An anti-electron radiation MOSFET ruggedized package structure

Abstract

The application provides an anti-electron radiation MOSFET reinforced packaging structure and belongs to the technical field of electronic power devices, and specifically comprises: a first anti-radiation conductive sheet, a second anti-radiation conductive sheet and a buffer conductive sheet; the first anti-radiation conductive sheet and the second anti-radiation conductive sheet cover a MOSFET chip; and the first anti-radiation conductive sheet and the second anti-radiation conductive sheet are both high-Z materials; one end of the first anti-radiation conductive sheet is connected with a source above the MOSFET chip through the buffer conductive sheet; one end of the second anti-radiation conductive sheet is connected with a drain below the MOSFET chip; the first anti-radiation conductive sheet is used for resisting electron radiation above the MOSFET chip; and the second anti-radiation conductive sheet is used for resisting electron radiation below the MOSFET chip. The application realizes a compromise between anti-radiation performance, volume, weight and cost.

Description

Technical Field

[0001] This invention belongs to the field of electronic power device technology, and more specifically, relates to a MOSFET ruggedized packaging structure resistant to electron radiation. Background Technology

[0002] When power semiconductor devices such as SiC MOSFETs operate in environments with high-energy radiation, they are threatened by high-energy electrons, heavy particles, and gamma rays, affecting their reliability. Specifically, when MOSFETs are exposed to electron irradiation, trapped charges and interface states are generated at the gate oxide interface, causing threshold voltage drift, transconductance degradation, and ultimately device aging and damage. Therefore, hardening the devices and improving their resistance to electron irradiation is crucial for their reliable operation under high-radiation conditions.

[0003] Currently, radiation hardening of MOSFET devices mainly focuses on improving the chip's structure to increase the chip's and device's radiation resistance. However, improving the chip's structure increases manufacturing complexity and cost. Radiation hardening of MOSFET devices from a packaging perspective offers the advantage of simpler processing, making it an important research direction in radiation hardening.

[0004] Currently, there is a lot of research on improving the radiation resistance of devices from the perspective of packaging in the field of electronic devices. For example, patent documents 201110320158.3 and 201720208903.8 achieve radiation hardening of devices by combining radiation-resistant materials and shells. However, there are also problems such as excessive redundant materials, which increases the weight, volume and cost of devices, which is not conducive to the operation of devices in space. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a radiation-resistant MOSFET hardened packaging structure. This structure addresses the problem that existing radiation hardening methods for MOSFET chips focus on modifying the chip body structure, which increases process difficulty and cost. Furthermore, improving the radiation resistance of MOSFET chips from a packaging perspective results in excessive redundant radiation-resistant materials, thereby increasing the weight, size, and cost of the MOSFET chip.

[0006] To achieve the above objectives, the present invention provides a MOSFET ruggedized package structure resistant to electron radiation, comprising: a first radiation-resistant conductive sheet, a second radiation-resistant conductive sheet, and a buffer conductive sheet;

[0007] The first and second radiation-resistant conductive sheets cover the MOSFET chip; the area of ​​the first and second radiation-resistant conductive sheets is larger than the area of ​​the MOSFET chip; and both the first and second radiation-resistant conductive sheets are high-Z materials (high atomic number materials);

[0008] The source of the MOSFET chip is connected to one end of the first radiation-resistant conductive plate via a buffer conductive plate; the drain of the MOSFET chip is connected to one end of the second radiation-resistant conductive plate via a drain.

[0009] The first radiation-resistant conductive sheet is used to block electron radiation from above the MOSFET chip; the second radiation-resistant conductive sheet is used to block electron radiation from below the MOSFET chip.

[0010] Preferably, the first radiation-resistant conductive sheet is connected to one side of the buffer conductive sheet by solder; the other side of the buffer conductive sheet is connected to the MOSFET chip by solder; the buffer conductive sheet is used to relieve stress on the MOSFET chip and the solder.

[0011] Preferably, the buffer conductive sheet material is a molybdenum sheet with a thickness of 0.6mm-3mm;

[0012] Preferably, the MOSFET ruggedized package structure resistant to electron radiation further includes: a third conductive sheet, a fourth conductive sheet, a fifth conductive sheet, and a power terminal;

[0013] One end of the fourth conductive sheet is connected to the other end of the first radiation-resistant conductive sheet via solder, and the other end is connected to the power terminal to bring out the source of the MOSFET chip.

