Power device terminal structure

Abstract

The invention belongs to the field of semiconductor integrated circuits, and particularly relates to a power device terminal structure, the terminal structure is arranged on a transition region and a terminal region, the terminal structure comprises an edge terminal region located near the main edge of a device and a corner terminal region located at the periphery of the device, and the edge terminal region and the corner terminal region comprise a plurality of P-type rings and N + cut-off rings, an oxide layer is arranged on the surface of the N-type epitaxial layer in the terminal region; a conductive material covering layer is further arranged on the oxide layer covering structure, the conductive material covering layer arranged on the surface of the edge terminal on the outer side of the P-type ring of the terminal area is of a multi-section parallel structure, and the conductive material layer at the corner terminal is arranged to be trapezoidal and used for reducing stress at the corners around a device and improving the reliability of the terminal structure. The reliability of the mechanical stress of the metal field plate is improved, and the influence of external movable charges on the electric field intensity of the surface of the drift region of the terminal region is reduced or prevented, so that the electric leakage of the device can be reduced, and the breakdown voltage of the device is increased.

Description

Technical Field

[0001] This invention relates to a semiconductor integrated circuit, and more particularly to a power device termination structure. Background Technology

[0002] Power devices typically consist of three regions: the cell region, the transition region, and the termination region. The cell region is the core functional area of ​​the device, responsible for the main current conduction and blocking functions. The transition region serves as a buffer zone between the cell region and the termination region, and its structural design ensures a smooth electric field transition, avoiding electric field concentration caused by abrupt structural changes. The termination region surrounds the outermost edge of the chip and is responsible for the high-voltage blocking function of the device. Its design directly affects the device's voltage withstand capability and reliability.

[0003] Traditional power device termination structures typically employ techniques such as field-limiting loops, field plates, or junction termination extensions to optimize surface electric field distribution; however, these techniques still face significant technical bottlenecks in practical applications. Because the drift layer surface in the termination region is often not completely shielded, external mobile charges such as Na+ can easily escape. + Ion and humidity-induced H + Charge interference tends to accumulate on the surface, which not only alters the electric field distribution of the depletion layer, leading to a significant reduction in breakdown voltage, but also significantly degrades the reliability of the device under high temperature and high humidity environments. Although some solutions attempt to mitigate this problem through local field plates or passivation layers, these methods cannot achieve full-coverage shielding of the terminal area surface, and the charge interference problem still exists.

[0004] On the other hand, the metal field plate structure used to improve the terminal withstand voltage faces the problem of mechanical stress caused by the mismatch of the thermal expansion coefficients of metal and semiconductor materials. This stress accumulation can lead to failure modes such as metal layer warping and passivation layer cracking, which seriously restricts the long-term reliability of the device.

[0005] In semiconductor power device applications, the shortcomings of traditional termination structures in charge shielding and stress management become more pronounced. These issues collectively lead to performance instability and decreased reliability of existing power device termination structures in high-voltage applications, necessitating an innovative solution that can simultaneously achieve complete charge shielding and low-stress design. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a power device termination structure that can reduce or prevent the influence of external movable charges on the electric field strength of the drift region surface of the termination region, thereby reducing the leakage current of the device, increasing the breakdown voltage of the device, and having low process cost.

[0007] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0008] A power device termination structure is provided, wherein the middle region of the power device is a cell region, a termination region surrounds the outer periphery of the cell region, and a transition region is located between the cell region and the termination region; a termination structure is disposed on the transition region and the termination region, the termination structure including an edge termination region located near the main edge of the device and corner termination regions located at the chamfered corners of the device, the edge termination region and the corner termination region comprising:

[0009] Multiple P-type rings 3 are formed in the terminal region. The P-type rings 3 and the P-type wells 10 in the charge flow region are not in contact. Both the P-type rings 3 and the P-type wells 10 are formed on the N-type epitaxial layer 12.

