Power semiconductor module and manufacturing process

Abstract

The invention relates to a power semiconductor module (1) comprising at least one power semiconductor chip (2), wherein the power semiconductor chip (2) has a semiconductor substrate (3) and chip metallizations (4, 5), wherein at least one chip metallization (4) is connected to a terminal contact (10), wherein an optical temperature sensor (12) is provided, wherein the optical temperature sensor (12) is arranged on the terminal contact (10) or is integrated into the terminal contact (10), and a method for manufacturing.

Description

[0001] The invention relates to a power semiconductor module with at least one power semiconductor chip and a method for manufacturing such a power semiconductor module.

[0002] For power semiconductor chips, temperature control is a crucial parameter. Appropriate measures must be taken to ensure the temperature does not exceed a certain limit, as this can lead to thermal destruction. Besides cooling the power semiconductor chip, other parameters can be used to control its power dissipation, although this comes at the cost of reduced performance. Generally, the aim is to fully utilize the chip's performance limits. Therefore, precise temperature control is essential. One approach is to integrate a temperature sensor into the semiconductor substrate. For example, a diode structure can be integrated into the semiconductor substrate. This diode structure must be isolated from the rest of the structure, thus reducing the active area available to the other components, which in turn reduces the current-carrying capacity of other structures (such as a transistor).If the temperature sensor is placed next to the semiconductor chip, no active area is lost, but the measurement is less accurate, so corresponding tolerances must be taken into account and the performance cannot be fully utilized.

[0003] Most temperature sensors use NTC resistors. However, optical temperature sensors have also been proposed, which differ technologically. What they all have in common is that they evaluate a temperature-dependent optical property.

[0004] US patent 2022 / 0244111 A1 discloses a power semiconductor module in which the optical temperature sensor is directly applied to a power semiconductor chip.

[0005] Power semiconductor chips are typically mounted and wired onto a substrate. Different substrates are used depending on the power class. In the lower power range, multilayer printed circuit boards are used, while in the higher power range, ceramic substrates (e.g., AMB, DCB, or IMS) are used, each featuring metallization on both sides.

[0006] From EP 3 886 156 A1, a power semiconductor module is known, wherein the power semiconductor module comprises at least one power semiconductor chip having a semiconductor substrate and chip metallizations. Furthermore, connection contacts are provided, which can be configured as bond wires, ribbons, plates, or rails. An optical temperature sensor is also provided, which is in thermal contact with the power semiconductor chip.

[0007] A power semiconductor module is known from US patent 2023 / 0 048 878 A1, wherein the power semiconductor module comprises power semiconductor chips connected by means of metal clips. An optical temperature sensor in the form of an IR diode is provided at a distance from the connection contact. Alternatively, a temperature sensor in the form of a resistance sensor is arranged on the metal clip.

[0008] The invention is based on the technical problem of creating an improved power semiconductor module with an optical temperature sensor and providing a suitable manufacturing process.

[0009] The solution to the technical problem is achieved by a power semiconductor module with the features of claim 1 and a method with the features of claim 6.

[0010] The power semiconductor module comprises at least one power semiconductor chip, the power semiconductor chip having a semiconductor substrate and chip metallizations. At least one chip metallization is connected to a terminal contact. The optical temperature sensor is arranged on the terminal contact or integrated into the terminal contact. This significantly simplifies the mounting of the optical sensor. In particular, it can also be provided that the terminal contact and the optical temperature sensor are pre-assembled, so that the temperature sensor is automatically positioned when the terminal contact is attached, thus eliminating the need for additional adjustment steps. When the temperature sensor is arranged on the terminal contact, an electrically insulating layer with good thermal conductivity can be applied to the terminal contact.

[0011] In one embodiment, the optical temperature sensor is at least partially enclosed in a sleeve. The sleeve can be made of copper, for example, or of an electrical insulator. The sleeve serves both as mechanical protection and as mechanical stabilization.

[0012] In one embodiment, the sleeve and the connecting contact are a single, integral component. By attaching the connecting contact to the chip metallization, the sleeve is aligned with the chip metallization. The optical temperature sensor can either be already positioned within the sleeve when the connecting contact is attached, or it can be positioned within the sleeve after the attachment process.

[0013] In an alternative embodiment, the terminal contact has a recess or opening in which the sleeve is arranged, with a chip metallization of the power semiconductor chip located below the sleeve. In this embodiment as well, the terminal contact and sleeve can be pre-assembled.

[0014] The connecting contact and the sleeve are preferably glued, crimped or soldered together.

[0015] A further disclosed method for manufacturing a power semiconductor module is presented, wherein the power semiconductor module comprises at least one power semiconductor chip having a semiconductor substrate and chip metallizations, wherein at least one chip metallization is connected to a terminal contact, and wherein an optical temperature sensor is arranged on or integrated into the terminal contact. For further embodiments, reference is made to the preceding descriptions.

[0016] The invention is explained in more detail below with reference to preferred embodiments. The figures show: Fig. 1 a schematic cross-sectional view through a power semiconductor module in a first embodiment and Fig. 2 a schematic cross-sectional view through a power semiconductor module in a second embodiment.

