Manufacturing method for semiconductor devices

Abstract

To reduce damage to a semiconductor element in a manufacturing method of a semiconductor device in which a support member for mounting a semiconductor element and the semiconductor element are joined via a metal sintered body.SOLUTION: A manufacturing method of a semiconductor device 5 includes a joining step of pressure-bonding a first member having a metal sintered body 1 on the surface, and a second member via the metal sintered body, in which one of the first member and the second member is a support member 2 for mounting a semiconductor element, and the other is a semiconductor element 3, and a reducing organic solvent is brought into contact with a surface of the metal sintered body during or before the joining step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a semiconductor device, a support member set for mounting semiconductor elements, and a semiconductor element set. [Background technology]

[0002] In recent years, semiconductor packaging materials have been required to have heat resistance (excellent stability and reliability under high temperature and high humidity conditions). For example, power semiconductors are widely used in inverters in hybrid vehicles, electric vehicles, railways, and distributed power sources, and as power density increases significantly, the packaging materials are exposed to high temperatures. Also, electronic control units (ECUs) that use conventional semiconductor chips used in the automotive electronics field, which were previously installed in the passenger compartment, are now being installed in the more demanding engine compartment, requiring even higher heat resistance. Furthermore, wide-bandgap semiconductors (such as SiC) are also being applied, and applications operating at high temperatures of 200°C or higher are anticipated.

[0003] Under such high-temperature conditions, solder, which has been used as a bonding material for semiconductor devices until now, is insufficient. Therefore, bonding using a metal sintered body obtained by sintering a sinterable bonding material containing metal particles (e.g., paste) has been proposed as a bonding technology that can withstand high temperatures (see, for example, Patent Document 1). However, when using a sinterable bonding material for pressure bonding, although it is possible to avoid or reduce the formation of voids in the metal sintered body by applying pressure, a side effect is that as the pressure increases during pressurization, a pressure load is also applied to the semiconductor device, increasing the failure rate of the semiconductor device and reducing the yield during bonding.

[0004] Therefore, a method has been proposed in which, after applying a sinterable bonding material containing metal particles to a support member, residual solvents that cause voids in the sinterable bonding material are removed by heating and drying before mounting a semiconductor element on the applied sinterable bonding material (see, for example, Patent Document 2). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2007-214340 [Patent Document 2] Japanese Patent Publication No. 2011-249801 [Overview of the project] [Problems that the invention aims to solve]

[0006] The method described in Patent Document 2 claims to reduce the required pressure by 10%, but this level of reduction is insufficient for substantial improvement. Furthermore, as the size of the semiconductor element increases, the pressure from the pressurizing device may not be uniformly distributed throughout the entire semiconductor element, potentially leading to uneven bonding or the semiconductor element being bonded at an angle to the support member for mounting the semiconductor element. This hinders the improvement of yield during bonding.

[0007] One of the objectives of the present invention is to reduce damage to the semiconductor element in a method for manufacturing a semiconductor device in which a support member for mounting a semiconductor element and a semiconductor element are joined via a metal sintered body. [Means for solving the problem]

[0008] One aspect of the present invention relates to the method for manufacturing a semiconductor device described below.

[0009] [1] A method for manufacturing a semiconductor device, comprising a bonding step of pressurizing and bonding a first member and a second member having a metal sintered body on their surfaces via the metal sintered body, wherein one of the first member and the second member is a support member for mounting a semiconductor element and the other is a semiconductor element, and a reducing organic solvent is brought into contact with the surface of the metal sintered body during or before the bonding step.

[0010] [2] The manufacturing method according to [1], wherein a reducing organic solvent is applied to the surface of the metal sintered body and / or the surface of the second member before the joining step.

[0011] [3] The manufacturing method according to [1] or [2], wherein the metal sintered body contains copper.

[0012] [4] The manufacturing method according to [3], wherein the content of copper in the metal sintered body is 95% by mass or more based on the total mass of the metal sintered body.

[0013] [5] The manufacturing method according to any one of [1] to [4], wherein the metal sintered body includes a structure derived from flaky metal particles oriented substantially parallel to the interface with the first member.

[0014] [6] The manufacturing method according to any one of [1] to [5], wherein the thickness of the metal sintered body is 1 to 1000 μm.

[0015] [7] The manufacturing method according to any one of [1] to [6], wherein the porosity of the metal sintered body is 5 to 60% by volume.

[0016] [8] The manufacturing method according to any one of [1] to [7], wherein the reducing organic solvent contains an oligomer, an organic solvent having flux activity, or a polyhydric alcohol having a boiling point of 200°C or higher.

[0017] [9] The manufacturing method according to any one of [1] to [8], wherein the bonding step is carried out in an atmosphere having a hydrogen concentration of 5 ppm or less.

[0018]

[10] The manufacturing method according to any one of [1] to [9], wherein the semiconductor element is a wide bandgap semiconductor.

[0019] Another aspect of the present invention relates to a support member set for mounting a semiconductor element, comprising a support member for mounting a semiconductor element having a metal sintered body on its surface and a reducing organic solvent.

[0020] Another aspect of the present invention relates to a semiconductor element set, comprising a semiconductor element having a metal sintered body on its surface and a reducing organic solvent. [Advantages of the Invention]

[0021] According to the present invention, in a method for manufacturing a semiconductor device in which a support member for mounting a semiconductor device and a semiconductor device are joined via a metal sintered body, damage to the semiconductor device can be reduced. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic cross-sectional view showing an example of a method for manufacturing a semiconductor device according to this embodiment. [Figure 2] This is a schematic cross-sectional view showing another example of a semiconductor device manufacturing method according to this embodiment. [Figure 3] This is a SEM image showing a cross-section of a metal sintered body with a flake-like structure. [Figure 4] This is a plan view showing an example of the shape of a sintered metal body. [Figure 5] This is a plan view showing a modified shape of a metal sintered body. [Figure 6] This is a plan view showing a modified shape of a metal sintered body. [Figure 7] This is a plan view showing a modified shape of a metal sintered body. [Figure 8] This is a plan view showing a modified shape of a metal sintered body. [Modes for carrying out the invention]

[0023] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions are omitted.

[0024] <Manufacturing method for semiconductor devices> A semiconductor device manufacturing method according to one embodiment comprises the steps of preparing a first member and a second member having a metal sintered body on their surfaces, and a joining step of pressurizing the first member and the second member together via the metal sintered body. Of the first member and the second member, one is a support member for mounting a semiconductor element, and the other is a semiconductor element. In this embodiment, a reducing organic solvent is brought into contact with the surface of the metal sintered body during or before the joining step. The surface of the metal sintered body is the surface that comes into contact with the second member during the joining step.

[0025] According to the manufacturing method of the above embodiment, compared to conventional methods in which sinterable bonding materials are sintered during pressure bonding, damage to semiconductor elements can be reduced and yield can be improved. Furthermore, the method is less susceptible to the effects of pressure variations caused by the pressurizing device, resulting in less uneven bonding and less tilting of the semiconductor element relative to the mounting support member during bonding. For these reasons, it can be said that semiconductor devices with excellent connection reliability can be easily obtained according to the manufacturing method of the above embodiment.

[0026] The reason why the manufacturing method of the above embodiment can reduce damage to semiconductor elements is presumed to be that the metal sintered body provided on the semiconductor element mounting support member or on the semiconductor element functions as a cushioning layer during pressure bonding, thereby reducing the impact on the semiconductor element.

