Method for producing a semiconductor assembly comprising a semiconductor element and a substrate, and corresponding device
Patent Information
- Application Number
- EP2023723581
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-06-29
- Filing Date
- 2023-05-05
- Publication Date
- 2025-02-05
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Method for producing a semiconductor assembly comprising a semiconductor element and a substrate, as well as the corresponding device
[0003] The invention relates to a method for producing a semiconductor device comprising a semiconductor element and a substrate.
[0004] Furthermore, the invention relates to a semiconductor device comprising a semiconductor element and a substrate.
[0005] Furthermore, the invention relates to a power converter with at least one such semiconductor arrangement.
[0006] Such a semiconductor module arrangement is generally used in a power converter. A power converter can be, for example, a rectifier, an inverter, a converter or a DC-DC converter. The semiconductor elements used in the semiconductor module arrangement include transistors, diodes, triacs or thyristors. The transistors are designed, for example, as insulated-gate bipolar transistors (IGBTs), field-effect transistors or bipolar transistors. Such transistors can comprise a control contact and load contacts. Semiconductor elements are usually contacted via bond wires, which in particular contain aluminum.
[0007] The published patent application EP 3 958 306 A1 describes a power module with at least two power semiconductor devices contacted on a substrate and arranged in a housing. To improve the reliability of the power module, it is proposed that the power semiconductor devices each have at least one semiconductor component, the housing having power terminals on opposite sides, the substrate having leads from the power terminals to the power semiconductor devices, the leads being arranged on the substrate in such a way that symmetrical current flow occurs.
[0008] The published patent application WO 2022 / 002464 A1 describes a power module with at least two power units, each comprising at least one power semiconductor and a substrate. In order to reduce the required installation space of the power module and to improve heat dissipation, it is proposed that the respective at least one power semiconductor be connected, in particular in a materially bonded manner, to the respective substrate, wherein the substrates of the at least two power units are each directly bonded to a surface of a common heat sink.
[0009] The patent specification DE 20 2012 004 434 Ul describes a metal molded body for creating a connection of a power semiconductor with top-side potential surfaces to thick wires or ribbons, wherein at least one segment is separated by a metal molded body which projects beyond one or more potential surfaces and from which it is electrically separated from the rest of the metal molded body, said segment extending from a contacting section on a potential surface of the power semiconductor to a fastening section for thick wires which is laterally spaced therefrom.
[0010] In particular, for ever larger currents impressed into the chip with a constant chip area, the bonding wires commonly used reach their limits, for example with regard to load cycling strength.
[0011] Against this background, it is an object of the present invention to provide a semiconductor device which has improved reliability.
[0012] This object is achieved according to the invention by a method for producing a semiconductor arrangement with a semiconductor element and a substrate comprising the following steps: materially connecting a first load contact of the semiconductor element to a first metallization of the substrate, materially connecting a metal molded body to a second load contact of the semiconductor element, which is arranged on a side of the semiconductor element facing away from the substrate, contacting a profiled contacting element, which is designed as a sheet, with the second load contact of the semiconductor element via the metal molded body, wherein a plurality of contact points are formed by means of the profiling and the pressing of the profiled contacting element onto the semiconductor element takes place via a housing cover,wherein the profiled contacting element (22) is contacted to connect the second load contact (8) to the first metallization (10) of the substrate (12).,
[0013] Furthermore, the object is achieved according to the invention by a semiconductor arrangement with a semiconductor element and a substrate, wherein the semiconductor element has a first load contact and a second load contact, wherein the first load contact is materially connected to a first metallization of the substrate, wherein a metal molded body is materially connected to the second load contact, wherein a profiled contacting element, which is designed as a sheet, is contacted via the metal molded body (20) with the second load contact, which is arranged on a side of the semiconductor element facing away from the substrate, wherein a plurality of contact points are formed by means of the profiling, wherein the profiled contacting element is pressed onto the semiconductor element via a housing cover,wherein the profiled contacting element is contacted to connect the second load contact with the first metallization of the substrate.,
[0014] Furthermore, the object is achieved according to the invention by a power converter having at least one such semiconductor device. The advantages and preferred embodiments listed below with regard to the semiconductor device can be applied analogously to the power converter and the method.
