Method for producing semiconductor component having semiconductor element and substrate

Abstract

The invention relates to a method for producing a semiconductor component (2) having a semiconductor element (4) and a substrate (12). In order to improve the reliability of the semiconductor component (2), the following steps are proposed: a first power contact (6) of the semiconductor element (4) is integrally bonded (A) to a first metallization (10) of the substrate (12), and a second power contact (8) of the semiconductor element (4) arranged on the side of the semiconductor element (4) facing away from the substrate (12) is integrally bonded (A) to a molded metal body (20), the metal contact element (22) is brought into contact (B) with the second power contact (8) via the metal molded body (20), the metal contact element (22) is pressed (C) onto the semiconductor element (4) via a dielectric pressing element (26), a force (F) acting vertically on the semiconductor element (4) being transmitted via the dielectric pressing element (26).

Description

Technical Field

[0001] The invention relates to a method for producing a semiconductor component having a semiconductor element and a substrate.

[0002] Furthermore, the invention relates to a semiconductor component having a semiconductor element and a substrate.

[0003] Furthermore, the invention relates to a power converter having at least one such semiconductor component. Background Art

[0004] Such semiconductor components are usually used in power converters. A power converter is understood to be, for example, a rectifier, an inverter, a converter or a DC transformer. In addition, the semiconductor elements used in the semiconductor module assembly are transistors, diodes, bidirectional thyristors or thyristors. The transistor is implemented, for example, as an insulated gate bipolar transistor (IGBT), a field effect transistor or a bipolar transistor. Such a transistor can include control contacts and load contacts. Usually, the semiconductor elements are contacted via bonding wires, which in particular contain aluminum.

[0005] Publication EP 3 958 306 A1 describes a power module having at least two power semiconductor components contacted on a substrate, the power semiconductor components being arranged in a housing. In order to improve the reliability of the power module, it is proposed that the power semiconductor components each have at least one semiconductor component, wherein the housing has power connectors on opposite sides, wherein the substrate has supply lines from the power connectors to the power semiconductor components, wherein the supply lines are arranged on the substrate in such a way that the current is supplied in a symmetrical manner.

[0006] Publication WO 2022 / 002464 A1 describes a power module having at least two power cells, each of which has at least one power semiconductor and a substrate. In order to reduce the required installation space of the power module and improve heat dissipation, it is proposed that at least one power semiconductor is connected to the corresponding substrate in a material-bonded manner, wherein the substrates of at least two power cells are each directly connected to the surface of a common heat sink in a material-bonded manner.

[0007] Patent document DE 20 2012 004 434 U1 describes a metal molded body for creating a connection of a power semiconductor with a top-side potential surface to a thick wire or a strip, wherein at least one section is separated by the metal molded body, the metal molded body is projected onto one or more surfaces and from which at least one section is electrically separated from the remaining metal molded body, the section extending from a contact section to the potential surface of the power semiconductor to a fastening section for a thick wire laterally spaced therefrom.

[0008] In particular, with increasing currents, which are injected into the chip at a constant chip area, the bond wires usually used reach their limits, for example with regard to load cycle durability. Summary of the invention

[0009] Against this background, the object of the present invention is to disclose a semiconductor component which has improved reliability.

[0010] According to the invention, this object is achieved by a method for producing a semiconductor component having a semiconductor element and a substrate, comprising the following steps: connecting a first power contact of the semiconductor element to a first metallization of the substrate in a materially fitting manner, and connecting a second power contact of the semiconductor element arranged on the side of the semiconductor element facing away from the substrate in a materially fitting manner to a metal molded body, contacting a metal contact element with the second power contact via the metal molded body, and pressing the metal contact element onto the semiconductor element via a dielectric clamping element, wherein a force acting perpendicularly on the semiconductor element is transmitted via the dielectric clamping element, wherein the metal contact element directly contacts the metal molded body in a planar manner.

[0011] Furthermore, according to the invention, the object is achieved by a semiconductor component having a semiconductor component and a substrate, wherein the semiconductor component has a first power contact and a second power contact, wherein the first power contact is connected to a first metallization portion of the substrate in a material-fitting manner, wherein the second power contact is connected to a metal molded body on a side of the semiconductor component facing away from the substrate in a material-fitting manner, wherein the metal contact element is in contact with the second power contact via the metal molded body, wherein the metal contact element is pressed onto the semiconductor component via a dielectric clamping element, wherein a force acting perpendicularly on the semiconductor component is transmitted via the dielectric clamping element, wherein the metal contact element is in direct contact with the metal molded body in a planar manner.

