Composite substrate and method for manufacturing same

Abstract

The invention provides a composite substrate which is small in warpage and high in heat dissipation performance. The composite substrate has: a metal substrate having a first surface and a second surface on the opposite side of the first surface; a ceramic substrate; and a bonding member that is disposed on the first surface and bonds the metal substrate and the ceramic substrate, the ceramic substrate having a plurality of partitions and a groove between adjacent partitions, the bonding member being present in the groove.

Description

Technical Field

[0001] The invention relates to a composite substrate and a method for manufacturing the same. Background Art

[0002] Among ceramic substrates, there are known composite substrates formed by laminating a ceramic substrate to a metal substrate in order to enhance heat dissipation. For a large-area composite substrate, stress is generated due to the difference in thermal expansion coefficients between the ceramic substrate and the metal substrate when the ceramic substrate and the metal substrate are laminated, so that the ceramic substrate may warp or crack. In order to suppress such stress, there is a known method of pre-setting a weak portion on the substrate to guide the crack (Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Utility Model Publication No. 62-103266 Summary of the invention

[0006] Problems to be solved by the invention

[0007] An object of one aspect of the present invention is to provide a composite substrate having reduced warpage and high heat dissipation performance, and a method for manufacturing the same.

[0008] Solutions to Solve Problems

[0009] The first scheme of the present invention is a composite substrate, wherein the composite substrate comprises: a metal substrate having a first surface and a second surface which is the opposite side of the first surface; a ceramic substrate; and a bonding member which is arranged on the first surface to bond the metal substrate to the ceramic substrate, wherein the ceramic substrate has a plurality of partitions and grooves between adjacent partitions, and the bonding member exists in the grooves.

[0010] A second embodiment of the present invention is a method for manufacturing a composite substrate, wherein the method for manufacturing the composite substrate includes the following steps: preparing a metal substrate having a first surface and a second surface opposite to the first surface, a ceramic substrate having a groove, and a bonding material; configuring the bonding material on the first surface; configuring the ceramic substrate on the bonding material in such a manner that the surface opposite to the surface having the groove, or the surface having the groove, faces the bonding material; pressing at least one of the ceramic substrate and the metal substrate toward the other and heating the bonding material to form a bonding member, thereby bonding the ceramic substrate to the metal substrate, and in the step of bonding the ceramic substrate to the metal substrate, at least a portion of the ceramic substrate is broken along the groove, and the bonding member is configured in the broken groove.

[0011] Effects of the Invention

[0012] According to one aspect of the present invention, it is possible to provide a composite substrate having reduced warpage and high heat dissipation performance and a method for manufacturing the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1A This is a schematic plan view showing the composite substrate according to the first embodiment.

[0014] Figure 1B It is shown Figure 1A A schematic cross-sectional view of the cross section taken along the IB-IB line.

[0015] Figure 2A This is a schematic cross-sectional view showing a metal substrate prepared in the method for manufacturing a composite substrate according to the first embodiment.

[0016] Figure 2B This is a schematic cross-sectional view showing a state in which a bonding material is arranged on a metal substrate in the method for manufacturing a composite substrate according to the first embodiment.

[0017] Figure 2C This is a schematic cross-sectional view showing a state in which a ceramic substrate is arranged on a bonding material in the method for producing a composite substrate according to the first embodiment.

[0018] Figure 2D This is a schematic cross-sectional view showing a state where a ceramic substrate and a metal substrate are bonded together in the method for manufacturing a composite substrate according to the first embodiment.

[0019] Figure 3A This is a schematic cross-sectional view showing a state in which a ceramic substrate is arranged on a bonding material in a method for producing a composite substrate according to a second embodiment.

[0020] Figure 3B It is a schematic cross-sectional view showing a composite substrate according to a second embodiment.

[0021] Figure 4A It is a schematic cross-sectional view showing a state where a ceramic substrate is arranged on a bonding material in a method for producing a composite substrate according to a third embodiment.

[0022] Figure 4B It is a schematic cross-sectional view showing a composite substrate according to a third embodiment.

[0023] Description of Reference Numerals

[0024] 1a composite substrate (first embodiment); 1b composite substrate (second embodiment); 1c composite substrate (third embodiment); 2 metal substrate; 3 ceramic substrate; 4 bonding member; 4a bonding material; 21 first surface of the metal substrate; 22 second surface of the metal substrate; 31 partition; 32 groove; 33 first surface of the ceramic substrate; 34 second surface of the ceramic substrate. DETAILED DESCRIPTION

[0025] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, the embodiments described below are used to concretize the technical ideas of the present invention, and the invention is not limited to the following methods unless otherwise specified. The contents described in one embodiment can also be applied to other embodiments and variations. In addition, the accompanying drawings are used to schematically illustrate the embodiments, and there are cases where the proportions or intervals, positional relationships, etc. of each component are exaggerated in order to make the description clear, or where a portion of the component is omitted or an end view showing only the cut surface is used as a sectional view. The directions shown in the figures indicate the relative positions between the constituent elements, and are not intended to indicate absolute positions. It should be noted that the same names and figure marks, in principle, represent the same or homogeneous components, and detailed descriptions are appropriately omitted.