[0027] Incidentally, while it is possible to reduce damage to semiconductor elements by joining them under a hydrogen atmosphere without pressure, this method requires large equipment to create a hydrogen atmosphere. On the other hand, in the manufacturing method of the above embodiment, the first member and the second member are joined by removing the oxide film on the surface of the metal sintered body provided on the semiconductor element mounting support member or the semiconductor element in advance with a reducing organic solvent. Therefore, a hydrogen atmosphere is not required in the joining process, and the advantages of being able to manufacture semiconductor devices at a lower cost and more simply are obtained.

[0028] Figure 1 is a schematic cross-sectional view showing an example of a semiconductor device manufacturing method according to one embodiment. In this example, the first member is a support member for mounting a semiconductor element, and the second member is a semiconductor element. That is, the manufacturing method of a semiconductor device comprises the steps of preparing a support member 2 for mounting a semiconductor element having a metal sintered body 1 on its surface and a semiconductor element 3 (Figure 1(a)), and a bonding step of pressurizing the support member 2 and the semiconductor element 3 together via the metal sintered body 1 (Figure 1(b)). In order to bring the surface of the metal sintered body 1 into contact with a reducing organic solvent during or before the bonding step, the surface 1a of the metal sintered body 1 in the bonding step (the surface in contact with the semiconductor element) may contain a reducing organic solvent, as shown in Figure 1(b).

[0029] Figure 2 is a schematic cross-sectional view showing another example of a method for manufacturing a semiconductor device according to one embodiment. In this example, the first component is a semiconductor element, and the second component is a support member for mounting the semiconductor element. That is, the method for manufacturing a semiconductor device comprises the steps of: preparing a semiconductor element 3 having a metal sintered body 1 on its surface and a support member 2 for mounting the semiconductor element; and a bonding step of pressurizing the semiconductor element 3 and the support member 2 for mounting the semiconductor element via the metal sintered body 1. In order to bring the surface of the metal sintered body 1 into contact with a reducing organic solvent during or before the bonding step, the surface 1b of the metal sintered body 1 in the bonding step (the surface in contact with the support member for mounting the semiconductor element) may contain a reducing organic solvent, as shown in Figure 2(b).

[0030] From the viewpoint of facilitating the formation of a metal sintered body, it is preferable that the first member is a support member for mounting a semiconductor element, and the second member is a semiconductor element.

[0031] Support members for mounting semiconductor devices include lead frames, ceramic substrates with metal plates attached (e.g., DBC), substrates for mounting semiconductor devices such as LED packages, metal wiring such as copper ribbons and metal frames, block bodies such as metal blocks, power supply members such as terminals, heat sinks, and water cooling plates.

[0032] In addition to common semiconductor materials such as silicon (Si), wide-bandgap semiconductor materials such as silicon carbide (SiC) and gallium nitride (GaN) can be used without particular limitations as semiconductor devices. Specific examples of semiconductor devices include IGBTs, diodes, Schottky barrier diodes, MOS-FETs, thyristors, logic circuits, sensors, analog integrated circuits, LEDs, semiconductor lasers, and oscillators.

[0033] A metal sintered body is a sintered body of metal particles, formed by sintering a sinterable bonding material (metal bonding paste) containing metal particles. A metal sintered body has, for example, a sintered metal and voids (pores) formed by the sintered metal. A metal sintered body is formed, for example, in layers. The metal contained in the metal sintered body is not particularly limited as long as it is a sinterable metal, and examples include copper and silver. It is preferable that the metal sintered body contains copper. In other words, it is preferable that the metal sintered body is a sintered body formed by sintering a sinterable bonding material (such as a copper bonding paste) containing copper particles.

[0034] The copper content in the metal sintered body may be 95% by mass or more, 97% by mass or more, 98% by mass or more, or 100% by mass, based on the total mass of the metal sintered body. Here, the copper content refers to the proportion of copper elements among the elements constituting the metal sintered body, excluding light elements. If the copper content in the metal sintered body is within the above range, the formation of intermetallic compounds or the precipitation of dissimilar elements at the grain boundaries of the metallic copper crystal can be suppressed, the properties of the metallic copper constituting the metal sintered body tend to become stronger, and even better connection reliability can be obtained.

[0035] Figure 3 is a cross-sectional SEM image showing an example of the morphology of a metal sintered body. The metal sintered body shown in Figure 3 includes a structure 11 derived from flake-shaped metal particles oriented substantially parallel to the interface with the first member (hereinafter referred to as "flake-shaped structure"), a structure 12 derived from other metal particles, and voids (pores) 13. When a metal sintered body includes a flake-shaped structure as shown in Figure 3, the bonding strength and connection reliability tend to improve. From the viewpoint of easily obtaining such effects, the flake-shaped metal particles are preferably flake-shaped copper particles. Note that "flake-shaped" includes flat plate-like shapes such as plate-like and flaky shapes.

[0036] The flake-like structure may have a ratio of 5 or more between its major axis and its thickness. The number-average diameter of the major axis of the flake-like structure may be 2 μm or more, 3 μm or more, or 4 μm or more. If the shape of the flake-like structure is within this range, the reinforcing effect of the flake-like structure contained in the metal sintered body is improved, and the bonding strength and connection reliability tend to be further improved.

[0037] The major axis and thickness of the flake-like structure can be determined, for example, from a cross-sectional SEM image of a sintered metal body. The following is an example of how to measure the major axis and thickness of the flake-like structure from a cross-sectional SEM image of a sintered metal body. First, cut out a sample from the sintered metal body to be used for measurement. Place the sample in a casting cup, pour epoxy casting resin into the cup so that the entire sample is filled, and allow it to harden. Cut the cast sample near the cross-section to be observed, grind the cross-section, and perform CP (cross-section polishing). Observe the cross-section of the sample at 5000x magnification using an SEM device. Cross-sectional images (e.g., 5000x magnification) of a sintered metal body are obtained. Dense, continuous portions that are linear, rectangular, or ellipsoidal in shape are identified. The longest linear portion contained within these portions is defined as the major axis, and the longest linear portion perpendicular to it and contained within these portions is defined as the thickness. Flake-like structures are defined as having a major axis of 1 μm or more and a major axis / thickness ratio of 4 or more. The major axis and thickness of these flake-like structures can then be measured using image processing software with a length-measuring function. The average values ​​are obtained by calculating the numerical mean of 20 or more randomly selected points.

[0038] A metal sintered body containing a flake-like structure can be formed by sintering a sinterable bonding material (metal bonding paste) containing flake-like metal particles.

[0039] The shape of the metal sintered body in plan view is not particularly limited. When the first member is a support member for mounting a semiconductor element, the metal sintered body is provided within the range of the outer edge of the semiconductor element. Figure 4 is a plan view showing the pattern of the metal sintered body when the metal sintered body 1 is provided on the support member 2 for mounting a semiconductor element. The metal sintered body 1 may be formed in a dot-like or radial pattern, for example, as shown in the modified examples in Figures 5 to 8.

