Metal-nitride laminate and insulated circuit board

Abstract

A metal-nitride laminate in which a metal solidified layer and an active metal nitride layer comprising Ti-N and / or Zr-N are bonded, the metal-nitride laminate being characterized in that: a modified nitride layer is formed between the active metal nitride layer and the metal solidified layer; the modified nitride layer has a composition in which a part of the active metal in the active metal nitride layer is substituted with either or both of Al and Si.

Description

Technical Field

[0001] The present invention relates to a metal-nitride laminate in which a metal solidified layer formed by solidifying molten metal is joined to an active metal nitride layer composed of Ti-N or Zr-N, and an insulating circuit board having the metal-nitride laminate.

[0002] This application claims priority based on Japanese Patent Application No. 2023-016687 filed on February 7, 2023, and Japanese Patent Application No. 2023-205396 filed on December 5, 2023, and incorporates their contents herein. Background Art

[0003] Power modules, LED modules, and thermoelectric modules have the following structure: on an insulating circuit board having a circuit layer made of a conductive material formed on one surface of an insulating layer, a power semiconductor element, an LED element, and a thermoelectric element are joined.

[0004] For example, high-power control power semiconductor elements used for controlling wind power generation, electric vehicles, hybrid vehicles, etc. generate a large amount of heat during operation. Therefore, as a substrate for mounting the power semiconductor element, an insulating circuit board has been widely used, which includes: a ceramic substrate; a circuit layer formed by joining a metal plate having excellent conductivity to one surface of the ceramic substrate; and a heat-dissipating metal layer formed by joining a metal plate to the other surface of the ceramic substrate.

[0005] For example, Patent Document 1 discloses a ceramic circuit board joined by a metal plate and an aluminum nitride substrate via Zr compounds such as Zr-N and Ti compounds such as Ti-N.

[0006] And, Patent Document 2 proposes a circuit board having a thin-film resistor made of a nickel-chromium alloy formed on an aluminum nitride base material, and a base layer made of Ti-N is formed between the base material and the resistor.

[0007] Here, since the toughness of active metal nitrides such as Zr-N or Ti-N is high, when an active metal nitride is coated on the surface of a ceramic component, cracks generated in the ceramic component can be suppressed.

[0008] Patent Document 1: Japanese Unexamined Patent Publication No. 05-163077

[0009] Patent Document 2: Japanese Unexamined Patent Publication No. 02-262392

[0010] However, the wettability of reactive metal nitrides such as Zr-N or Ti-N with molten metal is poor, so it is difficult to compound them with metals. Therefore, even if a joining material such as a solder is used to join a metal plate or the like to the surface of a reactive metal nitride such as Zr-N or Ti-N, peeling occurs at the interface between the metal solidification layer formed by melting and solidifying the metal contained in the joining material and the reactive metal nitride, and sufficient joining strength may not be obtained. SUMMARY OF THE INVENTION

[0011] The present invention has been made in view of the above circumstances, and an object thereof is to provide a metal-nitride laminate in which a metal solidification layer formed by solidifying molten metal is firmly joined to a reactive metal nitride such as Zr-N or Ti-N, and an insulating circuit board having the metal-nitride laminate.

[0012] In order to solve the above problems, the metal-nitride laminate according to aspect 1 of the present invention is a metal-nitride laminate in which a metal solidification layer is joined to a reactive metal nitride layer composed of any one or both of Ti-N and Zr-N, and is characterized in that a modified nitride layer is formed between the reactive metal nitride layer and the metal solidification layer, and the composition of the modified nitride layer is such that a part of the reactive metal in the reactive metal nitride layer is replaced by any one or both of Al and Si.

[0013] In the metal-nitride laminate according to aspect 1 of the present invention, a modified nitride layer is formed between the reactive metal nitride layer composed of any one or both of Ti-N and Zr-N and the metal solidification layer formed by solidifying molten metal, and the composition of the modified nitride layer is such that a part of the reactive metal in the reactive metal nitride layer is replaced by any one or both of Al and Si. Therefore, due to this modified nitride layer, the wettability of the reactive metal nitride layer with molten metal is improved, and the reactive metal nitride layer and the metal solidification layer are firmly joined.

