Joint body and method for producing the same

Abstract

The joint body of the present invention is formed by joining a semiconductor element to a joining layer containing Cu. The aforementioned joining layer has an extension extending laterally from the periphery of the aforementioned semiconductor element. In a cross-sectional view in the thickness direction, the aforementioned extension is a side wall surface that rises from the periphery or vicinity of the periphery of the bottom of the aforementioned semiconductor element and is substantially separated from the side surface of the semiconductor element. For the aforementioned extension, it is also suitable that there is no portion where the aforementioned side wall surface and the side surface of the aforementioned semiconductor element are in contact with each other. In addition, the present invention also provides a method for manufacturing a joint body.

Description

Technical Field

[0001] The present invention relates to a joined body and a method for producing the same. Background Art

[0002] With the global trend towards energy conservation in recent years, semiconductor devices called power devices are being actively used as power conversion / control devices such as inverters. Unlike integrated circuits such as memories and microprocessors, power devices are devices used to control high currents and high voltages, so they tend to generate a lot of heat when driven. Therefore, in order to prevent semiconductor elements from being damaged by the heat, thermal countermeasures such as cooling systems are required for semiconductor packages.

[0003] In addition, in order to achieve high efficiency and space saving of semiconductor elements, an electronic component called a power module is used, in which a plurality of semiconductor elements are mounted on a joint body in which Cu is arranged on both sides of a ceramic plate. However, as the power module is miniaturized, heat is easily accumulated during driving, so when a joint material with low heat resistance such as a solder material is used, there is a concern that the module may fail.

[0004] In order to solve such a problem, attention is being paid to bonding materials formed by sintering metal particles such as silver and copper instead of solder materials. For example, Patent Document 1 discloses a semiconductor device comprising: a first bonding layer disposed on the surface of a metal substrate; a semiconductor device disposed on the metal substrate via the first bonding layer; and a fillet layer disposed on the sidewalls of the semiconductor device and the first bonding layer and formed of the same material as the first bonding layer.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-120639 Summary of the invention

[0008] In the semiconductor device described in Patent Document 1, the fillet layer is in direct contact with the side wall surface of the semiconductor device. However, if the fillet layer containing Cu is in contact with the side wall surface of the semiconductor device formed of, for example, a SiC system, then under a high temperature environment such as during driving, Cu will thermally diffuse into the semiconductor device. As a result, the semiconductor device may fail, or the bonding layer and the fillet layer may be easily peeled off or cracked.

[0009] Therefore, an object of the present invention is to provide a junction body which is unlikely to have an adverse effect on the characteristics of a semiconductor element and has high heat resistance, and a method for producing the same.

[0010] The present invention provides a bonded body, which is formed by bonding a semiconductor element and a bonding layer containing Cu.

[0011] The bonding layer has an extension portion extending laterally from the periphery of the semiconductor element.

[0012] In a cross-sectional view in the thickness direction, the protruding portion has a side wall surface that rises from a periphery or a vicinity of a periphery of a bottom portion of the semiconductor element and is substantially separated from a side surface of the semiconductor element.

[0013] The present invention also provides a method for producing a bonded body, wherein the bonding layer composition is applied on the surface of a conductor to form a coating film, the coating film is dried to form a dry coating film, and then,

[0014] A semiconductor element is laminated on the dry coating film so that the dry coating film is sandwiched between the conductor and the semiconductor element to obtain a laminated body, and then,

[0015] The laminate is heated while being pressurized to sinter the metal powder, thereby bonding the conductor to the semiconductor element.

[0016] The bonding layer composition includes: metal powder containing Cu; and a solid reducing agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 middle, Figure 1 (a) is a schematic diagram of a joint body of the present invention when viewed from above, Figure 1 (b) is Figure 1 Cross-sectional view along line II in (a).

[0018] Figure 2 To enlarge the Figure 1 Schematic diagram of the important parts in (b).

