. In addition, the single crystal growth substrate can be removed by polishing or etching. The III-V semiconductor crystal surface from which the single crystal growth substrate has been removed is subjected to surface polishing and etching as necessary to finish the surface shape as desired, and then electrodes are formed by a technique such as vapor deposition or sputtering. . Further, it is cut into a predetermined shape by laser cutting or dicing to manufacture an LED light emitting element.

The holding substrate of the present invention needs to have chemical resistance characteristics in the LED light emitting device manufacturing process. Specifically, it is 1 in each of a 5N HCl solution at a temperature of 25 ° C. and a 10N NaOH solution at a temperature of 75 ° C. The weight loss per unit area of at least one principal surface when immersed for 0 minutes is 0. 2 mg / cm ² or less is preferable, and more preferably, the weight loss is 0.1 mg / cm ² or less. When the weight loss per unit area when immersed in a 5N HCl solution at a temperature of 25 ° C. and a 10N NaOH solution at a temperature of 75 ° C. for 1 minute exceeds 0.2 mg / cm ² , a metal-impregnated ceramic composite It is not preferable because characteristics such as thermal conductivity are reduced due to elution of metal components in the inside, and chipping occurs when cutting into a predetermined shape by laser cutting or dicing, and the yield of LED light emitting elements is reduced. . In the actual use of the holding substrate of the present invention, one main surface of the holding substrate is bonded to the III-V group semiconductor crystal through the metal layer, so that the non-bonded surface satisfies the above-mentioned chemical resistance characteristics. I just need it.

In the holding substrate of the present invention, the substrate itself has conductivity. For this reason, an electrode can be formed on both surfaces of the III-V semiconductor crystal which comprises LED. When an insulating material such as a sapphire substrate is used as the substrate, it is necessary to remove part of the upper p-type or n-type III-V group semiconductor crystal by etching or the like to form electrodes on the same surface side. In the present invention, the manufacturing process of the LED light emitting element can be reduced. Further, since it is not necessary to form an electrode by removing a part of the p-type or n-type III-V semiconductor crystal by etching or the like, the amount of light emission per unit area of the LED light-emitting element can be increased. . The volume resistivity of the metal-impregnated ceramic composite used for the holding substrate of the present invention is preferably 10 ⁻⁹ to 10 ⁻⁵ Ω · m. When the volume resistivity exceeds 10 ⁻⁵ Ω · m, the luminous efficiency is lowered, which is not preferable. The lower limit of the volume resistivity is not limited in terms of characteristics, but is generally 10 ⁻⁹ Ω · m or more from the material composition.

Methods for producing metal-impregnated ceramic composites are roughly classified into two types: impregnation methods and powder metallurgy methods. Of these, what is actually commercialized in terms of characteristics such as thermal conductivity is the impregnation method. There are various impregnation methods, and there are a method performed at normal pressure and a method performed under high pressure (high pressure forging method). High pressure forging methods include a molten metal forging method and a die casting method. A method suitable for the present invention is a high-pressure forging method in which impregnation is performed under high pressure, and a molten forging method is preferable to obtain a dense composite having excellent characteristics such as thermal conductivity. The molten metal forging method is a method in which a ceramic material or a compact is loaded into a high-pressure vessel, and a molten material such as an aluminum alloy is impregnated at high temperature and high pressure to obtain a composite material.

Hereafter, the example of a manufacturing method by the molten metal forging method is demonstrated. It is necessary to use a material having a high thermal conductivity and a low linear thermal expansion coefficient as the raw material ceramics. In the present invention, silicon carbide is used. The metal-impregnated ceramic composite of the present invention can adjust the thermal conductivity and the linear thermal expansion coefficient by compounding silicon carbide and an aluminum alloy. The metal-impregnated ceramic composite of the present invention is a composite material containing 50 to 90% by volume of silicon carbide and the balance being made of an aluminum alloy. The silicon carbide content is preferably 70 to 85% by volume. When the content of silicon carbide is less than 50% by volume, the coefficient of linear thermal expansion of the resulting metal-impregnated ceramic composite increases, which is not preferable as a substrate material for an LED light-emitting element. On the other hand, if the silicon carbide content exceeds 90% by volume, the aluminum alloy cannot be sufficiently impregnated at the time of compounding, and as a result, the thermal conductivity is lowered, which is not preferable.

