JOINTING CONNECTION, POWER MODULE ARRANGEMENT AND METHOD FOR ATTACHING A FIRST JOINTING PARTNER TO A SECOND JOINTING PARTNER

Abstract

A joining connection (1) for attaching a first joining partner (2) to a second joining partner (3) is specified with - a joining material (4) and - a layer (5) of an intermetallic phase, wherein - the joining material (4) is arranged between the first joining partner (2) and the second joining partner (3), - the layer (5) of an intermetallic phase is arranged between the joining material (4) and at least one of the first joining partner (2) and the second joining partner (3), - the layer (5) of an intermetallic phase has at least two areas, which have at least a first area (6) with a first height (8) and at least a second area (7) with a second height (9) that differ from each other. Furthermore, a power module arrangement (11) and a method for attaching a first joining partner (2) to a second joining partner (3) are specified.

Description

[0001] The present disclosure relates to a joining connection for attaching a first joining partner to a second joining partner, a power module arrangement and a method for producing a joining connection.

[0002] Embodiments of the disclosure relate to a joining connection that is particularly reliable. Further embodiments of the disclosure relate to a module arrangement with such a joining connection and a method for producing such a joining connection.

[0003] This is achieved through the subject matter of the independent claims. Further embodiments are evident from the dependent claims in the following description.

[0004] A joining connection for attaching a first joining partner to a second joining partner is described. For example, the joining connection is formed in a power semiconductor module with at least one power semiconductor device. The term "power" here and below refers, for example, to power semiconductor modules, power semiconductor devices, and / or power semiconductor chips designed for handling voltages and currents of more than 100 V and / or more than 10 A, for example, voltages up to 10 kV and currents up to 5000 A.

[0005] The first joining partner has, for example, a first joining area and / or the second joining partner has, for example, a second joining area. The first joining area and / or the second joining area are, in particular, formed of an electrically conductive material. The first joining area and / or the second joining area comprise, for example, a metal or a metal alloy. For example, the first joining area and / or the second joining area comprise at least one of copper, Cu, aluminum, Al, and nickel, Ni. In particular, the first joining area and / or the second joining area comprise an alloy containing at least two of the following materials: copper, Cu, aluminum, Al, nickel, Ni.

[0006] Specifically, the first connection area is a metallization of the first joining partner, and the second connection area is a metallization of the second joining partner. The metallization of the first joining partner and / or the second joining partner, i.e., the first connection area and / or the second connection area, can be a backside metallization of the chip, for example, a thin coating, or it can be a substrate metallization, for example, a solid metal, or it can be an entire surface of the chip backside or a portion of the surface of the substrate metallization. The substrate metallization may have an additional coating, at least locally. In some cases, a connection area may be a terminal foot or a clamping area.

[0007] The first joining partner and the second joining partner each extend in a principal plane of extension, with the principal planes of extension extending in lateral directions. The first joining partner and the second joining partner are arranged opposite each other in a vertical direction that is perpendicular to the lateral directions. In particular, the first joining area faces the second joining area such that the first joining area is arranged opposite the second joining area in a vertical direction. For example, in a plan view, the first joining area completely overlaps the second joining area in lateral directions.

[0008] For example, at least one of the first joining areas and the second joining area has a circular, elliptical, or polygonal shape in plan view, such as a square shape. For example, the joining area has the same shape as the first joining area and / or the second joining area in plan view. For example, in plan view, an extent of the shape of at least one of the first joining area and the second joining area is equal to or greater than the shape of the joining area.

[0009] According to one embodiment, the joining joint comprises a joining material. The joining material is, in particular, an electrically conductive material. The joining material comprises, for example, a metal or a metal alloy, or consists thereof. The joining material comprises, for example, at least one of the following materials: tin, tin (Sn), lead, lead (Pb), silver, silver (Ag), antimony, sable (Sb), and copper (Cu). In particular, the joining material comprises an alloy comprising, or consisting of, at least two of the following materials: tin, tin (Sn), lead, lead (Pb), silver, silver (Ag), antimony, sable (Sb), copper, and copper (Cu). The joining material may also include other substances such as rare earth elements, bismuth, or indium to influence material properties such as wetting behavior and / or diffusion rate.

[0010] According to the embodiment, the joining joint has a layer of an intermetallic phase. The layer of an intermetallic phase includes, for example, at least one of the metals of the joining material and at least one of the metals of either the first joining area or the second joining area.