[0026] (First Embodiment)

[0027] Reference Figure 1A , Figure 1B as well as FIG. 2A to FIG. 2D A composite substrate 1a and a method for manufacturing the composite substrate 1a according to a first embodiment will be described. Fig. 1A is a schematic plan view showing the composite substrate 1a. Figure 1B It is shown Figure 1A A schematic cross-sectional view of the cross section taken along the IB-IB line. Figure 2A to Figure 2D It is used for Figure 1A as well as Figure 1B A schematic cross-sectional view for explaining a method for manufacturing a composite substrate 1a is shown.

[0028] The composite substrate 1a of the first embodiment of the present invention comprises: a metal substrate 2 having a first surface 21 and a second surface 22 which is the opposite side of the first surface 21; a ceramic substrate 3; and a joining member 4 which is arranged on the first surface 21 to join the metal substrate 2 and the ceramic substrate 3, wherein the ceramic substrate 3 has a plurality of partitions 31, and grooves 32 are provided between adjacent partitions 31, and the joining member 4 exists in the grooves 32.

[0029] The manufacturing method of the composite substrate 1a of the first embodiment of the present invention includes the following steps: (a) preparing a metal substrate 2 having a first surface 21 and a second surface 22 which is the opposite side of the first surface 21, a ceramic substrate 3 having a groove 32, and a bonding material 4a; (b) arranging the bonding material 4a on the first surface 21; (c) arranging the ceramic substrate 3 on the bonding material 4a in such a manner that the surface which is the opposite side of the surface having the groove 32 faces the bonding material 4a; and (d) pressing at least one of the ceramic substrate 3 and the metal substrate 2 toward the other and heating the bonding material 4a to form a bonding member 4, thereby bonding the ceramic substrate 3 to the metal substrate 2, and in the step of bonding the ceramic substrate 3 to the metal substrate 2, at least a portion of the ceramic substrate 3 is broken along the groove 32, and the bonding material 4a is arranged in the broken groove 32, and is heated to form a bonding member 4. The manufacturing process is described in detail below.

[0030] (a) Preparing the Metal Substrate 2, the Ceramic Substrate 3, and the Bonding Material 4a

[0031] A metal substrate 2 having a first surface 21 and a second surface 22 opposite to the first surface 21, a ceramic substrate 3 having a groove 32, and a bonding material 4a ( Figure 2A ). It should be noted that Figure 2A In the figure, the ceramic substrate 3 and the bonding material 4a are not shown.

[0032] The metal substrate 2 supports the ceramic substrate 3 in the composite substrate 1a. Since the metal substrate 2 has a higher thermal conductivity than the ceramic substrate 3, the heat transferred to the ceramic substrate 3 is transferred to the metal substrate 2 and released to the outside efficiently.

[0033] The thickness of the metal substrate 2 is not particularly limited, but is preferably 200 μm or more and 2.0 mm or less, and more preferably 300 μm or more and 1.5 mm or less. By setting the thickness of the metal substrate 2 to be 200 μm or more, the heat capacity of the metal substrate 2 becomes larger, and the heat dissipation is further improved. By setting the thickness of the metal substrate 2 to be 2.0 mm or less, the thickness of the composite substrate 1a becomes smaller, which is conducive to miniaturization and low profile.

[0034] The material of the metal substrate 2 is not particularly limited as long as it has a high thermal conductivity. The material of the metal substrate 2 may contain at least one of Cu and Al. The metal substrate 2 may be substantially made of Cu or Al.

[0035] The ceramic substrate 3 is an insulating member that becomes a base for wiring and the like to be arranged later. The ceramic substrate 3 has a first surface 33 and a second surface 34 that is the opposite side of the first surface 33. The ceramic substrate 3 has a groove 32 on the first surface 33 side. The ceramic substrate 3 has a plurality of partitions 31 divided by the groove 32. The groove 32 is a groove with a bottom. The groove 32 is arranged in a lattice shape on the first surface side 33 side when viewed from above. That is, one partition 31 is rectangular when viewed from above.

[0036] The thickness of the ceramic substrate 3 may preferably be 50 μm or more and 500 μm or less, for example, 100 μm or more and 400 μm or less, or 150 μm or more and 300 μm or less.

[0037] The length of one side of a partition 31 may preferably be 30 mm or less, more preferably 25 mm or less, for example, 20 mm or less. By setting the length of one side of a partition 31 to the above range, stress when the composite substrate 1a is made, for example, stress caused by the difference in thermal expansion coefficient between the metal substrate 2 and the ceramic substrate 3, can be alleviated, thereby suppressing the warping of the composite substrate 1a. The length of one side of a partition 31 may preferably be 3 mm or more, more preferably 5 mm or more. By setting the length of one side of a partition 31 to the above range, the degree of freedom of configuration of wiring, etc., arranged on the composite substrate 1a is improved.

[0038] The depth of the groove 32 may be preferably 1 / 5 or more and 4 / 5 or less, and more preferably 2 / 5 or more and 3 / 5 or less, relative to the thickness of the ceramic substrate 3. By setting the depth of the groove 32 to be 1 / 5 or more of the thickness of the ceramic substrate 3, the ceramic substrate 3 is easily broken along the groove 32 when attached to the metal substrate 2, so that each partition 31 is easily independent, and the stress of the composite substrate 1a is easily relieved. By setting the depth of the groove 32 to be 4 / 5 or less of the thickness of the ceramic substrate 3, the strength of the ceramic substrate 3 is ensured, so that it is easy to handle.

