Method for manufacturing a semiconductor unit and method for manufacturing a semiconductor device

Abstract

Method for manufacturing a semiconductor unit (100) for a power converter, the method comprising a step of providing a printed circuit board apparatus comprising a printed circuit board (108) in which a power semiconductor (104) arranged on a substrate (102) is embedded, a step of removing a part of the printed circuit board (108) in order to at least partially expose a side of the substrate (102) facing away from the power semiconductor (104), and a step of forming a coolant guide structure (106) for guiding a liquid coolant in the substrate (102) starting from the side of the substrate (102) facing away from the power semiconductor (104).

Description

[0001] The present invention relates to a method for manufacturing a semiconductor unit and to a method for manufacturing a semiconductor device. Additionally, a semiconductor unit, a power converter, an electric axle drive, and a motor vehicle are presented.

[0002] Electrical components carrying current, such as power semiconductors, typically heat up, which is why cooling the components is common practice.

[0003] The state of the art is disclosed in US 2019 / 0 123 030 A1, US 2024 / 0 162 116 A1 and US 2020 / 0 105 644 A1.

[0004] Against this background, the present invention provides an improved method for manufacturing a semiconductor unit, an improved method for manufacturing a semiconductor device, an improved semiconductor unit, an improved power converter, an improved electric axle drive, and an improved motor vehicle according to the main claims. Advantageous embodiments are described in the dependent claims and the following description.

[0005] The presented approach offers a way to increase the cooling surface area for electrical components, thereby improving heat dissipation. This can advantageously reduce the risk of malfunctions due to overheating.

[0006] A method for manufacturing a semiconductor unit for a power converter is presented, wherein the method comprises a step of providing a printed circuit board apparatus having a printed circuit board in which a power semiconductor arranged on a substrate is embedded. The method further comprises a step of removing a portion of the printed circuit board to at least partially expose a side of the substrate facing away from the power semiconductor, and a step of forming a coolant guide structure for guiding a liquid coolant in the substrate from the side of the substrate facing away from the power semiconductor.

[0007] The printed circuit board (PCB) assembly can represent a circuit carrier that may include one or more embedded power semiconductors. A power semiconductor, together with the substrate, can be, for example, a power transistor, such as a GaN-on-Si transistor, or another component suitable for high electrical currents or voltages. For the power converter mentioned as an example, the PCB assembly could include six or twelve embedded power transistors. The power semiconductor can be a component consisting of layers of different semiconductor materials with varying band gaps, such as gallium nitride (GaN), aluminum gallium nitride (AlGaN), or aluminum indium nitride (AlInN). Thus, the power semiconductor can be a high-electron mobility transistor (HEMT). The substrate can be silicon.Power semiconductor structures can be grown or deposited on the substrate. The layered structure of power semiconductor and substrate can also be referred to as a bare die, which may be embedded into the printed circuit board (PCB) using a process called embedding. The PCB assembly can, for example, be a blank that can be machined to fabricate the semiconductor unit. The PCB can be, for example, a printed circuit board (PCB) that can serve as a carrier for electronic components. The coolant flow structure can advantageously form multiple cooling channels, creating numerous contact surfaces for the liquid coolant. This allows the liquid coolant to flow directly through a section of the substrate, thus enabling efficient heat dissipation.

[0008] According to one embodiment, the portion of the circuit board can be removed by drilling or milling during the removal step. Advantageously, known methods can be used, thereby saving manufacturing costs.

[0009] During the insertion step, a substrate layer can remain between the coolant conduction structure and the power semiconductor. This substrate layer prevents direct contact between the liquid coolant and the power semiconductor. Advantageously, this allows the use of any liquid coolant, thus reducing costs. Furthermore, the remaining substrate layer eliminates the need for electrical insulation of the coolant.

[0010] According to one embodiment, the coolant guide structure can be formed in the substrate by etching during the forming step. Advantageously, the coolant guide structure can be introduced into the substrate very precisely by laser etching or fluid etching.

[0011] In the provisioning step, the substrate can be a silicon substrate. Thus, a substrate known in connection with semiconductors can be used.

[0012] The power semiconductor can have an aluminum gallium nitride layer and a gallium nitride layer. Advantageously, this material combination allows for high electrical conductivity and enables high operating voltages.