[0012] Furthermore, according to the invention, the object is achieved by a power converter having at least one such semiconductor component.

[0013] The advantages and preferred embodiments described below with regard to the semiconductor component can be transferred analogously to the power converter and the method.

[0014] The idea of ​​the present invention is to improve the load cycle durability of semiconductor components by improved contact of semiconductor elements. The first load contact of the semiconductor element is connected to the first metallization of the substrate in a material-matching manner. The first metallization of the substrate can be implemented as a structured and arranged on a dielectric material layer, which can also contain ceramic materials, such as aluminum nitride or aluminum oxide or organic materials. For example, the first metallization is implemented as a copper covering layer. On the side of the semiconductor element facing away from the substrate, the metal molded body is connected to the second load contact of the semiconductor element in a material-matching manner. The metal molded body can also be implemented as a metal sheet, especially a copper sheet. The connection of the semiconductor element to the first metallization and to the material matching of the metal molded body can also be made by welding, sintering or by connecting an adhesive, such as an electrically conductive and thermally conductive adhesive. Alternatively, the metal molded body can be applied to the second load contact of the semiconductor element by means of an additional method, especially by means of a thermal spraying process, such as cold gas spraying, and in this way connected to the second load contact of the semiconductor element in a material-matching manner.

[0015] In a further step, the metal contact element is contacted with the second load contact via the metal molded body. Furthermore, the metal contact element can be implemented as a thin metal sheet or a metal disk, which can be made of copper, aluminum, silver, gold or alloys thereof, for example, and can achieve a large contact surface with the metal molded body. In particular, the metal contact element can be configured to contact the first metallization of the substrate or a connector leading to the outside.

[0016] The metal contact element is then pressed onto the metal molded body and thus onto the semiconductor element via the dielectric clamping element. The dielectric clamping element can, for example, contain a dielectric elastomer. The clamping is applied by transmitting a force acting vertically on the second load contact of the semiconductor element via the dielectric clamping element. In particular, the dielectric clamping element has at least one flat surface, which is placed in a planar manner on the metal contact element, wherein force is then applied to the dielectric clamping element in order to press the dielectric clamping element onto the metal molded body. In this way, a relatively large-area contact is achieved by the metal contact element, which leads to a high current carrying capacity and in particular improves the load cycle durability of the semiconductor component. Thus, for example, when it is installed in a power converter, an improved reliability of the semiconductor component is achieved. In addition, in particular compared to standard bonding processes, the architecture of the semiconductor component is retained to a large extent. In addition, such a manufacturing process can be integrated into a standard series production process simply and at low cost.

[0017] The metal contact element directly contacts the metal molded body in a planar manner. The direct contact is achieved without any other connection methods, such as soldering or adhesives. Such contact is simple and reliable, especially in combination with compression.

[0018] Another embodiment provides that the semiconductor component is encapsulated after the pressing. For example, a sealing compound containing silicone ensures that the required voltage gap is maintained. In addition, such an encapsulation serves to protect against harmful environmental influences.

[0019] A further embodiment provides that the dielectric clamping element undergoes a predominantly elastic deformation during the clamping. For example, the dielectric clamping element comprises a dielectric elastomer, such as PUR, PVC or silicone. The predominantly elastic deformation ensures sufficient contact pressure even during load changes and temperature fluctuations, thereby achieving improved reliability. Furthermore, height differences between the semiconductor element and the substrate as well as any tilting of the semiconductor element can be compensated, and this likewise has a positive effect on the reliability of the semiconductor component.

[0020] Another embodiment provides that the dielectric clamping element is clamped via the housing cover. In particular, in most cases, the housing cover is already made of a dielectric material, such as plastic, and can be fastened to the housing frame permanently, for example, by screwing or bonding, simply and inexpensively.