[0039] The depth of the groove 32 may preferably be 10 μm to 400 μm, for example, 20 μm to 300 μm, 30 μm to 240 μm, 40 μm to 240 μm, or 60 μm to 180 μm.

[0040] The groove 32 can be formed by, for example, etching, sandblasting, or laser processing. Alternatively, the ceramic substrate 3 having the groove 32 formed therein can be purchased.

[0041] Regarding the material of the ceramic substrate 3, ceramics with high thermal conductivity are preferred from the viewpoint of heat dissipation. For example, the material of the ceramic substrate 3 may include nitride-based ceramics such as silicon nitride, aluminum nitride, and boron nitride, or oxide-based ceramics such as aluminum oxide, silicon oxide, calcium oxide, and magnesium oxide. The ceramic substrate 3 is preferably a nitride-based ceramic.

[0042] (b) Arrangement of bonding material 4a

[0043] The bonding material 4a is arranged on the first surface 21 of the metal substrate 2 ( Figure 2B The bonding material 4 a is sintered by heating to form the bonding member 4 , bonding the ceramic substrate 3 and the metal substrate 2 .

[0044] As an example, the bonding material 4a may use a first metal paste containing metal powder, active metal powder, and an organic binder. As described later, the first metal paste may be fired at 780°C or higher and 1100°C or lower.

[0045] As an example, the first metal paste preferably contains 63% by mass or more and 85% by mass or less of metal powder, 1% by mass or more and 15% by mass or less of active metal powder, and 5% by mass or more and 15% by mass or less of an organic binder as a solvent as a state before sintering. The first metal paste as the bonding material 4a becomes a metal body as the bonding component 4 after sintering. The metal powder can cover the surface by covering the metal component, and the covering metal component is sometimes included in the metal body after sintering. The active metal powder becomes a metal compound after sintering. The first metal paste may contain an inorganic filler in addition to the metal.

[0046] For metal powder, the median particle size is preferably greater than 1 μm and less than 50 μm, and more preferably greater than 5 μm and less than 40 μm. If the metal powder is greater than 1 μm, it is difficult to agglomerate and easy to handle. In addition, if the metal powder is less than 50 μm in size, the thickness of the bonding component can be thinned. The metal powder is preferably in a state of being dispersed in the first metal paste together with the active metal powder, the organic binder, and the inorganic filler as appropriate. In addition, in the case where unmelted metal powder is contained in the first metal paste even after firing, it is sometimes in a state where the metal powder is dispersed in the metal body after firing. That is, in the case where only metal powder having a melting point below or near the firing temperature is used in the metal powder, although all the metal powders become metal bodies after firing, in the case where the metal powder contains metal powder having a melting point higher than the firing temperature, a part of the metal powder still remains in the metal body. If a metal powder having a melting point equal to or lower than the firing temperature is heated to a temperature above the melting point, the metal powder melts and becomes liquid, but when a metal powder having a melting point higher than the firing temperature is used, the metal powder itself does not melt and become liquid because it is heated at a temperature lower than the melting point of the metal powder. Since the metal powder does not melt and become liquid, it is difficult to produce a large flow in the first metal paste. In addition, since the first metal paste contains unmelted inorganic fillers, the volume shrinkage of the first metal paste is suppressed, thereby reducing the occurrence of warping. However, for metal powder, even at a firing temperature lower than the melting point, due to the reaction with the covering metal component or the particle size, firing atmosphere, etc., a part of the surface of the metal powder becomes softened, and sometimes it is configured in a state of contact or mixing with other metal powders. At this time, sometimes there is an interface between the metal powder and the metal body, but sometimes there is no interface. In this way, the metal powder and the metal body can also be made into a state without an interface, so the resistance value can be reduced, thereby improving electrical conductivity or thermal conductivity.

[0047] As an example, all or at least a part of the metal powder preferably contains at least one selected from Ag, Al, Zn, Sn, and Ag-Cu alloy. Ag and Ag-Cu alloy are particularly preferred. The melting point of Ag is 962°C, and the melting point of Ag-Cu alloy is about 780°C, so it can be sintered at a relatively low temperature.

[0048] The metal powder may include, for example, at least one selected from Cu, Cr, and Ni. The metal powder also includes alloys with Cu, Cr, and Ni as main components. The metal powder is particularly preferably Cu or a Cu alloy. This is because the thermal conductivity of Cu, Cr, and Ni is relatively high. The melting points of Cu, Cr, and Ni are relatively high. When the sintering temperature is below the melting point of these metals, these metals do not melt, but are dispersed in the metal body, and have a relatively high thermal conductivity. In addition, at least one covering metal member selected from Ag, Al, Zn, Sn, and Ag-Cu alloy may be used to cover at least one selected from Cu, Cr, and Ni. In other words, since the metal powder is covered with a covering metal member of a specified thickness, even after sintering, the metal powders will not contact or separate from each other to a greater extent than necessary. The metal powder is appropriately dispersed in this way, so that the deviation of the heat in the through hole can also be suppressed.