[0019] Figure 3 middle, Figure 3 (a) to (c) are schematic diagrams showing the arrangement positions of the extension portion and the semiconductor element in the embodiment of the bonded body of the present invention.

[0020] Figure 4 It is a schematic diagram showing the arrangement positions of the extension portion and the semiconductor element of another embodiment of the bonded structure of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be described below based on preferred embodiments and with reference to the accompanying drawings. Figure 1As shown in (a) and (b), the junction body 1 is formed by joining a semiconductor element 2 and a joining layer 3 containing Cu. The junction body 1 shown in these figures also includes a conductor 5 such as a substrate, and the semiconductor element 2 and the conductor 5 are joined by the joining layer 3 so that the semiconductor element 2 and the conductor 5 can be electrically connected.

[0022] The semiconductor element 2 is a component constituting a part of the junction body 1, and has a semiconductor chip 2A and an electrode 2B arranged on the bottom surface of the chip 2A. The semiconductor chip 2A in the semiconductor element 2 preferably mainly contains Si, and more preferably contains more than 50% by mass of Si. Depending on the purpose of use of the junction body 1, in the semiconductor element 2, atoms such as Ga, Ge, C, N, As, etc. can be included on the basis of Si or instead of Si. In addition, an upper electrode (not shown) is arranged on the upper part of the semiconductor chip 2A in the semiconductor element 2, which can be conductive in the thickness direction Z. In addition, it is preferred that a protective layer (not shown) is provided on the bottom surface of the semiconductor element 2 to prevent the bottom surface from directly contacting the junction layer 3. As long as the protective layer is a conductive layer, the layer used in this technical field can be used without particular restrictions. For example, a metal layer containing Au, Ag, Ti and Ni can be used.

[0023] The bonding layer 3 contains Cu, preferably contains 50 mass % or more, more preferably contains 60 mass % or more of Cu. Figure 1 As shown in (a) and (b), the bonding layer 3 is sandwiched between the semiconductor element 2 and the conductor 5. In addition, the bonding layer 3 has an extension portion 3A extending laterally from the periphery 2P of the semiconductor element 2. The extension portion 3A in the present embodiment is formed by the extension of the bonding layer 3 sandwiched between the semiconductor element 2 and the conductor 5, so the bonding layer 3 and the extension portion 3A are composed of the same raw material. The Cu content in the bonding layer 3 and the extension portion 3A can be determined as follows: for example, taking a cross section in the thickness direction of the junction 1 as the object, the bonding layer 3 and the extension portion 3A present in the cross section are analyzed and quantified by EDX (energy dispersive X-ray segmentation method) of a scanning electron microscope, thereby determining.

[0024] In the cross-sectional view of the joint body 1 in the thickness direction Z, the extension 3A rises from the periphery 2P of the bottom 2a of the semiconductor element 2 or the vicinity of the periphery 2P to form a side wall surface 3S of the extension 3A. The "vicinity" mentioned here refers to an area separated from the periphery 2P by a distance of 20 μm or less along the top view of the joint body 1. The above distance is measured by polishing the joint body after embedding it with resin and observing its polished surface with an electron microscope.

[0025] As the erected form of the extension portion 3A, for example, the following can be cited. Figure 3As shown in (a) to (c) of FIG. 1 , the extension 3A is erected from the vicinity of the peripheral edge 2P of the bottom 2a of the semiconductor element. Alternatively, the following may be mentioned: Figure 4 As shown in FIG. 1 , the extension portion 3A is in a state of directly rising from the peripheral edge 2P of the bottom 2 a of the semiconductor element 2 .