[0013] According to one embodiment, during the molding step, the coolant guide structure can be formed in the substrate in a rib-like, labyrinthine, or pin-like manner. The coolant guide structure advantageously increases the cooling surface area between the liquid coolant and the substrate. Furthermore, the flow direction of the liquid coolant can be controlled.

[0014] During the assembly step, the printed circuit board (PCB) can have at least one via for electrically contacting a terminal of the power semiconductor. Advantageously, the PCB can also have additional vias to, for example, electrically contact three terminals of a power transistor. This eliminates the need for bond wires, thus avoiding the problem of bond wire deformation due to pressure.

[0015] According to one embodiment, a contact section for electrically contacting the power semiconductor via the substrate can remain adjacent to the coolant guide structure during the forming step. For example, the contact section can be used to contact a gate of a power transistor.

[0016] During the removal step, an adjacent portion of the printed circuit board (PCB) can be removed to create a channel for directing the liquid coolant along the PCB. The liquid coolant can then be routed to or from the coolant guide structure via this channel. For example, material from the PCB can be removed from opposite sides of the coolant guide structure to form a continuous cooling channel.

[0017] Advantageously, more than one power semiconductor can be embedded in the printed circuit board (PCB). Thus, in the provisioning step, the PCB assembly can be provided, which includes the PCB in which at least one additional power semiconductor, mounted on an additional substrate, is embedded. In the removal step, an additional portion of the PCB can be removed to at least partially expose the side of the additional substrate facing away from the additional power semiconductor. In the forming step, an additional coolant guide structure for guiding the liquid coolant within the additional substrate can be formed from the side of the additional substrate facing away from the additional power semiconductor. Thus, each embedded power semiconductor can be provided with its own coolant guide structure.Advantageously, adjacent coolant guide structures can be connected via a guide channel formed in the circuit board to guide the liquid coolant.

[0018] Furthermore, a method for manufacturing a semiconductor device for a power converter is presented, wherein the method comprises a step of providing a first semiconductor unit and a second semiconductor unit, which are units manufactured using a method in a previously mentioned variant. In an assembly step, the first semiconductor unit and the second semiconductor unit are joined together, wherein the coolant guide structure of the first semiconductor unit and the coolant guide structure of the second semiconductor unit are arranged opposite each other to form a common cooling channel.

[0019] Advantageously, the semiconductor units can be implemented in a uniform manner. The semiconductor device can advantageously be used for a power converter, such as those used in vehicles.

[0020] According to one embodiment, the coolant guide structure and the further coolant guide structure can be connected directly or using intermediate pieces during the assembly step. The intermediate pieces can be designed as extensions to lengthen the coolant guide structures so that they can be connected. Advantageously, this increases the contact area for the liquid coolant.

[0021] Furthermore, a semiconductor unit for a power converter is presented, wherein the semiconductor unit comprises a power semiconductor arranged on a substrate, wherein the substrate has a coolant guide structure for guiding a liquid coolant on a side of the substrate facing away from the power semiconductor, and a printed circuit board in which the power semiconductor arranged on the substrate is embedded, wherein the printed circuit board has a recess leading to the coolant guide structure.

[0022] Advantageously, heat can be dissipated more easily, since the recess with the coolant guide structure can be shaped as part of a cooling channel through which the liquid coolant can be guided.

[0023] According to one embodiment, the printed circuit board (PCB) can have an additional power semiconductor arranged on an additional substrate, wherein the additional substrate can have an additional coolant guide structure for guiding the liquid coolant on a side of the additional substrate facing away from the additional power semiconductor. The additional power semiconductor arranged on the additional substrate can be embedded in the PCB, wherein the PCB can have an additional recess leading to the additional coolant guide structure. The recess and the additional recess can be connected to each other by a guide channel in the PCB for directing the liquid coolant from the power semiconductor to the additional power semiconductor. Advantageously, this allows a plurality of transistors to be arranged on one and the same PCB and cooled via a common cooling channel.

