Super junction power device and manufacturing method thereof

Abstract

The embodiment of the present application provides a super-junction power device and a manufacturing method thereof. The super-junction power device comprises a substrate of a first conductive type and an epitaxial layer. The epitaxial layer is provided with at least two first doped columns, at least two second doped columns and at least two third doped columns of a second conductive type. Each first doped column extends along a first direction and is spaced from each other. Each third doped column extends along a second direction intersecting the first direction and is spaced from each other. Each second doped column is located between the first doped column and the third doped column and extends away from the substrate. The length of each second doped column decreases in sequence along the direction from the first doped column to the second doped column. The length of each third doped column increases in sequence along the direction away from the substrate. The embodiment can improve the terminal efficiency of the super-junction power device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor power devices, in particular to a super-junction power device and a manufacturing method thereof. BACKGROUND

[0002] In the technical field of power semiconductor devices, super-junction structures have been widely adopted. The super-junction structure mainly changes the relationship between the withstand voltage of a device and the resistivity of a current path of the device, achieving high voltage and low voltage drop, and thus has been widely applied in the industry. The termination efficiency of a super-junction structure device is one of the most important performances of the device, and therefore how to effectively improve the termination efficiency of a super-junction power device is an important direction that the technical personnel in the field have been committed to researching. SUMMARY

[0003] Based on the above, the present application provides a super-junction power device and a manufacturing method thereof, which can effectively improve the termination efficiency of the super-junction power device.

[0004] First, in a first aspect, the embodiments of the present application provide a super-junction power device, comprising a substrate and an epitaxial layer arranged on the substrate; wherein:

[0005] The epitaxial layer is arranged with at least two first doped columns, at least two second doped columns, and at least two third doped columns, the substrate and the epitaxial layer have a first conductivity type, and the first doped columns, the second doped columns, and the third doped columns have a second conductivity type;

[0006] Each of the first doped columns extends along a first direction and is spaced apart from each other, each of the third doped columns extends along a second direction intersecting the first direction and is spaced apart from each other, and each of the second doped columns is located between the first doped column and the third doped column and extends away from the substrate;

[0007] The length of each of the second doped columns decreases in turn along the direction of the first doped column to the second doped column;

[0008] The length of each of the third doped columns increases in turn along the direction away from the substrate.

[0009] Based on a possible implementation manner of the first aspect, a main junction region and a cutoff region are arranged on the side of the epitaxial layer away from the substrate, the main junction region and the cutoff region are respectively located at opposite ends of the epitaxial layer in the second direction; wherein the main junction region is below the first doped column and / or the second doped column in contact with the main junction region.

[0010] In a possible implementation of the first aspect, the epitaxial layer further comprises a surface doping region between the main junction region and the cutoff region, the surface doping region is in contact with the main junction region and is spaced apart from the cutoff region.

[0011] In a possible implementation of the first aspect, each of the second doping columns is aligned with each other at one end close to the substrate, and an angle is formed between a line connecting the other end away from the substrate and the substrate, the angle is greater than or equal to 42 degrees and less than or equal to 45 degrees.

[0012] In a possible implementation of the first aspect, the second doping columns are inclined to the main junction region at an angle less than 90 degrees between the extension direction of the second doping columns and the substrate.

[0013] In a possible implementation of the first aspect, the main junction region, the cutoff region, and the surface doping region have a second conductivity type.

[0014] The spacing between the first doping columns is different from the spacing between the second doping columns, the doping concentration of the second doping columns is lower than the doping concentration of the first doping columns, and the doping concentration of the third doping columns is lower than the doping concentration of the second doping columns.

[0015] In a second aspect, the present application further provides a manufacturing method of a super junction power device, the method comprising:

[0016] forming multiple layers of epitaxial material layers with a set thickness on a substrate by multiple epitaxial doping, wherein each epitaxial doping comprises the following steps:

[0017] forming a selective implantation mask film on the currently formed epitaxial material layer, the selective implantation mask film comprising a plurality of first doping windows, a plurality of second doping windows, and a plurality of third doping windows, the plurality of second doping windows being located between the plurality of first doping windows and the plurality of third doping windows;

[0018] performing impurity implantation through the first doping windows, the second doping windows, and the third doping windows of the selective implantation mask film to form a plurality of first doping units, a plurality of second doping units, and a plurality of third doping units on the epitaxial material layer, respectively; wherein for any two adjacent epitaxial material layers, the number of second doping units formed in the epitaxial material layer close to the substrate is greater than the number of second doping units formed in the epitaxial material layer away from the substrate, and the number of third doping units formed in the epitaxial material layer close to the substrate is less than the number of third doping units formed in the epitaxial material layer away from the substrate;

[0019] Annealing or diffusion processes are performed on the multilayer epitaxial material layers formed on the substrate to form an epitaxial layer having at least two first doped pillars, at least two second doped pillars, and at least two third doped pillars;

[0020] The substrate and the epitaxial layer have a first conductivity type, and the first doped pillar, the second doped pillar and the third doped pillar have a second conductivity type.