[0026] As described above, the extension 3A has a side wall surface 3S. The side wall surface 3S is substantially separated from the side surface 2S of the semiconductor element 2. The "substantially" mentioned here is intended to exclude the situation where the contact portion between the side surface 2S of the semiconductor element and the extension 3A is intentionally formed during the manufacturing process of the joint body 1, and allows the situation where the contact portion C between the side surface 2S of the semiconductor element 2 and the extension 3A is inevitably formed locally. When there is a contact portion C between the side surface 2S of the semiconductor element and the extension 3A, the case where the length of the contact portion C along the thickness direction Z in the cross-sectional view of the thickness direction Z is less than 20μm, and the length of the contact portion C in the top view direction is less than 20μm in the top view is recorded as "substantially separated". From the aspect of being able to suppress the diffusion of Cu contained in the bonding layer into the semiconductor element, it is preferred that the length of the contact portion C along the thickness direction Z and the length of the contact portion C in the top view direction are both less than 10μm.

[0027] As a method of inevitably forming the contact portion C, for example, there can be cited: Figure 3 As shown in (b), it is inevitable to form a contact portion C between the side surface 2S on the bottom surface side of the semiconductor element 2 and the extension portion 3A; Figure 3 The contact portion C between the side surface 2S on the upper surface side of the semiconductor element 2 and the extension 3A is inevitably formed as shown in (c), but is not limited to these. The length of the contact portion C is measured by polishing the bonded body in the thickness direction or the top view direction after resin embedding, and observing the polished surface with an electron microscope.

[0028] It should be noted that, for the sake of convenience, the vertical state of the extension 3A and the separation state of the extension 3A from the side surface 2S of the semiconductor element are described through a cross-sectional view in the thickness direction of the bonded body 1. Figure 1 It is arranged around the semiconductor element 2 as shown in (a), so it is preferred that, assuming that an imaginary circle is drawn with the center of the drawing in the top view of the semiconductor element 2 as the center, and imaginary radial straight lines are drawn passing through the center of the imaginary circle and cutting the imaginary circle every 30°, the distances measured by observing the cross-sections obtained by cutting the joint 1 in the top view every 30° using the imaginary radial straight lines are all within the above-mentioned range. Figure 1In (a), the extension portion 3A is formed in the entire area around the semiconductor element 2 , but the present invention is not limited thereto, and the extension portion 3A may be formed intermittently around the semiconductor element 2 .

[0029] According to the junction body having the above-mentioned structure, since the semiconductor element and the conductor are joined by the junction layer containing Cu in a state where the contact area on the side of the semiconductor element is minimized, even when the electronic component having the junction body is driven to form a high-temperature environment, the Cu contained in the junction layer can be suppressed from diffusing into the semiconductor element. As a result, the characteristics of the semiconductor element can be fully expressed. In addition, since the Cu in the junction layer is difficult to diffuse to the semiconductor element side, the junction layer is not prone to cracking even in a high-temperature environment, and the heat resistance is high. On this basis, for the junction layer containing Cu, compared with the case of forming a junction layer containing Ag that is not easy to cause atoms to diffuse into the semiconductor element, it also has the advantages of reducing manufacturing costs and being able to fully express the strength and conductivity of the junction layer.

[0030] From the viewpoint of effectively preventing the adverse effects on the semiconductor element caused by the diffusion of Cu, the extension 3A in the bonding layer 3 preferably does not have a portion where the side wall surface 3S and the side surface 2S of the semiconductor element 2 are in contact with each other. Figure 3 (a) and Figure 4 As shown, the side wall surface 3S is completely separated from the side surface 2S of the semiconductor element 2, and the contact portion C is completely absent. Such a configuration can be made, for example, by appropriately adjusting the thickness of the coating formed by the manufacturing method described later, the drying conditions of the coating, and the conditions of pressure sintering. It should be noted that, for the sake of convenience, the above description is explained using a cross-sectional view of any area in the thickness direction of the joint body 1, but the description is preferably also appropriately applied to the entire area around the semiconductor element 2.

[0031] In addition, from the same point of view, the average distance D3 between the side wall surface 3S and the side surface 2S of the semiconductor element 2 is preferably 1 μm or more, and more preferably 5 μm or more. In addition, from the perspective of reducing unnecessary space in the joint body and reducing the material used in the formation of the joint body to achieve cost reduction, it is realistic for the average distance D3 to be 5 mm or less.