[0014] The other end of the second radiation-resistant conductive sheet is connected to the power terminal via solder to bring out the drain of the MOSFET chip;

[0015] One end of the third conductive plate is connected to the gate of the MOSFET chip, and the other end is connected to the fifth conductive plate through solder, which is used to bring out the gate of the MOSFET chip through the power terminal.

[0016] Preferably, an epoxy resin injection molding process is used to fix and protect the MOSFET reinforced package structure.

[0017] Preferably, the first radiation-resistant conductive sheet, the second radiation-resistant conductive sheet, and the third conductive sheet are made of tungsten or tantalum and have a thickness of 0.2 mm to 2 mm.

[0018] Preferably, the fourth conductive sheet, the fifth conductive sheet, and the power terminal are made of copper.

[0019] Preferably, the MOSFET is a SiMOSFET or a SiCMOSFET.

[0020] In summary, the technical solutions conceived by this invention have the following beneficial effects compared with the prior art:

[0021] In this invention, the areas of the first and second radiation-resistant conductive sheets are larger than the area of ​​the MOSFET chip and can cover the MOSFET chip. Since the first and second radiation-resistant conductive sheets can be closely attached to the MOSFET chip, they can block about 90% of external electron radiation. At the same time, this invention has less redundant metal, so the overall MOSFET ruggedized package structure combined with the MOSFET chip has a smaller size and weight, achieving a compromise in radiation resistance, size, weight, and even cost. Furthermore, it can be manufactured using existing mature processes without increasing the difficulty of the process.

[0022] In this invention, a second radiation-resistant conductive sheet is connected to a power terminal to bring out the drain of the MOSFET chip; the gate is brought out through a conductive sheet and a power terminal, and the source is brought out through a fourth conductive sheet and a power terminal. This eliminates the bonding wires in the traditional packaging structure, reduces parasitic inductance, and effectively reduces voltage overshoot caused by parasitic inductance when the MOSFET chip is turned off, as well as electromagnetic interference under high-frequency operating conditions. This is beneficial for leveraging the high switching speed advantage of existing silicon carbide devices.

[0023] In this invention, the fourth conductive sheet, the fifth conductive sheet, and the power terminal are all made of copper, which has no negative impact on the radiation resistance of the MOSFET chip. At the same time, the use of copper reduces the weight of the MOSFET chip. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the MOSFET ruggedized package structure resistant to electron radiation provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the structure of a conventional SiC MOSFET device based on bonding wires provided in an embodiment of the present invention;

[0026] Figure 3 This is a three-dimensional schematic diagram of the MOSFET ruggedized package structure resistant to electron radiation provided in an embodiment of the present invention;

[0027] Figure 4 These are the radiation resistance experimental results of traditional SiC MOSFET devices based on bonding wires and SiC MOSFET devices with an electron radiation-resistant MOSFET ruggedized packaging structure;

[0028] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0029] 1-MOSFET chip; 2-Buffer conductive sheet; 3-First radiation-resistant conductive sheet; 4-Second radiation-resistant conductive sheet; 5-Third conductive sheet; 6-Fourth conductive sheet; 7-Fifth conductive sheet; 8-Power terminal; 9-Epoxy resin; 10-Upper electron irradiation; 11-Lower electron irradiation; 12-Solder layer. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0031] Example

[0032] like Figure 1 As shown, this embodiment provides a MOSFET ruggedized package structure resistant to electronic radiation, including: a buffer conductive sheet 2, a first radiation-resistant conductive sheet 3, a second radiation-resistant conductive sheet 4, a third conductive sheet 5, a fourth conductive sheet 6, a fifth conductive sheet 7, a power terminal 8, an epoxy resin 9, and a solder layer 12.

[0033] like Figure 1 and Figure 3 As shown, the drain of the MOSFET chip 1 is connected to the second radiation-resistant conductive sheet 4 through the solder layer 12. The second radiation-resistant conductive sheet 4 leads out the drain of the chip through the power terminal 8. The area of ​​the second radiation-resistant conductive sheet 4 is much larger than the area of ​​the MOSFET chip 1, and it is used to block electron radiation from below the MOSFET chip.