[0024] Furthermore, a semiconductor device is presented comprising a first semiconductor unit in a previously mentioned variant and a second semiconductor unit in a previously mentioned variant, wherein the coolant guide structure of the first semiconductor unit and the coolant guide structure of the second semiconductor unit are arranged opposite each other to create a common cooling channel.

[0025] The semiconductor device advantageously allows for more efficient use of existing installation space.

[0026] In addition, a power converter, in particular an inverter, for a motor vehicle is presented, comprising a semiconductor unit or semiconductor device in the previously mentioned variant. The power converter is characterized by the fact that the semiconductor unit or semiconductor device is configured as described.

[0027] In addition, an electric axle drive for a motor vehicle is presented, comprising at least one electric motor, a transmission unit, and an inverter. The electric axle drive is characterized by the fact that the inverter is designed as described.

[0028] The transmission device may include a gearbox for reducing the speed of the electric machine as well as a differential.

[0029] In addition, a motor vehicle with an electric axle drive and / or a power converter and / or a semiconductor unit is presented. The motor vehicle is characterized by the fact that the electric axle drive and / or the power converter and / or the semiconductor unit is designed as described.

[0030] The invention is explained in more detail by way of example with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of a semiconductor unit with a coolant guide structure according to an exemplary embodiment; Fig. 2 a schematic representation of an unprocessed printed circuit board device according to an exemplary embodiment; Fig. 3 a schematic representation of an exemplary embodiment of a machined printed circuit board device; Fig. 4 a schematic representation of an embodiment of a semiconductor unit for forming the coolant guide structure; Fig. 5 a schematic sectional view of an exemplary embodiment of a semiconductor unit; Fig. 6 a schematic sectional view of an exemplary embodiment of a semiconductor unit; Fig. 7 a schematic sectional view of an exemplary embodiment of a semiconductor unit; Fig. 8 a schematic sectional view of an embodiment of a semiconductor device with machined semiconductor units; Fig. 9 a flowchart of an exemplary embodiment of a method for manufacturing a semiconductor unit; Fig. 10 a flowchart of an embodiment of a method for manufacturing a semiconductor device; Fig. 11 a schematic representation of a motor vehicle according to an exemplary embodiment; and Fig. 12 a schematic representation of an exemplary embodiment of an arrangement of semiconductor units.

[0031] In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, without repeating these elements.

[0032] Fig. Figure 1 shows a schematic representation of a semiconductor unit 100 according to an exemplary embodiment. The semiconductor unit 100 is used, for example, in a power converter, which in turn can be used, for example, in a vehicle. The semiconductor unit 100 has been manufactured, for example, using a method as described with reference to the following figures.

[0033] The semiconductor unit 100 comprises a power semiconductor 104 mounted on a substrate 102. The substrate 102 with the power semiconductor 104 is also referred to, for example, as an unpackaged chip 105 or bare die. For example, the chip 105 represents a power transistor. The substrate 102 has a coolant guide structure 106, which is shaped to guide a liquid coolant. The coolant guide structure 106 is located on a side of the substrate 102 facing away from the power semiconductor 104.

[0034] The substrate 102 with the power semiconductor 104 is embedded in a printed circuit board 108, which in turn has a recess 110 leading to the coolant guide structure 106. According to one embodiment, the substrate 102 with the power semiconductor 104 is completely enclosed by the printed circuit board 108, except for the recess leading to the coolant guide structure 106.

[0035] According to this embodiment, the printed circuit board 108 has at least one via 112 configured to electrically contact a terminal of the power semiconductor 104. In particular, according to this embodiment, the printed circuit board 108 has a plurality of vias 112.

[0036] In Fig. Figure 1 shows a section axis 113. An example section along the section axis 113 is shown below. Fig. 5 shown.

[0037] According to one embodiment, the substrate 102 is designed as a silicon substrate. The power semiconductor 104 is based, by way of example, on a material combination of aluminum gallium nitride and gallium nitride. Thus, the power semiconductor 104 has, by way of example, an aluminum gallium nitride layer and a gallium nitride layer.

