Terminal structure of power device and power device

Abstract

The present invention discloses a terminal structure of a power device and a power device, wherein the terminal structure of the power device includes a substrate, a plurality of field limiting rings, a cutoff ring, a plurality of first field plates, an oxide layer and an insulating layer, wherein the plurality of field limiting rings and the cutoff ring are formed in the substrate; the plurality of first field plates correspond to the plurality of field limiting rings one by one, and the plurality of first field plates and the plurality of field limiting rings are electrically connected; the oxide layer is located between the substrate and the plurality of first field plates; the insulating layer is at least partially located between the plurality of first field plates and the cutoff ring, and the insulating layer is arranged on the surface of the oxide layer. The technical solution of the present invention adopts an insulating layer arranged between the ends of the plurality of first field plates and the cutoff ring, which can be used as a pole similar to a capacitor plate, so that the potential of the end area of ​​the first field plate decreases, thereby causing the depletion area in the substrate surface to change slowly, avoiding the concentration of the electric field, and reducing the electric field peak at the ends of the plurality of first field plates.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic devices, and in particular to a terminal structure of a power device and a power device. Background Art

[0002] In the design of power devices (IGBT, power MOSFET, etc.), the terminal structure is an important component. At present, the field limiting ring combined with the field plate structure is the most common terminal design. This design can effectively alleviate the concentration of the electric field and improve the withstand voltage. However, the field plate structure introduced by this structure has obvious weaknesses, that is, the electric field generated by the introduced equivalent charge cannot be offset. Therefore, a new electric field peak will be introduced at the end of the field plate, which can easily cause the terminal structure to break down prematurely. Summary of the invention

[0003] The main purpose of the present invention is to provide a terminal structure of a power device, aiming to reduce the electric field peak at the end of the field plate.

[0004] To achieve the above object, the terminal structure of the power device proposed in the present invention includes:

[0005] substrate;

[0006] A plurality of field limiting rings and cut-off rings, wherein the plurality of field limiting rings and the cut-off rings are formed in the substrate;

[0007] A plurality of first field plates, the plurality of first field plates correspond to the plurality of field limiting rings one by one, and the plurality of first field plates and the plurality of field limiting rings are electrically connected;

[0008] an oxide layer, the oxide layer being located between the substrate and the plurality of first field plates;

[0009] An insulating layer, wherein the insulating layer is at least partially located between the plurality of first field plates and the cut-off ring, the insulating layer is disposed on a surface of the oxide layer, and the resistivity of the insulating layer is equal to or less than the resistivity of the oxide layer.

[0010] In one embodiment, the insulating layer includes a first protective layer and a second protective layer, the second protective layer covers the first protective layer, and a material of one of the first protective layer and the second protective layer is silicon dioxide, and a material of the other is silicon nitride.

[0011] In one embodiment, the first protection layer covers outer surfaces of the plurality of first field plates and an oxide layer between any adjacent first field plates.

[0012] In one embodiment, the thickness of the first protective layer is set to 0.1 μm to 10 μm, and the thickness of the second protective layer is set to 0.1 μm to 10 μm.

[0013] In one embodiment, the first field plate close to the cut-off ring is an end field plate, and the length of the end field plate is greater than the length of the remaining first field plates.

[0014] In one embodiment, a second field plate is further disposed between the end field plate and the substrate, and the second field plate is electrically connected to the end field plate.

[0015] In one embodiment, the terminal structure of the power device further includes a metal plate, which is arranged corresponding to the cut-off ring and electrically connected to the cut-off ring, and the insulating layer is at least partially located between the metal plate and the first field plate adjacent to the metal plate.

[0016] In one embodiment, the insulating layer is made of silicon nitride.

[0017] In one embodiment, the insulating layer is made of silicon dioxide.

[0018] In one embodiment, the thickness of the insulating layer is set to be 0.1 μm to 10 μm.

[0019] In one embodiment, the insulating layer is configured as an insulator or a semi-insulator.

[0020] The present invention also proposes a power device, which includes a terminal structure of the power device, and the terminal structure of the power device includes a substrate, multiple field limiting rings, a cut-off ring, multiple first field plates, an oxide layer and an insulating layer, wherein the multiple field limiting rings and the cut-off rings are formed in the substrate; the multiple first field plates correspond to the multiple field limiting rings one by one, and the multiple first field plates and the multiple field limiting rings are electrically connected; the oxide layer is located between the substrate and the multiple first field plates; the insulating layer is at least partially located between the multiple first field plates and the cut-off rings, the insulating layer is arranged on the surface of the oxide layer, and the resistivity of the insulating layer is equal to or less than the resistivity of the oxide layer.