[0014] The metal-nitride laminate according to aspect 2 of the present invention is characterized in that, in the metal-nitride laminate according to aspect 1, when in the modified nitride layer, the content ratio of Ti and Zr is set to X, the content ratio of Al and Si is set to Y, and the content ratio of N is set to Z in terms of atomic ratio, the following formulas (1) to (3) are satisfied.

[0015] X + Y + Z = 1 (1)

[0016] Y / (X + Y) < 0.7 (2)

[0017] 0.4 ≤ Z ≤ 0.5 (3)

[0018] In the metal-nitride laminate according to aspect 2 of the present invention, in the modified nitride layer, in terms of atomic ratio, the content ratio X of Ti and Zr and the content ratio Y of Al and Si have a relationship of Y / (X + Y) < 0.7. Therefore, the modified nitride layer has an NaCl-type structure and has particularly excellent wettability with respect to the metal.

[0019] Moreover, in the modified nitride layer, the content ratio Z of N is set to 0.4 ≤ Z ≤ 0.5. Therefore, sufficient wettability can be maintained as a nitride.

[0020] The metal-nitride laminate according to aspect 3 of the present invention is characterized in that, in the metal-nitride laminate according to aspect 1 or aspect 2, the active metal nitride layer is formed on the surface of the ceramic component.

[0021] In the metal-nitride laminate according to aspect 3 of the present invention, since the active metal nitride layer is formed on the surface of the ceramic component, the ceramic component can be firmly joined.

[0022] The metal-nitride laminate according to aspect 4 of the present invention is characterized in that, in the metal-nitride laminate according to any one of aspects 1 to 3, the metal solidified layer is formed on the joining surface of the joined body.

[0023] In the metal-nitride laminate according to aspect 4 of the present invention, since the metal solidified layer is formed on the joining surface of the joined body, the joined body can be firmly joined.

[0024] The insulating circuit board according to aspect 5 of the present invention is an insulating circuit board in which a circuit layer made of metal is formed on the surface of a ceramic substrate, and is characterized in that a metal-nitride laminate according to any one of aspects 1 to 4 is formed at the joining interface between the ceramic substrate and the circuit layer.

[0025] In the insulating circuit board according to aspect 5 of the present invention, since a metal-nitride laminate according to any one of aspects 1 to 4 is formed at the joining interface between the ceramic substrate and the circuit layer, the ceramic substrate and the circuit layer can be firmly joined.

[0026] According to the present invention, it is possible to provide a metal-nitride laminate in which a metal solidified layer formed by solidifying molten metal and an active metal nitride such as Zr-N or Ti-N are firmly joined, and an insulating circuit board having the metal-nitride laminate. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic explanatory view of a power module including an insulating circuit board joined by the metal-nitride laminate according to the embodiment of the present invention.

[0028] Figure 2 It is an enlarged explanatory view of the metal-nitride laminate according to the first embodiment of the present invention.

[0029] Figure 3 It is a flowchart of a method for manufacturing the metal-nitride laminate according to the first embodiment of the present invention.

[0030] Figure 4 It is an enlarged explanatory view of the metal-nitride laminate according to the second embodiment of the present invention.

[0031] Figure 5 It is a flowchart of a method for manufacturing the metal-nitride laminate according to the second embodiment of the present invention.

[0032] Figure 6A It is a photograph of the metal-nitride laminate in Invention 1 of the examples.

[0033] Figure 6B It is a photograph of the metal-nitride laminate in Invention 5 of the examples.

[0034] Figure 7A It is a side view showing the cutting stage and the peeling stage of the surface cutting test in the examples.

[0035] Figure 7B It is an explanatory view showing the relationship between the cutting time and the horizontal load in the cutting stage and the peeling stage of the surface cutting test in the examples. Detailed Embodiments

[0036] <First Embodiment>

[0037] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0038] The metal-nitride laminate according to the present embodiment is formed by bonding a metal solidified layer and an active metal nitride layer composed of Ti-N or Zr-N.

