Method for producing semiconductor assembly having semiconductor element and substrate, and corresponding device

Abstract

The invention relates to a method for producing a semiconductor component (2) having a semiconductor element (4) and a substrate (12), comprising the following steps: cohesively bonding (A) a first load contact (6) of the semiconductor element (4) to a first metallization (10) of the substrate (12), cohesively bonding (A) a metal molded body (20) to a second load contact (8) of the semiconductor element (4), a second load contact (8) is arranged on the surface of the semiconductor element (4) facing away from the substrate (12), contacting (B) a contoured contact element (22), which is designed as a metal sheet, with the second load contact (8) of the semiconductor element (4) via a molded metal body (20), a plurality of contact points (28) being formed by means of the contoured part (26), pressing (C) a contoured contact element (22) to the semiconductor element (4) via the housing cover (30), the contoured contact element (22) being in contact with the first metallization (10) of the substrate (12) in order to connect the second load contact (8). The invention also relates to a corresponding semiconductor component.

Description

Technical Field

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

[0002] The invention further 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 module arrangements are usually used in power converters. A power converter can be understood, for example, as a rectifier, an inverter, a converter or a DC voltage converter. Semiconductor elements used in semiconductor module arrangements include, but are not limited to, transistors, diodes, triacs or thyristors. Transistors are designed, for example, as insulated gate bipolar transistors (IGBTs), field effect transistors or bipolar transistors. Such transistors can include control contacts and load contacts. The semiconductor elements are usually 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 element, wherein the housing has power connectors on opposite sides, wherein the substrate has leads from the power terminals to the power semiconductor components, wherein the leads 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 units, each of which includes at least one power semiconductor and a substrate. In order to reduce the structural space required for the power module and improve heat dissipation, it is proposed that at least one corresponding power semiconductor is connected to the corresponding substrate, in particular in a material-bonded manner, wherein the substrates of at least two power units are respectively directly bonded to the surface of a common cooling body in a material-bonded manner.

[0007] Patent document DE 20 2012 004 434 U1 describes a metal molded body for creating a connection between a power semiconductor and the top-side potential surface of a cable or a ribbon, wherein at least one section is segmented from the metal molded body, the metal molded body protruding beyond one or more surfaces, and at least one section from the metal molded body is electrically separated from the rest of the metal molded body, the section extending from a contact section to the potential surface of the power semiconductor and from there to a fixing part of a laterally spaced thick cable.

[0008] In particular, with ever-increasing currents that are fed into the chip at a constant chip area, conventional bonding wires reach their limits, for example with regard to load-changing resistance. Summary of the invention

[0009] Against this background, it is an object of the present invention to provide a semiconductor component having improved reliability.

[0010] According to the invention, the object is achieved by a method for producing a semiconductor component having a semiconductor element and a substrate, the method comprising the following steps: - bonding a first load contact of the semiconductor element to a first metallization of the substrate in a materially fitting manner; - bonding a metal molded body to a second load contact of the semiconductor element in a materially fitting manner, the second load contact being arranged on a surface of the semiconductor element facing away from the substrate; - contacting a contoured contact element constructed as a metal 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 contoured portion; - pressing the contoured contact element onto the semiconductor element via a housing cover, wherein, in order to connect the second load contact (8), the contoured contact element (22) is contacted with a first metallization (10) of the substrate (12).

[0011] Furthermore, according to the invention, the object is achieved by a semiconductor component, which comprises a semiconductor element and a substrate, wherein the semiconductor element comprises a first load contact and a second load contact, wherein the first load contact is materially bonded to a first metallization of the substrate, wherein a metal molded body is materially bonded to the second load contact, wherein a contoured contact element formed as a metal sheet is in contact with the second load contact via the metal molded body (20), the second load contact being arranged on a surface of the semiconductor element facing away from the substrate, wherein a plurality of contact points are formed by means of the contoured portion, wherein the contoured contact element is pressed against the semiconductor element via a housing cover, wherein, in order to connect the second load contact, the contoured contact element is in contact with the first metallization of the substrate.

[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 listed below with regard to the semiconductor component can reasonably be transferred analogously to the power converter and the method.