[0021] The technical solution of the present invention adopts an insulating layer between the ends of multiple first field plates and the cut-off ring. The insulating layer can act as a pole similar to a capacitor plate, so that the electric potential in the end area of ​​the first field plates decreases, thereby slowly changing the depletion region in the substrate surface, avoiding the concentration of the electric field and reducing the electric field peak at the ends of the multiple first field plates. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0023] Figure 1 It is a structural schematic diagram of an embodiment of a terminal structure of a power device of the present invention;

[0024] Figure 2 It is a structural schematic diagram of another embodiment of the terminal structure of the power device of the present invention;

[0025] Figure 3 for Figure 2 The electric field intensity distribution diagram in the substrate under the embodiment;

[0026] Figure 4 for Figure 3 The middle dashed line 1 is the line graph of the electric field strength from left to right;

[0027] Figure 5 for Figure 3 The middle dotted line 2 is the line graph of the electric field strength from top to bottom;

[0028] Figure 6 is a diagram showing the electric field intensity distribution in a substrate according to another embodiment;

[0029] Figure 7 for Figure 6 The middle dashed line 1 is the line graph of the electric field strength from left to right;

[0030] Figure 8 for Figure 6 The middle dotted line 2 is the line graph of the electric field strength from top to bottom;

[0031] Fig. 9 is the electric field intensity distribution diagram in the substrate when the insulating layer is silicon nitride;

[0032] Fig.10 for Fig. 9 The middle dashed line 1 is the line graph of the electric field strength from left to right;

[0033] Fig.11 for Fig. 9 The middle dotted line 2 is the line graph of the electric field strength from top to bottom;

[0034] Fig.12 is the electric field intensity distribution diagram in the substrate when the insulating layer is silicon dioxide;

[0035] Fig.13 for Fig.12 The middle dashed line 1 is the line graph of the electric field strength from left to right;

[0036] Fig.14 for Fig.12 The middle dotted line 2 is a line graph of the electric field strength from top to bottom.

[0037] Description of Figure Numbers:

[0038] Label name Label name 10 Substrate 20 First board 30 Oxide layer 40 Insulation layer 50 Second board 60 Metal Sheet 11 Field limiting ring 12 Cut-off ring 21 End field plate 41 First protective layer 42 Second protective layer

[0039] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0042] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if the meaning of "and / or" appearing in the full text is to include three parallel schemes, taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0043] Modern power devices are composed of multiple identical units connected in parallel on a silicon wafer. The surface voltages between the units are roughly the same, but the voltages between the terminal units and the substrate are very different. Therefore, terminal protection technology is generally used to prevent the terminal units from being broken down. Field plates, field limiting rings and their combined use technology are currently commonly used and very effective terminal protection measures in practical applications. An inherent disadvantage of the field plate is that there is a peak electric field at its end, which will affect the voltage resistance of the power device and may eventually cause the power device to be broken down by excessive voltage.

[0044] In view of this, the present invention proposes a terminal structure of a power device.

[0045] In the embodiment of the present invention, Figure 1 As shown, the terminal structure of the power device includes a substrate 10, a plurality of field limiting rings 11, a cut-off ring 12, a plurality of first field plates 20, an oxide layer 30 and an insulating layer 40, wherein the plurality of field limiting rings 11 and the cut-off ring 12 are formed in the substrate 10; the plurality of first field plates 20 correspond to the plurality of field limiting rings 11 one by one, and the plurality of first field plates 20 and the plurality of field limiting rings 11 are electrically connected; the oxide layer 30 is located between the substrate 10 and the plurality of first field plates 20; the insulating layer 40 is at least partially located between the plurality of first field plates 20 and the cut-off ring 12, the insulating layer 40 is arranged on the surface of the oxide layer 30, and the resistivity of the insulating layer 40 is equal to or less than the resistivity of the oxide layer 30.

[0046] The power device in the present invention can be SiC, IEGT, FRD, voltage-driven devices such as IGBT and MOSFET, or current-driven devices such as GTO and GTR, without specific limitation here.

[0047] The first field plate 20 increases the radius of curvature of the curved junction by changing the distribution of the surface potential of the substrate 10, suppresses the concentration of the electric field on the surface of the substrate 10, and thus improves the breakdown voltage of the device. The first field plate 20 may be a metallic field plate, or a polysilicon resistor or a semi-insulating polysilicon resistor field plate, which is not specifically limited here.