Ceramics can be compounded as a powder, but a porous body (hereinafter referred to as a preform) having a porosity of 10 to 50% by volume by forming a molded body using an inorganic binder or by performing a sintering process. ) Is preferably combined. The porosity of the preform is adjusted by adjusting the particle size of the raw material powder, molding pressure, sintering conditions, and the like. The preform can be molded by a general ceramic powder molding method such as press molding or cast molding. The outer shape of the preform is preferably 0.3 to 4.5 mm smaller than the final shape, and more preferably 0.4 to 4.0 mm smaller. The thickness of the aluminum or aluminum alloy formed on the outer periphery of the metal-impregnated ceramic composite thus obtained is 0.1 to 2.0 μm. When the outer shape of the preform is 4.5 mm or less, the thickness of the aluminum or aluminum alloy formed on the outer peripheral portion becomes thicker than 2.0 μm, and the yield of the final product on which the light emitting element is mounted is lowered, which is not preferable. In the above, the metal layer which has aluminum as a main component formed in an outer peripheral part becomes too thin to 0.1 micrometer or less, and is not preferable. The preform is formed into a flat plate shape or a cylindrical shape having a thickness of 0.6 to 5.0 mm, and then cut into a thickness of 0.6 to 5.0 mm. Furthermore, in the present invention, it is preferable to use a preform having a three-point bending strength of 50 MPa or more in order to process the final shape into a plate shape having a plate thickness of 0.05 mm to 1 mm. If the strength of the preform is low, warping may occur when processing the plate thickness into a plate shape of 0.05 mm to 1 mm by grinding or the like.

  Next, a hole is made smaller than the final outer shape, and the preform is inserted into a metal or ceramic frame whose thickness is 0.1 to 1.0 mm thinner than the preform, and each jig has a release agent. A plurality of layers are stacked on both sides of the applied release plate, and connected with bolts and nuts to form a stacked body. As the frame into which the preform is inserted, a jig made of stainless steel, iron or graphite can be used. More preferably, a frame 0.2 to 0.5 mm thinner than the preform is used. If the thickness is less than 0.1 mm, the aluminum alloy is not supplied and impregnation is poor. As the release plate, a stainless plate or a ceramic plate can be used, and there is no particular limitation as long as it is a dense body that is not impregnated with an aluminum alloy by a molten metal forging method. Moreover, about the mold release agent apply | coated to a jig | tool or a mold release plate, mold release agents, such as graphite, boron nitride, an alumina, can be used. Furthermore, it is preferable to apply a release agent after coating the surface of a jig or a release plate with alumina sol or the like.

  The obtained laminated body is heated at a temperature of about 600 to 800 ° C., and then one or two or more pieces are placed in a high-pressure vessel, and the aluminum alloy is heated to the melting point or more as quickly as possible to prevent the temperature of the laminated body from decreasing. A metal-impregnated ceramic composite is obtained by supplying a molten metal and pressurizing with a pressure of 30 MPa or more and impregnating the aluminum alloy into the voids of the preform. For the purpose of removing distortion during impregnation, the impregnated product may be annealed.

  When the heating temperature of the laminated body is less than 600 ° C., the aluminum alloy is not sufficiently combined, and the properties such as the thermal conductivity of the resulting metal-impregnated ceramic composite deteriorate. On the other hand, when the heating temperature exceeds 800 ° C., the surface of the ceramic powder is oxidized at the time of compounding with the aluminum alloy, and the characteristics such as thermal conductivity of the resulting metal-impregnated ceramic composite are deteriorated. Furthermore, regarding the pressure at the time of impregnation, if it is less than 30 MPa, the composite of the aluminum alloy becomes insufficient, and the properties such as the thermal conductivity of the resulting metal-impregnated ceramic composite deteriorate, which is not preferable. Preferably, the impregnation pressure is 50 MPa or more.

The aluminum alloy in the metal-impregnated ceramic composite of the present invention is an aluminum alloy containing 70% by mass or more of aluminum. If the aluminum content is less than 70% by mass, the thermal conductivity of the aluminum alloy is lowered, which is not preferable. The aluminum alloy preferably has a melting point as low as possible in order to sufficiently penetrate into the voids of the preform when impregnated. Examples of such an aluminum alloy include an aluminum alloy containing 5 to 25% by mass of silicon. Further, it is preferable to contain magnesium because the bond between the ceramic particles and the metal portion becomes stronger. The metal components other than aluminum, silicon, and magnesium in the aluminum alloy are not particularly limited as long as the characteristics do not change extremely. For example, copper or the like may be included.

Next, the obtained plate-shaped outer peripheral part is covered with aluminum or an aluminum alloy, and the thickness of the metal-impregnated ceramics composite is reduced with a processing machine such as a double-side grinding machine, a rotary grinding machine, a surface grinding machine, or a lapping machine. After performing surface processing so that the surface roughness (Ra) is 0.01 to 1 μm and 0.05 to 1 mm, using a processing machine such as a double-sided grinder, rotary grinder, surface grinder, or lapping machine Surface treatment is performed so that the plate thickness is 0.1 to 1 mm and the surface roughness (Ra) is 0.01 to 1 μm.