[0039] As Figure 1 shown, the metal-nitride laminate according to the present embodiment is formed at the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13 in the insulating circuit substrate 10, where the insulating circuit substrate 10 is formed by bonding a ceramic component (ceramic substrate 11) made of ceramic and a metal component (circuit layer 12 and metal layer 13) made of metal. That is, the ceramic component (ceramic substrate 11) and the metal component (circuit layer 12 and metal layer 13) as the objects to be bonded are bonded via the metal-nitride laminate according to the present embodiment.

[0040] As Figure 1As shown, this insulated circuit board 10 is used in various devices such as a power module 1.

[0041] Figure 1 The power module 1 shown includes: an insulated circuit board 10 provided with a circuit layer 12 and a metal layer 13; a semiconductor element 3 bonded to one surface (the upper surface in Figure 1 this case) of the circuit layer 12 via a bonding layer 2; and a heat sink 5 disposed on the other side (the lower side in Figure 1 this case) of the metal layer 13.

[0042] The semiconductor element 3 is made of a semiconductor material such as Si. The semiconductor element 3 is bonded to the circuit layer 12 via the bonding layer 2.

[0043] The bonding layer 2 is made of, for example, a solder material of the Sn - Ag system, Sn - In system, or Sn - Ag - Cu system.

[0044] The heat sink 5 is used to dissipate heat from the insulated circuit board 10. The heat sink 5 is made of copper or a copper alloy, and is made of phosphor - deoxidized copper in this embodiment. A flow path for a cooling fluid is provided in the heat sink 5.

[0045] In addition, in this embodiment, the heat sink 5 is bonded to the metal layer 13 by a solder layer 7 made of a solder material. The solder layer 7 is made of, for example, a solder material of the Sn - Ag system, Sn - In system, or Sn - Ag - Cu system.

[0046] And, as Figure 1 shown, the insulated circuit board 10 of this embodiment includes: a ceramic substrate 11; a circuit layer 12 disposed on one surface (the upper surface in Figure 1 this case) of the ceramic substrate 11; and a metal layer 13 disposed on the other surface (the lower surface in Figure 1 this case) of the ceramic substrate 11.

[0047] The ceramic substrate 11 is made of ceramics such as silicon nitride (Si3N4), aluminum nitride (AlN), or alumina (Al2O3) with excellent insulation and heat dissipation properties. In this embodiment, the ceramic substrate 11 is made of aluminum nitride (AlN) with particularly excellent heat dissipation properties. And the thickness of the ceramic substrate 11 is set, for example, in the range of 0.2 mm or more and 1.5 mm or less, and is set to 0.635 mm in this embodiment.

[0048] The circuit layer 12 is formed by bonding a metal plate made of a metal with excellent conductivity to one surface of the ceramic substrate 11.

[0049] In this embodiment, the circuit layer 12 is formed by bonding a copper plate to the ceramic substrate 11.

[0050] In addition, the thickness of the metal plate that forms the circuit layer 12 is set within the range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in the present embodiment.

[0051] The metal layer 13 is formed by bonding a metal plate made of a metal with excellent heat conductivity to the other surface of the ceramic substrate 11.

[0052] In the present embodiment, the metal layer 13 is formed by bonding a copper plate to the ceramic substrate 11.

[0053] In addition, the thickness of the metal plate that forms the metal layer 13 is set within the range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in the present embodiment.

[0054] And, Figure 2 The metal-nitride laminate 20 of the present embodiment formed at the bonding interface between the ceramic substrate 11 and the circuit layer 12 (metal layer 13) is shown.

[0055] In the metal-nitride laminate 20 of the present embodiment, as Figure 2 shown, it includes: a metal solidification layer 21; an active metal nitride layer 22 composed of any one or both of Ti-N and Zr-N; and a modified nitride layer 25 formed between the active metal nitride layer 22 and the metal solidification layer 21.

[0056] In addition, in the present embodiment, the active metal nitride layer 22 is formed on the bonding surface of the ceramic substrate 11, and the metal solidification layer 21 is formed on the bonding surface of the circuit layer 12 (metal layer 13).

[0057] That is, the metal-nitride laminate 20 of the present embodiment is formed when the ceramic substrate 11 and the metal plate that forms the circuit layer 12 (metal layer 13) are bonded using a bonding material.