[0010] Each P-ring 3 has a single metal layer connected to its top via a contact hole, forming a metal field plate;

[0011] The P-type ring 3 is located in the N-type epitaxial layer 12 in the terminal region. The P-type ring 3 and the terminal drift region form a PN junction with lateral depletion on the surface, which is used to withstand the lateral voltage of the power device.

[0012] N+ cutoff ring 8 is formed in the terminal region and is located on the outermost side of the N-type epitaxial layer 12;

[0013] An oxide layer is provided on the surface of the N-type epitaxial layer in the terminal region;

[0014] A conductive material covering layer is also provided on the oxide layer covering structure. The conductive material covering structure is located outside the P-type ring 3 in the terminal area. The conductive material covering structure covers the surface of each position between the terminal transition area and the N+ stop ring 8 with conductive material, which is used to prevent the influence of external movable charges on the surface electric field of the terminal and improve the voltage resistance of the terminal structure.

[0015] The conductive material covering layer disposed on the outer side terminal surface of the P-ring 3 in the terminal area is a multi-segment parallel structure, and its extension direction is perpendicular to the P-ring.

[0016] A conductive material layer disposed on the corner terminal surface outside the P-ring 3 in the terminal area is aligned with the chamfer radius of the corner terminal. The conductive material layer at the corner terminal is set in a trapezoidal shape to reduce stress at the corners of the device and improve the reliability of the terminal structure.

[0017] A further improvement is that the surface of the terminal drift region is provided with multiple spaced P-type doped floating rings.

[0018] A further improvement is that the conductive material covering structure includes two conductive material covering layers. The conductive material of the first conductive material covering layer is polycrystalline silicon, and the conductive material of the second conductive material covering layer is metal. In the direction perpendicular to the substrate, the first conductive material covering layer is located at the bottom of the second conductive material covering layer. In the direction parallel to the substrate, the first conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its edge terminal position; the second conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its edge terminal position; the first conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its corner terminal position; and the second conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its corner terminal position.

[0019] A further improvement is that a first conductive material capping layer is formed in the middle of the oxide layer 9, a second conductive material capping layer is formed on top of the oxide layer 9, a first oxide layer is isolated between the first conductive material capping layer and the N-type epitaxial layer, and a second oxide layer is isolated between the first conductive material capping layer and the second conductive material capping layer.

[0020] A further improvement is that the first conductive material covering layer has a parallel segmented structure at the edge terminal position, and the area between each segment of the first conductive material covering layer 6 is covered by the second conductive material covering layer, so that the surface of each position of the terminal is covered with conductive material; the second conductive material covering layer has a parallel segmented structure at the edge terminal position, and the material of the first conductive material covering layer 6 is disposed below the area between each segment of the second conductive material covering layer, so that the surface of each position of the terminal drift area is covered with conductive material.

[0021] A further improvement is that the first conductive material covering layer 6 has a trapezoidal segmented structure at the corner terminal position, and the area between each segment of the first conductive material covering layer is covered by the second conductive material covering layer, so that the surface of each position of the terminal is covered with conductive material; the second conductive material covering layer has a trapezoidal segmented structure at the corner terminal position, and the material of the first conductive material covering layer 6 is disposed below the area between each segment of the second conductive material covering layer, so that the surface of each position of the terminal drift area is covered with conductive material.

[0022] A further improvement is that the first conductive material covering layer 6 is suspended in mid-air without being connected to the electrodes; the second conductive material covering layer 5 is also suspended in mid-air without being connected to the electrodes.

[0023] A further improvement is that the width of each segment of the first conductive material covering layer 6 at the edge terminal is less than or equal to 10 micrometers, and the spacing between each segment is less than or equal to 10 micrometers; the length of each segment of the second conductive material covering layer at the edge terminal is less than or equal to 8 micrometers, and the spacing between each segment is less than or equal to 10 micrometers.