Next, the plate-like metal-impregnated ceramic composite whose outer peripheral portion is covered with aluminum or an aluminum alloy is formed by forming an aluminum layer having a thickness of 0.05 to 2.0 μm on the surface after washing the surface. When the aluminum layer thickness is 0.05 μm or less, an aluminum layer non-deposited part occurs or the aluminum layer reacts during plating pretreatment, etc., and pin holes are generated, resulting in an unplated part, resulting in reduced chemical resistance. It is not preferable. On the other hand, if the thickness of the aluminum layer exceeds 2.0 μm, the linear thermal expansion coefficient of the aluminum layer and the metal-impregnated ceramic composite are different. The aluminum layer thickness is more preferably 0.3 to 0.6 μm.

As a method for forming the aluminum layer, the aluminum layer is formed to have a thickness of 0.05 to 1.0 μm by vapor deposition or sputtering.

In the vapor deposition method, it is difficult to form an aluminum layer on the outer peripheral portion, and there is a possibility that plating is not deposited in the subsequent plating process. The metal-impregnated ceramic composite produced by the above method has a metal-impregnated ceramic composite whose entire surface is covered with aluminum or an aluminum alloy because the outer peripheral portion is covered with aluminum or an aluminum alloy.

As an aluminum alloy which comprises an aluminum layer, it is an aluminum alloy containing 70 mass% or more of aluminum. If the aluminum content is less than 70% by mass, Ni plating with sufficient adhesion by the zincate treatment cannot be performed, which is not preferable. The metal components other than aluminum and silicon in the aluminum alloy are not particularly limited as long as the characteristics do not change extremely. For example, magnesium, copper, and the like may be included.

  In the present invention, in order to improve the adhesion between the metal-impregnated ceramic composite and the aluminum layer, heat treatment is performed at a temperature of 460 to 650 ° C. for 1 minute or more in nitrogen, argon, hydrogen, helium or a vacuum atmosphere. When the treatment is performed in an oxidizing atmosphere, an oxide film is formed on the surface and subsequent plating defects occur, which is not preferable. The temperature is preferably 480-570 ° C. If the temperature is 460 ° C. or lower, the adhesion between the metal-impregnated ceramic composite and the aluminum layer is deteriorated, and if it is 650 ° C. or higher, the aluminum layer is dissolved and the surface roughness is deteriorated.

  Next, the metal-impregnated ceramic composite with the aluminum layer formed thereon is formed with an Ni plating layer having a thickness of 0.5 to 5.0 μm and a thickness of 0.05 to 2.0 μm by electroless plating or electroplating. The gold plating layer is formed. When the Ni plating layer thickness is 0.5 μm or less, pinholes are generated and chemical resistance is lowered, which is not preferable. On the other hand, when the Ni plating layer thickness is 5.0 μm or more, the thermal conductivity characteristics are lowered and the electric resistance is increased. When the thickness of the gold plating layer is 0.05 μm or less, pinholes are generated and chemical resistance is lowered, which is not preferable. On the other hand, when the thickness of the gold plating layer is 2.0 μm or more, the cost increases, which is not preferable.

  Examples of the pretreatment for plating include zincate treatment, palladium treatment, and the like, but zincate treatment capable of plating with adhesion to aluminum is more preferable.

Example 1
<Preparation of LED light-emitting element holding substrate>
1800 g of silicon carbide (hereinafter referred to as SiC) powder A (manufactured by Taiyo Random Co., Ltd., NG-60, average particle diameter 200 μm), silicon carbide powder B (manufactured by Taiyo Random Co., Ltd., NG-600, average particle diameter 20 μm) 900 g, 300 g of silicon carbide powder C (manufactured by Taiyo Random Co., Ltd., NC-6000, average particle size 2 μm) and 150 g of a molded binder (methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd., “Metroses”) are weighed and stirred for 30 minutes. After mixing, it was press-molded into a cylindrical shape with a size of Φ55 mm × 110 mm at a surface pressure of 10 MPa, and then CIP-molded at a molding pressure of 100 MPa to produce a compact.

  The obtained molded body was degreased in an air atmosphere at a temperature of 600 ° C. for 2 hours and then calcined in an argon atmosphere at a temperature of 2100 ° C. for 2 hours to produce a SiC preform having a porosity of 20% by volume. The obtained SiC preform was processed into a shape having an outer dimension of 49.2 mm × 100 mm using a diamond grindstone at a machining center. Further, a three-point bending strength measurement specimen (3 mm × 4 mm × 40 mm) was prepared by grinding, and the three-point bending strength was measured. The three-point bending strength was 120 MPa.