[0011] For example, during a process step to create the joint, the joining material is heated to such an extent that it melts and wets the corresponding joining area, thereby forming a metallurgical bond. For instance, atoms from the joining material and the joining area diffuse across the interface between the joining material and the joining area, forming a layer of intermetallic phase. This intermetallic phase layer comprises, or consists of, a metal alloy of at least one of the metals in the joining material and at least one of the metals in the first or second joining area.

[0012] According to the embodiment of the joining connection, the joining material is arranged between the first joining partner and the second joining partner. In particular, the joining material is arranged between the first joining area and the second joining area. That is, the first joining partner, the joining material, and the second joining partner are stacked one above the other along a stacking direction that is oriented vertically.

[0013] According to the embodiment of the joining connection, the layer of an intermetallic phase is arranged between the joining material and at least one of the first joining partner and the second joining partner. In particular, the layer of an intermetallic phase is an interface region between the joining material and at least one of the first joining partner and the second joining partner. The layer of an intermetallic phase is, for example, in direct contact with the joining material. For example, the layer of an intermetallic phase is in direct contact with at least one of the first joining partner and the second joining partner.

[0014] According to the embodiment of the joining compound, the layer of an intermetallic phase has at least two regions, comprising at least a first region with a first height and at least a second region with a second height that differs from each other. The height is the vertical extent of the layer of intermetallic phase.

[0015] In particular, such differing areas with the first height and the second height are not comparable to the roughness of an interface between the layer of an intermetallic phase and the joining material, or between the layer of an intermetallic phase and at least one of the first joining partner and the second joining partner. Such roughness of the corresponding interface is typically due to manufacturing tolerances. This means that a difference between the first height and the second height is greater than the roughness of the corresponding interfaces of the layer of an intermetallic phase. The roughness is typically in the range of a few micrometers at most.

[0016] In particular, the joining connection creates a mechanically stable as well as an electrically conductive connection and / or a thermally conductive connection between the first joining partner and the second joining partner.

[0017] Soldering is typically a commonly used joining technique in the assembly of power semiconductor devices and modules, for example, to connect a first component, i.e., a power semiconductor chip, to a second component, i.e., an insulating substrate, or vice versa, or to connect a substrate to a base plate. Generally, conventional reflow soldering remains the most widely used joining technique. During a conventional soldering process, conventional layers of an intermetallic phase are formed by interdiffusion of material at the interfaces between a conventional joining material, i.e., conventional solder, and the components being joined. Such conventional layers of an intermetallic phase have a predominantly homogeneous height in the vertical direction. "Predominantly" means that variations in height can occur due to manufacturing tolerances.

[0018] However, a typical interface area between a substrate and a base plate is comparatively large. This leads to locally varying stress levels, for example, due to temperature cycling during operation. For instance, under temperature cycling, the thermomechanical stress in the corners of a conventional soldered joint is significantly higher than in a central area. It is conceivable that the weakest area of ​​the conventional soldered joint is located at the point where the highest thermomechanical stress occurs.

[0019] In summary, such a joining connection with a layer of an intermetallic phase with a first and a second height can provide, among other things, the following advantages.

[0020] Since the thickness of the intermetallic phase layer influences the tensile strength of the joint, for example, due to the improved hardness of the intermetallic phase layer compared to a bare joining material, and thus its reliability, particularly under thermal cycling, the intermetallic phase layer has different thicknesses in its first and second regions. Consequently, this intentional local modification of the thickness, resulting in a structured intermetallic phase layer, locally improves the reliability of the soldered joint under thermomechanical stress.

[0021] Such structured layers of an intermetallic phase lead to improved reliability of the joint under thermomechanical stresses. In particular, the structured layer of an intermetallic phase results in a locally higher final strength of the joint, especially in critical areas where stress maxima occur, and thus longer cycle times.

[0022] If multiple structuring of the first and second heights is present, a cracking process similar to interlocking can occur, so that cracking and delamination due to stress can be suppressed and consequently reliability can be improved.

[0023] According to a further embodiment of the joining connection, the first height and the second height differ from each other by at least 50% in the vertical direction. For example, the first height is greater than the second height, in particular by at least a factor of 1.5. Alternatively, the second height is greater than the first height, in particular by at least a factor of 1.5.

[0024] For example, at least one of the first heights and the second height must be at least 1 µm and at most 100 µm.