[0021] Another embodiment provides that, for connecting the second power contact, the metal contact element is connected to the first metallization of the substrate in a material-fitting manner. The material-fitting connection can also be produced by soldering, sintering, or by adhesion, for example using an electrically and thermally conductive adhesive. Such an arrangement can be realized simply and cost-effectively.

[0022] A further embodiment provides that, for connecting the second power contact, the metal contact element is pressed onto the first metallization of the substrate via a dielectric clamping element. Such a connection achieves improved reliability, in particular in the case of frequent load changes and temperature fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention is described and explained in more detail hereinafter on the basis of exemplary embodiments shown in the drawings.

[0024] The accompanying drawings show:

[0025] Figure 1 shows a schematic cross-sectional view of a first embodiment of a semiconductor component,

[0026] Figure 2 A flow chart showing a method for manufacturing a semiconductor component,

[0027] Figure 3 shows a schematic cross-sectional view of a second embodiment of a semiconductor component,

[0028] Figure 4 shows a schematic perspective view of a third exemplary embodiment of a semiconductor component,

[0029] Figure 5 A schematic diagram of a power converter is shown.

[0030] The exemplary embodiments set forth below are preferred embodiments of the present invention. In the exemplary embodiments, the components described in each embodiment represent individual features of the present invention, which should be considered independent of each other, and the further development of the present invention in each embodiment is also independent of each other, and therefore should be considered as individual or combined parts of the present invention, rather than as shown. In addition, the described embodiments can also be increased by the other features already described of the present invention.

[0031] The same reference symbols have the same meaning in different figures. DETAILED DESCRIPTION

[0032] Figure 1 A schematic cross-sectional view of a first embodiment of a semiconductor component 2 is shown, which includes a semiconductor element 4, which is implemented as a vertical power transistor, in particular an insulated gate bipolar transistor (IGBT). Further examples of such semiconductor elements 4 are bidirectional thyristors, thyristors, diodes or other types of transistors, such as field effect transistors and bipolar transistors. The semiconductor element 4 has a first load contact 6, a second load contact 8 and a control contact 9.

[0033] The first load contact 6 of the semiconductor element 4 is connected to the structured first metallization 10 of the substrate 12 in a materially bonded manner. The materially bonded connection of the semiconductor element 4 to the substrate 12 can also be made by a solder connection and / or a sintering connection, or by an adhesive connection, for example, using an electrically and thermally conductive adhesive. In addition, the substrate 12 has a dielectric material layer 14 and a second metallization 16 arranged on the side of the substrate 12 facing away from the first metallization 10. The dielectric material layer 14 can also contain a ceramic material, in particular aluminum nitride or aluminum oxide or an organic material. In addition, the substrate 12 is connected to the cooling body 18 in a materially bonded manner via the second metallization 16, so that the semiconductor element 4 is electrically insulated and thermally conductively connected to the cooling body 18 via the substrate.

[0034] The second load contact 8 of the semiconductor element 4, which is arranged on the side of the semiconductor element 4 facing away from the substrate 12, is connected in a materially bonded manner to a metal molded body 20, which serves as a buffer layer. For example, the metal molded body 20 is implemented as a metal sheet, which can also contain copper, aluminum, silver, gold, molybdenum or alloys thereof, which is connected to the control contact contact surface via a sintered connection. In addition, the metal sheet can have a single-sided or double-sided coating, for example, for producing a bonding connection. Such a coating can also contain aluminum, silver, gold, zinc or alloys thereof. Alternatively, the metal molded body 20 can be applied by means of an additional method, in particular by means of a thermal spraying process, such as cold gas spraying.

[0035] In addition, the metal contact element 22 is electrically conductively connected to the second load contact 8 of the semiconductor element 4 via the metal molded body 20, wherein the metal contact element 22, that is, without further connection means and in a planar manner, is directly in contact with the metal molded body 20. The metal contact element 22 is substantially flat in the contacting region of the metal molded body 20. In addition, the metal contact element 22 is fastened to one face of the first metallization 10 of the substrate 12 via a material-fit connection 24 by way of example. The material-fit connection 24 can also be produced by sintering, soldering or welding processes. In particular, the metal contact element 22 is made of copper, aluminum, silver, gold or other alloys.