[0032] The average distance D3 is a value measured and calculated by the following method. Figure 2As shown, in the cross-sectional view of the joint body 1 in the thickness direction Z, when a third imaginary straight line L3 is drawn that passes through the upper end of the extension 3A in the thickness direction Z and is parallel to the bottom surface of the semiconductor element 2, the area of ​​the region defined by the side surface 2S, the side wall surface 3S and the third imaginary straight line L3 of the semiconductor element 2 is calculated. Assuming that an imaginary rectangle S1 having the same area as the area at this time and having a line segment of the same length as the distance along the thickness direction Z between the first imaginary straight line L1 as the imaginary extension line of the bottom surface and the third imaginary straight line L3 is used as one side, the length of the other side is set to the average distance D3. In addition, as shown in Figure 3 In the case where there is a contact portion above the semiconductor element 2 as shown in (c), the average distance is set to the following average distance D3. In the cross-sectional view in the thickness direction Z of the joint body 1, it is assumed that a virtual rectangle having the same area as the area of ​​the area drawn by the side surface 2S and the side wall surface 3S of the semiconductor element 2 and having a line segment of the same length as the distance between the first virtual straight line L1 and the contact portion C in the thickness direction Z is set as one side, and the length of the other side of the virtual rectangle is set as the average distance D3. The above distance can be measured and calculated by observation using an electron microscope in the same way as the measurement method of the contact portion C. It should be noted that, for the sake of convenience, the separation form of the extension 3A is described using a cross-sectional view in the thickness direction of any portion of the junction 1, but it is preferred that, assuming that an imaginary circle is drawn with the center of the drawing in the top view of the semiconductor element 2 as the center, and imaginary radial straight lines are drawn passing through the center of the imaginary circle and cutting the imaginary circle every 30°, the average distance measured by observing the cross-section obtained by cutting the junction 1 in the top view every 30° using the imaginary radial straight line using an electron microscope is within the above-mentioned range.

[0033] In order to effectively prevent the adverse effects on the semiconductor element caused by the diffusion of Cu, the junction body 1 is preferably formed in such a manner that the distance between the side wall surface 3S and the side surface 2S of the semiconductor element 2 is, for example, Figure 3 (a) and (b) and Figure 4 As shown, the extension 3A gradually increases from the bottom 2a of the semiconductor element 2 toward the upper part. Alternatively, it is also preferable to form the side wall surface 3S in a manner that the distance between the side wall surface 3S and the side surface 2S of the semiconductor element 2 is constant instead of the above manner. That is, it is also preferable that the side wall surface 3S is formed along the thickness direction Z. By adopting such a structure, it is possible to prevent the extension 3A from accidentally contacting the side surface 2S of the semiconductor element 2 due to the application of external force or the like.

[0034] From the viewpoint of improving manufacturing efficiency, developing bonding strength, and ensuring conductivity, the thickness H1 of the bonding layer 3 (see Figure 2) is preferably greater than 1 μm and less than 200 μm, and more preferably greater than 3 μm and less than 150 μm. The thickness of the bonding portion can be controlled, for example, by adjusting the thickness of the coating formed by the manufacturing method described later and the conditions of press bonding. For the thickness of the bonding layer 3, it is preferred that, for example, an imaginary circle is drawn with the center of the drawing in the top view of the semiconductor element 2 as the center, and an imaginary radial straight line is drawn passing through the center of the imaginary circle and cutting the imaginary circle every 30°, and the average value of the value measured by observing the cross section obtained by cutting the joint 1 in the top view every 30° using the imaginary radial straight line using an electron microscope is within the above range.