[0025] According to another embodiment of the joining connection, the first area is arranged in a central area of ​​the joining connection and the second area is arranged in a peripheral area of ​​the joining connection, which at least partially surrounds the central area.

[0026] For example, the central area is located at a centroid of the joint and extends laterally towards the edges of at least one of the first and second joint areas. The peripheral area extends laterally along an edge region of the joint that bounds the central area. The peripheral area partially or completely surrounds the central area laterally.

[0027] The second area is located at least regionally or entirely within the peripheral area. For example, the second area surrounds the central area like a frame. "Frame-like" should not be understood as restrictive with regard to the shape of the reinforcement structure.

[0028] According to a further embodiment of the joining connection, the second region is formed from several parts spaced apart from each other in later directions, each part having the second height. For example, the parts of the second region each have the second height. The parts of the second region are spaced apart from each other, for example, in later directions.

[0029] If the second height is smaller than the first height, the parts of the second area are spaced apart from each other laterally by the first area. This is the case, for example, when the first area is positioned between the parts of the second area.

[0030] If the second height is greater than the first height, the parts of the second area are spaced apart laterally by the joining material and / or by at least one part of the first and second connection areas. This means, for example, that the joining material and / or at least one part of the first and second connection areas are positioned between the parts of the second area.

[0031] According to a further embodiment of the joining connection, each part is arranged in a corner of the joining connection. If the joining connection, in particular at least one of the first joining area and the second joining area, has a polygonal shape in plan view, each part is arranged in an area at one of the corners of the polygonal shape.

[0032] According to a further embodiment of the joining connection, at least one of the first region and one of the second region have a width of at least 100 µm in lateral directions. The width is a minimum extent of the first region or the second region in lateral directions.

[0033] According to a further embodiment of the joining compound, the layer of an intermetallic phase has a plurality of first regions with a first height and a plurality of second regions with a second height. Each of the first regions has the same first height and each of the second regions has the same second height.

[0034] According to a further embodiment of the joining connection, the first and second regions are arranged laterally at virtual grid points of a virtual grid. The virtual grid serves solely to clarify the positions of the first and second regions. The virtual grid is, for example, a regular one-dimensional or a regular two-dimensional grid. If the virtual grid is a regular two-dimensional grid, it is a polygonal grid, for example, a triangular grid, a quadrilateral grid, in particular a square grid, or a hexagonal grid.

[0035] According to another embodiment of the joining connection, the first areas are each formed as a first strip and the second areas as a second strip. If the first and second areas are arranged at the virtual grid points of the regular one-dimensional grid, each first area is formed as a first strip and each second area as a second strip.

[0036] A strip has a width and a length extending in lateral directions. The length extends along a principal direction of extension of the strip. The length is greater than the width; in particular, the length is at least 20% or at least 50% greater than the width.

[0037] According to a further embodiment of the joining connection, the first strips and the second strips are arranged alternately side by side in one of the lateral directions. In particular, the first strips and the second strips are arranged alternately side by side along an arrangement direction that is perpendicular to the main extension direction of the strips.

[0038] According to a further embodiment of the joining connection, the first areas are each formed as a first quadrilateral and the second areas as a second quadrilateral. For example, the first quadrilaterals and / or the second quadrilaterals each have the same extent in lateral directions. In particular, the first quadrilaterals and / or the second quadrilaterals are each squares with equal side lengths.

[0039] According to another embodiment of the joining connection, the first and second quadrilaterals are arranged alternately next to each other in lateral directions, so that each first quadrilateral has a side adjacent to one of the second quadrilaterals and vice versa. This means that the first and second quadrilaterals form a checkerboard pattern.

[0040] According to another embodiment of the joining connection, the first height increases or decreases continuously towards the second height. In particular, the layer of an intermetallic phase gradually increases from the first height to the second height, with the first height and the second height being maximum and minimum extents in the vertical direction.

[0041] According to a further embodiment of the joining joint, the first height and the second height change periodically in one of the lateral directions, and the width of one period is at least 200 µm in lateral directions. That is, if the joining joint has several first regions and second regions arranged alternately along one another, directly adjacent maximum heights of the first region corresponding to the first heights and / or directly adjacent minimum heights of the second region corresponding to the second heights are spaced apart from each other by at least 200 µm in lateral directions.