[0058] Here, the modified nitride layer 25 is composed of a modified nitride in which a part of the active metal (Ti or Zr) in the active metal nitride layer 22 is replaced by any one or both of Al and Si. That is, when the active metal nitride layer 22 is composed of Ti-N, the modified nitride layer 25 is composed of any one or both of (Ti, Al)-N and (Ti, Si)-N modified nitrides.

[0059] And, when the active metal nitride layer 22 is composed of Zr-N, the modified nitride layer 25 is composed of any one or both of (Zr, Al)-N and (Zr, Si)-N modified nitrides.

[0060] In addition, in the present embodiment, the active metal nitride layer 22 and the modified nitride layer 25 are formed by sintering a liquid-phase forming material. In addition, pores may be formed inside the active metal nitride layer 22 and the modified nitride layer 25 composed of a sintered body. And the molten metal can invade into the pores.

[0061] Here, in the present embodiment, as Figure 2 shown, a grain boundary phase 23 is formed in the active metal nitride layer 22, and modified nitrides constituting the modified nitride layer 25 are present along the grain boundary phase 23.

[0062] And elements contained in the liquid-phase forming material are present in the grain boundary phase 23.

[0063] Next, with reference to Figure 3 the manufacturing method of the metal-nitride laminate 20 as the present embodiment will be described.

[0064] In the present embodiment, as Figure 3 shown in the flowchart, it includes a liquid-phase forming material disposing step S01, a liquid-phase sintering step S02, a surface grinding step S03, and a molten metal solidification step S04.

[0065] (Liquid-phase forming material disposing step S01)

[0066] First, the liquid-phase forming material is disposed on the bonding surface of the ceramic substrate 11. Here, the liquid-phase forming material contains any one or two of active metals (Ti, Zr), Al, and Si, and a low-melting-point metal. In addition, as the low-melting-point metal, for example, In, Sn, etc. can be cited.

[0067] (Liquid-phase sintering step S02)

[0068] Next, a liquid phase is generated by heating the liquid-phase forming material, and then cooled to sinter the generated liquid phase. At this time, the active metal nitride layer 22 is formed on the bonding surface of the ceramic substrate 11, and the modified nitride layer 25 in which a part of the active metal is replaced by Al or Si is formed. At this time, elements contained in the liquid-phase forming material are present in the grain boundary phase 23 of the active metal nitride layer 22.

[0069] In addition, the heating temperature and the holding time at the heating temperature in the liquid-phase sintering step S02 are preferably appropriately set according to the liquid-phase forming material used.

[0070] (Surface grinding step S03)

[0071] Next, the surfaces of the active metal nitride layer 22 and the modified nitride layer 25 formed on the bonding surface of the ceramic substrate 11 in the liquid-phase sintering step S02 are ground until they become flat. At this time, a part of the modified nitride layer 25 and the active metal nitride layer 22 on the surface of the bonding surface with the circuit layer 12 and the metal layer 13 can be removed.

[0072] In addition, the thickness of the modified nitride layer 25 is preferably 1 nm or more and 30 nm or less, and more preferably 1 nm or more and 15 nm or less.

[0073] (Molten metal solidification step S04)

[0074] Next, a bonding material is disposed between the metal plate that becomes the circuit layer 12 and the metal layer 13 and the ceramic substrate 11 formed with the active metal nitride layer 22, and the bonding material is melted and solidified, thereby forming a metal solidification layer 21.

[0075] Here, as the bonding material, a bonding material such as a Cu-Ag-In-Al system, a Cu-Ag-In-Si system, a Cu-Ag-Sn-Al system, a Cu-Ag-Sn-Si system, a Cu-In-Al system, a Cu-In-Si system, a Cu-Sn-Al system, a Cu-Sn-Si system, an Ag-In-Al system, an Ag-In-Si system, an Ag-Sn-Al system, or an Ag-Sn-Si system can be used.

[0076] At this time, by reacting Al and Si present in the grain boundary phase 23 of the active metal nitride layer 22 with the active metal nitride layer 22, the modified nitride layer 25 is formed again.