[0049] The active metal powder is at least partially or completely converted into a metal compound by firing. The metal compound is sometimes arranged between the metal powders or in a layered manner at the interface with the ceramic substrate 3. The active metal powder is dispersed in the first metal paste, and the metal compound after firing is also dispersed in the metal body. For example, when titanium hydride (TiHH2) is used as the active metal powder, titanium hydride releases hydrogen due to firing, and on the other hand, titanium is oxidized or nitrided to become titanium oxide or titanium nitride. In the case where the ceramic substrate 3 is a nitride-based ceramic, the active metal powder contained in the first metal paste reacts with the nitrogen in the ceramic substrate to form a reaction layer of titanium nitride at the interface between the first metal paste and the ceramic substrate. In addition, in the case where the ceramic substrate 3 is an oxide-based ceramic, the active metal powder contained in the first metal paste reacts with the oxygen in the ceramic substrate to form a reaction layer of titanium oxide at the interface between the first metal paste and the ceramic substrate. In addition, the reactants of metal compounds such as titanium nitride or titanium oxide are arranged in a manner that will become a continuous space between the metal powders or arranged at the grain boundary. The metal compound is arranged in a state of direct contact with the metal powder, a state of surrounding the metal powder, or a state of surrounding the inorganic filler. In addition, the metal compound improves the adhesion strength with the ceramic substrate.

[0050] The active metal powder is preferably selected from one or more materials selected from TiHH2, CeHH2, ZrH2, LaH2, and MgH2. By sintering the active metal powder, all or part of the hydrogen is separated and reacts with nitrogen, oxygen, carbon, etc. contained in the ceramic substrate, inorganic filler, etc., to change into nitride metal, oxide metal, carbide metal, etc. The product of this change is a metal compound. It is particularly preferred to use TiHH2 as the active metal powder, which reacts with nitrogen contained in the ceramic substrate, etc. by containing TiHH2, thereby forming a reaction layer such as TiN.

[0051] The inorganic filler is dispersed in the first metal paste to reduce the generation of cracks. In addition, the inorganic filler can make the thickness of the ceramic substrate and the metal substrate constant by making the particle size consistent. As an example, the inorganic filler can include ceramic fillers, metal fillers, glass fillers, etc. Specifically, the inorganic filler can use aluminum oxide, silicon oxide, etc. It should be noted that the inorganic filler is contained in a content within a range that does not hinder the effects of other contents.

[0052] The organic binder is a member contained in the first metal paste before firing. The organic binder evaporates after firing and does not remain in the first metal paste. As an example, the organic binder may be a solvent or a resin material generally used as a via material.

[0053] As a different example of the bonding material 4a, a second metal paste containing an organic solvent having a boiling point of 200°C to 300°C and having reducing properties at a ratio of 5% to 20% of the weight of the metal particles can also be used. As described later, the firing of the second metal paste can be performed at 150°C to 300°C. Since the boiling point of the second metal paste is in the temperature range for firing or slightly lower than the firing temperature, the organic solvent can be vaporized and removed during the firing of the second metal paste. In addition, since the organic solvent has reducing properties, it is possible to inhibit the oxidation of the metal particles, thereby promoting sintering. However, the boiling point of the organic solvent contained in the second metal paste can also be in a temperature range slightly lower than the firing temperature. This is because the organic solvent sometimes vaporizes even in a temperature range lower than the firing temperature. This is caused by the thickness or size of the second metal paste, the way heat is applied to the second metal paste during firing, etc. Here, the boiling point of the organic solvent contained in the second metal paste in the temperature range slightly lower than the firing temperature means that the boiling point of the organic solvent can be in a temperature range lower than the firing temperature and having a difference of 80° C. or less, or 50° C. or less.

[0054] The second metal paste used as the bonding material 4a contains metal powder, for example, at least one of Ag and Cu. By using the second metal paste as the bonding material 4a, the heating temperature for bonding the ceramic substrate 3 and the metal substrate 2 can be set to a lower temperature, thereby reducing the burden on the ceramic substrate 3 and the metal substrate 2. For example, the stress caused by the difference in thermal expansion coefficient between the ceramic substrate 3 and the metal substrate 2 can be reduced, and the warping of the composite substrate 1a can be reduced.

[0055] The median particle size of the metal powder is preferably 0.1 μm or more and 20 μm or less, more preferably 0.5 μm or more and 10 μm or less, and further preferably 1 μm or more and 5 μm or less. By setting the median particle size of the metal powder to be 0.1 μm or more, agglomeration can be suppressed. On the other hand, by setting the median particle size of the metal powder to be 20 μm or less, the filling property can be improved. In addition, the shape of the metal powder is preferably spherical or ellipsoidal from the perspective of fluidity, but can also be flat or needle-shaped. This is because by setting it to a flat or needle-shaped shape, the contact between the particles can be increased or the thermal conductivity can be improved.

[0056] The second metal paste used as the bonding material 4a may further include an organic resin adhesive. The viscosity of the bonding material 4a can be adjusted according to the type or amount of the organic resin adhesive. As the organic resin adhesive, for example, a solvent commonly used for metal paste, or a resin material such as acrylic acid, epoxy, urethane, ethyl cellulose, silicone, phenol, polyimide, polyurethane, melamine, urea, etc. can be used. It should be noted that the organic resin adhesive can be decomposed by heating described later, thereby evaporating and removing.