[0035] From the same viewpoint, the length H2 of the overhanging portion 3A in the thickness direction Z (hereinafter, also referred to as “height H2”) is Figure 2 ) is preferably less than 250 μm, and more preferably less than 150 μm. The height H2 of the extension 3A can be controlled, for example, by appropriately adjusting the thickness of the coating formed by the manufacturing method described later, as well as the drying conditions and pressure sintering conditions of the coating. The height H2 is the arithmetic mean of the entire circumference of the extension 3A formed on the bonding layer 1, and can be measured by the same method as the above-mentioned length H1.

[0036] Next, the manufacturing method of the joint body is described. The manufacturing method is roughly divided into the following three steps: a coating step, coating a bonding layer composition containing Cu on the surface of a conductive body such as a substrate to form a coating film; a drying step, drying the coating film to form a dry coating film; and a bonding step, stacking a semiconductor element on the dry coating film and bonding them while applying pressure and heating.

[0037] First, a bonding layer composition containing Cu is applied on the surface of the conductor to form a coating film. The bonding layer composition will be described in detail later.

[0038] The coating means of the bonding layer composition is not particularly limited, and known coating methods can be used. For example, screen printing, dispenser printing, gravure printing, offset printing, etc. can be used. From the viewpoint of improving coating properties, the bonding layer composition is preferably a paste-like or ink-like composition comprising a liquid medium.

[0039] The thickness of the coating film is preferably set to be 1 μm or more and 250 μm or less, and more preferably 5 μm or more and 150 μm or less, from the viewpoint of forming a bonded body with high bonding strength stably. In addition, from the viewpoint of improving the bonding strength with the bonding object, the coating film is preferably applied to an area larger than the bottom surface of the semiconductor element as the bonding object in a plan view.

[0040] Next, the formed coating is dried to obtain a dry coating. In this process, at least a portion of the liquid medium is removed from the coating by drying to obtain a dry coating in which the amount of the liquid medium in the coating is reduced. By removing the liquid medium from the coating, the shape retention of the dry coating can be improved. In addition, since the semiconductor element is bonded to the substrate in this state, the bonding strength can be high. A dry coating refers to a coating in which the proportion of the liquid medium relative to the total mass of the film is less than 9% by mass. The coating is substantially the same as the content of each constituent material of the dry coating formed by drying the coating, except for the liquid medium, so the proportion of the liquid medium can be calculated, for example, by measuring the mass change of the coating before and after drying.

[0041] In order to dry and remove the liquid medium, a drying method such as natural drying, hot air drying, infrared irradiation, hot plate drying, etc. that utilizes the volatility of the liquid medium can be used to volatilize the liquid medium. For the proportion of the liquid medium in the dry coating film after the liquid medium is removed, relative to the total mass of 100 parts by mass of the coating film, as described above, it is preferably 9 parts by mass or less, more preferably 7 parts by mass or less, and more preferably 5 parts by mass or less. This step can be appropriately changed according to the composition of the bonding layer composition used, but it is preferably carried out in an atmospheric atmosphere, at 40°C or more and 150°C or less, and at atmospheric pressure for more than 1 minute and less than 60 minutes.

[0042] Finally, a semiconductor element is laminated and bonded on the dry coating film. Specifically, after the dry coating film is obtained through the above steps, the semiconductor element is laminated on the dry coating film to obtain a laminated body in which the conductor, the semiconductor element, and the dry coating film are sandwiched therebetween.

[0043] Next, the laminate is pressurized and heated at the same time to sinter the metal powder contained in the dry coating, thereby forming a bonding layer that bonds the conductor to the semiconductor element. The atmosphere during sintering is preferably an inert gas atmosphere such as nitrogen. The sintering temperature is preferably lower than 300°C, more preferably above 150°C and lower than 300°C, further preferably above 200°C and lower than 300°C, and further preferably above 230°C and lower than 300°C. The pressure applied during sintering is preferably above 0.001MPa, more preferably above 0.001MPa and below 20MPa, and further preferably above 0.01MPa and below 15MPa. For the sintering time, it is preferably less than 20 minutes, more preferably more than 0.5 minutes and less than 20 minutes, and further preferably more than 1 minute and less than 30 minutes, provided that the sintering temperature is within the above range.