[0077] In this way, the metal-nitride laminate 20 of the present embodiment is formed, and the ceramic substrate 11 is bonded to the metal plate that becomes the circuit layer 12 and the metal layer 13, thereby manufacturing Figure 1 the insulating circuit board 10 shown.

[0078] According to the metal-nitride laminate 20 of the present embodiment configured as described above, a modified nitride layer 25 is formed between the active metal nitride layer 22 composed of any one or both of Ti-N and Zr-N and the metal solidification layer 21 formed by solidifying the molten metal. The modified nitride layer 25 is formed by replacing a part of the active metal in the active metal nitride layer 22 with any one or both of Al and Si. Therefore, through the modified nitride layer 25, the wettability between the active metal nitride layer 22 and the molten metal is improved, and the active metal nitride layer 22 and the metal solidification layer 21 are firmly bonded.

[0079] Also, while being flattened by performing the surface grinding process S03 and the molten metal solidification process S04, a structure having the modified nitride layer 25 is formed.

[0080] In the insulating circuit board 10 of the present embodiment, the active metal nitride layer 22 is formed on the bonding surface of the ceramic substrate 11, and the metal solidification layer 21 is formed on the bonding surface of the circuit layer 12 and the metal layer 13. Therefore, there is a modified nitride layer 25 between these active metal nitride layer 22 and the metal solidification layer 21, and the ceramic substrate 11 can be firmly bonded to the circuit layer 12 and the metal layer 13.

[0081] <Second Embodiment>

[0082] Next, with reference to Figure 4 , Figure 5 , the metal-nitride laminate 120 as the second embodiment of the present invention will be described.

[0083] Similar to the first embodiment, the metal-nitride laminate 120 as the second embodiment of the present invention is formed at the bonding interface between the ceramic substrate 11 and the circuit layer 12 and the metal layer 13 in the insulating circuit board 10, where the insulating circuit board 10 is formed by bonding a ceramic component (ceramic substrate 11) made of ceramic and a metal component (circuit layer 12 and metal layer 13) made of metal.

[0084] In the metal-nitride laminate 120 as the present embodiment, as Figure 4 shown, it includes: a metal solidification layer 121; an active metal nitride layer 122 composed of any one or both of Ti-N and Zr-N; and a modified nitride layer 125 formed between the active metal nitride layer 122 and the metal solidification layer 121.

[0085] In addition, in the present embodiment, the active metal nitride layer 122 is formed on the bonding surface of the ceramic substrate 11, and the metal solidification layer 21 is formed on the bonding surface of the circuit layer 12 (metal layer 13).

[0086] That is, the metal-nitride laminate 120 as the present embodiment is formed when the ceramic substrate 11 is bonded to a metal plate that becomes the circuit layer 12 (metal layer 13) using a bonding material.

[0087] Here, the modified nitride layer 125 is composed of a modified nitride in which a part of the active metal in the active metal nitride layer 122 is replaced by any one or both of Al and Si.

[0088] That is, when the active metal nitride layer 122 is composed of Ti-N, the modified nitride layer 125 is composed of any one or both of the modified nitrides (Ti, Al)-N and (Ti, Si)-N.

[0089] Moreover, when the active metal nitride layer 122 is composed of Zr-N, the modified nitride layer 125 is composed of any one or both of the modified nitrides (Zr, Al)-N and (Zr, Si)-N.

[0090] In addition, in the present embodiment, the active metal nitride layer 122 is formed by solid-phase sintering, and the modified nitride layer 125 is formed by a sputtering method or the like. That is, the modified nitride layer 125 is not formed by reacting with the active metal nitride layer 122, but is formed by film formation independently, and its composition can be preset.

[0091] Here, in the present embodiment, the modified nitride layer 125 preferably has the following composition: when the content ratios of Ti and Zr are set as X, the content ratios of Al and Si are set as Y, and the content ratio of N is set as Z in terms of atomic ratio, the following formulas (1) to (3) are satisfied.