[0034] The source of the MOSFET chip 1 is connected to the buffer conductive sheet 2 via the solder layer 12; the other end of the buffer conductive sheet 2 is connected to the first radiation-resistant conductive sheet 3 via the solder layer 12, and the source of the MOSFET chip is led out through the fourth conductive sheet 6 and the power terminal 8; wherein, the buffer conductive sheet 2 plays the role of relieving the stress on the MOSFET chip 1 and the solder layer 12; the area of ​​the first radiation-resistant conductive sheet 3 is larger than the area of ​​the MOSFET chip 1, and is used to block electron radiation from above the MOSFET chip;

[0035] The gate of MOSFET chip 1 is connected to the third conductive sheet 5 through solder layer 12, and then the gate of MOSFET chip 1 is led out through the fifth conductive sheet 7 and power terminal 8.

[0036] The third conductive sheet 5 and the first radiation-resistant conductive sheet 3 together resist electron radiation from above the MOSFET chip;

[0037] The first radiation-resistant conductive sheet 3, the second radiation-resistant conductive sheet 4, and the third conductive sheet 5 are conductive sheets made of high-Z materials such as tungsten and tantalum. Their thickness is 0.2mm-2mm at the distance from directly above or below the MOSFET chip 1, and they are used to resist high-energy electron radiation. The upper surfaces of the first radiation-resistant conductive sheet 3 and the third conductive sheet 5 are at the same height.

[0038] The fourth conductive sheet 6, the fifth conductive sheet 7, and the power terminal 8 are all made of copper. Copper has virtually no effect on the radiation resistance of the MOSFET chip 1, so copper is used to reduce the weight of the device.

[0039] Finally, all components are formed into a solid state using an injection molding process, which protects the MOSFET chip.

[0040] The first radiation-resistant conductive sheet 3, the second radiation-resistant conductive sheet 4, and the third conductive sheet 5 are sufficient to withstand 90% of the electron radiation around the MOSFET chip, compared to Figure 2 Compared with the conventional packaging structure with bonding wires shown, the present invention significantly improves the radiation resistance of the device. At the same time, by eliminating the bonding wires, the parasitic inductance of the device is also reduced, thereby reducing voltage overshoot caused by parasitic inductance when the device is turned off and electromagnetic interference problems under high-frequency operating conditions.

[0041] It should be noted that the MOSFET is either a SiMOSFET or a SiCMOSFET.

[0042] Verification Experiment

[0043] Table 1 below shows the parasitic inductance extraction results of the electron-irradiation-resistant MOSFET ruggedized package structure and the traditional bond wire-based package structure; where L gsloop and L dsloop These are the parasitic inductances of the drive circuit and power circuit of the MOSFET device, respectively. As can be seen from the results, compared with the traditional bonding wire-based packaging structure, although the MOSFET rugged packaging structure provided by this invention has additional radiation-resistant conductive sheet and buffer layer, its drive circuit and power circuit parasitic inductances are still reduced by 13.16% and 35.28%, respectively.

[0044] Table 1

[0045]

[0046] To verify the radiation resistance performance of the packaging structure provided by this invention, a 1.2kV / 149A SiC MOSFET radiation-resistant packaging structure and a conventionally packaged SiC MOSFET device were used in the verification experiment. The first radiation-resistant conductive sheet 3 and the second radiation-resistant conductive sheet 4 of the former were made of high-Z tungsten material with a thickness of 0.5mm. An EBLab-200ebeam Technologies electron beam irradiation device was used to conduct electron irradiation experiments on the SiC MOSFET device to be irradiated, with an electron energy of 0.2MeV and the irradiation dose increasing sequentially. Finally, the changes in the threshold voltage of the MOSFET ruggedized packaging structure and the conventionally packaged SiC MOSFET device under different doses of electron irradiation were obtained. The results are as follows: Figure 4 As shown in the figure, compared with traditional packaged SiC MOSFET devices, under the same external conditions, the radiation resistance of the proposed radiation-hardened SiC MOSFET packaging structure is significantly improved without increasing process complexity, which is beneficial for its application in aerospace and other environments. Furthermore, with the gradual increase of the cumulative radiation dose Φ, the threshold voltage change ΔV under 0.2MeV irradiation... th It will exhibit a pattern of initial significant changes followed by a gradual leveling off.