[0040] The thickness of the metal sintered body is preferably 1 μm or more, more preferably 30 μm or more, even more preferably 50 μm or more, even more preferably 100 μm or more, particularly preferably 150 μm or more, and extremely preferably 200 μm or more, from the viewpoint of further reducing the pressure on the semiconductor element during pressure bonding and further reducing damage to the semiconductor element. The thickness of the metal sintered body may be 3000 μm or less, 1000 μm or less, 500 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, or 150 μm or less. The thickness of the metal sintered body is preferably 1 μm or more and 1000 μm or less, but may be 10 μm or more and 500 μm or less, 50 μm or more and 200 μm or less, 10 μm or more and 3000 μm or less, 15 μm or more and 500 μm or less, 20 μm or more and 300 μm or less, 5 μm or more and 500 μm or less, 10 μm or more and 250 μm or less, or 15 μm or more and 150 μm or less.

[0041] The porosity of the metal sintered body can be 60 volume% or less, based on the volume of the metal sintered body. In this case, it is possible to suppress the formation of large voids inside the metal sintered body and the sparseness of the sintered metal connecting the flake-like structure. As a result, sufficient thermal conductivity can be obtained, the bonding strength between the component and the metal sintered body is improved, and excellent connection reliability tends to be obtained. The porosity of the metal sintered body may be 55 volume% or less, or 50 volume% or less, based on the volume of the metal sintered body. The porosity of the metal sintered body is preferably 5 volume% or more, more preferably 10 volume% or more, even more preferably 20 volume% or more, and particularly preferably 25 volume% or more, based on the volume of the metal sintered body, from the viewpoint of further reducing the pressure on the semiconductor element during pressure bonding and further reducing damage to the semiconductor element, and from the viewpoint of ease of the manufacturing process. The porosity can be obtained by analyzing a cross-sectional image of the metal sintered body observed with a scanning electron microscope, scanning ion microscope, etc., using image analysis software. Furthermore, if the composition of the materials constituting the metal sintered body is known, the volume can also be determined from the difference between the volume of the metal sintered body and the volume ratio of the metal within the metal sintered body.

[0042] The volume percentage of metal (e.g., copper) in a metal sintered body can be 40% or more by volume, based on the volume of the metal sintered body. If the metal content in the metal sintered body is within the above range, it is possible to suppress the formation of large voids inside the metal sintered body and the sparseness of the sintered metal connecting the flake-like structure. As a result, sufficient thermal conductivity can be obtained, the bonding strength between the component and the metal sintered body is improved, and excellent connection reliability tends to be obtained. The metal content in the metal sintered body may be 45% or more by volume, or 50% or more by volume, based on the volume of the metal sintered body. The metal content in the metal sintered body may be 90% or less by volume, based on the volume of the metal sintered body, from the viewpoint of further reducing the pressure on the semiconductor element during pressure bonding and further reducing damage to the semiconductor element, as well as from the viewpoint of ease of the manufacturing process.

[0043] If the composition of the materials constituting the metal sintered body is known, the volume percentage of metal in the metal sintered body can be determined, for example, by the following procedure. First, the metal sintered body is cut into a rectangular parallelepiped, the length and width of the metal sintered body are measured with calipers or an external shape measuring device, and the thickness is measured with a film thickness gauge to calculate the volume of the metal sintered body. From the volume of the cut metal sintered body and the weight of the metal sintered body measured with a precision balance, the apparent density M1 (g / cm³) can be calculated. 3 ) is calculated. The calculated M1 is used to determine the density of the metal (for example, the density of copper is 8.96 g / cm³). 3 Using ), the volume percentage (volume %) of the metal in the metal sintered body can be determined from the following formula (1). Volume percentage of metal in a sintered metal body (volume %) = [(M1) / (density of metal)] × 100 ... (1)

[0044] The bonding strength of the metal sintered body (bonding strength with the first member) may be 10 MPa or more, 15 MPa or more, 20 MPa or more, or 30 MPa or more. The bonding strength can be measured using a universal bond tester (4000 series, manufactured by DAGE Corporation), etc.

[0045] The step of bringing a reducing organic solvent into contact with the surface of the metal sintered body (contact step) may be performed during the joining step or before the joining step.

[0046] For example, before the joining process, a reducing organic solvent may be placed (e.g., applied) on the surface of the metal sintered body and / or the surface of the second member (the surface that comes into contact with the metal sintered body during the joining process), thereby bringing the surface of the metal sintered body into contact with the reducing organic solvent during or before the joining process. In this case, the method of providing the reducing organic solvent is not particularly limited as long as it is a method that can deposit the reducing organic solvent. Examples of such methods include using a spin coater, screen printing, inkjet printing, etc. According to the above method, the surface of the metal sintered body can be brought into contact with the reducing organic solvent in a simple and reliable manner.

[0047] Furthermore, for example, a sheet containing a reducing organic solvent may be placed (e.g., laminated) on the surface of the metal sintered body and / or the surface of the second member before the joining process, thereby bringing the surface of the metal sintered body into contact with the reducing organic solvent during or before the joining process.

[0048] The reducing organic solvent may remain on the surface of the metal sintered body after the contact process. In this case, during the joining process, the first member, the metal sintered body, the reducing organic solvent, and the second member are arranged in this order. However, it is preferable that the reducing organic solvent is removed by heating during joining after the completion of the joining process.

[0049] Reducing organic solvents are organic solvents that have alcoholic hydroxyl groups or generate alcoholic hydroxyl groups during sintering decomposition.

[0050] The reducing organic solvent may be a monomer or an oligomer. A reducing organic solvent is preferable to be a reducing oligomer, as it tends to remain on the surface of the metal sintered body until midway through the bonding process (resintering of the metal) and is quickly removed at the sintering temperature. Low molecular weight compounds are removed before reaching the firing temperature, making it difficult to achieve reducing properties during sintering. On the other hand, polymers (compounds with more than 50 monomer units) have a low weight loss rate even at the sintering temperature and tend to remain after sintering. Note that an oligomer is a polymer of a monomer compound, meaning a compound with 4 to 50 monomer units.

[0051] Examples of reducing oligomers include polyester, polyethylene glycol, and polyvinyl alcohol.

[0052] As a reducing organic solvent, compounds having multiple alcoholic hydroxyl groups (polyhydric alcohols) are preferred, and polyhydric alcohols with a boiling point of 200°C or higher are more preferred. Examples of polyhydric alcohols with a boiling point of 200°C or higher include diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, butylene glycol, glycerin, and diglycerin.

[0053] Reducing organic solvents are preferably flux-active. Examples of flux-active organic solvents include sugars such as phloroglucinol and glucose, carboxylic acids such as oxalic acid and 2,2-bis(hydroxymethyl)propionic acid, and hydrazides such as adipic acid dihydrazide.

[0054] Based on the above, it is preferable that the reducing organic solvent includes a polyhydric alcohol, oligomer, or flux-active organic solvent with a boiling point of 200°C or higher.

[0055] When a reducing organic solvent has a boiling point or thermal decomposition temperature, the 95% weight loss temperature of the reducing organic solvent in TG-DTA (in nitrogen) is preferably 200°C or higher, more preferably 240°C or higher, and even more preferably 280°C or higher, from the viewpoint that the organic solvent is likely to remain on the surface of the metal sintered body until midway through the bonding process (re-sintering of the metal). The 95% weight loss temperature of the reducing organic solvent in TG-DTA (in nitrogen) is preferably 450°C or lower, more preferably 420°C or lower, and even more preferably 400°C or lower, from the viewpoint of suppressing the residue of the reducing organic solvent in the semiconductor device after the bonding process. From these viewpoints, the boiling point of the reducing organic solvent is preferably 200 to 450°C, more preferably 240 to 420°C, and even more preferably 280 to 400°C.