[0044] Particularly in this manufacturing method, a dry coating film with high shape retention is formed due to the volatilization of the liquid medium, so the dry coating film will not undergo plastic deformation such as melting and softening caused by heating, and the shape retention of the dry coating film will be maintained even during the pressurized baking of the coating film. Thus, in the portion where the semiconductor element is present, the dry coating film is compressed to form a bonding layer. On this basis, the dry coating film present at the periphery of the semiconductor element is not sintered under pressure, so that an extension is formed in a manner that extends from the periphery of the semiconductor element to the side and stands up from the periphery of the bottom of the element. As a result, under the state of minimizing the contact area on the side of the semiconductor element, the semiconductor element and the conductor are bonded using a bonding layer containing Cu, so even when driving an electronic component having a bonding body and becoming a high temperature environment, the Cu contained in the bonding layer can be suppressed from diffusing into the semiconductor element.

[0045] The bonding layer of the bonding body formed by the above steps is a sintered body of metal particles containing Cu constituting the bonding layer composition. In addition, the bonding layer has an extension extending laterally from the periphery of the semiconductor element. When the bonding layer contains Cu and the bonding layer composition contains a solid reducing agent described later, the following structure (3) is formed in the bonding layer.

[0046]

[0047] In formula (3), R 3 ~R 5 Each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a hydrocarbon group having 1 to 10 carbon atoms and having a hydroxyl group. 3 ~R 5 The details of the above are appropriately applied to the description of the chemical formulae (1) and (2) described later. In addition, * indicates a bonding site with Cu.

[0048] Whether the aforementioned structure (3) is formed in the bonding layer can be confirmed by performing mass spectrometry analysis based on TOF-SIMS on the cross section of the bonding portion. For example, when BIS-TRIS is used as a reducing agent, a fragment with a molecular weight of 152 derived from CN(Cu)2 is observed in the mass spectrum on the positive electrode side of TOF-SIMS.

[0049] The bonding layer composition contains metal powder containing Cu, and preferably further contains a solid reducing agent and a liquid medium.

[0050] The metal powder used in the present invention is preferably formed by an aggregate of metal particles containing Cu. The metal powder may further contain at least one metal of gold, silver, palladium, aluminum, nickel and tin as required. As the containing mode of these metals, an aggregate of Cu particles substantially only formed by Cu, an aggregate of the aforementioned Cu particles and other metal particles formed by a single metal, an aggregate of Cu alloy particles containing Cu and other metals, or an aggregate of the aforementioned Cu particles and the aforementioned Cu alloy particles can be used.

[0051] The shape of the metal particles constituting the metal powder used in the present invention is, for example, spherical, flat (plate-like), dendritic (branch-like), rod-like, etc. These can be used alone or in combination of two or more.

[0052] The solid reducing agent contained in the bonding layer composition is solid at room temperature (25°C) and is used to promote the sintering of metal particles brought about by the calcination of the composition, thereby exhibiting high bonding strength. For this purpose, it is advantageous for the solid reducing agent to be a substance having a chemical structure of at least one amino group and multiple hydroxyl groups. "Solid at room temperature (25°C)" means that the melting point of the solid reducing agent exceeds 25°C.

[0053] The melting point of the solid reducing agent is preferably below the sintering temperature of the metal powder. In addition, it is also preferred that the boiling point of the solid reducing agent is higher than the boiling point of the liquid medium described later. By using a solid reducing agent with such a physical property, when the coating film of the bonding layer composition is dried to obtain a dry coating film, the solid reducing agent can be left in the bonding layer composition in a solid form, and as a result, the shape retention of the dry coating film of the bonding layer composition can be improved. In addition, since the dry coating film of the bonding layer composition is melted and diffused into the coating film when being roasted, the sintering of the metal powder is uniformly promoted, and a joint body with a high conductive reliability having a denser sintered structure can be obtained.