[0057] The configuration method of the bonding material 4a is not particularly limited. For example, when the bonding material 4a is the first metal paste or the second metal paste, the first metal paste or the second metal paste can be applied in a close contact manner and configured on the first surface 21 of the metal substrate 2. It should be noted that the bonding material 4a configured on the first surface 21 of the metal substrate 2 becomes the bonding member 4 through the subsequent heating process.

[0058] The thickness of the bonding material 4 a layer on the first surface 21 of the metal substrate 2 is preferably 5 μm to 250 μm, more preferably 10 μm to 200 μm, and further preferably 20 μm to 100 μm.

[0059] (c) Configuring a ceramic substrate 3

[0060] The ceramic substrate 3 is disposed on the bonding material 4a so that the surface opposite to the surface having the groove 32 faces the bonding material 4a ( Figure 2C ) The arrangement method of the ceramic substrate 3 is not particularly limited.

[0061] (d) Bonding the ceramic substrate 3 and the metal substrate 2

[0062] The ceramic substrate 3 and the metal substrate 2 are bonded to each other by pressing at least one of the ceramic substrate 3 and the metal substrate 2 toward the other and heating the bonding material 4a to form the bonding member 4. Figure 2D ). Thus, the composite substrate 1a of the first embodiment is obtained.

[0063] Regarding the bonding of the ceramic substrate 3 and the metal substrate 2, for example, the ceramic substrate 3 may be pressed toward the metal substrate 2 side, or the metal substrate 2 may be pressed toward the ceramic substrate 3. Thus, the ceramic substrate 3 is broken along the grooves 32. In the first embodiment, the ceramic substrate 3 is broken along all the grooves 32, but it is not limited thereto, as long as at least a part of it is broken. For example, the ceramic substrate 3 is preferably broken along more than 30% of the grooves 32, more preferably along more than 50% of the grooves 32, further preferably along more than 70% of the grooves 32, further preferably along more than 90% of the grooves 32, and particularly preferably along more than 95% of the grooves 32. Since the ceramic substrate 3 is broken along the grooves 32, the ceramic substrate 3 is divided into partitions 31. By dividing the ceramic substrate 3 into partitions 31, the stress caused by the difference in thermal expansion coefficient between the ceramic substrate 3 and the metal substrate 2 can be reduced, and the warping of the composite substrate 1a can be reduced. In addition, since the ceramic substrate 3 is broken along the grooves 32, the bonding material 4a enters the grooves 32. It should be noted that the division of the ceramic substrate 3 does not need to be caused only by the above-mentioned pressing, but may also be caused by thermal expansion due to heating as described below.

[0064] The magnitude of the pressing is preferably 0.01 MPa to 10 MPa, more preferably 0.05 MPa to 5 MPa. By pressing at a pressure within the above range, the ceramic substrate 3 is easily broken along the grooves 32 .

[0065] The pressing method is not particularly limited, and a method that can press the ceramic substrate 3 or the metal substrate 2 as a whole is preferred. For example, a method of using a plate to press the ceramic substrate 3 or the metal substrate 2 as a whole, and a method of using rollers to press the ceramic substrate 3 or the metal substrate 2 in one direction or in two orthogonal directions can be cited. By pressing the whole, it is easy to cause the ceramic substrate 3 to be broken as a whole throughout the groove 32. When pressing, it is preferred to press through a buffer. The buffer is preferably arranged between the ceramic substrate 3 and a pressing device, such as a plate. By pressing through a buffer, it is possible to suppress the ceramic substrate 3 from breaking in an undesirable portion, that is, a portion other than the groove 32.

[0066] The heating temperature of the above-mentioned heating is appropriately selected according to the bonding material 4a used. For example, when the bonding material 4a is the second metal paste, the heating temperature is, for example, 150°C or more and 300°C or less, preferably 180°C or more and 280°C or less. In addition, when the bonding material 4a is the first metal paste, the heating temperature is, for example, 780°C or more and 1100°C or less, preferably 800°C or more and 1050°C or less. By heating, the bonding material 4a becomes the bonding member 4. For example, when the bonding material 4a is the first metal paste, the bonding material 4a is sintered and becomes the bonding member 4. Through the bonding member 4, the metal substrate 2 is bonded to the ceramic substrate 3.

[0067] As described above, in the step of bonding the ceramic substrate 3 to the metal substrate 2, at least a portion of the ceramic substrate 3 is broken along the groove 32. Then, the bonding material 4a enters the broken groove 32 and is heated there to form the bonding member 4. In this way, since the ceramic substrate 3 is broken along the groove 32, the ceramic substrate 3 is divided into the partitions 31 by the groove 32. In addition, the bonding member 4 is arranged in the groove 32.

[0068] For the ceramic substrate 3, since it is divided into partitions 31, the influence of the stress caused by the difference in thermal expansion coefficient between the ceramic substrate 3 and the metal substrate 2 is reduced, thereby reducing the warping of the composite substrate 1a. The warping amount of the composite substrate 1a is preferably less than 300 μm, more preferably less than 200 μm, and further preferably less than 100 μm. The above-mentioned warping amount means the maximum distance in the thickness direction (i.e., the stacking direction) from the straight line connecting the two ends of the upper surface of the composite substrate 1a (the first surface 33 of the ceramic substrate 3 in the first embodiment) to the upper surface located between the above-mentioned two ends. The warping amount can be measured, for example, by a laser microscope or a contact height difference measuring machine. For example, VR-5200 manufactured by KEYENCE can be used. In addition, a contact height difference measuring machine (Alpha-Step D-500 manufactured by KLA-Tenchore) can also be used.