[0056] The amount of reducing organic solvent brought into contact with the surface of the metal sintered body is not particularly limited. The reducing organic solvent may be brought into contact with a part of the surface of the metal sintered body or with the entire surface of the metal sintered body.

[0057] In the bonding process, first, the semiconductor elements are placed on a semiconductor element mounting support member so that the first member and the second member are stacked via a metal sintered body. Methods for placing the semiconductor elements on the semiconductor element mounting support member include, for example, using a chip mounter, a flip-chip bonder, or a positioning jig made of carbon or ceramic.

[0058] Next, the resulting laminate is subjected to a heating and pressing treatment to join the semiconductor element mounting support member and the semiconductor element via a metal sintered body. For the heating treatment, for example, a hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device, heater heating device, steam heating furnace, etc. For the pressing treatment, for example, a pressing jig using weights, spring jigs, silicone rubber, etc., a thermocompression bonding device, a hot plate press device, etc., can be used. At this time, because a metal sintered body is formed on the first member, the impact of pressure on the semiconductor element by the pressing device and the effects of pressure variations are suppressed, and the yield is improved.

[0059] The gas atmosphere in the bonding process may be an oxygen atmosphere or an oxygen-free atmosphere. Examples of oxygen-free atmospheres include an oxygen-free gas atmosphere such as nitrogen or a noble gas, or a vacuum atmosphere. The hydrogen (hydrogen gas) concentration in the gas atmosphere may be 5 ppm or less. In this embodiment, since it is not necessary to include a large amount of hydrogen in the gas atmosphere, large equipment is not required, and semiconductor devices can be manufactured at low cost and in a simple manner.

[0060] The maximum temperature reached during the heat treatment may be between 250°C and 450°C, between 250°C and 400°C, or between 250°C and 350°C, from the viewpoint of reducing thermal damage to semiconductor elements and support members for mounting semiconductor elements and improving yield. If the maximum temperature reached is 250°C or higher, sintering tends to proceed sufficiently when the maximum temperature is held for 60 minutes or less.

[0061] The time required to maintain the highest temperature reached may be 1 minute or more and 60 minutes or 1 minute or more and 40 minutes or 1 minute or more and 30 minutes or less, from the viewpoint of sufficiently (preferably all) volatilizing the reducing organic solvent and improving yield.

[0062] By the above method, the semiconductor device 5 shown in Figures 1(c) and 2(c) is obtained. The semiconductor device 5 comprises a semiconductor element mounting support member 2, a semiconductor element 3, and a metal sintered body 4 that joins the semiconductor element mounting support member 2 and the semiconductor element 3. The metal sintered body 4 may be different from the metal sintered body 1 of the first part of the component as a result of the contact process and the joining process.

[0063] Next, a method for forming a metal sintered body on the surface of the first component will be described.

[0064] A method for forming a metal sintered body on the surface of a first member comprises the steps of providing a sinterable bonding material on the surface of the first member and a sintering step of heat-treating the sinterable bonding material to sinter it.

[0065] The method for applying the sinterable bonding material to the surface of the first member is not particularly limited as long as it is a method that can deposit the sinterable bonding material. Examples of such methods include screen printing, transfer printing, offset printing, jet printing, dispensers, jet dispensers, needle dispensers, comma coaters, slit coaters, die coaters, gravure coaters, slit coats, letterpress printing, intaglio printing, gravure printing, stencil printing, soft lithography, bar coating, applicators, particle deposition methods, spray coaters, spin coaters, dip coaters, electrodeposition coating, and the like.

[0066] Heat treatment for sintering sinterable bonding materials can be carried out using, for example, a hot plate, hot air dryer, hot air heating furnace, nitrogen dryer, infrared dryer, infrared heating furnace, far infrared heating furnace, microwave heating device, laser heating device, electromagnetic heating device, heater heating device, steam heating furnace, etc.

[0067] The gas atmosphere in the sintering process may be an oxygen-free atmosphere from the viewpoint of suppressing oxidation of the metal sintered body and the first component. The gas atmosphere in the sintering process may also be a reducing atmosphere from the viewpoint of removing oxides from the surface of metal particles contained in the sinterable bonding material. Examples of oxygen-free atmospheres include oxygen-free gas atmospheres such as nitrogen and noble gases, or a vacuum atmosphere. Examples of reducing atmospheres include a pure hydrogen gas atmosphere, a mixed gas atmosphere of hydrogen and nitrogen represented by a forming gas, a nitrogen atmosphere containing formic acid gas, a mixed gas atmosphere of hydrogen and noble gases, and a noble gas atmosphere containing formic acid gas.

[0068] The maximum temperature reached during the heat treatment may be between 250°C and 450°C, between 250°C and 400°C, or between 250°C and 350°C, from the viewpoint of reducing thermal damage to the first component and improving yield. If the maximum temperature reached is 250°C or higher, sintering tends to proceed sufficiently when the maximum temperature is held for 60 minutes or less.

[0069] The maximum temperature holding time may be 1 minute or more and 60 minutes or 1 minute or more and 40 minutes or 1 minute or more and 30 minutes or less, from the viewpoint of sufficiently (preferably all) volatilizing the dispersion medium in the sinterable bonding material and improving yield.

[0070] Next, an example of a sinterable bonding material is shown below.

[0071] A sinterable bonding material, for example, contains metal particles and a dispersion medium, and can be called a metal paste (metal paste for bonding). If the sinterable bonding material contains copper particles as metal particles, it can be called a copper paste (copper paste for bonding).

[0072] Examples of metal particles include submicro copper particles, flake-shaped micro copper particles, other copper particles, and other metal particles.

[0073] Examples of submicro copper particles include those containing copper particles with a particle size of 0.12 μm or more and 0.8 μm or less. For example, copper particles with a volume average particle size of 0.12 μm or more and 0.8 μm or less can be used. If the volume average particle size of the submicro copper particles is 0.12 μm or more, it is easier to obtain effects such as suppression of the synthesis cost of the submicro copper particles, good dispersibility, and suppression of the amount of surface treatment agent used. If the volume average particle size of the submicro copper particles is 0.8 μm or less, it is easier to obtain the effect of excellent sinterability of the submicro copper particles. From the viewpoint of achieving the above effects even more, the volume average particle size of the submicro copper particles may be 0.15 μm or more and 0.8 μm or less, 0.15 μm or more and 0.6 μm or less, 0.2 μm or more and 0.5 μm or less, or 0.3 μm or more and 0.45 μm or less.

[0074] In this specification, volume-average particle size refers to the 50% volume-average particle size. To determine the volume-average particle size of copper particles, the raw copper particles, or dried copper particles obtained by removing volatile components from a metal paste, are dispersed in a dispersion medium using a dispersant, and the particle size can be determined by measuring the dispersed particles using a light scattering particle size distribution analyzer (for example, the Shimadzu nanoparticle size distribution analyzer (SALD-7500nano, manufactured by Shimadzu Corporation)). When using a light scattering particle size distribution analyzer, hexane, toluene, α-terpineol, etc., can be used as the dispersion medium.