[0048] In addition to providing multiple first field plates 20, the embodiment of the present invention also provides multiple field limiting rings 11 in the substrate 10 to avoid electric field concentration. When the voltage on the first main junction or field limiting ring 11 gradually increases, its depletion region gradually expands outward. Before the voltage increases to the avalanche voltage, the depletion regions of the two field limiting rings 11 (or two junctions) have already merged, which has the effect of increasing the curvature radius and improving the breakdown voltage.

[0049] The material of the substrate 10 is crystalline silicon, and the oxide layer 30 on the substrate 10 is silicon dioxide formed by natural oxidation of crystalline silicon. Generally speaking, the oxide layer 30 has certain insulation properties, but due to the natural oxidation process, when the oxidation reaches a certain degree, the diffusion rate of oxygen molecules into the substrate 10 will gradually decrease, so it will eventually reach a balance state to form a layer of oxide layer 30. Considering that the thickness of the oxide layer 30 has certain limitations, it cannot well reduce the peak voltage at the end of the first field plate 20.

[0050] In view of the above technical problems, the present invention is provided with an insulating layer 40, wherein the insulating layer 40 is at least located between the plurality of first field plates 20 and the cut-off ring 12, that is, the insulating layer 40 is located at the ends of the plurality of first field plates 20. The setting of the insulating layer 40 can be used as a pole similar to a capacitor plate, so that the electric potential in the end area of ​​the first field plate 20 decreases, and the depletion region in the surface of the substrate 10 changes slowly, thereby avoiding the concentration of the electric field. In addition, the electric potential of the substrate 10 is higher than that of the first field plate 20 and the insulating layer 40, which is beneficial to the expansion of the depletion region and improves the voltage resistance of the terminal structure.

[0051] The material of the insulating layer 40 may be silicon dioxide, silicon nitride, aluminum nitride, or semi-insulating polysilicon, which is not specifically limited here. Of course, the insulating layer 40 may not only be located between the multiple first field plates 20 and the cut-off ring 12, but also between any first field plate 20 and the first field plate 20, and the insulating layer 40 may also be arranged on the outer surface of the first field plate 20, and other positions of the insulating layer 40 are not specifically limited here. It should be further explained that in order to ensure that the insulating layer 40 is equivalent to the negative electrode of the capacitor plate and the substrate is used as the positive electrode of the capacitor plate, the resistivity of the insulating layer 40 is set to be less than or equal to the resistivity of the oxide layer 30. When the insulating layer 40 is silicon dioxide, the resistivity of the insulating layer 40 is equal to the resistivity of the oxide layer 30. When the insulating layer 40 is a material such as silicon nitride, the resistivity of the insulating layer 40 is less than the resistivity of the oxide layer 30.

[0052] The technical solution of the present invention adopts an insulating layer 40 provided between the ends of the plurality of first field plates 20 and the cut-off ring 12, which can serve as a pole similar to a capacitor plate, so that the electric potential in the end area of ​​the first field plates 20 decreases, thereby causing the depletion region in the surface of the substrate 10 to change slowly, avoiding the concentration of the electric field and reducing the electric field peak at the ends of the plurality of first field plates 20.

[0053] In one embodiment, see Figure 2 The insulating layer 40 includes a first protective layer 41 and a second protective layer 42 , wherein the second protective layer 42 covers the first protective layer 41 , and one of the first protective layer 41 and the second protective layer 42 is made of silicon dioxide, and the other is made of silicon nitride.

[0054] It should be noted that, in the above embodiment, an insulating layer 40 is provided between the ends of the plurality of first field plates 20 and the cutoff ring 12 to reduce the peak electric field at the ends of the plurality of first field plates. Further, the insulating layer 40 also includes a first protective layer 41 and a second protective layer 42. The provision of a double protective layer is more conducive to reducing the peak electric field at the end of the first field plate 20, and the second protective layer 42 covers the first protective layer 41. The material of one of the first protective layer 41 and the second protective layer 42 is silicon dioxide, and the material of the other is silicon nitride; the material of the first protective layer 41 may be silicon dioxide, and the material of the second protective layer 42 may be silicon nitride; or the material of the first protective layer 41 may be silicon nitride, and the material of the second protective layer 42 may be silicon dioxide, and no specific limitation is made here. Of course, the material of the first protective layer 41 and the second protective layer 42 may not be limited to silicon dioxide and silicon nitride, and the material of the first protective layer 41 and the second protective layer 42 may also be aluminum nitride and / or semi-insulating polysilicon, etc.