[0069] In the composite substrate 1a, the bonding member 4 is also arranged in the groove 32, the contact area between the ceramic substrate 3 and the bonding member 4 is increased, the thermal conductivity between the ceramic substrate 3 and the bonding member 4 is improved, and the heat dissipation effect is improved.

[0070] In the composite substrate 1a, at least one of the ceramic substrate 3 and the metal substrate 2 is pressed toward the other and the bonding material is heated, so that the air contained in the bonding material 4a or the gas generated by heating is pushed out to the outside, and the porosity of the resulting bonding member 4 becomes smaller. In particular, the ceramic substrate 3 is broken at the groove 32 in such a process, so the groove 32 also functions as a discharge portion for the above-mentioned gas, and the porosity of the bonding member 4 can be further reduced.

[0071] The porosity of the bonding member 4 below the partition 31 of the ceramic substrate 3 is preferably 1% or less, more preferably 0.5% or less. By reducing the porosity of the bonding member 4, the thermal conductivity of the bonding member 4 is improved, and the heat dissipation effect of the composite substrate 1a is improved.

[0072] The thickness of the bonding member 4 is preferably 5 μm or more and 200 μm or less, and more preferably 5 μm or more and 200 μm or less. By increasing the thickness of the bonding member 4, the bonding property of the bonding member 4 is improved. In addition, by reducing the thickness of the bonding member 4, heat conduction from the ceramic substrate 3 to the metal substrate 2 can be performed more efficiently. That is, by setting the thickness of the bonding member 4 to the above range, both bonding property and thermal conductivity can be taken into account.

[0073] The standard deviation of the thickness of the bonding member 4 between the plurality of sections 31 of the ceramic substrate 3 is preferably 10 μm or less, more preferably 5 μm or less. By setting the standard deviation of the thickness of the bonding member 4 within the above range, the variation in the thickness of the composite substrate 1a is reduced, and reliability is improved.

[0074] The bonding member 4 in the groove 32 of the ceramic substrate 3 may preferably be present in a manner of filling 20% ​​or more, more preferably 50% or more, further preferably 70% or more, further preferably 80% or more, and particularly preferably 90% or more relative to the thickness of the ceramic substrate 3, but may also be filled 100%. By setting the filling amount of the bonding member 4 in the groove 32 to the above range, the contact area between the bonding member 4 and the ceramic substrate 3 is increased, and the heat dissipation effect of the composite substrate 1a is improved. Filling 100% of the bonding member 4 relative to the thickness of the ceramic substrate 3 means that the bonding member 4 is completely filled in both the broken groove and the initially formed groove, and the bonding member 4 is coplanar with the surface of the ceramic substrate 3. When the bonding member 4 is coplanar with the surface of the ceramic substrate 3, it is preferred to press in a manner that the flat plate-shaped member contacts the surface of the ceramic substrate 3. Alternatively, it is preferred that the surface of the ceramic substrate 3 is ground or polished after the metal substrate 2 and the ceramic substrate 3 are bonded.

[0075] The porosity, thickness, and standard deviation of the thickness of the bonding member 4 can be obtained by cutting the composite substrate 1a in the thickness direction and observing its cross section using a scanning electron microscope (SEM) or the like. Typically, the cut portion is the portion at the center of the partition 31 when viewed from above. For example, when the partition 31 is rectangular, the cut is made at the portion connecting the midpoints of the two opposing sides viewed from above. Regarding the porosity, it can be calculated by calculating the proportion of the void portion of the bonding member 4 under the partition 31. Alternatively, it can be calculated by the area of ​​the hole-generating portion in X-ray observation from the surface of the substrate or ultrasonic microscope observation. For example, it can be measured by X-ray CT method. The thickness is the thickness of the thickest part under the partition 31 in the above-mentioned cross section. The standard deviation of the thickness can be calculated by measuring the thickness under each partition 31 observed in the above-mentioned cross section and calculating the standard deviation of the thickness.

[0076] (Second Embodiment)

[0077] Reference Figure 3A as well as Figure 3B A composite substrate 1 b according to the second embodiment and a method for manufacturing the same will be described. Figure 3A Corresponding to the first embodiment Figure 2C . Figure 3B It is a schematic cross-sectional view showing a cross section of a composite substrate 1 b according to the second embodiment.

[0078] The manufacturing method of the composite substrate 1b is different from the manufacturing method of the composite substrate 1a of the first embodiment in that (c) when the ceramic substrate 3 is arranged on the bonding material 4a, the ceramic substrate 3 is arranged on the bonding material 4a in such a manner that the surface having the groove 32 faces the bonding material 4a. That is, in the manufacturing method of the composite substrate 1b, the ceramic substrate 3 is arranged in such a manner that the second surface 34 faces the bonding material 4a.