After slicing the obtained SiC preform to a thickness of 1.4 mm with a multi-wire source, a thickness of 1.2 mm with a hole of Φ50.3 mm coated with a boron nitride release agent was applied, and external dimensions: 70 mm Insert into a 70 mm x 100 mm stainless steel plate, and then apply a graphite release material to a 70 mm x 100 mm x 0.8 mmt stainless steel plate to produce a release plate, shape of 140.8 mm x 140.8 mm x 100 mm Then, a 12 mm-thick iron plate was placed on both sides, and connected with eight M10 bolts to form one laminate. Next, the laminate is preheated to a temperature of 700 ° C. in an electric furnace and then placed in a pre-heated press mold having an inner diameter of Φ400 mm × 300 mmH, and contains 12% by mass of silicon and 1% by mass of magnesium. The molten metal (temperature: 800 ° C.) was poured and pressurized at 100 MPa for 25 minutes to impregnate the SiC preform with the aluminum alloy. After cooling to room temperature, it was cut along the shape of the release plate with a wet band saw, the release plate was peeled off, and the metal-impregnated ceramic composite was extracted from the stainless steel plate. The obtained metal-impregnated ceramic composite was annealed at a temperature of 530 ° C. for 3 hours in order to remove strain during impregnation.

Next, from the obtained metal-impregnated ceramic composite, a thermal expansion coefficient measurement specimen (diameter 3 mm, length 10 mm), thermal conductivity measurement specimen (25 mm × 25 mm × 1 mm), three-point bending strength by grinding. A test specimen for measurement (3 mm × 4 mm × 40 mm) and a test specimen for measuring volume resistivity (50 mm × 50 mm × 5 mm) were prepared. Using each test specimen, the thermal expansion coefficient at a temperature of 25 ° C. to 150 ° C. was measured with a thermal dilatometer (manufactured by Seiko Denshi Kogyo; TMA300), and the thermal conductivity at a temperature of 25 ° C. was measured with a laser flash method (manufactured by ULVAC; TC3000), a three-point bending strength was measured with a bending strength tester, and a volume resistivity was measured with a four-terminal method (based on JIS R1637). As a result, the thermal expansion coefficient at a temperature of 40 ° C. to 150 ° C. is 4.9 × 10 ⁻⁶ / K, the thermal conductivity at a temperature of 25 ° C. is 250 W / mK, the three-point bending strength is 350 MPa, and the volume resistivity is 8 ×. 10 ⁻⁷ Ω · m.

  Grinding the disk-shaped metal-impregnated ceramics composite with 0.7 mm aluminum alloy layer formed on the outer periphery to a plate thickness of 0.22 mm with a double-side grinding machine using a # 600 diamond grindstone After polishing to a thickness of 0.2 mm using diamond abrasive grains on a lapping machine, ultrasonic cleaning is performed in pure water and then in isopropyl alcohol, followed by drying and metal-impregnated ceramics. A composite material substrate was produced. As a result of measuring the surface roughness (Ra) with a surface roughness meter, it was Ra 0.05 μm.

  Next, an aluminum layer having a thickness of 0.5 μm was formed on the surface of the metal matrix composite material by vapor deposition, and heat treatment was performed at 530 ° C. for 30 minutes in a nitrogen atmosphere. Next, electroless Ni-P and electrogold plating were performed on the metal-impregnated ceramic composite material substrate on which the aluminum layer was formed, and a plating layer of 1.3 μm (Ni-P: 1 μm + Au: 0.3 μm) was formed on the surface. . The characteristic value of the obtained metal-impregnated ceramic composite material substrate was calculated from the thickness ratio of the physical property value of the plating layer metal and the physical property value of the metal-impregnated ceramic composite material substrate before plating. The results are shown in Table 1. Further, the metal matrix composite material after the plating film is formed is immersed in a 5N HCl solution at a temperature of 25 ° C. and a 10N NaOH solution at a temperature of 75 ° C. for 1 minute, and the amount of weight reduction per unit area by each treatment is determined. It was measured. Furthermore, the surface roughness (Ra) of the metal-impregnated ceramic composite material substrate after plating was measured with a surface roughness meter. The results are shown in Table 2.

<Production of LED light-emitting element>
On a single crystal sapphire substrate having a thickness of 0.5 mm, ammonia gas and trimethyl gallium are used, and a mixed gas of hydrogen and nitrogen is used as a carrier gas, and the temperature is 1100 ° C. by MOCVD (1) to (4 ) Single crystal GaN was grown to a thickness of 4 μm. FIG. 1 shows the structure.
(1) n-type GaN buffer layer 2
(2) n-type GaN semiconductor layer 3
(3) GaN active layer (light emitting layer) 4
(4) p-type GaN semiconductor layer 5

Next, a silver / tin alloy was deposited to a thickness of 2 μm on the surface of the p-type GaN semiconductor layer by vacuum deposition. On the other hand, a silver / tin alloy was deposited to a thickness of 2 μm on the surface of one side of the LED light emitting element holding substrate in the same manner. Both substrates were laminated as shown in FIG. 1 where the silver / tin alloy layer was in contact, and held at a temperature of 400 ° C. under a pressure of 5 MPa for 5 minutes for bonding. The obtained bonded body was irradiated with a nitrogen gas laser from the sapphire substrate side so that the output was 40 MW / cm ^2, and the sapphire substrate was peeled off. The n-type GaN buffer layer was decomposed into Ga and nitrogen by laser irradiation, and the sapphire substrate could be peeled off by the generated nitrogen gas.