[0042] According to a further embodiment of the joining connection, the first height increases or decreases discontinuously towards the second height. For example, the first height increases or decreases towards the second height in an interface region between the first region and the second region. This interface region has, for example, a width in lateral directions that is at least one order of magnitude smaller than the width of at least one of the first region and the second region. For example, the layer of an intermetallic phase, viewed from the side, exhibits a step shape in a region of the first region and the second region that are directly adjacent to each other.

[0043] According to another embodiment, the joining connection is at least one of a soldered joint, a diffusion soldered joint and a sintered joint.

[0044] According to a further embodiment of the joining connection for a power module arrangement comprising a semiconductor chip, the first joining partner and the second joining partner comprise at least one of a substrate and a base plate, a substrate and a terminal, a semiconductor chip and a substrate and a terminal, or a clamp and a semiconductor chip.

[0045] The base plate, substrate, and / or connection can be part of a power semiconductor module. The semiconductor chip is specifically a power semiconductor chip. In particular, the first and second joining partners are contained within a power semiconductor module. In this case, at least one of the first and second joining partners is formed from a power semiconductor chip.

[0046] For example, the first joining partner is the substrate and the second joining partner is the base plate, or the first joining partner is the substrate and the second joining partner is the connector, or the first joining partner is the semiconductor chip and the second joining partner is the substrate, or vice versa.

[0047] Furthermore, a power module arrangement is described here which may have a joining connection as described above. Therefore, the features in connection with the joining connection are also disclosed in connection with the power module arrangement and vice versa.

[0048] According to one embodiment, the power module arrangement has a first joining partner, in particular the first joining partner described above.

[0049] According to the embodiment, the power module arrangement has a second joining partner, in particular the second joining partner described above.

[0050] According to the embodiment, the power module arrangement has a joining connection, in particular the joining connection described above.

[0051] According to the embodiment of the power module arrangement, the joining connection has a joining material and at least one layer of an intermetallic phase.

[0052] According to the embodiment of the power module arrangement, the joining material is arranged between the first joining partner and the second joining partner.

[0053] According to the embodiment of the power module arrangement, the layer of an intermetallic phase is arranged between the joining material and at least one of the first joining partner and the second joining partner.

[0054] According to the embodiment of the power module arrangement, the layer of an intermetallic phase has at least two regions, comprising at least a first region with a first height and at least a second region with a second height that differ from each other.

[0055] According to another embodiment of the power module arrangement, the first joining partner is a substrate and the second joining partner is a power semiconductor device, or vice versa. This means that the power module arrangement is, in particular, part of a power semiconductor module. The power semiconductor device may include a power semiconductor chip.

[0056] For example, a power semiconductor device is an electronic component designed to handle high levels of electrical power, as specified above. The power semiconductor device is designed, for example, to control and convert electrical power, e.g., from alternating current to direct current or vice versa, or to change the frequency of voltage and / or current by means of appropriate switching operations. The power semiconductor device includes, for example, at least one thyristor, one power metal oxide semiconductor field-effect transistor (MOSFET), one insulated-gate bipolar transistor (IGBT), one high electron mobility transistor (HEMT), and one power diode.

[0057] For example, a power semiconductor module comprises one or more of the power semiconductor devices together with other components such as a substrate, a base plate, a heat sink, at least one terminal and a control circuit arrangement.

[0058] The joining connection can be arranged, for example, between two of the following elements of the power semiconductor module: power semiconductor device, substrate, base plate, heat sink, at least one terminal and a control circuit arrangement.

[0059] Furthermore, a method for fastening a first joining partner to a second joining partner is described here, with which a joining connection as described above can be produced or is produced. Therefore, the features in connection with the joining connection are also disclosed in connection with the method and vice versa.

[0060] According to one embodiment of the method, a first joining partner and a second joining partner are provided.

[0061] According to the embodiment of the method, a joining material is applied to the first joining partner. The joining material is applied, for example, to the first joining area.

[0062] According to the embodiment of the method, the second joining partner is applied to the joining material. This means that the first joining partner, the joining material, and the second joining partner are stacked on top of each other in the stacking direction and, in particular, are in direct and immediate contact with each other.

[0063] According to the embodiment of the method, an arrangement comprising the first joining partner, the joining material, and the second joining partner is heated so that a layer of an intermetallic phase forms. During heating, the joining material melts and wets, for example, the first joining area. During heating, atoms diffuse from the joining material and the joining area across the interface between the joining material and the first joining area.