[0079] In the manufacturing method of the composite substrate 1b of the second embodiment, the ceramic substrate 3 is arranged on the bonding material 4a so that the surface having the groove 32 faces the bonding material 4a, so that the bonding material 4a easily enters the groove 32, and it becomes easy to arrange the bonding member 4 in the groove 32. In addition, the second surface 34 of the ceramic substrate 3 without the groove 32 becomes the surface of the composite substrate 1b, so that the surface unevenness of the ceramic substrate 3 can be reduced or eliminated.

[0080] In the composite substrate 1b, the bonding member 4 in the groove 32 of the ceramic substrate 3 preferably accounts for 90% or more, more preferably accounts for 95% or more, and further preferably accounts for 100% of the thickness of the ceramic substrate 3. The bonding member 4 accounting for 100% of the thickness of the ceramic substrate 3 means that the bonding member 4 is completely filled in the broken groove, and the bonding member 4 is coplanar with the surface of the ceramic substrate 3. When the bonding member 4 is coplanar with the surface of the ceramic substrate 3, it is preferred to press the flat plate-shaped member in contact with the surface of the ceramic substrate 3. Alternatively, it is preferred that the surface of the ceramic substrate 3 is ground or polished after the metal substrate 2 and the ceramic substrate 3 are bonded.

[0081] (Third Embodiment)

[0082] Reference Figure 4A as well as Figure 4B A composite substrate 1c according to a third embodiment and a method for manufacturing the same will be described. Figure 4A Corresponding to the first embodiment Figure 2C . Figure 4B It is a schematic cross-sectional view showing a cross section of a composite substrate 1 c according to the third embodiment.

[0083] The composite substrate 1 c of the third embodiment is different from the composite substrate 1 a of the first embodiment in that a ceramic substrate 3 b different from the ceramic substrate 3 a is provided on both the first surface 21 and the second surface 22 of the metal substrate 2 .

[0084] The manufacturing method of the composite substrate 1c is different from that of the composite substrate 1a of the first embodiment in that: (b) when configuring the bonding material 4a, the bonding material 4a1 is configured on the first surface 21 of the metal substrate 2, and the bonding material 4a2 is configured on the second surface 22; (c) when configuring the ceramic substrate, the ceramic substrate 3a is configured on the bonding material 4a1, and the ceramic substrate 3b is configured on the bonding material 4a2.

[0085] It should be noted that in the example shown in the figure, the ceramic substrates 3a and 3b can be arranged in a manner such that the surface opposite to the surface having the groove 32 faces the bonding material 4a1 or 4a2, or the ceramic substrates 3a and 3b can be arranged in a manner such that the surface having the groove 32 faces the bonding material 4a1 or 4a2, as in the second embodiment.

[0086] Embodiments of the present invention include the following.

[0087] [Item 1]

[0088] A composite substrate, wherein

[0089] The composite substrate comprises:

[0090] A metal substrate having a first surface and a second surface opposite to the first surface;

[0091] Ceramic substrates; and

[0092] a bonding member disposed on the first surface and bonding the metal substrate and the ceramic substrate together;

[0093] The ceramic substrate has a plurality of partitions, and grooves are provided between adjacent partitions.

[0094] The engagement member is present in the groove.

[0095] [Item 2]

[0096] In the composite substrate according to Item 1, the grooves are arranged in a lattice pattern in a plan view.

[0097] [Item 3]

[0098] In the composite substrate according to item 2, the partitions of the ceramic substrate are rectangular with a side of 30 mm or less in a plan view.

[0099] [Item 4]

[0100] In the composite substrate described in any one of Items 1 to 3, the ceramic substrate has a thickness of 50 μm or more and 500 μm or less.

[0101] [Item 5]

[0102] In the composite substrate described in any one of Items 1 to 4, the thickness of the metal substrate is 200 μm or more and 2.0 mm or less.

[0103] [Item 6]

[0104] In the composite substrate described in any one of Items 1 to 5, the thickness of the bonding member is 5 μm or more and 200 μm or less.

[0105] [Item 7]

[0106] In the composite substrate described in any one of Items 1 to 6, a standard deviation of the thickness of the bonding member between the plurality of sections of the ceramic substrate is 5 μm or less.

[0107] [Item 8]

[0108] In the composite substrate described in any one of Items 1 to 7, a porosity of the bonding member in the partition of the ceramic substrate is 1% or less.

[0109] [Item 9]

[0110] In the composite substrate described in any one of items 1 to 8, the warpage amount of the composite substrate is 300 μm or less.

[0111] [Item 10]

[0112] In the composite substrate described in any one of Items 1 to 9, the ceramic substrate is a nitride-based ceramic substrate.

[0113] [Item 11]

[0114] In the composite substrate described in any one of Items 1 to 10, the metal substrate contains at least one of Cu and Al.

[0115] [Item 12]

[0116] In the composite substrate described in any one of Items 1 to 11, the bonding member contains at least one of Ag and Cu.

[0117] [Item 13]

[0118] In the composite substrate described in any one of items 1 to 12, a bonding member and a ceramic substrate are further arranged on the second surface of the metal substrate.