Thereafter, the n-type GaN buffer layer exposed on the surface was removed by etching, and then a transparent conductor layer of indium tin oxide was formed. Then, Au was vapor-deposited as an n-type electrode, and it was set as each LED light emitting element by dicing. It was confirmed that the obtained LED light emitting element was able to suppress a decrease in luminous efficiency due to an increase in element temperature due to heat radiation from the holding substrate.

(Examples 2-8, Comparative Examples 1-3)
An aluminum-formed metal-impregnated ceramic composite substrate obtained by forming an aluminum layer of 0.5 μm or 0.6 μm by vapor deposition on the metal-impregnated ceramic composite substrate prepared in Example 1 and performing heat treatment at 530 ° C. for 30 minutes in a nitrogen atmosphere. The plating film shown in Table 4 was formed on the surface. Table 3 shows the characteristic values of the obtained metal-impregnated ceramic composite material substrate. Further, the metal matrix composite material after the plating film is formed is immersed in a 5N HCl solution at a temperature of 25 ° C. and a 10N NaOH solution at a temperature of 75 ° C. for 1 minute, and the amount of weight reduction per unit area by each treatment is determined. It was measured. Furthermore, the surface roughness (Ra) of the metal-impregnated ceramic composite material substrate after the plating film was formed was measured with a surface roughness meter. The results are shown in Table 4.

(Examples 9 to 12, Comparative Example 4)
An aluminum-formed metal-impregnated ceramic composite material substrate obtained by forming an aluminum layer having the thickness shown in Table 5 on the metal-impregnated ceramic composite material substrate prepared in Example 1 by a vapor deposition method and performing heat treatment at 530 ° C. for 30 minutes in a nitrogen atmosphere. A 1.2 μm thick Ni plating and a 0.3 μm plating film were formed on the surface. Table 5 shows the characteristic values of the obtained metal matrix composite. Further, the metal-impregnated ceramic composite substrate after the plating film is formed is immersed in a 5N HCl solution at a temperature of 25 ° C. and a 10N NaOH solution at a temperature of 75 ° C. for 1 minute, and the weight per unit area is reduced by each treatment. The amount was measured. Furthermore, the surface roughness (Ra) of the metal-impregnated ceramic composite material substrate after the plating film was formed was measured with a surface roughness meter. The results are shown in Table 6.
Moreover, in Comparative Example 4, no plating was observed.

(Examples 13 to 19)
<Preparation of LED light-emitting element holding substrate>
1800 g of silicon carbide (hereinafter referred to as SiC) powder A (manufactured by Taiyo Random Co., Ltd., NG-60, average particle diameter 200 μm), silicon carbide powder B (manufactured by Taiyo Random Co., Ltd., NG-600, average particle diameter 20 μm) 900 g, 300 g of silicon carbide powder C (manufactured by Taiyo Random Co., Ltd., NC-6000, average particle size 2 μm) and 150 g of a molded binder (methyl cellulose, manufactured by Shin-Etsu Chemical Co., Ltd., “Metroses”) are weighed and stirred for 30 minutes. After mixing, it was press-molded into a cylindrical shape with a size of Φ55 mm × 1.5 mm at a surface pressure of 30 MPa to produce a molded body.

  The molded body obtained above was degreased at a temperature of 600 ° C. for 2 hours in an air atmosphere and then fired for 2 hours at a temperature of 1950 ° C. in an argon atmosphere to produce a SiC preform having a porosity of 30% by volume. . The obtained SiC preform was processed into a shape having an outer dimension of Φ50.0 mm × 1.0 mm using a diamond grindstone at a machining center. Further, a three-point bending strength test specimen (3 mm × 4 mm × 40 mm) was prepared by grinding a SiC preform having a porosity of 30% and a diameter of 50 mm × 10 mm produced by the same method to obtain a three-point bending strength. It was measured. The three point bending strength was 80 MPa.