[0015] The invention is based on the idea of improving the load cycling strength of a semiconductor device by improved contacting of semiconductor elements. A first load contact of the semiconductor element is materially connected to a first metallization of a substrate. The first metallization of the substrate can be structured and arranged on a dielectric material layer which can contain, among other things, a ceramic material such as aluminum nitride or aluminum oxide or an organic material. For example, the first metallization is designed as a copper cladding. The materially bonded connection of the semiconductor element to the first metallization can be produced, among other things, by soldering, sintering, but also by an adhesive bond, e.g. with an electrically and thermally conductive adhesive.
[0016] A profiled contacting element is then contacted with a second load contact which, as is usual, for example, in a vertical power semiconductor, in particular IGBT, is arranged on a side of the semiconductor element facing away from the substrate, a large number of contact points being formed by means of the profiling. In particular, the contacting of the profiled contacting element on the semiconductor element takes place loosely, i.e. without a materially integral connection. The contacting element can be designed, among other things, as a sheet metal element, in particular a spring sheet metal element, which can be alternately periodically profiled in the region of the contact with the second load contact. An alternately periodic profiling can, among other things, comprise an infinitely continueable sequence of interconnected point-symmetrical individual profilings.An alternating periodic profiling, for example, is a substantially sinusoidal waveform. The contacting element can, for example, be configured to contact the first metallization of the substrate or to be connected to an external terminal.
[0017] In a further step, the profiled contacting element is pressed onto the semiconductor element via a housing cover. For example, a housing cover made of a dielectric material, in particular a polymer, exerts a force on the profiling of the contacting element that acts orthogonally to the second load contact. When the contacting element is subjected to pressure, it is deformed, in particular elastically. Contacting elements of this type have a high current-carrying capacity and, in particular, improve the load cycling strength of the semiconductor device. This leads to improved reliability. Furthermore, the architecture of the semiconductor device is largely retained, particularly in comparison to a standard bonding process, and a manufacturing process of this type can be easily and cost-effectively integrated into a standard series production process.
[0018] A materially bonded connection between a metal molded body and the second load contact of the semiconductor element takes place before contacting the profiled contacting element. Contacting the profiled contacting element with the second load contact of the semiconductor element takes place via the metal molded body. The metal molded body can be designed as a sheet which can contain, among other things, copper, aluminum, silver, gold, molybdenum or one of their alloys. The materially bonded connection between the semiconductor element and the metal molded body can be produced, among other things, by soldering, sintering, but also by an adhesive connection, e.g. with an electrically 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 additive process, in particular by means of a thermal spraying process such as cold gas spraying, and in this way be materially connected to the second load contact of the semiconductor element. The metal molded body distributes the pressure generated by the large number of contact points onto the semiconductor element. This ensures a more even pressure distribution, particularly in the event of mechanical or thermal load fluctuations occurring during operation, thus preventing, for example, breakage of the semiconductor element. The metal molded body thus improves the reliability of the semiconductor device.
[0019] Another embodiment provides for encapsulation of the semiconductor device after pressing. A potting compound, which contains, for example, silicone, maintains the required voltage gaps. Furthermore, such encapsulation serves as protection against harmful environmental influences.
[0020] A further embodiment provides for the profiled contact element to be contacted directly on the metal molded body. Direct contact is achieved without the need for additional connecting materials such as solder or adhesive. This type of contact is simple and reliable, especially when combined with pressing.
[0021] A further embodiment provides for the profiled contacting element to be predominantly elastically deformed when pressed on. For example, the profiled contacting element contains an elastic copper alloy such as CuZn37, CuSn6, CuNi18Zn20, copper beryllium, or a spring steel. Predominantly elastic deformation ensures sufficient contact pressure even during load changes and temperature fluctuations, thus achieving improved reliability. Furthermore, height differences between the semiconductor element and substrate, as well as any tilting of the semiconductor element, can be compensated for, which also has a positive effect on the reliability of the semiconductor device.
[0022] A further embodiment provides for a plurality of contact points to be formed by means of an S-shaped or trapezoidal profile of the profiled contacting element. Such profiles are simple and cost-effective to produce. Furthermore, such profiles achieve a homogeneous force and heat distribution as well as heat spreading across the chip surface.
[0023] A further embodiment provides that the profiled contacting element for connecting the second load contact is connected, in particular in a material-to-material manner, to a first metallization of the substrate. The material-to-material connection can be produced, among other things, by soldering, sintering, or even by adhesion, e.g., with an electrically and thermally conductive adhesive. Such an arrangement is simple and cost-effective to implement.