[0055] Please continue reading Figures 3 to 5 ,in Figure 3 is the electric field strength in the substrate 10 in this embodiment, Figure 3 It is a color picture. After grayscale processing, it should be noted that the darker the color of the area near the end of the first field plate 20, the higher the electric field strength, the lighter the color, the lower the electric field strength, and the darker the color of the area far from the end of the first field plate 20, the lower the electric field strength. It can be seen that the electric field strength near the end of the first field plate 20 is higher and has a peak value.

[0056] exist Figure 3 After analyzing the data at the dotted line 1 and the dotted line 2, we can get Figure 4 and Figure 5 ,in Figure 4 The horizontal axis represents multiple points selected from left to right at the dotted line 1, and the vertical axis represents the electric field strength. Figure 4 There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0057] Figure 5 The horizontal axis represents multiple points selected from top to bottom at the dotted line 2, and the vertical axis is the electric field strength. Figure 5There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0058] It can be concluded from the above analysis that the first protection layer 41 and the second protection layer 42 provided between the plurality of first field plates 20 and the cut-off ring 12 can effectively reduce the peak field intensity at the ends of the plurality of first field plates 20 .

[0059] Optionally, in one embodiment, see Figure 6 The first protection layer 41 covers the outer surfaces of the plurality of first field plates 20 and the oxide layer 30 between any adjacent first field plates 20 .

[0060] In the above embodiment, the insulating layer 40 is at least located between the ends of the plurality of first field plates 20 and the cutoff ring 12. The location of the insulating layer 40 is not limited thereto. The first protective layer 41 can also cover the outer surfaces of the plurality of first field plates 20 and the oxide layer 30 between any adjacent first field plates 20. The second protective layer 42 covers the first protective layer 41. The second protective layer 42 also covers the outer surfaces of the plurality of first field plates 20 and the oxide layer 30 between any adjacent first field plates 20. Such a configuration helps to further reduce the electric field peak at the ends of the plurality of first field plates. In addition, a charge channel from the cutoff ring 12 region to the emitter can be provided to prevent charge accumulation at the interface between the substrate 10 and the oxide layer 30.

[0061] Please continue reading Figures 6 to 8 ,in Figure 6 is the electric field strength in the substrate 10 in this embodiment, Figure 6 It is a color picture. After grayscale processing, it should be noted that the darker the color of the area near the end of the first field plate 20, the higher the electric field strength, the lighter the color, the lower the electric field strength, and the darker the color of the area far from the end of the first field plate 20, the lower the electric field strength. It can be seen that the electric field strength near the end of the first field plate 20 is higher and has a peak value.

[0062] exist Figure 6 After analyzing the data at the dotted line 1 and the dotted line 2, we can get Figure 7 and Figure 8 ,in Figure 7 The horizontal axis represents multiple points selected from left to right at the dotted line 1, and the vertical axis represents the electric field strength. Figure 7There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0063] Figure 8 The horizontal axis represents multiple points selected from top to bottom at the dotted line 2, and the vertical axis is the electric field strength. Figure 8 There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0064] The above analysis shows that the first protection layer 41 covers the outer surfaces of the first field plates 20 and the oxide layer 30 between any adjacent first field plates 20 , which can effectively reduce the peak field intensity at the ends of the first field plates 20 .

[0065] In one embodiment, see Figure 2 , the thickness of the first protective layer 41 is set to 0.1 μm to 10 μm, and the thickness of the second protective layer 42 is set to 0.1 μm to 10 μm.

[0066] It should be noted that the thickness of the first protective layer 41 is set to 0.1μm to 10μm, the thickness of the second protective layer 42 is set to 0.1μm to 10μm, and the second protective layer 42 covers the first protective layer 41. In view of this, in this embodiment, the thickness of the double-layered insulating layer 40 is set to 0.2μm to 20μm. Considering that if the thickness of the first protective layer 41 and the second protective layer 42 is too small, it will not achieve the effect of reducing the peak electric fields at the ends of the multiple first field plates. In this way, the thickness of the first protective layer 41 and the second protective layer 42 is set to be greater than or equal to 0.1μm. It is also considered that if the thickness of the first protective layer 41 or the second protective layer 42 is too large, it may affect the interface quality between the insulating layer 40 and the oxide layer 30. In this way, the thickness of the first protective layer 41 and the second protective layer 42 is set to be less than or equal to more than 10μm.