[0024] A further improvement is that the length of each segment of the first conductive material covering layer 6 at the edge terminal is set according to the distance between the outermost metal field plate and the stop ring metal 7. The setting principle is that the distance between each segment and the outermost metal field plate is less than or equal to 5 micrometers, and the distance between each segment and the stop ring metal 7 is less than or equal to 5 micrometers. The length of each segment of the second conductive material covering layer 5 at the edge terminal is set according to the distance between the outermost metal field plate 4 and the stop ring metal 7. The setting principle is that the distance between each segment and the outermost metal field plate 4 is less than or equal to 5 micrometers, and the distance between each segment and the stop ring metal 7 is less than or equal to 5 micrometers.

[0025] A further improvement is that, at the corner end, the width of the upper base of each trapezoid in the first layer of conductive material covering layer is less than or equal to 8 micrometers, the distance between the upper bases of each trapezoid is less than or equal to 10 micrometers, and the distance between the legs of two adjacent trapezoids is less than or equal to 10 micrometers; at the corner end, the width of the upper base of each trapezoid in the second layer of conductive material 5 covering layer is less than or equal to 10 micrometers, the distance between the upper bases of each trapezoid is less than or equal to 10 micrometers, and the distance between the legs of two adjacent trapezoids is less than or equal to 10 micrometers.

[0026] A further improvement is that the power device is a vertical structure device, and the N-type epitaxial layer at the bottom of the P-type well in the charge flow region constitutes the device region drift region; the P-type well and the device region drift region form a vertical PN junction, the top of the P-type well is connected to the first electrode composed of the front metal layer through a contact hole, and the top of the P-type ring is connected to the second conductive material cover layer through a contact hole.

[0027] And / or the power device is a power PN junction diode, VDMOS, or IGBT.

[0028] The beneficial effects of this invention are: improving the reliability of mechanical stress in the metal field plate, reducing or preventing the influence of external movable charges on the electric field strength of the drift region surface in the terminal area, thereby reducing the leakage current of the device and increasing the breakdown voltage of the device. Attached Figure Description

[0029] Figure 1 This is a cross-sectional structural diagram of the power device terminal in an embodiment of this application.

[0030] Figure 2 This is a schematic cross-sectional view of AA', the terminal of the power device in an embodiment of this application. AA' points from the active region to the cutoff ring and passes through the terminal region.

[0031] Figure 3 This is a schematic cross-sectional view of the power device terminal BB' in an embodiment of this application. BB' is a floating metal field plate perpendicular to the extension direction of the floating metal field plate, extending from one floating metal field plate at the edge terminal to another floating metal field plate at the edge terminal, and passing through the floating metal field plate and the floating polycrystalline silicon field plate between the two.

[0032] Figure 4 This is a schematic cross-sectional view of the IGBT device terminal AA' in an embodiment of this application.

[0033] Explanation of icon numbers

[0034] 1—Active region, 2—Termination region, 3—P-type ring, 4—Metal field plate, 5—Second conductive material capping layer, 6—First conductive material capping layer, 7—Stop ring metal, 8—N+ stop ring, 9—Oxide layer, 10—P-type well, 11—Active region metal electrode, 12—N-type epitaxial layer. Detailed Implementation

[0036] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] like Figure 2 As shown, a power device termination structure is provided. The middle region of the power device is a cell region, and a termination region surrounds the outer periphery of the cell region. A transition region is located between the cell region and the termination region. The termination structure is disposed on the transition region and the termination region. The termination structure includes an active region 1 and a termination region 2. The termination structure includes an edge termination region located near the main edge of the device and a corner termination region located at the chamfered corners around the device. The edge termination region and the corner termination region include:

[0038] Multiple P-type rings 3 are formed in the terminal region. The P-type rings 3 and the P-type wells 10 in the charge flow region are not in contact. Both the P-type rings 3 and the P-type wells 10 are formed on the N-type epitaxial layer 12. Typically, the N-type epitaxial layer 12 is formed on the surface of a semiconductor substrate, which is usually a silicon substrate. In this case, the N-type epitaxial layer 12 is a silicon epitaxial layer. The surface of the N-type epitaxial layer 12 is covered with an oxide layer 9.