[0024] A further embodiment provides that the profiled contacting element for connecting the second load contact is pressed onto the first metallization of the substrate via the housing cover. Such a connection achieves improved reliability, particularly in the case of frequent load changes and temperature fluctuations.
[0025] In the following, the invention is described and explained in more detail with reference to the exemplary embodiments shown in the figures.
[0026] It shows :
[0027] FIG 1 is a schematic cross-sectional view of a first embodiment of a semiconductor device,
[0028] FIG 2 shows a flow diagram of a method for producing a semiconductor device,
[0029] FIG 3 is a schematic cross-sectional view of a second embodiment of a semiconductor device,
[0030] FIG 4 shows a schematic cross-sectional view of a third embodiment of a semiconductor device, FIG 5 shows a schematic perspective view of a fourth embodiment of a semiconductor device,
[0031] FIG 6 is a schematic diagram of a power converter.
[0032] The exemplary embodiments explained below are preferred embodiments of the invention. In the exemplary embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another. These also further develop the invention independently of one another and are thus to be regarded as components of the invention, either individually or in a combination other than that shown. Furthermore, the described embodiments can also be supplemented by further features of the invention already described.
[0033] The same reference symbols have the same meaning in the different figures.
[0034] FIG. 1 shows a schematic cross-sectional view of a first embodiment of a semiconductor arrangement 2, which comprises a semiconductor element 4 designed as a vertical power transistor, in particular as an insulated-gate bipolar transistor (IGBT). Further examples of such semiconductor elements 4 are triacs, thyristors, diodes, or other transistor types such as field-effect transistors and bipolar transistors. The semiconductor element 4 has a first load contact 6 and a second load contact 8; a control contact is not shown in FIG. 1 for reasons of clarity.
[0035] The first load contact 6 of the semiconductor element 4 is materially connected to a structured first metallization 10 of a substrate 12. The materially connected connection of the semiconductor element 4 to the substrate 12 can be produced, among other things, by a soldered connection and / or a sintered connection, but also by an adhesive connection, e.g. with an electrically and thermally conductive adhesive. The substrate 12 also has a dielectric material layer 14 and a second metallization 16 arranged on a side of the substrate 12 facing away from the first metallization 10. The dielectric material layer 14 can contain, among other things, a ceramic material, in particular aluminum nitride or aluminum oxide, or an organic material.Furthermore, the substrate 12 is connected to a heat sink 18 via the second metallization 16, in particular in a materially bonded manner, so that the semiconductor element 4 is in an electrically insulating and thermally conductive connection to the heat sink 18 via the substrate.
[0036] The second load contact 8 of the semiconductor element 4, which is arranged on a side of the semiconductor element 4 facing away from the substrate 12, is materially connected to a metal molded body 20 which functions as a buffer layer. For example, the metal molded body 20 is designed as a sheet, in particular as a copper sheet, which is connected to the control contact surface via a sintered connection. Furthermore, the sheet can have a one-sided and / or double-sided coating, for example for producing a bond connection. Such a coating can contain, among other things, aluminum, silver, gold, zinc or one of their alloys. Alternatively, the metal molded body 20 can be applied by means of an additive process, in particular by means of a thermal spraying process such as cold gas spraying.
[0037] Furthermore, a profiled contacting element 22, which is made of a metallic material, is in direct contact with the second load contact 8 via the shaped metal body 20, i.e. without any further connecting means. The profiled contacting element 22 is, for example, fastened on both sides to the first metallization 10 of the substrate 12 via a material-fit connection 24. The material-fit connection 24 can be produced, among other things, by sintering, soldering or a welding process. Furthermore, the contacting element 22 has an S-shaped profile 26 in the region of the contact with the second load contact 8, which profile is predominantly elastically deformable. For example, the profiled contacting element 22 contains an elastic copper alloy such as CuZn37, CuSn6, CuNi18Zn20, copper-beryllium or a spring steel.By means of the S-shaped profiling 26, a plurality of essentially linear contact points 28 are formed with the load contact 8. In particular, the contacting element 22 is designed as a spring plate which has a wave-shaped profile in the area of contact with the second load contact 8.