[0014] The present invention is based on the following considerations: improving the load-changing durability of a semiconductor component by improving the contact of a semiconductor element. The material of the first load contact of the semiconductor element is combined with the material of the first metallization of the substrate. The first metallization of the substrate can be structured and arranged on a dielectric material layer, which includes but is not limited to ceramic materials or organic materials that can contain such as aluminum nitride or aluminum oxide. For example, the first metallization is configured as a copper cladding. The material combination of the semiconductor element and the first metallization includes but is not limited to being able to be established by soldering, sintering, but can also be established by an adhesive connection, for example by means of an electrically and thermally conductive adhesive.

[0015] The profiled contact element then contacts the second load contact, which is arranged on the face of the semiconductor element facing away from the substrate, as is common, for example, in vertical power semiconductors, in particular IGBTs, wherein a plurality of contact points are formed by means of the profiled portion. In particular, the contact of the profiled contact element on the semiconductor element is performed loosely, i.e., without a material connection. The contact element includes, but is not limited to, being able to be configured as a metal sheet, in particular a spring sheet, which can be profiled alternately and periodically in the area in contact with the second load contact. The alternating periodic profile is, for example, a substantially sinusoidal waveform. The contact element can be configured, for example, so as to contact the first metallization of the substrate or to lead to an external connector.

[0016] In a further step, the profiled contact element is pressed onto the semiconductor component via the housing cover. For example, the housing cover made of a dielectric material, in particular a polymer, applies a force acting orthogonally to the second load contact to the profiled portion of the contact element. By applying pressure to the contact element, the contact element is deformed, in particular elastically. Such a contact element has a high current carrying capacity and in particular improves the load-changing resistance of the semiconductor component. This leads to an improvement in reliability. In addition, in particular compared to standard bonding processes, the architecture of the semiconductor component is largely retained and the manufacturing method can be integrated into a standard series manufacturing process simply and cost-effectively.

[0017] The material matching connection of the metal molded body and the second load contact of the semiconductor element is carried out before the contact contouring contact element. The contouring contact element contacts the second load contact of the semiconductor element via the metal molded body. The metal molded body can be configured as a metal sheet, which includes but is not limited to being able to contain one of copper, aluminum, silver, gold, molybdenum or their alloys. The material matching connection of the semiconductor element and the metal molded body includes but is not limited to being able to be established by soldering, sintering, but also by bonding connection, for example, by means of conductive and thermal conductive adhesives. Alternatively, the metal molded body can be applied to the second load contact of the semiconductor element by means of an additive method, in particular by means of a thermal spraying method such as cold gas spraying, and in this way is connected to the second load contact of the semiconductor element in a material matching manner. The pressure established by multiple contact points is distributed to the semiconductor element by the metal molded body. This ensures a more uniform pressure distribution, especially in the case of mechanical or thermal load fluctuations during operation, so that, for example, the semiconductor element is prevented from breaking. Therefore, the reliability of the semiconductor component is improved by the metal molded body.

[0018] Another embodiment provides that the semiconductor components are encapsulated after the pressing. The required voltage spacing is ensured by an encapsulation material, which contains silicone, for example. This encapsulation also serves to protect against harmful environmental influences.

[0019] Another embodiment provides that the contacting of the contoured contact element is carried out directly on the metal molded body. Direct contacting is carried out without any additional connecting means, such as solder or adhesive. Such contacting is simple and reliable, especially in combination with press-fitting.

[0020] Another embodiment provides that the profiled contact element is predominantly elastically deformed during the pressing. For example, the profiled contact element contains an elastic copper alloy, such as CuZn37, CuSn6, CuNi18Zn20, copper beryllium or spring steel. Even in the case of alternating loads and temperature fluctuations, a sufficient pressing force is ensured by the predominantly elastic deformation, so that improved reliability is achieved. In addition, the height between the semiconductor element and the substrate and, if necessary, the tilting of the semiconductor element can also be compensated, which also proves to have an effect on the reliability of the semiconductor component.

[0021] Another embodiment provides that the plurality of contact points are formed by means of an S-shaped or trapezoidal contouring of the contoured contact element. Such contouring is simple and cost-effective to manufacture. Furthermore, such a contouring enables a uniform force and heat distribution and heat diffusion on the chip surface.