[0039] Each P-ring 3 has a single metal layer connected to its top via a contact hole, forming a metal field plate;

[0040] The P-type ring 3 is located in the N-type epitaxial layer 12 in the terminal region. The P-type ring 3 and the terminal drift region form a PN junction with lateral depletion on the surface, which is used to withstand the lateral voltage of the power device.

[0041] N+ cutoff ring 8 is formed in the terminal region and is located on the outermost side of the N-type epitaxial layer 12;

[0042] An oxide layer is provided on the surface of the N-type epitaxial layer in the terminal region;

[0043] A conductive material covering layer is also provided on the oxide layer covering structure. The conductive material covering structure is located outside the P-type ring 3 in the terminal area. The conductive material covering structure covers the surface of each position between the terminal transition area and the N+ stop ring 8 with conductive material, which is used to prevent the influence of external movable charges on the surface electric field of the terminal and improve the voltage resistance of the terminal structure.

[0044] The conductive material covering layer disposed on the outer side terminal surface of the P-ring 3 in the terminal area is a multi-segment parallel structure, and its extension direction is perpendicular to the P-ring.

[0045] A conductive material layer disposed on the corner terminal surface outside the P-ring 3 in the terminal area is aligned with the chamfer radius of the corner terminal. The conductive material layer at the corner terminal is set in a trapezoidal shape to reduce stress at the corners of the device and improve the reliability of the terminal structure.

[0046] Preferably, the surface of the terminal drift region is provided with a plurality of spaced P-type doped floating rings.

[0047] Preferably, the conductive material covering structure includes two conductive material covering layers. The conductive material of the first conductive material covering layer is polycrystalline silicon, and the conductive material of the second conductive material covering layer is metal. In the direction perpendicular to the substrate, the first conductive material covering layer is located at the bottom of the second conductive material covering layer. In the direction parallel to the substrate, the first conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its edge terminal position; the second conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its edge terminal position; the first conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its corner terminal position; and the second conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings 3 at its corner terminal position.

[0048] Preferably, a first conductive material capping layer is formed in the middle of the oxide layer 9, and a second conductive material capping layer is formed above the oxide layer 9. A first oxide layer is isolated between the first conductive material capping layer and the N-type epitaxial layer, and a second oxide layer is isolated between the first conductive material capping layer and the second conductive material capping layer.

[0049] Preferably, the first conductive material covering layer has a parallel segmented structure at the edge terminal position, and the area between each segment of the first conductive material covering layer 6 is covered by the second conductive material covering layer, so that the surface of each position of the terminal is covered by conductive material; the second conductive material covering layer has a parallel segmented structure at the edge terminal position, and the material of the first conductive material covering layer 6 is disposed below the area between each segment of the second conductive material covering layer, so that the surface of each position of the terminal drift area is covered by conductive material.

[0050] Preferably, the first conductive material covering layer 6 has a trapezoidal segmented structure at the corner terminal position, and the area between each segment of the first conductive material covering layer is covered by the second conductive material covering layer, so that the surface of each position of the terminal is covered by conductive material; the second conductive material covering layer has a trapezoidal segmented structure at the corner terminal position, and the material of the first conductive material covering layer 6 is disposed below the area between each segment of the second conductive material covering layer, so that the surface of each position of the terminal drift area is covered by conductive material.

[0051] Preferably, the first conductive material covering layer 6 is suspended in mid-air without being connected to the electrodes; the second conductive material covering layer 5 is also suspended in mid-air without being connected to the electrodes.

[0052] Preferably, the width of each segment of the first conductive material covering layer 6 at the edge terminal is less than or equal to 10 micrometers, and the spacing between each segment is less than or equal to 10 micrometers; the length of each segment of the second conductive material covering layer at the edge terminal is less than or equal to 8 micrometers, and the spacing between each segment is less than or equal to 10 micrometers.