[0075] Submicro copper particles can contain 10% by mass or more of copper particles with a particle size of 0.12 μm or more and 0.8 μm or less. From the viewpoint of the sinterability of the metal paste, submicro copper particles can contain 20% by mass or more, 30% by mass or more, or even 100% by mass of copper particles with a particle size of 0.12 μm or more and 0.8 μm or less. When the content of copper particles with a particle size of 0.12 μm or more and 0.8 μm or less in the submicro copper particles is 20% by mass or more, the dispersibility of the copper particles is further improved, and the increase in viscosity and decrease in paste concentration can be further suppressed.

[0076] The particle size of copper particles can be calculated, for example, from scanning electron microscope (SEM) images. Copper particle powder is placed on a carbon tape for SEM using a spatula to create an SEM sample. This SEM sample is observed at 5000x magnification using an SEM device. A rectangle circumscribing the copper particles in this SEM image is drawn using image processing software, and the length of one side of this rectangle is taken as the particle size.

[0077] The submicro copper particle content may be 20% to 90% by mass, 30% to 90% by mass, 35% to 85% by mass, or 40% to 80% by mass, based on the total mass of the metal particles. Having a submicro copper particle content within the above range facilitates the formation of a metal sintered body with excellent bonding properties.

[0078] The submicro copper particle content may be 20% to 90% by mass, based on the sum of the mass of submicro copper particles and flake-shaped micro copper particles. If the submicro copper particle content is 20% by mass or more, it is possible to sufficiently fill the spaces between the flake-shaped micro copper particles, making it easy to form a metal sintered body with excellent bonding properties. If the submicro copper particle content is 90% by mass or less, the volume shrinkage when the metal paste is sintered can be sufficiently suppressed, making it easy to form a metal sintered body with excellent bonding properties. From the viewpoint of achieving the above effects even more, the submicro copper particle content may be 30% to 85% by mass, 35% to 85% by mass, or 40% to 80% by mass, based on the sum of the mass of submicro copper particles and flake-shaped micro copper particles.

[0079] The shape of the submicro copper particles is not particularly limited. Examples of submicro copper particle shapes include spherical, lumpy, needle-shaped, flake-shaped, approximately spherical, and aggregates thereof. From the viewpoint of dispersibility and packing, the shape of the submicro copper particles may be spherical, approximately spherical, or flake-shaped, and from the viewpoint of flammability, dispersibility, and miscibility with flake-shaped microparticles, they may be spherical or approximately spherical.

[0080] The submicro copper particles may have an aspect ratio of 5 or less, or 3 or less, from the viewpoint of dispersibility, packing, and miscibility with flake-like microparticles. In this specification, "aspect ratio" refers to the ratio of the long side to the thickness of the particle. The long side and thickness of the particle can be determined, for example, from a SEM image of the particle.

[0081] Submicro copper particles may be treated with a specific surface treatment agent. Examples of specific surface treatment agents include organic acids having 8 to 16 carbon atoms. Examples of organic acids having 8 to 16 carbon atoms include caprylic acid, methylheptanoic acid, ethylhexanoic acid, propylpentanoic acid, pelargonic acid, methyloctanoic acid, ethylheptanoic acid, propylhexanoic acid, capric acid, methylnonanoic acid, ethyloctanoic acid, propylheptanoic acid, butylhexanoic acid, undecanoic acid, methyldecanoic acid, ethylnonanoic acid, propyloctanoic acid, butylheptanoic acid, lauric acid, methylundecanoic acid, ethyldecanoic acid, propylnonanoic acid, butyloctanoic acid, Saturated fatty acids such as pentylheptanoic acid, tridecanoic acid, methyldodecanoic acid, ethylundecanoic acid, propyldecanoic acid, butylnonanoic acid, pentyloctanoic acid, myristic acid, methyltridecanoic acid, ethyldodecanoic acid, propylundecanoic acid, butyldecanoic acid, pentylnonanoic acid, hexyloctanoic acid, pentadecanoic acid, methyltetradecanoic acid, ethyltridecanoic acid, propyldodecanoic acid, butylundecanoic acid, pentyldecanoic acid, hexylnonanoic acid, palmitic acid, methylpentadecanoic acid, ethyltetradecanoic acid, propyltridecanoic acid, butyldodecanoic acid, pentylundecanoic acid, hexyldecanoic acid, heptylnonanoic acid, methylcyclohexanecarboxylic acid, ethylcyclohexanecarboxylic acid, propylcyclohexanecarboxylic acid, butylcyclohexanecarboxylic acid, pentylcyclohexanecarboxylic acid, hexylcyclohexanecarboxylic acid, heptylcyclohexanecarboxylic acid, octylcyclohexanecarboxylic acid, nonylcyclohexanecarboxylic acid, etc. Examples include acids, unsaturated fatty acids such as nonenic acid, methylnonenic acid, 10-hydroxy-2-decenoic acid, undecenoic acid, dodecenoic acid, tridecenoic acid, tetradecenoic acid, myristoleic acid, pentadecenoic acid, hexadecenoic acid, palmitoleic acid, and sapienic acid; and aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, o-phenoxybenzoic acid, methylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, pentylbenzoic acid, hexylbenzoic acid, heptylbenzoic acid, octylbenzoic acid, and nonylbenzoic acid. Organic acids may be used individually or in combination of two or more.By combining such an organic acid with the submicro copper particles, it tends to be possible to achieve both the dispersibility of the submicro copper particles and the desorbability of the organic acid during sintering.

[0082] The treatment amount of the surface treatment agent may be an amount that adheres to the surface of the submicro copper particles in a monolayer to a trilayer. This amount depends on the number of molecular layers (n) adhering to the surface of the submicro copper particles, the specific surface area (A p )(unit: m 2 / g) of the submicro copper particles, the molecular weight (M s )(unit: g / mol) of the surface treatment agent, the minimum coating area (S S )(unit: m 2 / particle) of the surface treatment agent, and Avogadro's number (N A )(6.02×10 23 particles) and can be calculated from them. Specifically, the treatment amount of the surface treatment agent is calculated according to the formula: treatment amount of the surface treatment agent (mass%) = {(n·A p ·M s ) / (S S ·N A + n·A p ·M s )} × 100%.

[0083] The specific surface area of the submicro copper particles can be calculated by measuring the dried submicro copper particles by the BET specific surface area measurement method. The minimum coating area of the surface treatment agent is 2.05×10 -19 m 2 / molecule when the surface treatment agent is a straight-chain saturated fatty acid. In the case of other surface treatment agents, it can be measured, for example, by calculation from a molecular model or by the method described in "Chemistry and Education" (Katsuhiro Ueda, Junko Inafuku, Iwao Mori, 40(2), 1992, p114 - 117). An example of a method for quantifying the surface treatment agent is shown. The surface treatment agent can be identified by a thermal desorption gas - gas chromatograph mass spectrometer for the dry powder obtained by removing the dispersion medium from the metal paste, and thereby the carbon number and molecular weight of the surface treatment agent can be determined. The carbon content ratio of the surface treatment agent can be analyzed by carbon content analysis. Examples of the carbon content analysis method include, for example, high-frequency induction heating furnace combustion / infrared absorption method. The amount of the surface treatment agent can be calculated from the carbon number, molecular weight, and carbon content ratio of the identified surface treatment agent using the above formula.

[0084] The amount of surface treatment agent used may be 0.07% by mass or more and 2.1% by mass or less, 0.10% by mass or more and 1.6% by mass or less, or 0.2% by mass or more and 1.1% by mass or less.