[0067] In one embodiment, see Figure 1 The first field plate 20 close to the cut-off ring 12 is an end field plate 21 , and the length of the end field plate 21 is greater than the length of the remaining first field plates 20 .

[0068] It should be noted that the electric field is concentrated on the first field plate 20 close to the cut-off ring 12. This field plate is the first field plate 20 with the highest peak electric field among the multiple first field plates 20. In order to make the charge distribution of the end field plate 21 more uniform and disperse the concentrated voltage as much as possible, the length of the end field plate 21 is lengthened. In this way, the length of the field of the end field plate 21 is greater than that of the remaining first field plates.

[0069] In one embodiment, see Figure 1 A second field plate 50 is further disposed between the end field plate 21 and the substrate 10 , and the second field plate 50 is electrically connected to the end field plate 21 .

[0070] It should be noted that a second field plate 50 is also arranged between the end field plate 21 and the substrate 10, wherein the second field plate 50 can be a metal field plate or a resistive field plate. In the present embodiment, the second field plate 50 is made of polysilicon. Compared with the resistive field plate, the second field plate 50 is electrically connected to the end field plate 21, so that the second field plate 50 can disperse the charge distribution at the end field plate 21.

[0071] In one embodiment, see Figure 1 The terminal structure of the power device also includes a metal plate 60, which is arranged corresponding to the cut-off ring 12, and the metal plate 60 is electrically connected to the cut-off ring 12, and the insulating layer 40 is at least partially located between the metal plate 60 and the first field plate 20 adjacent to the metal plate 60.

[0072] Specifically, a metal plate 60 is further provided, wherein the charge flow direction between the metal plate 60 and the plurality of first field plates 20 is opposite, and the metal plate 60 is used to limit the position of the insulating layer 40 .

[0073] In one embodiment, see Figure 1 and Fig. 9 , the material of the insulating layer 40 is set to silicon nitride.

[0074] It should be noted that silicon nitride has good insulation properties and does not increase leakage current. At the same time, a capacitor-like structure of the substrate 10 combined with the oxide layer 30 and then combined with the insulating layer 40 can be formed. In this way, the material of the insulating layer 40 is set to silicon nitride.

[0075] Please continue reading Figures 9 to 11 ,in Fig. 9 is the electric field strength in the substrate 10 when the insulating layer 40 is made of silicon nitride. Fig. 9It is a color picture. After grayscale processing, it should be noted that the darker the color of the area near the end of the first field plate 20, the higher the electric field strength, the lighter the color, the lower the electric field strength, and the darker the color of the area far from the end of the first field plate 20, the lower the electric field strength. It can be seen that the electric field strength near the end of the first field plate 20 is higher and has a peak value.

[0076] exist Fig. 9 After analyzing the data at the dotted line 1 and the dotted line 2, we can get Fig.10 and Fig.11 ,in Fig.10 The horizontal axis represents multiple points selected from left to right at the dotted line 1, and the vertical axis represents the electric field strength. Fig.10 There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0077] Fig.11 The horizontal axis represents multiple points selected from top to bottom at the dotted line 2, and the vertical axis is the electric field strength. Fig.11 There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0078] It can be concluded from the above analysis that when the insulating layer 40 is configured as silicon nitride, the peak field intensity at the ends of the plurality of first field plates 20 can be effectively reduced.

[0079] In one embodiment, see Figure 1 and Fig.12 , the material of the insulating layer 40 is set to silicon dioxide.

[0080] Silicon dioxide also has good insulation properties, please continue to refer to Figure 12 to Figure 14 ,in Fig.12 is the electric field strength in the substrate 10 when the insulating layer 40 is made of silicon dioxide. Fig.12 It is a color picture. After grayscale processing, it should be noted that the darker the color of the area near the end of the first field plate 20, the higher the electric field strength, the lighter the color, the lower the electric field strength, and the darker the color of the area far from the end of the first field plate 20, the lower the electric field strength. It can be seen that the electric field strength near the end of the first field plate 20 is higher and has a peak value.