[0022] Another embodiment provides that the profiled contact element is connected to the first metallization of the substrate, in particular bonded by material, to connect the second load contact. Materially bonded connections include, but are not limited to, being able to be established by soldering, sintering, but can also be established by bonding, for example by means of an electrically and thermally conductive adhesive. Such an arrangement can be realized simply and cost-effectively.

[0023] Another embodiment provides that the profiled contact element is pressed onto the first metallization of the substrate via the housing cover to connect the second load contact. This connection achieves improved reliability, in particular in the case of frequent load changes and temperature fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The invention is described and explained in more detail below with reference to the exemplary embodiments shown in the drawings.

[0025] The accompanying drawings show:

[0026] Figure 1 A schematic cross-sectional view showing a first specific embodiment of a semiconductor component,

[0027] Figure 2 A flow chart showing a method for producing a semiconductor component,

[0028] Figure 3 A schematic cross-sectional view shows a second specific embodiment of a semiconductor component,

[0029] Figure 4 A schematic cross-sectional view shows a third specific embodiment of a semiconductor component,

[0030] Figure 5 a schematic perspective view showing a fourth specific embodiment of a semiconductor component,

[0031] Figure 6 A schematic diagram of a power converter is shown. DETAILED DESCRIPTION

[0032] The embodiments explained below are preferred embodiments of the present invention. In the embodiments, the described combinations of the embodiments are the individual features of the present invention that can be considered independently of each other, and the feature distribution also improves the present invention independently of each other and can also be considered as a component of the present invention individually or in a combination different from that shown. In addition, the described factual mode can also be supplemented by other features of the present invention that have already been described.

[0033] The same reference symbols have the same meaning in different figures.

[0034] Figure 1A schematic cross-sectional view of a first specific embodiment of a semiconductor component 2 is shown, which comprises a semiconductor element 4 which is designed as a vertical power transistor, in particular as an insulated gate bipolar transistor (IGBT). Further examples of such a semiconductor element 4 are triacs, 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 and a second load contact 8; for the sake of clarity, the semiconductor element 4 is shown in FIG. Figure 1 The control contacts are not shown.

[0035] 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 includes, but is not limited to, being able to be established by a soldering connection and / or a sintering connection, and can also be established by an adhesive connection, for example, by means of an electrically and thermally conductive adhesive. In addition, the substrate 12 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 includes, but is not limited to, being able to contain a ceramic material, in particular aluminum nitride or aluminum oxide, or an organic material. In addition, the substrate 12 is connected to the heat sink 18 via the second metallization 16, in particular in a materially bonded manner, so that the semiconductor element 4 is electrically insulated and thermally connected to the heat sink 18 via the substrate.

[0036] 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 bonded to the metal molded body 20 used as a buffer layer. For example, the metal molded body 20 is configured as a metal sheet, in particular as a copper sheet, which is connected to the control contact contact surface via a sintered connection. In addition, the plate can have a single-sided and / or double-sided coating, for example for establishing a bonding connection. Such coatings include, but are not limited to, one of aluminum, silver, gold, zinc or their alloys. Alternatively, the metal molded body 20 can be applied by means of an additive method, in particular by means of a thermal spraying method (e.g. cold gas spraying).

[0037] In addition, the profiled contact element 22 made of metal material is directly in contact with the second load contact 8 via the metal molded body 20, that is, without any connection mechanism. The profiled contact element 22 is fixed to the first metallization 10 of the substrate 12 via a material-fit connection 24 on both sides. The material-fit connection 24 includes, but is not limited to, being able to be manufactured via a sintering, soldering or welding method. In addition, the contact element 22 has an S-shaped profiled portion 26 in the area in contact with the second load contact 8, and the profiled portion can be mainly elastically deformed. For example, the profiled contact element 22 contains an elastic copper alloy, such as CuZn37, CuSn6, CuNi18Zn20, copper beryllium or spring steel. With the help of the S-shaped profiled portion 26, a plurality of substantially linear contact points 28 of the load contact 8 are formed. In particular, the contact element 22 is configured as a spring sheet, which is contoured in a wave-shaped manner in the area in contact with the second load contact 8.