[0119] [Item 14]

[0120] A method for manufacturing a composite substrate, wherein:

[0121] The method for manufacturing the composite substrate comprises the following steps:

[0122] preparing a metal substrate having a first surface and a second surface opposite to the first surface, a ceramic substrate having a groove, and a bonding material;

[0123] disposing the bonding material on the first surface;

[0124] placing the ceramic substrate on the bonding material in such a manner that the surface opposite to the surface having the groove or the surface having the groove faces the bonding material; and

[0125] The ceramic substrate and the metal substrate are bonded to each other by pressing at least one of the ceramic substrate and the metal substrate toward the other and heating the bonding material to form a bonding member.

[0126] In the step of bonding the ceramic substrate and the metal substrate, at least a portion of the ceramic substrate is fractured along the groove, and the bonding member is disposed in the fractured groove.

[0127] [Item 15]

[0128] In the manufacturing method described in Item 14, in the step of bonding the ceramic substrate and the metal substrate, the heating temperature is 780° C. or higher and 1100° C. or lower.

[0129] [Item 16]

[0130] In the manufacturing method described in Item 14, in the step of bonding the ceramic substrate and the metal substrate, the heating temperature is 150° C. or higher and 300° C. or lower.

[0131] [Item 17]

[0132] In the manufacturing method described in any one of Items 14 to 16, in the step of bonding the ceramic substrate and the metal substrate, the magnitude of the pressing is 0.1 MPa to 10 MPa.

[0133] [Item 18]

[0134] In the manufacturing method described in any one of Items 14 to 17, in the step of bonding the ceramic substrate and the metal substrate, pressing is performed via a buffer member.

[0135] [Item 19]

[0136] In the manufacturing method described in any one of items 14 to 18, during the preparation, the thickness of the ceramic substrate is greater than or equal to 50 μm and less than or equal to 500 μm, and the depth of the groove is greater than or equal to 1 / 5 and less than or equal to 4 / 5 of the thickness of the ceramic substrate.

Claims

1. A composite substrate, wherein: The composite substrate comprises: A metal substrate having a first surface and a second surface opposite to the first surface; Ceramic substrate; as well as a bonding member disposed on the first surface and bonding the metal substrate and the ceramic substrate together; The ceramic substrate has a plurality of partitions, and grooves are provided between adjacent partitions. The engagement member is present in the groove.

2. The composite substrate according to claim 1, wherein: The grooves are arranged in a lattice shape in a plan view.

3. The composite substrate according to claim 2, wherein: The partitions of the ceramic substrate are rectangular with a side of less than 30 mm in a plan view.

4. The composite substrate according to claim 1, wherein: The ceramic substrate has a thickness of 50 μm or more and 500 μm or less.

5. The composite substrate according to claim 1, wherein: The metal substrate has a thickness of 200 μm or more and 2.0 mm or less.

6. The composite substrate according to claim 1, wherein: The bonding member has a thickness of 5 μm or more and 200 μm or less.

7. The composite substrate according to claim 1, wherein: A standard deviation of the thickness of the bonding member between the plurality of sections of the ceramic substrate is 5 μm or less.

8. The composite substrate according to claim 1, wherein: The porosity of the bonding member under the partition of the ceramic substrate is 1% or less.

9. The composite substrate according to claim 1, wherein: The warpage amount of the composite substrate is 300 μm or less.

10. The composite substrate according to claim 1, wherein: The ceramic substrate is a nitride-based ceramic substrate.

11. The composite substrate according to claim 1, wherein: The metal substrate includes at least one of Cu and Al.

12. The composite substrate according to claim 1, wherein: The bonding member includes at least one of Ag and Cu.

13. The composite substrate according to claim 1, wherein: A bonding member and a ceramic substrate are further arranged on the second surface of the metal substrate.

14. A method for manufacturing a composite substrate, wherein: The method for manufacturing the composite substrate comprises the following steps: preparing a metal substrate having a first surface and a second surface opposite to the first surface, a ceramic substrate having a groove, and a bonding material; disposing the bonding material on the first surface; The ceramic substrate is disposed on the bonding material in such a manner that the surface opposite to the surface having the groove or the surface having the groove faces the bonding material; as well as The ceramic substrate and the metal substrate are bonded to each other by pressing at least one of the ceramic substrate and the metal substrate toward the other and heating the bonding material to form a bonding member. In the step of bonding the ceramic substrate and the metal substrate, at least a portion of the ceramic substrate is fractured along the groove, and the bonding member is disposed in the fractured groove.

15. The manufacturing method according to claim 14, wherein: In the step of bonding the ceramic substrate and the metal substrate, the heating temperature is 780° C. or higher and 1100° C. or lower.

16. The manufacturing method according to claim 14, wherein: In the step of bonding the ceramic substrate and the metal substrate, the heating temperature is 150° C. or higher and 300° C. or lower.

17. The manufacturing method according to claim 14, wherein: In the step of bonding the ceramic substrate and the metal substrate, the magnitude of the pressing force is greater than or equal to 0.1 MPa and less than or equal to 10 MPa.

18. The manufacturing method according to claim 14, wherein: In the step of bonding the ceramic substrate and the metal substrate, the ceramic substrate and the metal substrate are pressed via a buffer member.

19. The manufacturing method according to claim 14, wherein: In the preparation, the thickness of the ceramic substrate is not less than 50 μm and not more than 500 μm, and the depth of the groove is not less than 1 / 5 and not more than 4 / 5 of the thickness of the ceramic substrate.

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