[0092] X + Y + Z = 1 (1)

[0093] Y / (X + Y) < 0.7 (2)

[0094] 0.4 ≤ Z ≤ 0.5 (3)

[0095] Here, Y / (X + Y) defines the substitution ratio of Al and Si. If Y / (X + Y) is less than 0.7, the modified nitride layer 125 has an NaCl-type structure.

[0096] Moreover, Z is the content ratio of nitrogen, and by setting it within the range of 0.4 or more and 0.5 or less, sufficient wettability can be ensured as a nitride.

[0097] Next, with reference to Figure 5 , the manufacturing method of the metal-nitride laminate 120 as the present embodiment will be described.

[0098] In the present embodiment, as shown in the flowchart of Figure 5 , it includes a solid-phase sintering step S101, a film formation step S102, and a molten metal solidification step S103.

[0099] (Solid-phase sintering step S101)

[0100] First, by means of solid-phase sintering, an active metal nitride layer 122 composed of either or both of Ti-N and Zr-N is formed on the bonding surface of the ceramic substrate 11. Additionally, pores can be formed inside the active metal nitride layer 122 composed of a sintered body.

[0101] (Film formation process S102)

[0102] Next, a modified nitride layer 125 is formed on the surface of the active metal nitride layer 122. The film formation method is not particularly limited, and existing technologies such as sputtering can be applied. Additionally, when forming the modified nitride layer 125, it is preferable to adjust the composition in such a way that the content ratio of Ti and Zr is set as X, the content ratio of Al and Si is set as Y, and the content ratio of N is set as Z to satisfy the above formulas (1) to (3).

[0103] (Molten metal solidification process S103)

[0104] Next, a bonding material is disposed between the metal plates that become the circuit layer 12 and the metal layer 13 and the ceramic substrate 11 on which the active metal nitride layer 122 and the modified nitride layer 125 are formed, and the bonding material is melted and solidified, thereby forming a metal solidification layer 121. Additionally, the molten metal can penetrate into the pores of the active metal nitride layer 122.

[0105] Here, as the bonding material, bonding materials such as Cu-Ag-In-Al-based, Cu-Ag-In-Si-based, Cu-Ag-Sn-Al-based, Cu-Ag-Sn-Si-based, Cu-In-Al-based, Cu-In-Si-based, Cu-Sn-Al-based, Cu-Sn-Si-based, Ag-In-Al-based, Ag-In-Si-based, Ag-Sn-Al-based, or Ag-Sn-Si-based can be used.

[0106] Additionally, the thickness of the modified nitride layer 125 is preferably 1 nm or more and 30 nm or less, and more preferably 1 nm or more and 15 nm or less.

[0107] In this way, the metal-nitride laminate 120 of the present embodiment is formed, and the ceramic substrate 11 is bonded to the metal plates that become the circuit layer 12 and the metal layer 13, thereby manufacturing Figure 1 the insulating circuit board 10 shown.

[0108] According to the metal-nitride laminate 120 of the present embodiment configured as described above, similarly to the first embodiment, a modified nitride layer 125 is formed between the active metal nitride layer 122 and the metal solidification layer 121. Therefore, the wettability with the molten metal is improved by this modified nitride layer 125, and the active metal nitride layer 122 and the metal solidification layer 121 are firmly bonded.

[0109] Further, according to the present embodiment, the composition of the modified nitride layer 125 is as follows: when the content ratios of Ti and Zr are X, the content ratios of Al and Si are Y, and the content ratio of N is Z in terms of atomic ratio, the above formulas (1) to (3) are satisfied. Therefore, the modified nitride layer 125 has an NaCl-type structure and particularly excellent wettability with metals. Moreover, in the modified nitride layer 125, sufficient wettability can be maintained as a nitride.

[0110] The embodiments of the present invention have been described above, but the present invention is not limited thereto, and appropriate modifications can be made without departing from the technical idea of the invention.

[0111] For example, in the present embodiment, the method of bonding a copper plate via a metal solidification layer has been described, but it is not limited thereto. Even for metal components or other objects to be bonded other than the copper plate, as long as they are bonded via the metal solidification layer.