[0064] In particular, the heated arrangement is subsequently cooled so that the molten material of the joining material solidifies and atoms from the joining material form the layer of an intermetallic phase.

[0065] According to the embodiment of the method, the layer of an intermetallic phase is modified to have at least two regions, comprising at least a first region with a first height and at least a second region with a second height that differ from each other.

[0066] This allows conventional joints produced with existing standard solder alloys and / or standard soldering processes to be advantageously treated for improved reliability. In addition, the proposed method, through local treatment of the joint alongside the standard reflow process with a defined temperature profile, offers further control and variation over the soldering process.

[0067] According to a further embodiment of the method, a local magnetic field is applied to one of the at least two areas during the heating of the arrangement, wherein the height of the layer of an intermetallic phase depends on a magnetic flux of the local magnetic field.

[0068] If the magnetic flux is applied to the second regions during heating and / or cooling of the arrangement, the second height is smaller than the first height. This is because the magnetic flux reduces the diffusion rate.

[0069] According to a further embodiment of the method, during the heating of the arrangement a local electric current is applied to one of the at least two areas, wherein the height of the layer of an intermetallic phase depends on an electric current density of the local electric current.

[0070] If the electric current is applied to the second regions during the heating and / or cooling of the arrangement, the second height is smaller than the first height. This is because the electric current reduces the diffusion rate.

[0071] According to a further embodiment of the method, additional heat is applied to one of the at least two areas during the heating of the arrangement, wherein the thickness of the layer of an intermetallic phase depends on the temperature of the heat. For example, the additional heat is applied using a local heat source or a local heat probe.

[0072] Alternatively or additionally to applying additional heat, additional cooling is applied to one of the at least one areas, wherein the thickness of the layer of an intermetallic phase depends on the temperature of the cooling. For example, the additional cooling is applied using a local cooling source or a local cooling probe.

[0073] According to a further embodiment of the method, the joining material comprises at least two different material systems corresponding to the at least two areas to be produced. For example, the material system of the joining material applied to the first area of ​​the layer to be produced from an intermetallic phase differs from the material system of the joining material applied to the second area of ​​the layer to be produced from an intermetallic phase. The material systems can differ in their substances and / or in the proportion of substances contained in each material system.

[0074] According to a further embodiment of the method, the joining material has at least two different maximum doping concentrations corresponding to the at least two areas to be produced. For example, the maximum doping concentrations of the joining material applied to the first area of ​​the intermetallic phase layer to be produced differ from the maximum doping concentrations of the joining material applied to the second area of ​​the intermetallic phase layer to be produced.

[0075] For example, the joining material contains a dopant up to the maximum doping concentration. The maximum doping concentration is at most 2% or at most 1% of the joining material per unit volume. The dopant can be, for example, a rare earth element or bismuth (Bi) or indium (In). For example, the wettability and / or diffusion of the joining material depends on the doping concentration.

[0076] If the maximum doping concentration in the first area is greater than in the second area, the first height is greater than the second height in the layer to be produced from an intermetallic phase, or vice versa.

[0077] Alternatively or additionally, the joining material comprises at least two different dopant materials corresponding to the at least two areas to be produced. For example, the dopant material of the joining material applied to the first area of ​​the layer to be produced from an intermetallic phase differs from the dopant material of the joining material applied to the second area of ​​the layer to be produced from an intermetallic phase.

[0078] According to a further embodiment of the method, a joining surface of the first joining partner and / or a joining surface of the second joining partner has at least two different metallization materials corresponding to the at least two areas to be produced. For example, the metallization material of the first joining area, which is placed on the first area of ​​the layer to be produced from an intermetallic phase, differs from the metallization material that is placed on the second area of ​​the layer to be produced from an intermetallic phase.

[0079] In particular, the at least two metallization materials can differ by at least one metal from the connection areas described above.

[0080] According to a further embodiment of the method, a first joining surface of the first joining partner and / or a second joining surface of the second joining partner has at least two different surface roughnesses that correspond to the at least two areas to be produced.

[0081] For example, the first joining surface of the first joining partner is an upper surface of the first joining area facing the second joining partner. For example, the second joining surface of the second joining partner is a lower surface of the second joining area facing the first joining partner.