[0038] The coolant guide structure 106 has a suitable structure and is, for example, formed in a rib-like, labyrinthine, or pin-like manner within the substrate 102. The flow velocity of the liquid coolant can be influenced by a suitable choice of structure. In particular, according to this embodiment, the coolant guide structure 106 has a plurality of ribs 114, which increase the cooling surface area between the liquid coolant, also described as a fluid, and the substrate 102. This increases the cooling capacity. Due to the ribs 114, the liquid coolant experiences a low pressure drop when flowing through the coolant guide structure 106.

[0039] According to one embodiment, a contact section 116 for electrically contacting the power semiconductor 104 via the substrate 102 is formed adjacent to the coolant guide structure 106. The contact section 116 is contacted using at least one of the vias 112. Thus, the power semiconductor 104 can have electrical connections on both sides.

[0040] In other words, the described approach enables liquidon chip cooling for embedded electronic systems. The approach combines an embedding technology with liquid cooling of the chip 105 to both reduce parasitic currents and improve thermal performance. According to this embodiment, a portion of the printed circuit board 102 is removed to form the recess 110 after the chip 105 has been embedded in the printed circuit board 108. The resulting recess 110 then serves as a cooling surface for the liquid cooling on the chip 105.

[0041] In other words, the power semiconductor 104 is embedded on the substrate 102, which is referred to, for example, as GaN-on-Si. The substrate 102 is accessed, for example, by using lasers or drilling, and the coolant conduction structure 106 is formed by etching the substrate material. For example, a pattern is used during etching to create residual silicon columns to improve heat transfer. This enables, for example, liquid cooling on the chip 105 with suitable liquids to dissipate heat from the chip 105. Optionally, multiple chips 105 are arranged in 3D for electrical, mechanical, or thermal improvements, such as low-inductance layouts.

[0042] Due to its embedding in the printed circuit board 108, parasitic capacitances are minimal. High thermal performance is achieved through direct cooling of the chip 105, a so-called "liquid-on-chip cooling," as well as through the coolant guide structure 106, which is formed as cooling structures in the substrate 102. Advantageously, it is not necessary to electrically insulate the coolant flowing through the coolant guide structure 106, as would be required with standard liquid cooling on the chip 105.

[0043] Fig. Figure 2 shows a schematic representation of a printed circuit board (PCB) device 200 according to an exemplary embodiment. The PCB device 200 is, for example, designed as a blank that is processed in the method for manufacturing a semiconductor unit in order to produce the semiconductor unit, as is the case, for example, in Fig. As described in Figure 1. According to this embodiment, the chip 105 is still completely surrounded by printed circuit board material of the printed circuit board 108. Furthermore, according to this embodiment, the substrate 102 is unstructured. The substrate 102 and the power semiconductor 104 are stacked on top of each other, with the power semiconductor 104 extending, for example, over an entire surface of the substrate 102 facing the power semiconductor 104.

[0044] According to one embodiment, the vias 112 are already formed in the printed circuit board 108. For example, two of the vias 112 contact a surface of the power semiconductor 104 opposite the substrate 102. If the power semiconductor 104 is configured as a transistor, these two vias 112 are configured, for example, as a drain and source terminal. At least one further via 112 contacts, for example, a surface of the substrate 102 opposite the power semiconductor 104. If the power semiconductor 104 is configured as a transistor, this via 112 is configured, for example, as a gate terminal.

[0045] Fig. Figure 3 shows a schematic representation of an embodiment of a printed circuit board device 200, which is used, for example, in Fig. The circuit board device described in section 2 is similar. The only difference, according to this embodiment, is that compared to... Fig. Figure 2 shows a later intermediate result of a manufacturing process for the semiconductor unit. This means that, according to this embodiment, a portion of the printed circuit board material of the printed circuit board 108 was removed at the level of the substrate 102. This formed the recess 110 extending down to the substrate 102, as shown in Figure 2. Fig. 1 was described, was developed.

[0046] According to one embodiment, additional printed circuit board material adjacent to the recess 110 of the printed circuit board 108 has been removed to form a guide channel for directing the liquid coolant along the printed circuit board 108. The guide channel allows the liquid coolant used for cooling to be directed to the coolant guide structure 106 formed in the next process step, and vice versa. Furthermore, the guide channel allows the coolant guide structure 106 to be fluidically connected to at least one optional additional coolant guide structure 106, as is the case, for example, in Fig. 12 is shown.