The SiC preform was coated with a boron nitride mold release agent and inserted into a stainless steel plate having a diameter of 0.8 mm and an outer dimension of 70 mm × 70 mm × 100 mm, and then 70 mm × 100 mm × 0 A graphite release material is applied to an 8 mmt stainless steel plate to produce a release plate, which is laminated with a release plate sandwiched so as to have a shape of 140.8 mm × 140.8 mm × 100 mm. An iron plate was arranged and connected with eight M10 bolts to form one laminate. Next, the laminate is preheated to a temperature of 700 ° C. in an electric furnace and then placed in a pre-heated press mold having an inner diameter of Φ400 mm × 300 mmH, and contains 12% by mass of silicon and 1% by mass of magnesium. The molten metal (temperature: 800 ° C.) was poured and pressurized at 100 MPa for 25 minutes to impregnate the SiC preform with the aluminum alloy. After cooling to room temperature, it was cut along the shape of the release plate with a wet band saw, the release plate was peeled off, and the metal-impregnated ceramic composite was extracted from the stainless steel plate. The obtained metal-impregnated ceramic composite was annealed at a temperature of 530 ° C. for 3 hours in order to remove strain during impregnation.

Next, from the obtained metal-impregnated ceramic composite, a thermal expansion coefficient measurement specimen (diameter 3 mm, length 10 mm), thermal conductivity measurement specimen (25 mm × 25 mm × 1 mm), three-point bending strength by grinding. A test specimen for measurement (3 mm × 4 mm × 40 mm) and a test specimen for measuring volume resistivity (50 mm × 50 mm × 5 mm) were prepared. Measurement was performed in the same manner as in Example 1 using each specimen. As a result, the thermal expansion coefficient at a temperature of 40 ° C. to 150 ° C. is 6.9 × 10 ⁻⁶ / K, the thermal conductivity at a temperature of 25 ° C. is 220 W / mK, the three-point bending strength is 380 MPa, and the volume resistivity is 4 ×. 10 ⁻⁷ Ω · m.

  Grind the disc-shaped metal-impregnated ceramics composite with the 0.4 mm aluminum alloy layer formed on the outer periphery to a thickness of 0.2 mm with a double-side grinding machine using a # 800 diamond grindstone. Processing was performed to produce a metal-impregnated ceramic composite material substrate.

Next, after cleaning the surface of the metal-impregnated ceramic composite material substrate, an aluminum layer having a thickness of 1.0 μm or 0.6 μm was formed by vapor deposition. Next, after heat-treating the metal-impregnated ceramic composite material substrate on which the aluminum layer was formed under the conditions shown in Table 7, electroless Ni-P and electrogold plating were performed, and 1.3 μm (Ni-P) was formed on the surface. : 1 μm + Au: 0.3 μm) was formed. Table 7 shows the characteristic values of the obtained metal-impregnated ceramic composite material substrate. Further, the metal-impregnated ceramic composite substrate after the plating film is formed is immersed in a 5N HCl solution at a temperature of 25 ° C. and a 10N NaOH solution at a temperature of 75 ° C. for 1 minute, and the weight per unit area is reduced by each treatment. The amount was measured. Furthermore, the surface roughness (Ra) of the metal-impregnated ceramic composite material substrate after the plating film was formed was measured with a surface roughness meter. The results are shown in Table 8.

<Production of LED light-emitting element>
Next, preparation examples of LED light emitting devices using the LED light emitting device holding substrates of Examples 13 to 19 will be described.
After forming a growth substrate by forming a SiC layer with a thickness of 2 μm on a single crystal Si substrate having a thickness of 0.5 mm by a CVD method, ammonia gas and gallium chloride are used, hydrogen gas is used as a carrier gas, and temperature is increased. The GaN single crystals (1) to (3) were grown to a thickness of 4 μm by HVPE at 1050 ° C. FIG. 3 shows the structure.
(1) n-type GaN semiconductor layer 3
(2) GaN active layer (light emitting layer) 4
(3) p-type GaN semiconductor layer 5

  Next, silver was deposited to a thickness of 0.5 μm on the surface of the p-type GaN semiconductor layer by a vacuum deposition method, and then an Au / tin alloy was deposited to a thickness of 1.5 μm. On the other hand, Au / tin alloy was vapor-deposited to a thickness of 1.5 μm on the surface of one side of the LED light emitting element holding substrates of Examples 13 to 19 in the same manner. The two substrates were laminated as shown in FIG. 3 where the Au / tin alloy layer was in contact, and held at a temperature of 500 ° C. under a pressure of 5 MPa for 5 minutes for bonding. In the obtained bonded body, the single crystal Si layer was removed by etching by acid treatment, and then the SiC layer was completely removed by grinding.

Thereafter, the surface of the exposed n-type GaN layer was roughened by etching, and then a transparent conductor layer of indium tin oxide was formed. Next, Au was vapor-deposited as an n-type electrode, and individual LED light-emitting elements were formed by laser processing. It was confirmed that the obtained LED light emitting element was able to suppress a decrease in luminous efficiency due to an increase in element temperature due to heat radiation from the holding substrate.