[0085] Commercially available submicro copper particles can be used. Examples of commercially available submicro copper particles include CH-0200 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle size 0.36 μm), HT-14 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle size 0.41 μm), CT-500 (manufactured by Mitsui Mining & Smelting Co., Ltd., volume average particle size 0.72 μm), and Tn-Cu100 (manufactured by Taiyo Nippon Sanso Corporation, volume average particle size 0.12 μm).

[0086] Examples of flake-shaped microcopper particles include those with a maximum diameter of 1 μm to 20 μm and an aspect ratio of 4 or more. For example, copper particles with an average maximum diameter of 1 μm to 20 μm and an aspect ratio of 4 or more can be used. If the average maximum diameter and aspect ratio of the flake-shaped microcopper particles are within the above range, the volume shrinkage when the metal paste is sintered can be sufficiently reduced, making it easy to form a sintered product with excellent bonding properties. From the viewpoint of achieving the above effect even more effectively, the average maximum diameter of the flake-shaped microcopper particles may be 1 μm to 10 μm, or 3 μm to 10 μm. The maximum diameter and average maximum diameter of the flake-shaped microcopper particles can be determined, for example, from an SEM image of the particles, and are obtained as the major axis X and the average value of the major axis Xav of the flake-shaped structure, as described later.

[0087] The flake-shaped micro-copper particles may contain 50% or more by mass of copper particles with a maximum diameter of 1 μm to 20 μm. From the viewpoint of orientation within the sintered material, reinforcing effect, and filling properties of the bonding paste, the flake-shaped micro-copper particles may contain 70% or more by mass of copper particles with a maximum diameter of 1 μm to 20 μm, 80% or more by mass, or even 100% by mass. From the viewpoint of suppressing bonding defects, it is preferable that the flake-shaped micro-copper particles do not contain particles that exceed the bonding thickness, such as particles with a maximum diameter exceeding 20 μm.

[0088] This section illustrates a method for calculating the major axis X of flake-shaped microcopper particles from SEM images. A powder of flake-shaped microcopper particles is placed on a carbon tape for SEM using a spatula to create an SEM sample. This SEM sample is observed at 5000x magnification using an SEM device. A rectangle circumscribing the flake-shaped microcopper particles in the SEM image is drawn using image processing software, and the longest side of this rectangle is defined as the major axis X of the particle. This measurement is performed on 50 or more flake-shaped microcopper particles using multiple SEM images, and the average major axis Xav is calculated.

[0089] The flake-shaped microcopper particles may have an aspect ratio of 4 or more, or 6 or more. If the aspect ratio is within the above range, the flake-shaped microcopper particles in the metal paste are oriented substantially parallel to the bonding surface, which suppresses volume shrinkage when the metal paste is sintered, making it easy to form a metal sintered body with excellent bonding properties.

[0090] The content of flake-shaped microcopper particles may be 1% to 90% by mass, 10% to 70% by mass, or 20% to 50% by mass, based on the total mass of the metal particles. If the content of flake-shaped microcopper particles is within the above range, it becomes easy to form a metal sintered body with excellent bonding properties.

[0091] The total content of sub-micro copper particles and flake-shaped micro copper particles may be 80% by mass or more, based on the total mass of metal particles. If the total content of sub-micro copper particles and flake-shaped micro copper particles is within the above range, it becomes easier to form a sintered product with excellent bonding properties. From the viewpoint of achieving the above effect even more, the total content of sub-micro copper particles and flake-shaped micro copper particles may be 90% by mass or more, 95% by mass or more, or 100% by mass, based on the total mass of metal particles.

[0092] In the case of flake-shaped microcopper particles, there is no particular limitation on whether or not they are treated with a surface treatment agent. From the viewpoint of dispersion stability and oxidation resistance, the flake-shaped microcopper particles may be treated with a surface treatment agent. The surface treatment agent may be removed during bonding. Examples of such surface treatment agents include aliphatic carboxylic acids such as palmitic acid, stearic acid, arachidic acid, and oleic acid; aromatic carboxylic acids such as terephthalic acid, pyromellitic acid, and o-phenoxybenzoic acid; aliphatic alcohols such as cetyl alcohol, stearyl alcohol, isobornylcyclohexanol, and tetraethylene glycol; aromatic alcohols such as p-phenylphenol; alkylamines such as octylamine, dodecylamine, and stearylamine; aliphatic nitriles such as stearonitrile and decanonitrile; silane coupling agents such as alkylalkoxysilane; and polymeric treatment agents such as polyethylene glycol, polyvinyl alcohol, polyvinylpyrrolidone, and silicone oligomers. One type of surface treatment agent may be used alone, or two or more types may be used in combination.

[0093] The amount of surface treatment agent applied may be one molecular layer or more on the particle surface. This amount of surface treatment agent varies depending on the specific surface area of ​​the flake-shaped microcopper particles, the molecular weight of the surface treatment agent, and the minimum coverage area of ​​the surface treatment agent. The amount of surface treatment agent applied is typically 0.001% by mass or more. The specific surface area of ​​the flake-shaped microcopper particles, the molecular weight of the surface treatment agent, and the minimum coverage area of ​​the surface treatment agent can be calculated using the method described above.

[0094] When preparing a metal paste using only the above-mentioned sub-micro copper particles, the volume shrinkage and sintering shrinkage due to the volatilization of the dispersion medium are large, making the metal paste prone to peeling from the bonded surface during sintering. This makes it difficult to obtain sufficient die-shear strength and connection reliability when bonding semiconductor devices and the like. By using sub-micro copper particles in combination with flake-shaped micro copper particles, the volume shrinkage when the metal paste is sintered is suppressed, making it easier to form a metal sintered body with excellent bonding properties.

[0095] Commercially available flake-shaped microcopper particles can be used. Examples of commercially available flake-shaped microcopper particles include MA-C025 (manufactured by Mitsui Mining & Smelting Co., Ltd., average maximum diameter 4.1 μm), 3L3 (manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., average maximum diameter 7.3 μm), 1110F (manufactured by Mitsui Mining & Smelting Co., Ltd., average maximum diameter 5.8 μm), and 2L3 (manufactured by Fukuda Metal Foil & Powder Industry Co., Ltd., average maximum diameter 9 μm).

[0096] In metal pastes, the micro-copper particles used as the blending particles include flake-shaped micro-copper particles with a maximum diameter of 1 μm to 20 μm and an aspect ratio of 4 or more, and the content of micro-copper particles with a maximum diameter of 1 μm to 20 μm and an aspect ratio of less than 2 is 50% by mass or less, preferably 30% by mass or less, based on the total amount of the flake-shaped micro-copper particles. When using commercially available flake-shaped micro-copper particles, it is also possible to select those that include flake-shaped micro-copper particles with a maximum diameter of 1 μm to 20 μm and an aspect ratio of 4 or more, and the content of micro-copper particles with a maximum diameter of 1 μm to 20 μm and an aspect ratio of less than 2 is 50% by mass or less, preferably 30% by mass or less, based on the total amount of the flake-shaped micro-copper particles.

[0097] The metal particles may include other metal particles besides the sub-micro copper particles and micro copper particles mentioned above, such as nickel, silver, gold, palladium, and platinum. The volume-average particle size of the other metal particles may be 0.01 μm to 10 μm, 0.01 μm to 5 μm, or 0.05 μm to 3 μm. If other metal particles are included, their content may be less than 20% by mass or 10% by mass or less, based on the total mass of the metal particles, from the viewpoint of obtaining sufficient bonding properties. Other metal particles may not be included. The shape of the other metal particles is not particularly limited.