[0082] For example, the surface roughness of the first joining surface in the first area of ​​the layer to be produced from an intermetallic phase differs from the surface roughness in the second area of ​​the layer to be produced from an intermetallic phase. For example, the surface roughnesses differ by at least 10% or at least 50%.

[0083] According to a further embodiment of the method, a first joining surface of the first joining partner and / or a second joining surface of the second joining partner has a diffusion barrier in an area corresponding to at least one of the two areas to be produced. The diffusion barrier is applied, for example, by a coating process.

[0084] If the diffusion barrier is positioned at the second level and the assembly is heated, the second level is lower than the first. As a result, the diffusion barrier reduces or blocks diffusion in the second level and thus at the second level.

[0085] The accompanying figures are for illustrative purposes. Elements with the same structure and / or functionality may be designated with the same reference symbols in the figures. It should be noted that the embodiments shown in the figures are for illustrative purposes only and are not necessarily drawn to scale. Fig. Figure 1 shows a schematic view of a joining connection according to an exemplary embodiment, Fig. 2 and Fig. Figure 3 each shows a schematic view of process steps for producing a joining joint according to an exemplary embodiment and Fig. 4 and Fig. Figure 5 each shows a diagram with characteristics for the heights of the layer of an intermetallic phase of a joining joint according to an exemplary embodiment.

[0086] The joining connection 1 according to the exemplary embodiment in Fig. 1 attaches a first joining partner 2 to a second joining partner 3. Between the first joining partner 2 and the second joining partner 3, a joining material 4 and a layer 5 of an intermetallic phase are arranged. In particular, the layer 5 of an intermetallic phase comprises or consists of materials of the joining material 4 and the first joining area 12. This means that the layer 5 of an intermetallic phase is partially located within the joining material 4 and the first joining area 12, the thickness of which depends in particular on a wetting behavior and / or a diffusion rate, which is determined with reference to Fig. 2 will be described in more detail.

[0087] The first joining partner 2 has a first joining area 12 and the second joining partner 3 has a second joining area 13. The first joining area 12 and the second joining area 13 are each a metallization of the respective joining partner.

[0088] The first connection area 12, the layer 5 of an intermetallic phase, the joining material 4, and the second connection area 13 are arranged one above the other along a stacking direction, which is a vertical direction. The layer 5 of an intermetallic phase is located at an interface between the joining material 4 and the first connection area 12 and extends over a first area 6 and a second area 7.

[0089] The first region 6 is located in a central area of ​​the joint 1, and the second region 7 is located in a peripheral area of ​​the joint 1, completely surrounding the central area in lateral directions extending perpendicular to the vertical direction. This means that, in the top view, the second region 7 completely surrounds the first region 6 in lateral directions. The top view corresponds to a view of the joint 1 along the vertical direction.

[0090] The joining compound 1 has a first height 8 in the first region 6 and a second height 9 in the second region 7. The first height 8 is greater than the second height 9. The layer 5 of an intermetallic phase gradually increases from the second height 9 to the first height 8. In particular, the layer 5 of an intermetallic phase has a shape that corresponds to one of the following: Fig. The 4 periods shown correspond to this and extend from one of the minima to a directly adjacent one. This means that the first height 8 corresponds to a maximum height of the first region 6 and the second height 9 corresponds to a minimum height in the second region 7.

[0091] For example, the width of the first region 6 is at least 100 µm in lateral directions.

[0092] The first joining partner 2 and the second joining partner 3, which are mechanically stably connected by the joining connection 1, form a power module arrangement 11 according to an exemplary embodiment.

[0093] For example, the first joining partner 2 is a substrate for a power semiconductor device, and the second joining partner 3 is the power semiconductor device. This means that the power module arrangement 11 is a power semiconductor module in this case.

[0094] For example, the power semiconductor device includes or consists of at least one thyristor, one power metal oxide semiconductor field-effect transistor (MOSFET), one insulated gate bipolar transistor (IGBT), one high electron mobility transistor (HEMT), and one power diode.

[0095] According to the exemplary embodiment according to Fig. 2. An arrangement comprising the first joining region 12, the joining material 4, and the second joining region 13 is heated to produce the layer 5 of an intermetallic phase. The arrangement is then cooled. In particular, such a process produces a joining connection 1 with a layer 5 of an intermetallic phase, as described in the exemplary embodiment. Fig. 1 corresponds to.