[0053] Preferably, the length of each segment of the first conductive material covering layer 6 at the edge terminal is set according to the distance between the outermost metal field plate and the stop ring metal 7. The setting principle is that the distance between each segment and the outermost metal field plate is less than or equal to 5 micrometers, and the distance between each segment and the stop ring metal 7 is less than or equal to 5 micrometers. The length of each segment of the second conductive material covering layer 5 at the edge terminal is set according to the distance between the outermost metal field plate 4 and the stop ring metal 7. The setting principle is that the distance between each segment and the outermost metal field plate 4 is less than or equal to 5 micrometers, and the distance between each segment and the stop ring metal 7 is less than or equal to 5 micrometers.

[0054] Preferably, at the corner end, the width of the upper base of each trapezoid in the first conductive material covering layer is less than or equal to 8 micrometers, the distance between the upper bases of each trapezoid is less than or equal to 10 micrometers, and the distance between the legs of two adjacent trapezoids is less than or equal to 10 micrometers; at the corner end, the width of the upper base of each trapezoid in the second conductive material 5 covering layer is less than or equal to 10 micrometers, the distance between the upper bases of each trapezoid is less than or equal to 10 micrometers, and the distance between the legs of two adjacent trapezoids is less than or equal to 10 micrometers.

[0055] Preferably, the power device is a vertical structure device, and the N-type epitaxial layer at the bottom of the P-type well in the charge flow region constitutes the device region drift region; the P-type well and the device region drift region form a vertical PN junction, the top of the P-type well is connected to the first electrode composed of the front metal layer through a contact hole, and the top of the P-type ring is connected to the second conductive material cover layer through a contact hole.

[0056] And / or the power device is a power PN junction diode, VDMOS, or IGBT.

[0057] The metal field plates completely cover and extend beyond each of the P-rings, with a spacing of less than or equal to 5 micrometers between each segment of the metal field plates. The width of each segment of the metal field plates is adjusted according to its spacing. The metal field plates serve to shield the P-rings 3 from external charges.

[0058] The N-type epitaxial layer 12 located in the terminal region forms a terminal drift region, and the P-type ring 3 and the terminal drift region form a PN junction with lateral depletion on the surface, which is used to withstand the lateral voltage of the power device.

[0059] The N+ cutoff ring 8 is connected to the second electrode, which is composed of a front metal layer, through a contact hole to form the cutoff ring metal 7.

[0060] A conductive material covering layer is formed on the surface between the terminal area and the stop ring metal 7. This shielding layer completely covers all exposed surfaces between the terminal area and the stop ring, shielding against interference from external movable charges, thereby stabilizing the surface electric field distribution of the terminal area and significantly improving the breakdown voltage characteristics of the terminal structure.

[0061] like Figure 1 The diagram shown is a cross-sectional view of the power device terminal structure according to an embodiment of the present invention. A first conductive material cover layer 6 is formed in the middle of the oxide layer 9, and a second conductive material cover layer 5 is formed above the oxide layer 9. The first conductive material cover layer 6 extends laterally at the edge terminal position in a direction perpendicular to the P-ring 3; the second conductive material cover layer 5 extends laterally at the edge terminal position in a direction perpendicular to the P-ring 3.

[0062] The first conductive material covering layer 6 has a parallel segmented structure at the edge terminal position. The area between each segment of the first conductive material covering layer 6 is covered by the second conductive material covering layer 5, so that the surface of each position of the terminal is covered with conductive material. The second conductive material covering layer 5 has a parallel segmented structure at the edge terminal position. The material of the first conductive material covering layer 6 is disposed below the area between each segment of the second conductive material covering layer 5, so that the surface of each position of the terminal drift area is covered with conductive material.