[0054] From the viewpoint of achieving both high bonding strength during press bonding and high electrical conductivity reliability after press bonding, it is preferable to use an amino alcohol compound represented by the following chemical formula (1) or (2) as the solid reducing agent.

[0055]

[0056] In the chemical formula (1) or (2), R 1～ R 6 Each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a hydrocarbon group having 1 to 10 carbon atoms and having a hydroxyl group. 7It represents a hydrocarbon group having 1 to 10 carbon atoms, or a hydrocarbon group having 1 to 10 carbon atoms and having a hydroxyl group. Examples of the hydrocarbon group include saturated or unsaturated aliphatic groups. The aliphatic group may be linear or branched.

[0057] The reducing agent represented by the chemical formula (1) is preferably R 1 ～ R 5 At least one of them contains a hydroxyl group, more preferably 3 or more of them contain a hydroxyl group, further preferably 4 or more of them contain a hydroxyl group, and further preferably R 1～ R 5 All of them contain hydroxyl groups. From the same viewpoint, the reducing agent represented by the chemical formula (2) is preferably R 1～ R 6 At least one of the R contains a hydroxyl group, more preferably three or more of the R contains a hydroxyl group, further preferably four or more of the R contains a hydroxyl group, and further preferably four or more of the R contains a hydroxyl group. 1～ R 6 In the embodiment in which a hydroxyl group is included, the hydroxyl group itself may be a hydrocarbon group having 1 to 10 carbon atoms and having a hydroxyl group, or a combination thereof may be used.

[0058] Specific examples of the amino alcohol compound represented by the chemical formula (1) or (2) include bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (BIS-TRIS, melting point: 104°C, boiling point: over 300°C, equivalent to the chemical formula (1)), 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS, melting point: 169 to 173°C, boiling point: over 300°C, equivalent to the chemical formula (1)), and 1,3-bis(tris(hydroxymethyl)methylamino)propane (BIS-TRIS propane, melting point: 164 to 165°C, boiling point: over 300°C, equivalent to the chemical formula (2)). Among these, bis(2-hydroxyethyl)iminotris(hydroxymethyl)methane (BIS-TRIS) is preferably used as the solid reducing agent from the viewpoint of improving the sinterability of the metal particles and obtaining a bonded body having a high bonding strength.

[0059] The above-mentioned solid reducing agent can be used alone or in combination of two or more. In any case, from the viewpoint of improving the sinterability of metal particles, the proportion of the solid reducing agent in the bonding layer composition is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, relative to 100 parts by mass of metal powder. In addition, from the viewpoint of maintaining the proportion of metal powder in the bonding layer composition and exerting the coating performance suitable for the conductor, it is realistic to set it to 10 parts by mass or less, preferably 8 parts by mass or less, and more preferably 5 parts by mass or less.

[0060] From the viewpoint of improving the coating properties of the coating film, the bonding layer composition preferably further contains a liquid medium. From the same viewpoint, the liquid medium is preferably liquid at room temperature (25°C) and preferably has a boiling point lower than 300°C.

[0061] From the viewpoint of coating property of the bonding layer composition, solubility of the solid reducing agent, and moderate volatility of the liquid medium, the liquid medium is preferably a non-aqueous solvent, more preferably a monovalent or polyvalent alcohol, and further preferably a polyol. As a polyol, for example, propylene glycol (boiling point: 188°C), ethylene glycol (boiling point: 197°C), hexylene glycol (boiling point: 197°C), diethylene glycol (boiling point: 245°C), 1,3-butylene glycol (boiling point: 207°C), 1,4-butylene glycol (boiling point: 228°C), dipropylene glycol (boiling point: 231°C), tripropylene glycol (boiling point: 273°C), glycerol (boiling point: 290°C), polyethylene glycol 200 (boiling point: 250°C), polyethylene glycol 300 (boiling point: 250°C), etc. The liquid medium can be used alone or in combination of two or more.