[0047] Fig. Figure 4 shows a schematic representation of an embodiment of a semiconductor unit 100, which is used, for example, in Fig. The semiconductor unit described in section 1 corresponds to the semiconductor unit 100. This semiconductor unit is defined as a result of the process described in at least one of the Fig. The manufacturing process mentioned in sections 1 to 3 is carried out. According to this embodiment, the coolant guide structure 106 is formed in the substrate 102, for example, by means of a symbolically represented etching process 400, whereby a continuous substrate layer 402 remains between the coolant guide structure 106 and the power semiconductor 104. According to this embodiment, the etching process 400 is carried out via the recess 110. The coolant guide structure 106 corresponds, for example, to that described in Fig. The coolant guide structure described in 1 differs in that the coolant guide structure 106 is also implemented in a rib-like manner according to this embodiment.

[0048] Based on the Fig. Figures 2 to 4 illustrate the fabrication of a semiconductor unit 100 comprising a single power semiconductor 104. A semiconductor unit 100 comprising multiple power semiconductors can be fabricated in a similar manner. First, a printed circuit board 108 is provided, into which at least one additional power semiconductor, arranged on an additional substrate, is embedded. Then, an additional portion of the printed circuit board is removed to at least partially expose a side of the additional substrate facing away from the additional power semiconductor. This recess is used, as shown in Figures 2 to 4, to fabricate a semiconductor unit 100 comprising multiple power semiconductors. Fig. 4 shows how to form an additional coolant guide structure in the additional substrate.

[0049] Fig. Figure 5 shows a schematic sectional view of an embodiment of a semiconductor unit 100, which is used, for example, in at least one of the Fig. The semiconductor unit described or at least mentioned in sections 1 to 5 corresponds to this embodiment. According to this embodiment, the semiconductor unit 100 is shown as a top view along a cross-sectional axis, as is the case, for example, in Fig. As described in Figure 1. According to this embodiment, the substrate 102 is surrounded on at least two sides by the printed circuit board 108. The substrate 102 also has, according to this embodiment, the rib-like coolant guide structure 106, which forms a plurality of small cooling channels through the ribs 114. The ribs 114 thus define a flow direction 502 of the liquid coolant, which is represented symbolically in this embodiment.

[0050] Fig. Figure 6 shows a schematic sectional view of an embodiment of a semiconductor unit 100, which is used, for example, in Fig. The semiconductor unit described in section 5 is similar. Only the coolant conduction structure 106 differs from that described in section 5. Fig. The coolant guide structure 106 is described in Section 5. According to this embodiment, the coolant guide structure 106 is implemented in a labyrinthine manner. More precisely, according to this embodiment, the coolant guide structure 106 has a plurality of longitudinal struts 600, each with a plurality of transverse struts 602 arranged on the longitudinal struts 600. The longitudinal struts 600 are arranged parallel to and spaced apart from one another and extend at least approximately over the entire length of the substrate 102. The transverse struts 602 are offset from adjacent transverse struts 602 and extend transversely to the longitudinal struts 600 into the channels formed between the longitudinal struts 600. According to this embodiment, the substrate 102 has a coolant inlet 604 for introducing the liquid coolant into the cooling channel formed by the coolant guide structure 106.According to this embodiment, the coolant inlet 604 is arranged in a first corner region 606 of the substrate 102. Furthermore, according to this embodiment, the substrate 102 has a coolant outlet 608 for releasing the liquid coolant from the cooling channel formed by the coolant guide structure 106. According to this embodiment, the coolant outlet 608 is arranged in a second corner region 610 of the substrate 102, which is diagonally opposite the first corner region 606. According to this embodiment, the liquid coolant flows through the substrate 102 in a meandering pattern with respect to the longitudinal struts 600 and additionally in a meandering pattern with respect to the transverse struts 602 until it is released via the coolant outlet 608.Due to the multiple meandering flow direction 502 of the liquid coolant through the coolant guide structure 106, the flow velocity is slowed down and thus, according to this embodiment, a higher pressure loss occurs than, for example, in . Fig. 5. In this embodiment as well, the coolant guide structure 106 increases the cooling surface area between the liquid coolant and the substrate 102, thus increasing the cooling capacity. Furthermore, the direction of the coolant flow is controlled.