[0063] like Figure 1 As shown, the first conductive material covering layer 6 has a trapezoidal segmented structure at the corner end position. The area between each segment of the first conductive material covering layer 6 is covered by the second conductive material covering layer 5, so that the surface of each position of the terminal is covered with conductive material. The second conductive material covering layer 5 has a trapezoidal segmented structure at the corner end position. The material of the first conductive material covering layer 6 is disposed below the area between each segment of the second conductive material covering layer 5, so that the surface of each position of the terminal drift area is covered with conductive material.

[0064] like Figure 1 As shown, the first conductive material cover layer 6 is symmetrically arranged on both sides of the center line of the corner terminal. The length of the first conductive material cover layer 6 located at the center line of the corner terminal can be set to the longest. The remaining first conductive material cover layers 6 on both sides of the longest first conductive material cover layer 6 are symmetrically and equally spaced to ensure that the width of the trapezoidal base of the first conductive material cover layer 6 near the P-ring 3 is less than or equal to 8 micrometers and the minimum distance between it and the outermost metal field plate 4 is less than or equal to 5 micrometers. The width of the first conductive material cover layer 6 near the stop ring metal 7 is determined based on two adjacent first conductive material cover layers 6 to ensure that the distance between the two adjacent waists of the two adjacent trapezoidal first conductive material cover layers 6 is less than or equal to 10 micrometers and the minimum distance between it and the stop ring metal 7 is less than or equal to 5 micrometers.

[0065] like Figure 1As shown, the second conductive material cover layer 5 is symmetrically arranged on both sides of the center line of the corner terminal. The length of the second conductive material cover layer 5 on both sides of the center line of the corner terminal can be set to the longest. The remaining second conductive material cover layers 5 on both sides of the longest second conductive material cover layer 5 are symmetrically and equally spaced to ensure that the width of the trapezoidal base of the second conductive material cover layer 5 near the P-ring 3 is less than or equal to 10 micrometers and the minimum distance between it and the outermost metal field plate 4 is less than or equal to 5 micrometers. The width of the second conductive material cover layer 5 near the stop ring metal 7 is determined according to two adjacent second conductive material cover layers 5 to ensure that the distance between the two adjacent waists of the two adjacent trapezoidal second conductive material cover layers 5 is less than or equal to 10 micrometers and the minimum distance between it and the stop ring metal 7 is less than or equal to 5 micrometers.

[0066] like Figure 2 As shown, the first conductive material cover layer 6 is suspended in mid-air.

[0067] like Figure 2 As shown, the second conductive material cover layer 5 is suspended in mid-air.

[0068] like Figure 3 As shown, in the horizontal direction, the staggered arrangement of the segments of the first conductive material cover layer 6 and the second conductive material cover layer 5 results in the segmented areas of the first conductive material cover layer 6 and the second conductive material cover layer 5 forming a complementary cover in the horizontal direction, with a spacing of less than or equal to 2 micrometers in the horizontal direction.

[0069] Whether it is a side terminal or a corner terminal, the first conductive material covering layer 6 and the second conductive material covering layer 5 are set in segments with equal spacing, so that there is no large area of ​​continuous coverage of the entire conductive material layer. This can reduce or prevent the influence of external movable charges on the electric field strength of the drift area surface of the terminal area and effectively avoid failure modes such as metal layer warping and passivation layer cracking.

[0070] Taking the power device as a power PN junction diode as an example, the cell structure of the power PN junction diode is directly composed of a PN junction with a vertical structure formed by the P-type well and the device region drift region, and the active region metal electrode 11 is the anode; a back metal layer is formed on the N-type epitaxial layer 12 and forms the cathode.