[0112] Moreover, in the present embodiment, as an example of the ceramic substrate on which the active metal nitride layer is to be formed, an example of being composed of aluminum nitride (AlN) has been described, but it is not limited thereto, and other ceramic substrates such as alumina (Al2O3) and silicon nitride (Si3N4) can also be used. In addition, instead of the ceramic substrate, a component composed of an active metal nitride can also be used.

[0113] Furthermore, in the present embodiment, the method of forming a power module by mounting a semiconductor element on an insulating circuit board has been described, but it is not limited thereto. For example, an LED module can be formed by mounting an LED element on the circuit layer of the insulating circuit board, or a thermoelectric module can be formed by mounting a thermoelectric element on the circuit layer of the insulating circuit board.

[0114] Examples

[0115] Hereinafter, the results of the confirmation experiments conducted to confirm the effects of the present invention will be described.

[0116] First, ceramic substrates (40 mm × 40 mm) described in Table 1 were prepared. And, as the metal plates serving as the circuit layers, in Invention Example 2 and Invention Example 6, aluminum plates with a purity of 99.99 mass% or more and a thickness of 0.25 mm and a size of 37 mm × 37 mm were prepared, and in Invention Example 1, Invention Examples 3 to 5, Invention Examples 7 to 12, and Comparative Examples 1 to 3, copper plates with a thickness of 0.25 mm and a size of 37 mm × 37 mm made of oxygen-free copper were prepared.

[0117] In Examples 1 to 8 of the present invention, using the liquid-phase forming materials shown in Table 1, an active metal nitride layer and a modified nitride layer shown in Table 2 were formed by liquid-phase sintering. In Comparative Example 1, using the liquid-phase forming materials shown in Table 1, only the active metal nitride layer shown in Table 2 was formed by liquid-phase sintering.

[0118] In Examples 9 to 12 of the present invention, as shown in Tables 1 and 2, an active metal nitride layer was formed by solid-phase sintering, and a modified nitride layer was formed by sputtering. In Comparative Examples 2 and 3, only the active metal nitride layer shown in Table 2 was formed by solid-phase sintering.

[0119] Moreover, a bonding material equivalent to the metal solidification layer shown in Table 2 was disposed between the ceramic substrate and the metal plate, and the ceramic substrate and the metal plate were bonded at the bonding temperature shown in Table 2.

[0120] Observation of the bonding interface and a surface cutting test were performed on the obtained insulating circuit substrate (metal-nitride laminate).

[0121] In addition, observation of the metal-nitride laminate formed at the bonding interface was performed as follows. The observation results of Example 1 and Example 5 of the present invention are shown in Figure 6A and Figure 6B .

[0122] Figure 6A shows a cross-section of the bonding interface of the metal-nitride laminate of Example 1 of the present invention, Figure 6B shows a cross-section of the bonding interface of the metal-nitride laminate of Example 5 of the present invention. In Figure 6A and Figure 6B , the bonding interfaces (HAADF-STEM images) of the metal-nitride laminates of Example 1 and Example 5 of the present invention, an Ag element map, a Cu element map, a Ti element map, an N element map, and an Al element map at the bonding interface are shown from left to right, respectively. In each element map, white or gray mapping images represent the distribution of each element.

[0123] Observation specimens were collected from the obtained insulating circuit board (metal-nitride laminate). For the cross-section of the bonding interface between the metal and the nitride laminate, a scanning transmission electron microscope (Titan G2 ChemiSTEM manufactured by Thermo Fisher Scientific Inc.) was used to observe a range of 30 nm in height and 20 nm in width at an acceleration voltage of 200 kV and a magnification of 640,000 times, or a range of 13 nm in height and 8 nm in width at a magnification of 1.5 million times. The total of Cu, Ag, In, Sn, Al, Si, Ti, Zr, and N was set to 100 atomic %. A region with an Al and Si concentration 1 atomic % or more higher than that in the active metal nitride layer and the metal solidified layer was judged as a modified nitride layer, and the area of this region was measured. The thickness of the modified nitride layer was calculated by dividing the measured area by the width of the measurement field of view. Measurements were carried out in five fields of view, and the average value is shown in Table 2.