[0051] Fig. Figure 7 shows a schematic sectional view of an embodiment of a semiconductor unit 100, which is described in the Fig. The semiconductor unit described or at least mentioned in sections 1 to 6 is at least similar. Only the coolant conduction structure 106 differs from that described in the Fig. 5 and Fig. The coolant guide structure described in Section 6 is derived from this embodiment. According to this embodiment, the coolant guide structure 106 is pin-like or implemented as an etched silicon labyrinth structure, which increases the cooling surface area between the liquid and the substrate 102 and thus increases the cooling performance. The flow direction 502 of the liquid coolant corresponds to that described in Section 6. Fig. The flow direction described in section 5. According to this embodiment, the coolant guide structure 106 causes a mean pressure drop of the liquid coolant. The coolant guide structure 106 was formed, for example, by an etching process. The pin fins, for example, increase the cooling surface area between the liquid and the substrate 102, which increases the cooling capacity.

[0052] Fig. Figure 8 shows a schematic sectional view of an embodiment of a semiconductor device 800, comprising a first semiconductor unit 100 and a second semiconductor unit 100'. The semiconductor units 100, 100' are implemented identically and correspond, for example, to the one in at least one of the Fig. 1 to 5 described or mentioned in the semiconductor unit. The coolant guide structure 106 of the first semiconductor unit 100 and the coolant guide structure 106' of the second semiconductor unit 100' are arranged opposite each other to form a common cooling channel 802. According to this embodiment, the coolant guide structure 106 and the second coolant guide structure 106' are connected directly or by means of intermediate pieces 804. According to this embodiment, the intermediate pieces 804 are designed as pin fins, which increase the cooling surface area between the liquid coolant and the substrate 102 of the semiconductor unit 100, or the second substrate 102' of the second semiconductor unit 100'.The two semiconductor units 100, 100' are realized in the same way, for example, in which two identical etched coolant guide structures 106, 106' are connected to create a single coolant flow channel 802 and thus reduce the number of cooling channels per design.

[0053] Fig. Figure 9 shows a flowchart of an embodiment of a method 900 for manufacturing a semiconductor unit, such as those found in at least one of the Fig. 1 to 7 described or at least mentioned. Method 900 comprises a provisioning step 902, a removal step 904, and a forming step 906. In provisioning step 902, a printed circuit board apparatus is provided, comprising a printed circuit board in which a power semiconductor arranged on a substrate is embedded. In removal step 904, a portion of the printed circuit board is removed to at least partially expose a side of the substrate facing away from the power semiconductor. In forming step 906, a coolant guide structure for guiding a liquid coolant in the substrate is formed from the side of the substrate facing away from the power semiconductor.

[0054] According to one embodiment, in step 902 of the provisioning process, the printed circuit board is provided which has at least one via for electrically contacting a terminal of the power semiconductor.

[0055] In step 904 of the removal process, the part of the circuit board is removed, for example, by drilling or milling.

[0056] Optionally, in step 906 of the forming process, a substrate layer remains between the coolant conduction structure and the power semiconductor. Furthermore, optionally, the coolant conduction structure is formed in the substrate by etching. According to this embodiment, in step 906 of the forming process, the coolant conduction structure is formed in the substrate in a rib-like, labyrinthine, or pin-like manner. Only optionally is a contact section left adjacent to the coolant conduction structure for electrically contacting the power semiconductor via the substrate.

[0057] When a semiconductor unit comprising multiple power semiconductors is manufactured, in step 902 of the provisioning process, the printed circuit board (PCB) is provided with at least one additional or several additional embedded power semiconductors, each arranged on an additional substrate. In step 904, further PCB material is removed to at least partially expose the at least one additional substrate. Optionally, further PCB material is removed to form one or more channels through which the liquid coolant can be circulated during operation of the semiconductor unit.