[0036] The metal contact element 22 is pressed onto the metal molded body 20 connected to the semiconductor element 4 via a dielectric clamping element 26, which contains, for example, a dielectric elastomer, wherein a force F acting perpendicularly on the semiconductor element 4 is transmitted via the dielectric clamping element 26. The dielectric clamping element 26 is mainly elastically deformed when pressing the metal contact element 22 onto the metal molded body 20. In addition, the dielectric clamping element 26 is Figure 1 The housing cover 28 is pressed onto the semiconductor element 4 via a housing cover 28 made of a dielectric material having less elasticity than the dielectric clamping element 26. The housing cover 28 is fastened to the housing frame, for example, by means of screwing or adhesive bonding, which is not shown in the figure for reasons of simplicity. Figure 1 The housing cover 28 and the dielectric clamping element 26 can be designed as a single piece. Furthermore, the semiconductor component 2 is encapsulated between the housing cover 28 and the substrate 12 by means of an encapsulation compound 30 which contains silicone, for example, and serves to maintain the required voltage spacing and to protect against harmful environmental influences.

[0037] Figure 2 A flow chart of a method for producing a semiconductor component 2 is shown, for example Figure 1 The method comprises connecting A the first load contact 6 of the semiconductor element 4 to the first metallization 10 of the substrate 12 in a materially bonding manner and connecting A the second power contact 8 of the semiconductor element 4 arranged on the side of the semiconductor element 4 facing away from the substrate 12 to the metal molded body 20 in a materially bonding manner.

[0038] In a further step, the metal contact element 22 contacts B with the second load contact 8 via the metal molded body 20. The profiled contact element 22 contacts B directly on the metal molded body 20 and in a planar manner.

[0039] In a further step, the metal contact element 22 is pressed C onto the semiconductor element 4 via the dielectric clamping element 26, wherein the dielectric clamping element 26 is deformed predominantly elastically during the pressing C and a force F acting perpendicularly on the semiconductor element 4 is transmitted via the dielectric clamping element 26. After the pressing C, the semiconductor component 4 is encapsulated D by means of an encapsulation compound 30.

[0040] Figure 3 A schematic cross-sectional view of a second exemplary embodiment of a semiconductor component 2 is shown. The metallic contact element 22 is designed as a spring blade with a closed cross section, which has a flat section 32 and a spring section 34 in the region of contact with the metallic molded body 20 .

[0041] The flat section 32 is pressed directly and in a planar manner onto the metal molded body 20 via the dielectric clamping element 26. In addition, the elastic section 34 of the metal contact element 22 is pressed on both sides onto the first metallization 10 of the substrate 12, wherein the elastic section 34 and the dielectric clamping element 26 are deformed primarily elastically. In this way, the second load contact 8 of the semiconductor element 4 is connected to the first metallization 10 of the substrate 12 in a force-fitting manner without a material-fitting connection and without a connecting method such as solder, sintering paste or adhesive. Figure 3 Another embodiment of the semiconductor component 2 corresponds to Figure 1 Embodiment of a semiconductor component.

[0042] Figure 4 A schematic perspective view of a third exemplary embodiment of a semiconductor component 2 is shown, which comprises a semiconductor element 4 which is embodied as a transistor T. The transistor T is embodied by way of example as an IGBT, whose control contact 9 is connected to the first metallization 10 of the substrate 12 via a bonding wire 36. The metal contact element 22 is embodied as a lead frame and by way of example comprises four supply wires 38 arranged on both sides and is connected to the first metallization 10 of the substrate 12 via a material-bonding connection 24. The flat section 32 of the metal contact element 22 is formed by means of a bonding wire 36 for reasons of simplicity. Figure 4 The dielectric clamping element 26, which is only indicated by a dashed line in the figure, is pressed onto the semiconductor element 4. The housing frame 40 completely surrounds the substrate 12. The encapsulation compound defined by the housing frame 40 and the housing cover, which presses the metal contact element 22 onto the metal molded body 20 and thus onto the second load contact 8 of the semiconductor element 4 via the dielectric clamping element 26, is not shown in the figure for the sake of simplicity. Figure 4 Not shown in FIG. Figure 4 Another embodiment of the semiconductor component 2 corresponds to Figure 1 Embodiment of a semiconductor component.