[0038] A force F acts on the S-shaped profile 26 of the contacting element 22 via a housing cover 30, which is made of a dielectric material, for example a polymer. In particular, the force F is directed so as to act orthogonally to the second load contact 8. In comparison to the profiled contacting element 22, the housing cover 30 does not deform noticeably. The profiled contacting element 22 is therefore pressed against the semiconductor element 4 by the housing cover 30. In order to exert a defined force F on the contacting element 22 by the housing cover 30, a defined distance d is created above the semiconductor element 4. The creation of the defined distance d from the semiconductor element 4 is realized in FIG 1 by way of example by a projection 32.Alternatively, the housing cover 30 can be designed in two parts with a, in particular cuboid-shaped, pressure element or, depending on the profiling 26 of the contacting element 22, can have a recess. Furthermore, the semiconductor arrangement 2 is potted between the housing cover 30 and the substrate 12 by means of a potting compound 34, which contains, for example, silicone and serves to maintain the required voltage distances and to protect against harmful environmental influences. FIG. 2 shows a flow diagram of a method for producing a semiconductor arrangement 2, which is designed, for example, as shown in FIG. 1, with a semiconductor element 4 and a substrate 12.The method comprises a material-to-material connection A of a first load contact 6 of the semiconductor element 4 to a first metallization 10 of the substrate 12 and of a second load contact 8 of the semiconductor element 4, which is arranged on a side of the semiconductor element 4 facing away from the substrate 12, to a metal molded body 20.
[0039] In a further step, contact B of a profiled contacting element 22 is made via the metal molded body 20 to the second load contact 8, wherein a plurality of contact points 28 are formed by means of the profiling 26. The contact B of the profiled contacting element 22 is made directly on the metal molded body 20.
[0040] In a further step, the profiled contacting element 22 is pressed C onto the semiconductor element 4 via a housing cover 30, wherein the profiled contacting element 22 is predominantly elastically deformed during the pressing C. After the pressing C, the semiconductor device 4 is potted D using a potting compound 34.
[0041] FIG 3 shows a schematic cross-sectional view of a second embodiment of a semiconductor arrangement 2. The profiled contacting element 22 is designed as a spring plate with a closed cross-section, which has an S-shaped profile 26 and, running parallel thereto, a straight section 36, the straight section 36 being in direct flat contact with the projection 32 of the housing cover 32. The S-shaped profile 26 of the contacting element 22 is pressed onto the metal molded body 20 and on both sides onto the first metallization 10 of the substrate 12 by the projection 32 of the housing cover 32. In this way, the second load contact 8 of the semiconductor element 4 is contacted with the first metallization 10 of the substrate 12 without a material-to-material connection and without connecting means such as solder, sintering paste or adhesive. The further design of the semiconductor device 2 in FIG 3 corresponds to that in FIG 1 .
[0042] FIG. 4 shows a schematic cross-sectional view of a third embodiment of a semiconductor device 2, wherein the contacting element 22 has a trapezoidal profile 26 in the region of the contact with the second load contact 8. The further embodiment of the semiconductor device 2 in FIG. 4 corresponds to that in FIG. 1.
[0043] FIG 5 shows a schematic perspective view of a fourth embodiment of a semiconductor arrangement 2, which comprises semiconductor elements 4 that are designed as transistors T1, T2 and diodes D1, D2. The transistors T1, T2, which are designed as IGBTs, for example, each have a control contact 38, which is connected to the first metallization 10 of the substrate 12 via a respective bonding wire 40. A housing frame 42 completely surrounds the substrate 12. A potting compound, which is delimited by the housing frame 42, and a housing cover, which contacts the profiled contacting elements 22 to the respective metal molded bodies 20 of the semiconductor elements 4, are not shown in FIG 5 for reasons of clarity. The housing cover is fastened to the housing frame 42 by means of screws. The further design of the semiconductor device 2 in FIG 5 corresponds to that in FIG 1 .
[0044] FIG 6 shows a schematic representation of a power converter 44, which comprises, for example, a semiconductor arrangement 2.
[0045] In summary, the invention relates to a method for producing a semiconductor arrangement 2 with a semiconductor element 4 and a substrate 12. In order to improve the reliability of the semiconductor arrangement 2, the following steps are proposed: materially bonding A of a first load contact 6 of the semiconductor element 4 to a first metallization 10 of the substrate 12, contacting B of a profiled contacting element 22 with a second load contact 8 of the semiconductor element 4, which is arranged on a side of the semiconductor element 4 facing away from the substrate 12, wherein a plurality of contact points 28 are formed by means of the profiling 26, pressing C of the profiled contacting element 22 onto the semiconductor element 4 via a housing cover 30.