[0096] During the heating and / or cooling of the arrangement, a local magnetic field is applied to the second region 7. Because a magnetic flux of the local magnetic field is applied to the second region 7, the diffusion rate in the second region 7 is reduced compared to the first region 6. Due to the reduced diffusion rate in the second region 7, the resulting second height 9 in the second region 7 is smaller than the resulting first height 8 in the first region 6.

[0097] According to the exemplary embodiment according to Fig. A diffusion barrier 10 is arranged on a first joining surface of the first joining partner 2, wherein the first joining surface of the first joining partner 2 is an upper surface of the first joining area 12 facing the second joining partner 3. The diffusion barrier 10 has varying heights. The height increases from an edge of the first joining surface to a central area of ​​the first joining surface.

[0098] During heating and / or cooling of the arrangement, the diffusion rate is reduced depending on the height of the diffusion barrier 10. The diffusion rate is inversely proportional to the height of the diffusion barrier 10. This means that the resulting second height 9 of the layer 5 consisting of an intermetallic phase in the second region 7 is greater than the resulting first height 8 in the first region 6.

[0099] On the y-axis of the diagram in Fig. 4 and Fig. 5 represents the height of layer 5 of an intermetallic phase as a function of the extent of layer 5 of an intermetallic phase along one of the lateral directions shown on the x-axis.

[0100] Layer 5 consists of an intermetallic phase according to Fig. 4 and Fig. 5 has a plurality of first areas 6 with a first height of 8 and a plurality of second areas 7 with a second height of 9. The first areas 6 and the second areas 7 are arranged alternately next to each other in lateral directions.

[0101] In the representation in Fig. 4 The first height 8 decreases continuously, in particular gradually, to the second height 9. This means that the layer 5, consisting of an intermetallic phase, has a sinusoidal shape with a plurality of periods in side view.

[0102] For example, the maxima of the sinusoidal shape are spaced apart in lateral directions by a distance of at least 200 µm. This means that one period has a width of at least 200 µm.

[0103] The first height 8 and the second height 9 exhibit a maximum height difference. For example, an interface between directly adjacent first regions 6 and second regions 7 is located at a height of layer 5 of an intermetallic phase that corresponds to half the maximum height difference.

[0104] In the representation in Fig. The first height 8 decreases discontinuously to the second height 9. This means that the first height 8 decreases to the second height 9 in an interface region between the first region 6 and the second region 7. This means that layer 5, consisting of an intermetallic phase, has a step shape in side view, exhibiting multiple periods.

[0105] For example, the first regions 6 are spaced apart laterally by a distance of at least 100 µm. This means that the lateral widths of the first regions 6 and the second regions 7 are each at least 100 µm. Reference sign 1 joining connection 2 first joining partner 3 second joining partner 4. Joining material 5 layers of an intermetallic phase 6 first area 7 second area 8 first height 9 second height 10 Diffusion barrier 11 Power module arrangement 12 first connection area 13 second connection area