[0058] Fig. Figure 10 shows a flowchart of an embodiment of a method 1000 for manufacturing a semiconductor device for a power converter, such as that found, for example, in Fig. 8 was described. The method 1000 comprises a step 1002 of providing a first semiconductor unit and a second semiconductor unit, which are produced using a method such as that described, for example, in Fig. The process 1000 comprises a step 1004 of joining the first semiconductor unit and the second semiconductor unit, wherein the coolant guide structure of the first semiconductor unit and the coolant guide structure of the second semiconductor unit are arranged opposite each other to create a common cooling channel. Optionally, the coolant guide structure and the other coolant guide structure are connected to each other directly or using intermediate pieces in step 1004 of the joining process.

[0059] Fig. Figure 11 shows a schematic representation of a motor vehicle 1100 according to an exemplary embodiment. The motor vehicle 1100 is also referred to, for example, as a vehicle and has an electric axle drive 1102, which in turn comprises at least one electric machine 1104, a transmission unit 1106, and a power converter 1108. The electric machine 1104 is also referred to, for example, as a drive unit or an electric motor and is coupled, for example, to the transmission unit 1106. The motor vehicle 1100 further comprises a power supply unit 1110, which is referred to, for example, as a battery. According to this exemplary embodiment, the power converter 1108 is connected between the power supply unit 1110 and the electric machine 1104. The power converter 1108 has a plurality of switches 1112, for example, six in number.The switches 1112 are implemented in the form of power semiconductors shaped as power transistors, which are part of a semiconductor unit 100 or a semiconductor device 800, as described with reference to the preceding figures or the following figure.

[0060] Fig. Figure 12 shows a schematic representation of an embodiment of a semiconductor unit 100, which is used, for example, in at least one of the Fig. The semiconductor unit described in sections 1 to 7 is at least similar, but in addition to a power semiconductor 104, it has a plurality of additional power semiconductors 1200, 1201. Each of the power semiconductors 104, 1200, 1201 represents, for example, a power transistor. Thus, the Fig. 12 Semiconductor units 100 shown, for example, for the purpose of Fig. The 11 power converters shown are used.

[0061] In particular, the semiconductor unit 100 according to this embodiment is similar to the one in Fig. 7 described semiconductor unit, since the in Fig. 12 Semiconductor unit 100 shown, the pin-like structured substrate 102, i.e., the one based on Fig. 7 described coolant guide structure 106, has.

[0062] According to this embodiment, the semiconductor unit 100 additionally comprises at least one additional power semiconductor 1200, which corresponds to the power semiconductor 104 and thus includes an additional substrate 1204 with an additional coolant guide structure 1206 for guiding the liquid coolant on a side of the additional substrate 1204 facing away from the additional power semiconductor 1200. The additional power semiconductor 1200 arranged on the additional substrate 1204 is embedded in the printed circuit board 108. The printed circuit board 108 has an additional recess 1208 leading to the additional coolant guide structure 1206.

[0063] According to this embodiment, the recess 110 and the additional recess 1208 are connected to each other by a guide channel 1210 of the circuit board 108 for guiding the liquid coolant from the power semiconductor 104 to the additional power semiconductor 1200.

[0064] The other 1201 power semiconductors are equipped with a corresponding coolant conduction structure. However, differently shaped coolant conduction structures can also be used.

[0065] According to one embodiment, the printed circuit board 108 has a plurality of guide channels 1210, 1212, 1214, which, for example, branch and / or are arranged parallel to each other. Each of the plurality of guide channels 1210, 1212, 1214 can therefore cool several of the power semiconductors 104, 1200, 1201.

[0066] According to one embodiment, each of the power semiconductors 104, 1200, 1201, together with the respective substrate 102, 1204, constitutes a transistor embedded in the printed circuit board 108. This is referred to in technical circles as "embedding". The bare-die transistor thus consists, in simplified terms, of the components in Fig. 1 layers shown, for example AlGaN / GaN for the power semiconductor 104, 1200, 1201 and silicon for the substrate 102, 1204.

[0067] According to one embodiment, these transistors are manufactured individually and embedded in the printed circuit board 108 during its manufacturing process. This printed circuit board 108, plus several embedded transistors, forms, for example, a converter unit or another circuit.