(Examples 20 to 25, Comparative Example 5)
<Preparation of LED light-emitting element holding substrate>
1300 g of silicon carbide powder D (manufactured by Taiyo Random Co., Ltd., NG-80, average particle size: 150 μm), 700 g of silicon carbide powder E (manufactured by Yakushima Electric Works, GC-1000F, average particle size: 10 μm), silica sol (Nissan Chemical Co., Ltd.) (Product: Snowtex) 300 g was weighed and mixed with a stirrer / mixer for 30 minutes, and then pressed into a cylindrical shape having a size of Φ110 mm × 100 mm at a surface pressure of 30 MPa to prepare a molded body. The obtained molded body was dried at a temperature of 120 ° C. for 1 hour and then calcined at a temperature of 1400 ° C. for 2 hours in a nitrogen atmosphere to obtain a SiC preform having a porosity of 35% by volume. The obtained SiC preform was processed into the outer shape shown in Table 9 using a diamond grindstone at a machining center. From the obtained SiC preform, a three-point bending strength measurement specimen (3 mm × 4 mm × 40 mm) was prepared by grinding, and the three-point bending strength was measured. As a result, the three-point bending strength was 50 MPa.

The obtained SiC preform was sliced with a multi-wire source to a thickness of 1.2 mm, and then a boron nitride release agent was applied to a hole having a diameter of 1.0 mm and outer dimensions shown in Table 9 : Insert into a 70 mm × 70 mm × 100 mm stainless steel plate, and then apply a graphite release material to a 70 mm × 100 mm × 0.8 mmt stainless steel plate to produce a release plate, 140.8 mm × 140.8 mm × 100 mm A 12 mm-thick iron plate is arranged on both sides and connected with eight M10 bolts to form one laminate. Next, the laminate is preheated to a temperature of 700 ° C. in an electric furnace and then placed in a pre-heated press mold having an inner diameter of Φ400 mm × 300 mmH, and contains 12% by mass of silicon and 1% by mass of magnesium. The molten metal (temperature: 800 ° C.) was poured and pressurized at 100 MPa for 25 minutes to impregnate the SiC preform with the aluminum alloy. After cooling to room temperature, it was cut along the shape of the release plate with a wet band saw, the release plate was peeled off, and the graphite jig part was removed with a lathe to obtain a metal-impregnated ceramic composite having a shape of Φ52 mm × 100 mm . The obtained metal-impregnated ceramic composite was annealed at a temperature of 530 ° C. for 3 hours in order to remove strain during impregnation.

Next, from the obtained metal-impregnated ceramic composite, a thermal expansion coefficient measurement specimen (diameter 3 mm, length 10 mm), thermal conductivity measurement specimen (25 mm × 25 mm × 1 mm), three-point bending strength by grinding. A test specimen for measurement (3 mm × 4 mm × 40 mm) and a test specimen for measuring volume resistivity (50 mm × 50 mm × 5 mm) were prepared. Measurement was performed in the same manner as in Example 1 using each specimen. As a result, the thermal expansion coefficient at a temperature of 40 ° C. to 150 ° C. is 7.6 × 10 ⁻⁶ / K, the thermal conductivity at a temperature of 25 ° C. is 200 W / mK, the three-point bending strength is 400 MPa, and the volume resistivity is 3 ×. 10 ⁻⁷ Ω · m.

  The plate-like metal-impregnated ceramic composite obtained as described above and having an aluminum alloy layer with the thickness shown in Table 9 formed on the outer periphery was obtained by using a # 800 diamond grindstone with a double-side grinding machine and a thickness of 0.2 mm. The metal-impregnated ceramic composite material substrate was fabricated by grinding.

Next, after cleaning the surface of the metal-impregnated ceramic composite material substrate, a 0.6 μm aluminum layer was formed by vapor deposition, and heat treatment was performed at 540 ° C. for 30 minutes in a nitrogen atmosphere. Next, electroless Ni-P and electrogold plating were performed on the metal-impregnated ceramic composite material substrate on which the aluminum layer was formed, and a plating layer of 1.3 μm (Ni-P: 1 μm + Au: 0.3 μm) was formed on the surface. . The obtained metal-impregnated ceramic composite substrate had a thermal conductivity of 200 W / mK, a linear thermal expansion coefficient of 7.6 ppm / K, and a volume resistivity of 3 × 10 ⁻⁷ Ω · m. Further, the metal-impregnated ceramic composite substrate after the plating film is formed is immersed in a 5N HCl solution at a temperature of 25 ° C. and a 10N NaOH solution at a temperature of 75 ° C. for 1 minute, and the weight per unit area is reduced by each treatment. The amount was measured. Furthermore, the surface roughness (Ra) of the metal-impregnated ceramic composite material substrate after the plating film was formed was measured with a surface roughness meter. The results are shown in Table 10.