[0098] By including metal particles other than copper particles, a metal sintered body can be obtained in which multiple types of metals are dissolved or dispersed. This improves the mechanical properties of the metal sintered body, such as yield stress and fatigue strength, and enhances connection reliability. Furthermore, the sintered product formed by adding multiple types of metal particles tends to have improved bonding strength and connection reliability for specific adherends. Note that the metal paste may not contain copper particles and may contain only other metal particles.

[0099] The dispersion medium is not particularly limited and may be volatile. Examples of volatile dispersion mediums include monohydric and polyhydric alcohols such as pentanol, hexanol, heptanol, octanol, decanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, α-terpineol, and isobornylcyclohexanol (MTPH); ethylene glycol butyl ether, ethylene glycol phenyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol butyl ether, diethylene glycol isobutyl ether, diethylene glycol hexyl ether, triethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, diethylene glycol isopropyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol butyl methyl ether, propylene glycol propyl ether, and dipropylene glycol. Examples include ethers such as methyl ether, dipropylene glycol ethyl ether, dipropylene glycol propyl ether, dipropylene glycol butyl ether, dipropylene glycol dimethyl ether, tripropylene glycol methyl ether, and tripropylene glycol dimethyl ether; esters such as ethylene glycol ethyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, dipropylene glycol methyl ether acetate (DPMA), ethyl lactate, butyl lactate, γ-butyrolactone, and propylene carbonate; acid amides such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide; aliphatic hydrocarbons such as cyclohexanone, octane, nonane, decane, and undecane; aromatic hydrocarbons such as benzene, toluene, and xylene; mercaptans having alkyl groups with 1 to 18 carbon atoms; and mercaptans having cycloalkyl groups with 5 to 7 carbon atoms.Examples of mercaptans having an alkyl group with 1 to 18 carbon atoms include ethyl mercaptan, n-propyl mercaptan, i-propyl mercaptan, n-butyl mercaptan, i-butyl mercaptan, t-butyl mercaptan, pentyl mercaptan, hexyl mercaptan, and dodecyl mercaptan. Examples of mercaptans having a cycloalkyl group with 5 to 7 carbon atoms include cyclopentyl mercaptan, cyclohexyl mercaptan, and cycloheptyl mercaptan.

[0100] The content of the dispersion medium may be 5 to 50 parts by mass, based on 100 parts by mass of the total mass of the metal particles. If the content of the dispersion medium is within the above range, the metal paste can be adjusted to a more appropriate viscosity, and the sintering of the copper particles will not be inhibited.

[0101] The metal paste may, as needed, contain wetting agents such as nonionic surfactants and fluorinated surfactants; defoaming agents such as silicone oil; and ion trapping agents such as inorganic ion exchangers.

[0102] The metal paste described above can be prepared by mixing the aforementioned metal particles and any additives in a dispersion medium. After mixing the components, stirring may be performed. The maximum particle size of the dispersion may be adjusted by a classification operation.

[0103] The metal paste may be prepared by first mixing sub-micro copper particles, a surface treatment agent, and a dispersion medium, then performing a dispersion treatment to prepare a dispersion of sub-micro copper particles, and further mixing in micro copper particles, other metal particles, and optional additives. This procedure improves the dispersibility of the sub-micro copper particles and improves their mixability with the micro copper particles, thereby further improving the performance of the metal paste. The dispersion of sub-micro copper particles may be subjected to a classification operation to remove aggregates.

[0104] <Support member set and semiconductor element set for mounting semiconductor elements> The first member having a metal sintered body on its surface and the reducing organic solvent used in the semiconductor device manufacturing method of the above embodiment may be provided as a set comprising the first member having a metal sintered body on its surface and the reducing organic solvent. That is, in one aspect, the present invention provides a semiconductor element mounting support member set comprising a semiconductor element mounting support member and a reducing organic solvent. Furthermore, in one aspect, the present invention provides a semiconductor element set comprising a semiconductor element having a metal sintered body on its surface and a reducing organic solvent.

[0105] In the above set, the first member having a metal sintered body on its surface and the reducing organic solvent may exist separately. Furthermore, in the above set, the reducing organic solvent may be applied to the surface of the metal sintered body opposite to the first member. That is, the above set may comprise the first member having a metal sintered body on its surface and the reducing organic solvent applied to the surface of the metal sintered body opposite to the first member. [Examples]

[0106] The present invention will be described in more detail below with reference to examples. However, the present invention is not limited to the following examples.

[0107] <Example 1> (Step a: Preparation of metal paste) 5.2 g of α-terpineol (manufactured by Wako Pure Chemical Industries, Ltd.) and 6.8 g of isobornylcyclohexanol (MTPH, manufactured by Nippon Terpene Chemical Co., Ltd.) were mixed in a poly bottle as dispersion media, along with 52.8 g of CH-0200 (manufactured by Mitsui Mining & Smelting Co., Ltd., containing 95% by mass of copper particles between 0.12 μm and 0.8 μm) as submicro copper particles to obtain a dispersion. 35.2 g of MA-C025 (manufactured by Mitsui Mining & Smelting Co., Ltd., with an average maximum diameter of 4.1 μm and an aspect ratio of 6.6, containing 100% by mass of copper particles) as flake-shaped microcopper particles were added to this dispersion, and the mixture was stirred with a spatula until no dry powder remained. The poly bottle was tightly sealed, stirred at 2000 rpm for 2 minutes, and then stirred under reduced pressure at 2000 rpm for 2 minutes to obtain a metal paste (bonding copper paste).

[0108] (Process b: Coating process) A metal paste was stencil-printed onto a copper substrate measuring 19mm x 25mm x 3mm (thickness) using a 100μm thick stainless steel mask and squeegee with a 5mm x 5mm square opening.

[0109] (Process c: Formation process of sintered copper layer) The copper substrate, after undergoing the coating process, was placed in a tube furnace (manufactured by AVC Co., Ltd.), and argon gas was flowed at 1 L / min to replace the air with argon gas. Then, while flowing hydrogen gas at 300 mL / min, the temperature was raised to 350°C over 10 minutes, and the furnace was heated and held at 350°C for 10 minutes to sinter the metal paste. As a result, a metal sintered body (sintered copper layer) was formed on the copper substrate. After that, the laminate was cooled while flowing argon gas at 0.3 L / min, and the laminate was removed into the air at a temperature of 50°C or lower.

[0110] (Process d: Mounting process) A copper substrate that had undergone a sintered copper layer formation process and a Si chip measuring 5 mm × 5 mm × 150 μm (thickness) with a titanium layer / nickel layer formed in that order on the entire bonding surface by sputtering were prepared. A reducing organic solvent was applied to the surface of the sintered copper layer that had been previously formed on the copper substrate using a brush. The Si chip was placed on the sintered copper layer coated with the reducing organic solvent, with the nickel layer facing the sintered copper layer. This resulted in a precursor laminate in which the Si chip, sintered copper layer, and copper substrate were stacked in that order.

[0111] (Process e: Bonding process) The pre-laminate was pressurized at 10 MPa for 10 minutes using a stainless steel stage and head heated to 300°C in nitrogen, bonding the Si chip and copper substrate via a sintered copper layer. During pressurization, a Teflon sheet (1 mm thick, "Teflon" is a registered trademark) was placed between the Si chip (the side of the Si chip opposite to the sintered copper layer side) and the stainless steel head.