[0038] The force F acts on the S-shaped contoured portion 26 of the contact element 22 via the housing cover 30, wherein the housing cover is made of a dielectric material, for example a polymer. In particular, the force F is directed to act perpendicularly to the second load contact 8. In contrast to the contoured contact element 22, the housing cover 30 is not significantly deformed. The contoured contact element 22 is therefore pressed against the semiconductor element 4 via the housing cover 30. In order to apply a defined force F to the contact element 22 via the housing cover 30, a defined distance d is established above the semiconductor element 4. The establishment of the defined distance d to the semiconductor element 4 is achieved, for example, by Figure 1 In the embodiment, the contact element 22 is provided by a projection 32. Alternatively, the housing cover 30 can be formed in two parts, in particular by means of a directional pressure element, or can have a depression depending on the contouring 26 of the contact element 22. Furthermore, the semiconductor component 2 is encapsulated between the housing cover 30 and the substrate 12 by means of an encapsulation compound 34, which contains silicone, for example, and serves to maintain the required voltage spacing and to protect against harmful environmental influences.

[0039] Figure 2 A flow chart showing a method for producing a semiconductor component 2, such as Figure 1 The semiconductor component is constructed as shown in FIG. 1 , and has a semiconductor element 4 and a substrate 12. The method comprises bonding A a first load contact 6 of the semiconductor element 4 to a first metallization 10 of the substrate 12 and bonding a second load contact 8 of the semiconductor element 4 to a metal molded body 4, wherein the second load contact is arranged on a surface of the semiconductor element 4 facing away from the substrate 12.

[0040] In a further step, the profiled contact element 22 is contacted via the metal profile 20 with the second load contact 8 , wherein a plurality of contact points 28 are formed by means of the profile 26 . The contacting of the profiled contact element 22 takes place directly at the metal profile 20 .

[0041] In a further step, the contoured contact element 22 is pressed C onto the semiconductor component 4 via the housing cover 30 , wherein the contoured contact element 22 is predominantly elastically deformed during the pressing C. After the pressing C, the semiconductor component 4 is encapsulated D by means of an encapsulation compound 34 .

[0042] Figure 3 A schematic cross-sectional view of a second embodiment of a semiconductor component 2 is shown. The profiled contact element 22 is designed as a spring blade of closed cross-section, which has an S-shaped profile 26 and a straight section 36 extending parallel thereto, wherein the straight section 36 is in direct contact with a projection 32 of a housing cover 32 in a planar manner. The S-shaped profile 26 of the contact element 22 is pressed onto the metal molded body 20 and onto the first metallization 10 of the substrate 12 on both sides via the projection 32 of the housing cover 32. In this way, the second load contact 8 of the semiconductor element 4 is in contact with the first metallization 10 of the substrate 12 without a material fit and without a connection mechanism for injecting solder, sintering paste or adhesive. Figure 3 Other embodiments of the semiconductor component 2 correspond to Figure 1 Implementation plan in .

[0043] Figure 4 A schematic cross-sectional view shows a third specific embodiment of a semiconductor component 2 , in which the contact element 22 has a contouring 26 of trapezoidal design in the region of contact with the second load contact 8 . Figure 4 Other embodiments of the semiconductor component 2 correspond to Figure 1 Implementation plan in .

[0044] Figure 5 A schematic perspective view of a fourth embodiment of a semiconductor component 2 is shown, which includes a semiconductor element 4 designed as a transistor T1, T2 and a diode D1, D2. For example, the transistors T1, T2 designed as IGBTs each have a control contact 38, which is connected to the first metallization 10 of the substrate 12 via a bonding wire 40. The housing frame 42 completely surrounds the substrate 12. For the sake of clarity, Figure 5 Not shown are the encapsulation material delimited by the housing frame 42 and the housing cover which attaches the contoured contact element 22 to the corresponding metal molding 20 of the semiconductor element 4. The housing cover is fastened to the housing frame 42 by means of screws. Figure 5 Other embodiments of the semiconductor component 2 correspond to Figure 1 Implementation plan in .

[0045] Figure 6 A schematic diagram of a power converter 44 is shown, which includes, for example, a semiconductor component 2 .

[0046] In summary, the present invention relates to a method for manufacturing 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 load contact portion 6 of the semiconductor element 4 is materially bonded to the first metallization portion 10 of the substrate 12, B a contoured contact element 22 is contacted to the second load contact portion 8 of the semiconductor element 4, the second load contact portion is arranged on the surface of the semiconductor element 4 facing away from the substrate 12, wherein a plurality of contact points 28 are formed by means of a contoured portion 26, and C the contoured contact element 22 is pressed onto the semiconductor element 4 via a housing cover 30.