[0081] exist Fig.12 After analyzing the data at the dotted line 1 and the dotted line 2, we can get Fig.13 and Fig.14 ,in Fig.13 The horizontal axis represents multiple points selected from left to right at the dotted line 1, and the vertical axis represents the electric field strength. Fig.13 There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0082] Fig.14 The horizontal axis represents multiple points selected from top to bottom at the dotted line 2, and the vertical axis is the electric field strength. Fig.14 There are the scheme of the present embodiment and the comparative scheme without the first protective layer 41 and the second protective layer 42, wherein the lighter colored broken line is the scheme of the present embodiment, and the darker colored broken line is the comparative scheme without the first protective layer 41 and the second protective layer 42. It can be clearly seen that the field intensity at the peak of the electric field intensity of the present embodiment is significantly lower than that of the comparative scheme.

[0083] It can be concluded from the above analysis that when the insulating layer 40 is configured as silicon dioxide, the peak field intensity at the ends of the plurality of first field plates 20 can be effectively reduced.

[0084] In one embodiment, see Figure 1 , the thickness of the insulating layer 40 is set to 0.1 μm to 10 μm.

[0085] Considering that if the thickness of the insulating layer 40 is too small, it cannot achieve the effect of reducing the peak electric fields at the ends of the multiple first field plates, so the thickness of the insulating layer 40 is set to be greater than or equal to 0.1 μm. Considering that if the thickness of the insulating layer 40 is too large, it may affect the interface quality between the insulating layer 40 and the oxide layer 30, so the thickness of the insulating layer 40 is set to be less than or equal to 10 μm.

[0086] In one embodiment, see Figure 1 , the insulating layer 40 is configured as an insulator or a semi-insulator.

[0087] In the embodiment of the present invention, the insulating layer 40 can be set as an insulator or a semi-insulator, specifically set as silicon dioxide, silicon nitride, aluminum nitride, semi-insulating polysilicon and the like. The present invention also provides a power device, the power device includes a terminal structure of the power device, the specific structure of the terminal structure of the power device refers to the above embodiment, since the power device adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0088] The above descriptions are only optional embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A terminal structure of a power device, characterized in that: include: substrate; A plurality of field limiting rings and cut-off rings, wherein the plurality of field limiting rings and the cut-off rings are formed in the substrate; A plurality of first field plates, the plurality of first field plates correspond to the plurality of field limiting rings one by one, and the plurality of first field plates and the plurality of field limiting rings are electrically connected; an oxide layer, the oxide layer being located between the substrate and the plurality of first field plates; An insulating layer, wherein the insulating layer is at least partially located between the plurality of first field plates and the cut-off ring, the insulating layer is disposed on a surface of the oxide layer, and the resistivity of the insulating layer is equal to or less than the resistivity of the oxide layer.

2. The terminal structure of a power device according to claim 1, characterized in that: The insulating layer includes a first protective layer and a second protective layer, the second protective layer covers the first protective layer, and one of the first protective layer and the second protective layer is made of silicon dioxide, and the other is made of silicon nitride.

3. The terminal structure of the power device according to claim 2, characterized in that: The first protection layer covers outer surfaces of the plurality of first field plates and an oxide layer between any adjacent first field plates.

4. The terminal structure of the power device according to claim 2, characterized in that: The thickness of the first protective layer is set to 0.1 μm to 10 μm, and the thickness of the second protective layer is set to 0.1 μm to 10 μm.

5. The terminal structure of a power device according to claim 1, characterized in that: The first field plate close to the cut-off ring is an end field plate, and the length of the end field plate is greater than the lengths of the remaining first field plates.

6. The terminal structure of a power device according to claim 5, characterized in that: A second field plate is further disposed between the end field plate and the substrate, and the second field plate is electrically connected to the end field plate.

7. The terminal structure of a power device according to claim 1, characterized in that: The terminal structure of the power device further includes a metal plate, which is arranged corresponding to the cut-off ring and electrically connected to the cut-off ring. The insulating layer is at least partially located between the metal plate and the first field plate adjacent to the metal plate.

8. The terminal structure of a power device according to claim 1, characterized in that: The material of the insulating layer is set to be silicon nitride.

9. The terminal structure of a power device according to claim 1, characterized in that: The material of the insulating layer is set to be silicon dioxide.

10. The terminal structure of a power device according to claim 1, characterized in that: The thickness of the insulating layer is set to 0.1 μm to 10 μm.

11. The terminal structure of a power device according to claim 1, characterized in that: The insulating layer is configured as an insulator or a semi-insulator.

12. A power device, characterized in that: A terminal structure of a power device comprising any one of claims 1 to 11.

Images