Claims

[1] Joining connection (1) for attaching a first joining partner (2) to a second joining partner (3) with - a joining material (4) and - a layer (5) of an intermetallic phase, wherein - the joining material (4) is arranged between the first joining partner (2) and the second joining partner (3), - the layer (5) of an intermetallic phase is arranged between the joining material (4) and at least one of the first joining partner (2) and the second joining partner (3), - the layer (5) of an intermetallic phase has at least two areas, which have at least a first area (6) with a first height (8) and at least a second area (7) with a second height (9) that differ from each other. [2] Joining connection (1) according to claim 1, wherein - the first height (8) and the second height (9) differ from each other by at least 50% in the vertical direction. [3] Joining connection (1) according to one of claims 1 or 2, wherein - the first area (6) is arranged in a central area of ​​the joining connection (1) and the second area (7) is arranged in a peripheral area of ​​the joining connection (1) that at least partially surrounds the central area. [4] Joining connection (1) according to any one of claims 1 to 3, wherein - the second area (7) is formed from several spaced-apart parts and each part has the second height, and - each part is arranged in a corner of the joint (1). [5] Joining connection (1) according to any one of claims 1 to 4, wherein - at least one of the first region (6) and the second region (7) has a width of at least 100 µm in lateral directions. [6] Joining connection (1) according to any one of claims 1 to 5, wherein - the layer (5) of an intermetallic phase has a plurality of first areas (6) with the first height (8) and a plurality of second areas (7) with the second height (9). [7] Joining connection (1) according to claim 6, wherein - the first areas (6) and the second areas (7) are arranged in lateral directions at virtual grid points of a virtual grid. [8] Joining connection (1) according to one of claims 6 or 7, wherein - the first areas (6) are each formed as a first strip and the second areas (7) are each formed as a second strip, and - the first stripes and the second stripes are arranged alternately next to each other in one of the lateral directions. [9] Joining connection (1) according to one of claims 6 or 7, wherein - the first areas (6) are each formed as a first quadrilateral and the second areas (7) are each formed as a second quadrilateral, and - the first quadrilaterals and the second quadrilaterals are arranged alternately next to each other in lateral directions, so that each first quadrilateral has a side that is adjacent to one of the second quadrilaterals. [10] Joining connection (1) according to any one of claims 1 to 9, wherein - the first height (8) continuously increases or decreases towards the second height (9), or - the first height (8) increases or decreases discontinuously to the second height (9). [11] Joining connection (1) according to any one of claims 6 to 10, wherein - the first height (8) of the first areas (6) and the second height (9) of the second areas (7) change periodically in one of the lateral directions and a width of one period in lateral directions is at least 200 µm. [12] Joining connection (1) according to any one of claims 1 to 11, wherein the joining connection (1) is at least one of - a soldered joint, - a diffusion solder joint and - a sintered compound. [13] Joining connection (1) according to one of claims 1 to 12 for a power module arrangement with a semiconductor chip, wherein the first joining partner (2) and the second joining partner (3) have at least one of - a substrate and a base plate, - a substrate and a connection, - a substrate and the semiconductor chip, and - a connector or clamp and the semiconductor chip. [14] Power module arrangement (11), comprising - a first joining partner (2), - a second joining partner (3) and - a joining connection (1) wherein - the joining connection (1) comprises a joining material (4) and at least one layer (5) of an intermetallic phase, - the joining material (4) is arranged between the first joining partner (2) and the second joining partner (3), - the layer (5) of an intermetallic phase is arranged between the joining material (4) and at least one of the first joining partner (2) and the second joining partner (3), and - the layer (5) of an intermetallic phase has at least two areas, which have at least a first area (6) with a first height (8) and at least a second area (7) with a second height (9) that differ from each other. [15] Power module arrangement (11) according to claim 14, wherein - the first joining partner (2) is a substrate for a power semiconductor device, and - the second joining partner (3) is a power semiconductor device. [16] Method for attaching a first joining partner (2) to a second joining partner (3), comprising - Providing a first joining partner (2) and a second joining partner (3), - Applying a joining material (4) to the first joining partner (2) and - Applying the second joining partner (3) to the joining material (4) and - Heating an arrangement comprising the first joining partner (2), the joining material (4) and the second joining partner (3) such that a layer (5) of an intermetallic phase is produced, - Modifying the layer (5) of an intermetallic phase with at least two regions having at least one first region (6) with a first height (8) and at least one second region (7) with a second height (9) that differ from each other. [17] Method according to claim 16, wherein at least one of the following steps is carried out during the heating of the arrangement: - a local magnetic field is applied to one of the at least two areas, wherein the height of the intermetallic phase depends on a magnetic flux of the local magnetic field, - a local electric current is applied to one of the at least two areas, wherein the height of the intermetallic phase depends on the electric current density of the local electric current, and - Additional heat and / or additional cooling is applied to one of the at least two areas, whereby the height of the intermetallic phase depends on the temperature of the heat. [18] Method according to claim 16 or 17, comprising at least one of the following: - the joining material (4) has at least two different material systems corresponding to the at least two areas to be produced, and - the joining material (4) has at least two different maximum doping concentrations corresponding to the at least two areas to be produced. [19] Method according to any one of claims 16 to 18, comprising at least one of the following: - a joining surface of the first joining partner (2) and / or a joining surface of the second joining partner (3) has at least two different metallization materials that correspond to the at least two areas to be produced, - a first joining surface of the first joining partner (2) and / or a second joining surface of the second joining partner (3) has at least two different surface roughnesses that correspond to the at least two areas to be produced. [20] Method according to any one of claims 16 to 19, wherein - a joining surface of the first joining partner (2) and / or a joining surface of the second joining partner (3) has a diffusion barrier (10) in an area that corresponds to at least one of the two areas to be produced.

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