[0047] In summary, compared with the prior art, the present invention has the following advantages:

[0048] In this invention, the area of ​​the first and second radiation-resistant conductive sheets is larger than that of the MOSFET chip and can cover the MOSFET chip. Since the first and second radiation-resistant conductive sheets can be tightly bonded to the MOSFET chip, they can withstand about 90% of external electron radiation. At the same time, this invention has less redundant metal, so the overall MOSFET ruggedized package structure combined with the MOSFET chip has a smaller volume and weight, achieving a compromise in radiation resistance, volume, weight, and even cost.

[0049] In this invention, a second radiation-resistant conductive sheet is connected to a power terminal to bring out the drain of the MOSFET chip; the gate is brought out through a conductive sheet and a power terminal, and the source is brought out through a fourth conductive sheet and a power terminal. This eliminates the bonding wires in traditional packaging structures, reduces parasitic inductance, and effectively reduces voltage overshoot caused by parasitic inductance when the MOSFET chip is turned off, as well as electromagnetic interference problems under high-frequency operating conditions. This is beneficial for leveraging the high switching speed advantage of existing silicon carbide devices.

[0050] In this invention, the fourth conductive sheet, the fifth conductive sheet, and the power terminal are all made of copper, which has no negative impact on the radiation resistance of the MOSFET chip. At the same time, the use of copper reduces the weight of the MOSFET chip.

[0051] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A MOSFET ruggedized package structure resistant to electron radiation, characterized in that, It includes a first radiation-resistant conductive sheet, a second radiation-resistant conductive sheet, a buffer conductive sheet, a third conductive sheet, a fourth conductive sheet, a fifth conductive sheet, and a power terminal; the first radiation-resistant conductive sheet and the second radiation-resistant conductive sheet cover the MOSFET chip; and both the first radiation-resistant conductive sheet and the second radiation-resistant conductive sheet are made of high-Z material; One end of the first radiation-resistant conductive sheet is connected to the source of the MOSFET chip above the buffer conductive sheet; one end of the second radiation-resistant conductive sheet is connected to the drain of the MOSFET chip below the MOSFET chip. The first radiation-resistant conductive sheet is used to block electron radiation above the MOSFET chip; the second radiation-resistant conductive sheet is used to block electron radiation below the MOSFET chip. One end of the fourth conductive sheet is connected to the other end of the first radiation-resistant conductive sheet via solder, and the other end is connected to the power terminal to bring out the source of the MOSFET chip; The other end of the second radiation-resistant conductive sheet is connected to the power terminal via solder, and is used to bring out the drain of the MOSFET chip; One end of the third conductive sheet is connected to the gate of the MOSFET chip, and the other end is connected to the fifth conductive sheet through solder, for leading out the gate of the MOSFET chip through the power terminal; The buffer conductive sheet is used to relieve stress on the MOSFET chip and solder; The first radiation-resistant conductive sheet, the second radiation-resistant conductive sheet, and the third conductive sheet are made of tungsten or tantalum and have a thickness of 0.2 mm to 2 mm.

2. The MOSFET ruggedized package structure according to claim 1, characterized in that, The first radiation-resistant conductive sheet is connected to one side of the buffer conductive sheet by solder; the other side of the buffer conductive sheet is connected to the MOSFET chip by solder.

3. The MOSFET ruggedized package structure according to claim 2, characterized in that, The buffer conductive sheet is made of molybdenum and has a thickness of 0.6mm-3mm.

4. The MOSFET ruggedized package structure according to claim 1, characterized in that, The fourth conductive sheet, the fifth conductive sheet, and the power terminal are made of copper.

5. The MOSFET ruggedized package structure according to claim 1 or 4, characterized in that, It is fixed and protected using epoxy resin injection molding process.

6. The MOSFET ruggedized package structure according to claim 1 or 2, characterized in that, The MOSFET is a SiMOSFET or a SiC MOSFET.

Images