Claims
Patent claims 1. A method for producing a semiconductor device (2) with a semiconductor element (4) and a substrate (12), comprising the following steps: materially bonding (A) a first load contact (6) of the semiconductor element (4) to a first metallization (10) of the substrate (12), materially bonding (A) a metal molding (20) with a second load contact (8) of the semiconductor element (4), which is arranged on a side of the semiconductor element (4) facing away from the substrate (12), contacting (B) a profiled contacting element (22), which is designed as a sheet, with the second load contact (8) of the semiconductor element (4) via the metal molded body (20), wherein a plurality of contact points (28) are formed by means of the profiling (26), Pressing (C) the profiled contacting element (22) onto the semiconductor element via a housing cover (30) (4), wherein the profiled contacting element (22) is contacted to connect the second load contact (8) to the first metallization (10) of the substrate (12).
2. Method according to claim 1, wherein the profiled contacting element (22) is alternately periodically profiled in the region of contact with the second load contact.
3. Method according to one of claims 1 or 2, wherein after the pressing (C) a potting (D) of the semiconductor device (4) takes place.
4. Method according to one of the preceding claims, wherein the contacting (B) of the profiled contacting element (22) takes place directly on the metal molded body (20).
5. Method according to one of the preceding claims, wherein the profiled contacting element (22) is predominantly elastically deformed during pressing (C).
6. Method according to one of the preceding claims, wherein the plurality of contact points (28) are formed by means of an S-shaped or trapezoidal profiling (26) of the profiled contacting element (22).
7. Method according to one of the preceding claims, wherein the profiled contacting element (22) for connecting the second load contact (8) is connected, in particular in a materially bonded manner, to the first metallization (10) of the substrate (12).
8. Method according to one of claims 1 to 6, wherein the profiled contacting element (22) for connecting the second load contact (8) is pressed via the housing cover (30) onto the first metallization (10) of the substrate (12).
9. Semiconductor arrangement (2) with a semiconductor element (4) and a substrate (12), wherein the semiconductor element (4) has a first load contact (6) and a second load contact (8), wherein the first load contact (6) is materially connected to a first metallization (10) of the substrate (12), wherein a metal molded body (20) is materially connected to the second load contact (8), wherein a profiled contacting element (22), which is designed as a sheet metal, is contacted via the metal molded body (20) with the second load contact (8), which is arranged on a side of the semiconductor element (4) facing away from the substrate (12), wherein a plurality of contact points (28) are formed by means of the profiling (26), wherein the profiled contacting element (22) is pressed onto the semiconductor element (4) via a housing cover (30), wherein the profiled contacting element (22) is contacted to connect the second load contact (8) to the first metallization (10) of the substrate (12).
10. Semiconductor arrangement (2) according to claim 9, wherein the profiled contacting element (22) is alternately periodically profiled in the region of the contact with the second load contact.
11. Semiconductor device (2) according to one of claims 9 or 10, which is cast by means of a casting compound (34).
12. Semiconductor device (2) according to one of claims 9 to 11, wherein the profiled contacting element (22) is directly contacted on the metal molded body (20).
13. Semiconductor device (2) according to one of claims 9 to 12, wherein the profiled contacting element (22) is predominantly elastically deformed by the pressing (C).
14. Semiconductor device (2) according to one of claims 9 to 13, wherein the profiled contacting element (22) is designed as a spring plate.
15. Semiconductor device (2) according to one of claims 9 to 14, wherein the profiling (26) of the profiled contacting element (22) is at least partially S-shaped or trapezoidal.
16. Semiconductor device (2) according to one of claims 9 to 15, wherein the profiled contacting element (22) for connecting the second load contact (8) is connected, in particular in a materially bonded manner, to the first metallization (10) of the substrate (12).
17. Semiconductor device (2) according to one of claims 9 to 15, wherein the profiled contacting element (22) for connecting the second load contact (8) is pressed onto the first metallization (10) of the substrate (12) via the housing cover (30).
18. Power converter (44) with at least one semiconductor device (2) according to one of claims 9 to 17.