[0068] In Fig. Figure 12 is merely an example of a possible representation of the cooling channels, here referred to as guide channels 1210, 1212, 1214, in a converter unit. Reference sign 100 semiconductor units 102 Substrat 104 Power semiconductors 105 Chip 106 Coolant guide structure 108 circuit boards 110 recess 112 Via 113 Cutting axis 114 ribs 116 Contact section 200 printed circuit board setup 400 Etching process 402 Substrate layer 502 Flow direction 600 longitudinal struts 602 cross braces 604 Coolant inlet 606 first corner area 608 Coolant outlet 610 second corner area 100' additional semiconductor unit 102' further substrate 106' further coolant guide structure 800 semiconductor device 802 Cooling channel 804 spacers 900 methods for manufacturing a semiconductor unit Step 902 of deployment 904th step of removal 906th step of shaping 1000 methods for manufacturing a semiconductor device Step 1002 of deployment Step 1004 of the assembly process 1100 motor vehicles 1102 electric axle drive 1104 electric machine 1106 Gearbox unit 1108 Power converters 1110 Energy supply facility 1112 Plural of switches 1200 additional power semiconductors 1201 additional power semiconductors 1204 additional substrate 1206 additional coolant guide structure 1208 additional recess 1210 guide channel 1212 further guide channel 1214 further guide channel

Claims

Method (900) for manufacturing a semiconductor unit (100) for a power converter (1108), wherein the method (900) comprises the following steps: providing (902) a printed circuit board apparatus (200) comprising a printed circuit board (108) in which a power semiconductor (104) arranged on a substrate (102) is embedded; removing (904) a portion of the printed circuit board (108) to at least partially expose a side of the substrate (102) facing away from the power semiconductor (104); and forming (906) a coolant guide structure (106) for guiding a liquid coolant in the substrate (102) from the side of the substrate (102) facing away from the power semiconductor (104). Method (900) according to claim 1, wherein in step (904) of removal the part of the circuit board (108) is removed by drilling or milling. Method (900) according to one of the preceding claims, wherein in step (906) of forming a substrate layer (402) remains between the coolant guide structure (106) and the power semiconductor (104). Method (900) according to one of the preceding claims, wherein in step (906) of forming the coolant guide structure (106) is formed by etching in the substrate (102). Method (900) according to one of the preceding claims, wherein in step (902) of provisioning the substrate (102) is a silicon substrate, and / or wherein the power semiconductor (104) comprises an aluminum gallium nitride layer or a gallium nitride layer. Method (900) according to one of the preceding claims, wherein in step (902) of provisioning the printed circuit board (108) has at least one via (112) for electrically contacting a terminal of the power semiconductor (104). Method (900) according to one of the preceding claims, wherein in step (906) of the forming process a contact section (116) for electrically contacting the power semiconductor (104) via the substrate (102) remains adjacent to the coolant guide structure (106). Method (900) according to one of the preceding claims, wherein in the removal step (904) a further part of the printed circuit board (108) adjacent to the part of the printed circuit board (108) is removed in order to form a guide channel (1210) for guiding the liquid coolant along the printed circuit board (108). Method (900) according to one of the preceding claims, wherein in the provisioning step (902) the printed circuit board device (200) is provided, which has the printed circuit board (108) in which at least one additional power semiconductor (1200) arranged on an additional substrate (1204) is embedded, in the removal step (904) an additional part of the printed circuit board (108) is removed in order to at least partially expose a side of the additional substrate (1204) facing away from the additional power semiconductor (1200), and in the forming step (906) an additional coolant guide structure (1206) for guiding the liquid coolant in the additional substrate (1204) is formed starting from the side of the additional substrate (1204) facing away from the additional power semiconductor (1200). Method (1000) for manufacturing a semiconductor device (800) for a power converter (1108), wherein the method (1000) comprises the following steps: providing (1002) a first semiconductor unit (100) and a second semiconductor unit (100'), the units being manufactured using a method (900) according to any one of claims 1 to 9; and joining (1004) the first semiconductor unit (100) and the second semiconductor unit (100'), wherein the coolant guide structure (106) of the first semiconductor unit (100) and the coolant guide structure (106') of the second semiconductor unit (100') are arranged opposite each other to form a common cooling channel (802). Method (1000) according to claim 10, wherein the coolant guide structure (106) and the further coolant guide structure (106') are joined together directly or using intermediate pieces (804) in step (1004).

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