[0017] In the Fig. Figure 1 schematically shows a power semiconductor module 1 in a sectional view, where, for clarity, not all parts are shown with hatching. The power semiconductor module 1 has two power semiconductor chips 2, each comprising a semiconductor substrate 3 and chip metallizations 4, 5. The power semiconductor chips 2 are arranged on a carrier 6, which has an electrically insulating ceramic 7 with a metal layer 8, 9 on both sides. The carrier 6 is configured, for example, as a DCB or IMS. The chip metallizations 4, 5 represent, for example, a drain and a source contact of a MOSFET. Connection contacts 10, configured, for example, as clips or leadframes, are arranged on the chip metallizations 4 of the power semiconductor chips 2. In the example shown, the connection contacts 10 are depicted as a single layer. However, multilayer structures are also possible.The power semiconductor module 1 is encapsulated with a molding compound 11, whereby the connection contacts 10 and the metal layer 8 remain accessible from the outside. In principle, however, other encapsulation materials are also conceivable, e.g., a soft encapsulation (e.g., silicone gel). Furthermore, each power semiconductor chip 2 is assigned an optical temperature sensor 12, which is arranged in a sleeve 13, the sleeve 13 also protruding from the molding compound 11. The sleeve 13 is, for example, hollow cylindrical. A temperature-sensitive part of the optical temperature sensor 12 is arranged on the metallization 4 or only slightly spaced from the metallization 4 within the sleeve 13, so that it detects the temperature of the metallization 4, which largely corresponds to the temperature of the semiconductor substrate 3. Fig. Figure 1 shows two embodiments of the sleeve 13. In the embodiment on the right, the connection contact 10 and the sleeve are formed as a single piece. In the embodiment on the left, however, the sleeve 13 is a separate component (recognizable by the different hatching) that is mechanically connected to the connection contact 10 (e.g., crimped, glued, soldered). For this purpose, the connection contact 10 has, for example, a circular opening. The sleeve 13 mechanically holds and protects the optical temperature sensor 12. Furthermore, the sleeve 13 simplifies the mounting and adjustment of the temperature sensor 12 on the chip metallization 4.

[0018] In the Fig. Figure 2 shows another power semiconductor module 1, with identical elements bearing the same reference symbols as in Figure 2. Fig.The embodiments shown on the right are characterized by the sleeve 13 being arranged on the chip metallization 4 independently of the connecting contact 10. The sleeve 13 can be connected to the chip metallization 4 using the same process step as the connecting contact 10, but this is not mandatory. On the left is another embodiment where the optical temperature sensor 12 is connected to the connecting contact 10 without the sleeve 13. In this embodiment, the optical temperature sensor 12 is arranged on an insulating layer 14, which is, for example, a polyamide layer. Analogous to the embodiment on the right with the sleeve 13, the optical temperature sensor 12 is shown vertically.It is also possible for the optical temperature sensor 12 to extend laterally outwards along the horizontal part of the terminal contact 10, thus increasing the contact area of ​​the temperature sensor 12 on the terminal contact 10 and simplifying mechanical mounting. In this case, the insulating layer 14 can be fully applied to the top surface of the terminal contact 10. The optical temperature sensor 12 can be pre-connected to the terminal contact 10, and the terminal contact 10 can then be connected to the chip metallization 4. The insulating layer 14 preferably has good thermal conductivity, so that the optical temperature sensor 12 essentially detects the temperature of the terminal contact 10, which is essentially the same as the temperature of the chip metallization 4. Reference symbol list 1 power semiconductor module 2 Power semiconductor chip 3 Semiconductor substrate 4 Chip Metallization 5 Chip Metallization 6 carriers 7 Ceramics 8 metal layer 9 metal layer 10 connection contacts 11 Molding compound 12 Temperature sensor 13 Sleeve 14 Insulation layer

Claims

[1] Power semiconductor module (1) comprising at least one power semiconductor chip (2), wherein the power semiconductor chip (2) has a semiconductor substrate (3) and chip metallizations (4, 5), wherein at least one chip metallization (4) is connected to a terminal contact (10), wherein an optical temperature sensor (12) is provided, wherein the optical temperature sensor (12) is arranged on the terminal contact (10) or is integrated into the terminal contact (10). [2] Power semiconductor module (1) according to claim 1, characterized by that the optical temperature sensor (12) is at least partially arranged in a sleeve (13). [3] Power semiconductor module (1) according to claim 2, characterized by , that the sleeve (13) and the connecting contact (10) are a single component. [4] Power semiconductor module (1) according to claim 2, characterized by, that the terminal contact (10) has a recess or opening in which the sleeve (13) is arranged, wherein below the sleeve (13) is a chip metallization (4) of the power semiconductor chip (2). [5] Power semiconductor module (1) according to claim 4, characterized by , that the connecting contact (10) and the sleeve (13) are glued, pressed or soldered together. [6] Method for manufacturing a power semiconductor module (1) wherein the power semiconductor module (1) comprises at least one power semiconductor chip (2) wherein the power semiconductor chip (2) comprises a semiconductor substrate (3) and chip metallizations (4, 5) wherein at least one chip metallization (4) is connected to a terminal contact (10) wherein an optical temperature sensor (12) is arranged on the terminal contact (10) or is integrated into the terminal contact (10). [7] Method according to claim 6, characterized by, that the optical temperature sensor (12) is connected to the terminal contact (10) and then the terminal contact is connected to the chip metallization (4). [8] Method according to claim 6, characterized by , that the temperature sensor (12) is at least partially arranged in a sleeve (13), wherein the sleeve (13) is connected to the terminal contact (10), and the terminal contact (10) is subsequently connected to the chip metallization (4). [9] Method according to claim 6, characterized by , that the temperature sensor (12) is at least partially arranged in a sleeve (13), wherein the sleeve (13) and the connection contact (10) are connected to the chip metallization (4) in the same process step.

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