[0071] Taking the power device as a VDMOS as an example, the cell structure of a VDMOS also includes a source region located in the P-type well. A gate structure covers the P-type well to form a channel, and a drain region is formed on the back side of the N-type epitaxial layer 12. A back metal layer is formed on the back side of the drain region to form the drain electrode. The active region metal electrode 11 is the source electrode. The gate structure of a VDMOS can be a planar gate structure or a trench gate structure. When a trench gate structure is used, a trench MOSFET is formed. The polysilicon of the first conductive material capping layer 5 can be formed simultaneously with the polysilicon gate of the planar gate structure or the trench gate structure, including polysilicon deposition and polysilicon etching processes. Figure 4 As shown, IGBT is formed by further modifications to VDMOS, mainly by forming a P+ doped collector region on the back side of the device region drift region.

[0072] In summary, by controlling the maximum spacing between the metal field plates 4 in the terminal drift region, the coverage area of ​​the metal field plates 4 is increased. This not only blocks the interference of external mobile charges (such as Na+, H+, etc.) on the surface potential of the P-ring 3, but also optimizes the lateral expansion characteristics of the depletion layer through the coupling effect between the field plates and the P-ring 3. A conductive material shielding layer formed on the surface between the outermost metal field plate 4 and the stop ring metal 7 shields the influence of external charges on the terminal drift region 2, and the conductive material shielding layer is arranged in segments with equal spacing. This segmented structure ensures complete shielding against external charges and, by introducing appropriate stress relief gaps, effectively avoids reliability problems such as metal layer warping and passivation layer cracking caused by thermal expansion coefficient mismatch in traditional continuous metal layers. Therefore, it improves the terminal withstand voltage capability while ensuring the long-term stability of the device.

[0073] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A power device termination structure, characterized in that: The middle region of the power device is a cell region, and a termination region surrounds the outer periphery of the cell region. A transition region is located between the cell region and the termination region. A termination structure is disposed on the transition region and the termination region. The termination structure includes an edge termination region located near the main edge of the device and corner termination regions located at the chamfered corners around the device. The edge termination region and the corner termination region include: Multiple P-type rings (3) are formed in the terminal region. The P-type rings (3) and the P-type wells (10) in the charge flow region are not in contact. Both the P-type rings (3) and the P-type wells (10) are formed on the N-type epitaxial layer (12). Each P-ring (3) has a single metal layer connected to its top through a contact hole to form a metal field plate; The P-type ring (3) is located in the N-type epitaxial layer (12) in the terminal region. The P-type ring (3) and the terminal drift region form a PN junction with lateral depletion on the surface, which is used to withstand the lateral voltage of the power device. An N+ cutoff ring (8) is formed in the terminal region and is located on the outermost side of the N-type epitaxial layer (12); An oxide layer is provided on the surface of the N-type epitaxial layer in the terminal region; A conductive material covering layer is provided on the oxide layer covering structure. The conductive material covering structure is located outside the P-type ring (3) in the terminal area. The conductive material covering structure covers the surface of each position between the terminal transition area and the N+ stop ring (8) with conductive material, which is used to prevent the influence of external movable charges on the surface electric field of the terminal and improve the voltage resistance of the terminal structure. The conductive material covering layer provided on the outer side terminal surface of the P-type ring (3) in the terminal area is a multi-segment parallel structure, and its extension direction is perpendicular to the P-type ring. The conductive material layer disposed on the corner terminal surface outside the P-ring (3) in the terminal area is aligned with the chamfer radius of the corner terminal. The conductive material layer at the corner terminal is set in a trapezoidal shape to reduce stress at the corners of the device and improve the reliability of the terminal structure.

2. The power device termination structure according to claim 1, characterized in that: The surface of the terminal drift region is provided with multiple spaced P-type doped floating rings.

3. The power device termination structure according to claim 1, characterized in that: The conductive material covering structure includes two conductive material covering layers. The conductive material of the first conductive material covering layer is polycrystalline silicon, and the conductive material of the second conductive material covering layer is metal. In the direction perpendicular to the substrate, the first conductive material covering layer is located at the bottom of the second conductive material covering layer. In the direction parallel to the substrate, the first conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings (3) at the edge end position. The second conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings (3) at the edge end position. The first conductive material covering layer extends perpendicularly to the arrangement direction of the P-rings (3) at the corner end position. The second conductive material covering layer extends laterally perpendicularly to the arrangement direction of the P-rings (3) at the corner end position.