[0043] Figure 5 A schematic diagram of a power converter 42 is shown which, by way of example, comprises a semiconductor component 2 .

[0044] In summary, the present invention relates to a method for producing a semiconductor component 2 having a semiconductor element 4 and a substrate 12. In order to improve the reliability of the semiconductor component 2, the following steps are proposed: a first power contact 6 of the semiconductor element 4 is connected A with a first metallization 10 of the substrate 12 in a materially bonding manner, and a second power contact 8 of the semiconductor element 4 arranged on the side of the semiconductor element 4 facing away from the substrate 12 is connected A with a metal molded body 20 in a materially bonding manner, a metal contact element 22 is contacted B with the second power contact 8 via the metal molded body 20, and the metal contact element 22 is pressed C onto the semiconductor element 4 via a dielectric clamping element 26, wherein a force F acting vertically on the semiconductor element 4 is transmitted via the dielectric clamping element 26.

Claims

1. A method for producing a semiconductor component (2), the semiconductor component having a semiconductor element (4) and a substrate (12), the method comprising the following steps: - connecting (A) a first power contact (6) of the semiconductor element (4) to a first metallization (10) of the substrate (12) in a materially bonded manner, and connecting a second power contact (8) of the semiconductor element (4) arranged on a side of the semiconductor element (4) facing away from the substrate (12) to a metal molded body (20) in a materially bonded manner, - contacting (B) a metal contact element (22) via the metal molded body (20) with the second power contact (8), - pressing (C) the metal contact element (22) onto the semiconductor element (4) via a dielectric clamping element (26), wherein a force (F) acting vertically on the semiconductor element (4) is transmitted via the dielectric clamping element (26), The metal contact element (22) is in direct contact with the metal molded body (20) in a planar manner.

2. The method according to claim 1, in, After the pressing (C), the semiconductor component (4) is encapsulated (D).

3. The method according to any one of the preceding claims, in, The dielectric clamping element (26) deforms predominantly elastically during the clamping (C).

4. The method according to any one of the preceding claims, in, The dielectric clamping element (26) is compressed via a housing cover (28).

5. The method according to any one of the preceding claims, in, In order to connect the second power contact (8), the metal contact element (22) is connected to the first metallization (10) of the substrate (12) in a material-fitting manner.

6. The method according to any one of claims 1 to 4, in, In order to connect the second power contact (8), the metal contact element (22) is pressed onto the first metallization (10) of the substrate (12) via the dielectric clamping element (26).

7. A semiconductor component (2) comprising a semiconductor element (4) and a substrate (12), in, The semiconductor element (4) has a first power contact (6) and a second power contact (8), The first power contact (6) is connected to the first metallization portion (10) of the substrate (12) in a material matching manner. The second power contact (8) is connected to the metal molded body (20) in a materially bonded manner on the side of the semiconductor element (4) facing away from the substrate (12), wherein the metal contact element (22) is in contact with the second power contact (8) via the metal molded body (20), The metal contact element (22) is pressed onto the semiconductor element (4) via a dielectric clamping element (26). wherein a force (F) acting vertically on the semiconductor element (4) is transmitted via the dielectric clamping element (26), The metal contact element (22) is in direct contact with the metal molded body (20) in a planar manner.

8. The semiconductor component (2) according to claim 7, The semiconductor component is encapsulated by means of a potting compound (34).

9. The semiconductor component (2) according to claim 7 or 8, in, The dielectric clamping element (26) is deformed primarily elastically by the compression (C).

10. The semiconductor component (2) according to any one of claims 7 to 9, in, The metal contact element (22) is embodied as a metal sheet or a lead frame.

11. The semiconductor component (2) according to any one of claims 7 to 10, in, The dielectric clamping element (26) is clamped via a housing cover (28).

12. The semiconductor component (2) according to any one of claims 7 to 11, in, In order to connect the second power contact (8), the metal contact element (22) is connected to the first metallization (10) of the substrate (12) in a material-fitting manner.

13. The semiconductor component (2) according to any one of claims 7 to 12, in, In order to connect the second power contact (8), the metal contact element (22) is pressed onto the first metallization (10) of the substrate (12) via the dielectric clamping element (26).

14. A power converter (42) having at least one semiconductor component (2) according to any one of claims 7 to 13.

Images