[0124] (Surface cutting test)

[0125] A surface cutting test was performed on the obtained insulating circuit board (metal-nitride laminate), and the bonding strength between the metal plate and the ceramic substrate was evaluated.

[0126] In the surface cutting test, first, the metal plate was cut to a thickness of 30 μm.

[0127] And, as Figure 7A shown, a cutting tool with a blade width of 0.3 mm was used to cut the metal plate at a horizontal cutting speed of 2 μm / second and a vertical cutting speed of 0.1 μm / second (cutting stage), and the cutting tool was moved only in the horizontal direction at the moment of reaching the interface between the metal plate and the ceramic substrate (peeling stage). As Figure 7B shown, the horizontal load at the moment when the horizontal load became constant in the peeling stage was measured.

[0128] The strength of the bonding interface (peeling strength) was calculated by dividing the measured horizontal load by the blade width. The evaluation results are shown in Table 2.

[0129] [Table 1]

[0130]

[0131] [Table 2]

[0132]

[0133] In Comparative Example 1, a modified nitride layer was not formed, and an active metal nitride layer composed of Ti-N and a metal solidified layer composed of Cu were stacked. However, the active metal nitride layer and the metal solidified layer were not sufficiently joined, and the peel strength between the ceramic substrate and the metal plate was low, being 0.4 N / mm, and the joining strength was insufficient.

[0134] In Comparative Example 2, a modified nitride layer was not formed, and an active metal nitride layer composed of Ti-N and a metal solidified layer composed of Cu were stacked. However, the active metal nitride layer and the metal solidified layer could not be joined, and the ceramic substrate and the metal plate were in an unjoined state.

[0135] In Comparative Example 3, a modified nitride layer was not formed, and an active metal nitride layer composed of Zr-N and a metal solidified layer composed of Cu were stacked. However, the active metal nitride layer and the metal solidified layer could not be joined, and the ceramic substrate and the metal plate were in an unjoined state.

[0136] In contrast, in Examples 1 to 12 of the present invention, a modified nitride layer was formed between the active metal nitride layer and the metal solidified layer. Therefore, the active metal nitride layer and the metal solidified layer were firmly joined, and the peel strength between the ceramic substrate and the metal plate showed a sufficiently high value.

[0137] Based on the results of the above confirmation experiments, it was confirmed that according to the examples of the present invention, it was possible to provide a metal-nitride laminate in which a metal solidified layer formed by solidifying a molten metal was firmly joined to an active metal nitride such as Zr-N or Ti-N.

[0138] Symbol Explanation

[0139] 11 Ceramic substrate (ceramic component)

[0140] 12 Circuit layer (body to be joined)

[0141] 13 Metal layer (body to be joined)

[0142] 20, 120 Metal-nitride laminate

[0143] 21, 121 Metal solidified layer

[0144] 22, 122 Active metal nitride layer

[0145] 25, 125 Modified nitride layer

Claims

1. A metal-nitride laminate, which is a metal-nitride laminate formed by bonding a metal solidification layer and an active metal nitride layer composed of any one or both of Ti-N and Zr-N, characterized in that a modified nitride layer is formed between the active metal nitride layer and the metal solidification layer, and the composition of the modified nitride layer is such that part of the active metal in the active metal nitride layer is replaced by any one or both of Al and Si.

2. The metal-nitride laminate according to claim 1, characterized in that when in the modified nitride layer, the content ratio of Ti and Zr is set as X, the content ratio of Al and Si is set as Y, and the content ratio of N is set as Z in terms of atomic ratio, the following formulas (1) to (3) are satisfied: X + Y + Z = 1 (1) Y / (X + Y) < 0.7 (2) 0.4≤Z≤0.5 (3)。 3. The metal-nitride laminate according to claim 1, characterized in that the active metal nitride layer is formed on the surface of a ceramic component.

4. The metal-nitride laminate according to claim 1, characterized in that the metal solidification layer is formed on the bonding surface of the object to be bonded.

5. An insulating circuit board, which is an insulating circuit board having a circuit layer made of metal formed on the surface of a ceramic substrate, characterized in that the metal-nitride laminate according to any one of claims 1 to 4 is formed at the bonding interface between the ceramic substrate and the circuit layer.

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