[0062] When a liquid medium is included in the bonding layer composition, the content of the liquid medium is preferably greater than 10 parts by mass and less than 40 parts by mass, and more preferably greater than 10 parts by mass and less than 35 parts by mass, relative to 100 parts by mass of the metal powder, from the viewpoint of improving the shape retention of the coating film when the bonding layer composition is applied to a conductor.

[0063] In order to improve the coating properties and shape retention of the coating film on the conductor, the bonding layer composition was subjected to a shearing rate of 10 s when not heated. -1 The viscosity at 25° C. is preferably 20 Pa·s to 200 Pa·s, more preferably 25 Pa·s to 150 Pa·s. The viscosity of the bonding layer composition can be measured using a rheometer (viscoelasticity measuring device) using a parallel plate sensor.

[0064] As long as the effect of the present invention is exerted, the bonding layer composition may also contain other components such as a binder component, a surface tension modifier, a defoamer, a viscosity modifier, etc. The total amount of other components is preferably 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the metal powder.

[0065] The bonded body having such a bonded portion can be suitably used in an environment exposed to high temperatures, such as an in-vehicle electronic circuit or an electronic circuit equipped with a power device, by utilizing its high bonding strength and thermal conductivity.

[0066] Industrial Applicability

[0067] According to the present invention, a bonded body which is unlikely to have adverse effects on the characteristics of a semiconductor element and has high heat resistance can be provided.

Claims

1. A bonded body, which is formed by bonding a semiconductor element and a bonding layer containing Cu, The bonding layer has an extension portion extending laterally from the periphery of the semiconductor element. In a cross-sectional view in the thickness direction, the protruding portion has a side wall surface that rises from the periphery or the vicinity of the periphery of the bottom of the semiconductor element and is substantially separated from the side surface of the semiconductor element. The length of the extension in the thickness direction is 150 μm or less, The average distance between the side wall surface and the side surface of the semiconductor element is greater than 1 μm. The bonding layer has a thickness of 1 μm or more and 200 μm or less.

2. The conjugate according to claim 1, wherein The bonding layer contains 50 mass % or more of Cu.

3. The conjugate according to claim 1 or 2, wherein: The semiconductor element contains 50 mass % or more of Si.

4. The conjugate according to claim 1 or 2, wherein: The protruding portion does not have a portion where the side wall surface and the side surface of the semiconductor element are in contact with each other.

5. The conjugate according to claim 1 or 2, wherein: The side wall surface is formed in such a manner that a distance between the side wall surface and the side surface of the semiconductor element gradually increases from the bottom toward the top of the semiconductor element, or the distance between the side wall surface and the side surface of the semiconductor element is constant.

6. The conjugate according to claim 1 or 2, wherein: The following structure (3) is formed in the bonding layer, In formula (3), R 3 ~R 5 Each independently represents a hydrogen atom, a hydroxyl group, a hydrocarbon group having 1 to 10 carbon atoms, or a hydrocarbon group having 1 to 10 carbon atoms and having a hydroxyl group, and * represents a bonding site to Cu.

7. A method for producing a joint body, wherein: A bonding layer composition is applied on the surface of the conductor to form a coating film, wherein the bonding layer composition contains metal powder containing Cu and a solid reducing agent. The coating film is dried to form a dry coating film, and then a semiconductor element is laminated on the dry coating film so that the dry coating film is sandwiched between the conductor and the semiconductor element to obtain a laminated body, and then, The laminate is heated while being pressurized, thereby forming an extension portion of the dry coating film extending laterally from the periphery of the semiconductor element, and sintering the metal powder, thereby bonding the conductor to the semiconductor element. The protruding portion rises from the periphery or the vicinity of the periphery of the bottom of the semiconductor element. The protruding portion has a side wall surface substantially separated from a side surface of the semiconductor element.

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