An LED light-emitting element was produced using the LED light-emitting element holding substrate obtained in Examples 20 to 25, and it was confirmed that a decrease in luminous efficiency due to an increase in element temperature was suppressed by heat dissipation from the holding substrate. Although the LED light emitting element was produced using the comparative example 5, since the aluminum alloy layer of the outer peripheral part was thick, the LED light emitting element in the range of the outer periphery of 1.0 mm could not be used, and the yield was lowered. It was.

The LED light-emitting element holding substrate of the present invention is a high thermal conductivity holding substrate having a low coefficient of linear thermal expansion with a group III-IV semiconductor crystal constituting the LED, and a high-power LED excellent in heat dissipation and reliability. A light-emitting element can be provided. Furthermore, the LED light-emitting element holding substrate of the present invention is excellent in chemical resistance against acid and alkali solutions used in the manufacture of LED light-emitting elements, is conductive, and has both sides of the group III-IV semiconductor crystal constituting the LED. An electrode can be formed on the substrate. Therefore, it is possible to reduce the manufacturing process of the LED light emitting element and increase the light emission amount per unit area, which is effective as a holding substrate for the LED light emitting element.

1) growth substrate 2) nitride buffer layer formed on the growth substrate 3) n-type III-V group semiconductor layer 4) light emitting layer 5) p-type group III-V semiconductor layer 6) metal layer (reflection) layer)
7) Metal layer 8) LED light-emitting element holding substrate 81) Metal-impregnated ceramic composite 82) Aluminum or aluminum alloy 83) Aluminum or aluminum alloy layer 84) Plating layer 9) Transparent conductive layer 10) Surface coating layer 11) Base material

Claims (7)

The outer peripheral portion is covered with aluminum or aluminum alloy (82) having a thickness of 0.1 to 2.0 mm, and aluminum or aluminum is formed on both main surfaces of the substrate where the metal-impregnated ceramic composite (81) is exposed on both main surfaces. For LED light-emitting devices in which an alloy layer (83) is formed to a thickness of 0.05 to 2 μm, and a Ni plating layer having a thickness of 0.5 to 5 μm and a gold plating layer (84) having a thickness of 0.05 to 2 μm are sequentially formed on the entire surface. Holding substrate (8). The ceramic of the metal-impregnated ceramic composite is made of silicon carbide, and the three-point bending strength of the metal-impregnated ceramic composite is 50 MPa or more, the thermal conductivity at a temperature of 25 ° C. is 150 to 300 W / mK, and the temperature is 25 ° C. to 150 ° C. 2. The LED light-emitting element holding substrate according to claim 1, wherein the coefficient of thermal expansion is 4 × 10 ^{−6 to} 9 × 10 ⁻⁶ / K, and the volume resistivity is 10 ⁻⁹ to 10 ⁻⁵ Ω · m. . A porous body made of silicon carbide is inserted into a frame made of metal or ceramic having a hole with an inner diameter smaller than the outer shape of the final product, and impregnated with aluminum or an aluminum alloy at an impregnation pressure of 30 MPa or more by a molten metal forging method. An impregnated ceramic composite is prepared. After processing the metal-impregnated ceramic composite to a plate thickness of 0.05 to 0.5 mm and a surface roughness (Ra) of 0.01 to 0.5 μm, an aluminum or aluminum alloy layer is formed by vapor deposition or sputtering. Formed on both main surfaces of the metal-impregnated ceramic composite whose outer peripheral portions are covered with aluminum or an aluminum alloy, and heat-treated at a temperature of 460 to 650 ° C. for 1 minute or longer in a nitrogen, argon, hydrogen, helium or vacuum atmosphere. . Then, a plating layer is formed by a step of sequentially forming a Ni plating layer and a gold plating layer on the surface of the aluminum or aluminum alloy layer formed on both main surfaces by an electroless plating method or an electroplating method. The manufacturing method of the holding substrate for LED light emitting elements of Claim 1 or 2 to do. The LED light emitting element manufactured through the following steps in sequence.
(1) A step of epitaxially growing a group III-V semiconductor crystal on one main surface of a disk-like or flat plate-like single crystal growth substrate.
(2) The method of laser irradiation, etching, or grinding is performed by joining the holding substrate for an LED light emitting device according to any one of claims 1 to 3 through a metal layer to a group III-V semiconductor crystal surface. A step of removing the single crystal growth substrate.
(3) A step of cutting after performing surface processing of the III-V semiconductor crystal surface and electrode formation. 5. The LED light emitting device according to claim 4, wherein the single crystal growth substrate is selected from the group consisting of single crystal sapphire, single crystal silicon carbide, single crystal GaAs, and single crystal Si. 6. The surface of the single crystal growth substrate is coated with a buffer layer of an n-type III-V semiconductor or a material selected from the group consisting of AlN, SiC, GaN, and GaAs. LED light emitting element. The LED light emitting device according to any one of claims 4 to 6, wherein the III-V group semiconductor crystal is any one of GaN, GaAs, and GaP.