Claims

1. A method for producing a semiconductor component (2) having a semiconductor element (4) and a substrate (12), the method comprising the following steps: - bonding (A) the first load contact portion (6) of the semiconductor element (4) to the first metallization portion (10) of the substrate (12) in a material-fitting manner, - bonding (A) the metal shaped body (20) to a second load contact (8) of the semiconductor element (4) in a materially bonding manner, the second load contact being arranged on a surface of the semiconductor element (4) facing away from the substrate (12), - contacting (B) a contoured contact element (22) designed as a metal 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 contouring (26), - pressing (C) the contoured contact element (22) onto the semiconductor element (4) via a housing cover (30), In order to connect the second load contact (8), the contoured contact element (22) is in contact with the first metallization (10) of the substrate (12).

2. The method according to claim 1, wherein: The profiled contact element (22) is profiled alternately and periodically in the region in contact with the second load contact.

3. The method according to any one of claims 1 or 2, wherein: After the pressing (C), the semiconductor component (4) is encapsulated (D).

4. A method according to any one of the preceding claims, wherein: The contact (B) of the profiled contact element (22) takes place directly on the metal shaped body (20).

5. A method according to any one of the preceding claims, wherein: The contoured contact element (22) is deformed predominantly elastically during the pressing (C).

6. A method according to any one of the preceding claims, wherein: The plurality of contact points (28) are formed by means of an S-shaped or trapezoidal contouring (26) of the contoured contact element (22).

7. A method according to any one of the preceding claims, wherein: In order to connect the second load contact (8), the contoured contact element (22) is connected to the first metallization (10) of the substrate (12), in particular in a materially bonded manner.

8. The method according to any one of claims 1 to 6, wherein: In order to connect the second load contact (8), the contoured contact element (22) is pressed via the housing cover (30) onto the first metallization (10) of the substrate (12).

9. A semiconductor component (2) comprising a semiconductor element (4) and a substrate (12), in, The semiconductor element (4) has a first load contact portion (6) and a second load contact portion (8), The first load contact portion (6) is connected to the first metallization portion (10) of the substrate (12) in a materially compatible manner. The metal molded body (20) is connected to the second load contact portion (8) in a materially bonded manner. A contoured contact element (22) in the form of a metal sheet is in contact with the second load contact (8) via the metal molded body (20), the second load contact being arranged on a surface of the semiconductor element (4) facing away from the substrate (12). In this case, a plurality of contact points (28) are formed by means of the contouring (26), wherein the contoured contact element (22) is pressed onto the semiconductor element (4) via a housing cover (30), In order to connect the second load contact (8), the contoured contact element (22) is in contact with the first metallization (10) of the substrate (12).

10. The semiconductor component (2) according to claim 9, wherein: The profiled contact element (22) is profiled alternately and periodically in the region in contact with the second load contact.

11. The semiconductor component (2) as claimed in claim 9 or 10, which is encapsulated by means of an encapsulation compound (34).

12. The semiconductor component (2) according to any one of claims 9 to 11, wherein: The contoured contact element (22) is in direct contact with the metal molded body (20).

13. The semiconductor component (2) according to any one of claims 9 to 12, wherein: The contoured contact element (22) is deformed primarily elastically by the pressing (C).

14. The semiconductor component (2) according to any one of claims 9 to 13, wherein: The contoured contact element (22) is designed as a spring blade.

15. The semiconductor component (2) according to any one of claims 9 to 14, wherein: The contoured portion (26) of the contoured contact element (22) is at least partially S-shaped or trapezoidal.

16. The semiconductor component (2) according to any one of claims 9 to 15, wherein: In order to connect the second load contact (8), the contoured contact element (22) is connected to the first metallization (10) of the substrate (12), in particular in a materially bonded manner.

17. The semiconductor component (2) according to any one of claims 9 to 15, wherein: In order to connect the second load contact (8), the contoured contact element (22) is pressed via the housing cover (30) onto the first metallization (10) of the substrate (12).

18. A power converter (44) having at least one semiconductor component (2) according to any one of claims 9 to 17.

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