[0112] (Damage assessment of Si chips) After the bonding process, the joint between the Si chip and the sintered copper layer was cross-sectioned to check for any fracture or delamination at the Si chip. 50 samples were evaluated based on the following criteria. A sample was judged as good if it met criteria A and B below. The results are shown in Table 1. A: No damage found in 50 samples. B: Damage occurred in 1-2 samples. C: Damage occurred in samples 3-10. D: Damage occurred in 11 or more samples.

[0113] (Evaluation of Si chip tilt) After the bonding process, the joint between the Si chip and the sintered copper layer was cross-sectioned, and the inclination of the Si chip relative to the copper substrate interface was observed and evaluated using a digital microscope (Keyence). 50 samples were evaluated based on the following criteria. A sample was judged as good if it met criteria A and B below. The results are shown in Table 1. A: The slope was 0.02° or less in 50 samples. B: A tilt of 0.02° or more occurred in 1-2 samples. C: A tilt of 0.02° or greater occurred in samples 3 to 10. D: A tilt of 0.02° or greater occurred in 11 or more samples.

[0114] <Example 2> Except for adjusting the amount of dispersion medium in step a of Example 1 so that the porosity of the sintered copper layer was 20 volume% (the volume percentage of copper was 80 volume%), a metal paste was prepared and used, and a semiconductor device was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0115] <Example 3> Except for adjusting the amount of dispersion medium in step a of Example 1 so that the porosity of the sintered copper layer was 30 volume% (the volume percentage of copper was 70 volume%), a metal paste was prepared and used, and a semiconductor device was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0116] <Example 4> In step b of Example 1, a stainless steel plate with a thickness of 500 μm was used instead of a stainless steel plate with a thickness of 100 μm, and the porosity of the sintered copper layer was changed to 10 volume% (copper volume ratio of 90 volume%) and the thickness to 250 μm. Otherwise, a semiconductor device was fabricated and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[0117] <Example 5> Except for the fact that in step a of Example 4, a metal paste was prepared and used in which the amount of dispersion medium was adjusted so that the porosity of the sintered copper layer was 20 volume% (the volume percentage of copper was 80 volume%), the semiconductor device was fabricated and evaluated in the same manner as in Example 4. The results are shown in Table 1.

[0118] <Example 6> Except for the fact that in step a of Example 4, a metal paste was prepared and used in which the amount of dispersion medium was adjusted so that the porosity of the sintered copper layer was 30 volume% (the volume percentage of copper was 70 volume%), the semiconductor device was fabricated and evaluated in the same manner as in Example 4. The results are shown in Table 1.

[0119] <Example 7> A semiconductor device was fabricated and evaluated in the same manner as in Example 1, except that in step e of Example 1, the pressure was increased to 5 MPa for 10 minutes instead of 10 MPa. The results are shown in Table 1.

[0120] <Example 8> A semiconductor device was fabricated and evaluated in the same manner as in Example 2, except that in step e of Example 2, the pressure was increased to 5 MPa for 10 minutes instead of 10 MPa. The results are shown in Table 1.

[0121] <Example 9> A semiconductor device was fabricated and evaluated in the same manner as in Example 3, except that in step e of Example 3, the pressure was increased to 5 MPa for 10 minutes instead of 10 MPa. The results are shown in Table 1.

[0122] <Example 10> A semiconductor device was fabricated and evaluated in the same manner as in Example 4, except that in step e of Example 4, the pressure was increased to 5 MPa for 10 minutes instead of 10 MPa. The results are shown in Table 1.

[0123] <Example 11> A semiconductor device was fabricated and evaluated in the same manner as in Example 5, except that in step e of Example 5, the pressure was increased to 5 MPa for 10 minutes instead of 10 MPa. The results are shown in Table 1.

[0124] <Example 12> A semiconductor device was fabricated and evaluated in the same manner as in Example 6, except that in step e of Example 6, the pressure was increased to 5 MPa for 10 minutes instead of 10 MPa. The results are shown in Table 1.

[0125] <Comparative Example 1> A copper substrate measuring 19 mm × 25 mm × 3 mm (thickness), a Si chip measuring 5 mm × 5 mm × 150 μm (thickness) with a titanium layer / nickel layer formed in that order on the entire bonding surface by sputtering, and a metal paste obtained from step a of Example 1 were prepared. A 500 μm thick stainless steel mask with a 5 mm × 5 mm square opening was placed on the copper substrate, and then the metal paste was stencil printed onto the copper substrate using a squeegee. The Si chip was placed on the printed metal paste so that the nickel layer was in contact with the metal paste. This resulted in a laminate in which the Si chip, metal paste, and copper substrate were stacked in that order. The process thereafter was carried out in the same manner as from step e onward in Example 1. The results are shown in Table 1. The porosity of the metal sintered body in the obtained semiconductor device was 10 volume%, and the thickness was 250 μm.

[0126] <Comparative Example 2> A semiconductor device was fabricated and evaluated in the same manner as in Comparative Example 1, except that in step e of Example 1, the pressure was increased to 5 MPa for 10 minutes instead of 10 MPa. The results are shown in Table 1. The porosity of the metal sintered body in the obtained semiconductor device was 10 volume%, and the thickness was 250 μm.

[0127] [Table 1]

[0128] As shown in the examples, by forming a sintered copper layer on the semiconductor element mounting support member in advance, the impact on the semiconductor element during pressurized bonding was reduced, and the semiconductor element could be bonded without tilting relative to the semiconductor element mounting support member. On the other hand, as shown in Comparative Examples 1 and 2, when a sintered copper layer was not formed on the semiconductor element mounting support member in advance, damage and tilting were observed in the Si chip, resulting in low yield and connection reliability during bonding. [Explanation of symbols]

[0129] 1...metal sintered body, 1a, 1b...surface of metal sintered body, 2...support member for mounting semiconductor element, 3...semiconductor element, 5...electronic device.

Claims

1. The method includes a joining step of pressurizing and joining a first member and a second member, each having a metal sintered body on its surface, via the metal sintered body. The first member is a support member for mounting a semiconductor element, and the second member is a semiconductor element. The metal sintered body includes a structure derived from flake-shaped microcopper particles oriented substantially parallel to the interface with the first member, a structure derived from submicrocopper particles, and voids. The porosity of the aforementioned metal sintered body is 5 to 60 volume%, A method for manufacturing a semiconductor device, characterized by depositing the organic solvent on the surface of the metal sintered body by applying a reducing organic solvent to the surface of the metal sintered body before the bonding step.

2. The manufacturing method according to claim 1, wherein the copper content in the metal sintered body is 95% by mass or more based on the total mass of the metal sintered body.

3. The manufacturing method according to claim 1 or 2, wherein the thickness of the metal sintered body is 1 to 1000 μm.

4. The manufacturing method according to any one of claims 1 to 3, wherein the reducing organic solvent includes an oligomer, a flux-active organic solvent, or a polyhydric alcohol having a boiling point of 200°C or higher.

5. The manufacturing method according to any one of claims 1 to 4, wherein the bonding step is carried out in an atmosphere with a hydrogen concentration of 5 ppm or less.

6. The manufacturing method according to any one of claims 1 to 5, wherein the semiconductor element is a wide-bandgap semiconductor.

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