4. The power device termination structure according to claim 1, characterized in that: A first conductive material cover layer is formed in the middle of the oxide layer (9), and a second conductive material cover layer is formed above the oxide layer (9). A first oxide layer is isolated between the first conductive material cover layer and the N-type epitaxial layer, and a second oxide layer is isolated between the first conductive material cover layer and the second conductive material cover layer.

5. The power device termination structure according to claim 1, characterized in that: The first conductive material covering layer has a parallel segmented structure at the edge terminal position. The area between each segment of the first conductive material covering layer (6) is covered by the second conductive material covering layer, so that the surface of each position of the terminal is covered by conductive material. The second conductive material covering layer has a parallel segmented structure at the edge terminal position. The material of the first conductive material covering layer (6) is disposed below the area between each segment of the second conductive material covering layer, so that the surface of each position of the terminal drift area is covered by conductive material.

6. The power device termination structure according to claim 1, characterized in that: The first conductive material covering layer (6) has a trapezoidal segmented structure at the corner end position. The area between each segment of the first conductive material covering layer is covered by the second conductive material covering layer, so that the surface of each position of the terminal is covered by conductive material. The second conductive material covering layer has a trapezoidal segmented structure at the corner end position. The material of the first conductive material covering layer (6) is disposed below the area between each segment of the second conductive material covering layer, so that the surface of each position of the terminal drift area is covered by conductive material.

7. The power device termination structure according to claim 1, characterized in that: The first conductive material covering layer (6) is suspended without being connected to an electrode; the second conductive material covering layer (5) is suspended without being connected to an electrode.

8. The power device termination structure according to claim 5, characterized in that: The width of each segment of the first conductive material covering layer (6) at the edge terminal is less than or equal to 10 micrometers, and the spacing between each segment is less than or equal to 10 micrometers; the length of each segment of the second conductive material covering layer at the edge terminal is less than or equal to 8 micrometers, and the spacing between each segment is less than or equal to 10 micrometers. And / or the length of each segment of the first conductive material covering layer (6) at the edge terminal is set according to the distance between the outermost metal field plate and the stop ring metal (7), the setting principle is that the distance between each segment and the outermost metal field plate is less than or equal to 5 micrometers, and the distance between each segment and the stop ring metal (7) is less than or equal to 5 micrometers; the length of each segment of the second conductive material covering layer (5) at the edge terminal is set according to the distance between the outermost metal field plate (4) and the stop ring metal (7), the setting principle is that the distance between each segment and the outermost metal field plate (4) is less than or equal to 5 micrometers, and the distance between each segment and the stop ring metal (7) is less than or equal to 5 micrometers.

9. A power device termination structure according to claim 6, characterized in that: The width of the upper base of each trapezoid in the first layer of conductive material covering at the corner terminal is less than or equal to 8 micrometers, the distance between the upper bases of each trapezoid is less than or equal to 10 micrometers, and the distance between the legs of two adjacent trapezoids is less than or equal to 10 micrometers; the width of the upper base of each trapezoid in the second layer of conductive material (5) covering at the corner terminal is less than or equal to 10 micrometers, the distance between the upper bases of each trapezoid is less than or equal to 10 micrometers, and the distance between the legs of two adjacent trapezoids is less than or equal to 10 micrometers.

10. A power device termination structure according to claim 1, characterized in that: The power device is a vertical structure device, and the N-type epitaxial layer at the bottom of the P-type well in the charge flow region constitutes the device region drift region; the P-type well and the device region drift region form a vertical PN junction, the top of the P-type well is connected to the first electrode composed of the front metal layer through a contact hole, and the top of the P-type ring is connected to the second conductive material cover layer through a contact hole. And / or the power device is a power PN junction diode, VDMOS, or IGBT.

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