[0021] Based on one possible implementation of the second aspect, the method further includes:

[0022] A main junction region and a cutoff region are formed at opposite ends on the side of the epitaxial layer away from the substrate, such that the main junction region is in contact with the first doped pillar and / or the second doped pillar, and a surface doped region is formed between the main junction region and the cutoff region, such that the surface doped region is in contact with the main junction region and spaced apart from the cutoff region.

[0023] The main junction region, the cutoff region, and the surface doped region have a second conductivity type.

[0024] In one possible implementation of the second aspect, the concentration of impurity implanted through the second doping window is less than the concentration of impurity implanted through the first doping window, and the concentration of impurity implanted through the third doping window is less than the concentration of impurity implanted through the second doping window.

[0025] Based on one possible implementation of the second aspect, in two adjacent outer edge material layers, the number of second doped windows in the selective implantation masking film used in the outer edge material layer closer to the substrate is greater than the number of second doped windows in the selective implantation masking film used in the epitaxial material layer farther from the substrate, and the number of third doped windows in the selective implantation masking film used in the outer edge material layer closer to the substrate is less than the number of third doped windows in the selective implantation masking film used in the epitaxial material layer farther from the substrate.

[0026] Compared to existing technologies, the superjunction power device and its manufacturing method provided in this application, by gradually reducing the height of the P-pillars and N-pillars near the substrate in the terminal region from the main junction region (active region) to the cutoff region, and vertically distributing them; simultaneously, the P-pillars and N-pillars near the surface of the terminal region (formed based on the third doped pillar 8) are designed to gradually widen and are arranged horizontally. In this way, the terminal region falls in both the horizontal and vertical directions along the highest breakdown voltage directions of the P-pillars and N-pillars of the superjunction structure, and the transition region between the vertical and horizontal electric fields, i.e., the stepped region formed by the P-pillars and N-pillars (corresponding to the region of the second doped pillar 7), is the vector sum of the two directions. Considering the fluctuations in the manufacturing process, appropriately reducing the tilt angle of the transition region, i.e., the stepped region formed by the P-pillars and N-pillars, relative to the substrate, can further ensure the breakdown voltage margin. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as limiting the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is one of the schematic diagrams of a superjunction power device provided in the embodiments of this application.

[0029] Figure 2 This is a second schematic diagram of a superjunction power device provided in an embodiment of this application.

[0030] Figure 3 This is a schematic diagram of an optional shape of the second doped pillar in the superjunction power device provided in this application embodiment.

[0031] Figure 4 This is the third schematic diagram of a superjunction power device provided in the embodiments of this application.

[0032] Figure 5 This is a schematic diagram provided in the embodiments of this application for illustrating the PN column electric field and withstand voltage electric field of a superjunction power device.

[0033] Figures 6-8 This is a schematic diagram of the device structure changes during the manufacturing process of the superjunction power device provided in the embodiments of this application.

[0034] Figure 9 This is a schematic diagram illustrating the relationship between the breakdown voltage of the superjunction power device and the structure of the second doped pillar in the embodiments of this application. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0037] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0038] In the description of this application, it should be understood that the terms "upper", "lower", "inner", "outer", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are used only for the convenience of describing this application and simplifying the description, and are not intended to indicate or imply that the equipment or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0039] Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0040] In the description of this application, it should also be noted that, unless otherwise explicitly specified and limited, terms such as "setup" and "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] Based on the technical problems mentioned in the background section, in order to improve the termination efficiency of superjunction power devices, this application provides a superjunction power device and its manufacturing method. The specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0042] First, such as Figure 1The diagram shown is one of the structural schematic diagrams of a superjunction power device provided in this application embodiment. The superjunction power device provided in this embodiment includes a substrate 1 and an epitaxial layer 2 disposed on the substrate 1. The epitaxial layer 2 contains at least two first doped pillars 6, at least two second doped pillars 7, and at least two third doped pillars 8. In this embodiment, the substrate 1 and the epitaxial layer 2 have a first conductivity type, and the first doped pillars 6, second doped pillars 7, and third doped pillars 8 have a second conductivity type different from the first conductivity type. For example, in one possible implementation, the first conductivity type can be the electronic conductivity type corresponding to an N-type semiconductor, and the second conductivity type can be the hole conductivity type corresponding to a P-type semiconductor. Alternatively, in another possible implementation, the first conductivity type can be the hole conductivity type corresponding to a P-type semiconductor, and the second conductivity type can be the electronic conductivity type corresponding to an N-type semiconductor. When the first doped pillars 6, second doped pillars 7, and third doped pillars 8 are of the hole conductivity type corresponding to a P-type semiconductor, they can be referred to as P-pillars, and the region between the P-pillars forms an N-pillar. Conversely, when the first doped pillar 6, the second doped pillar 7, and the third doped pillar 8 are hole-conducting types corresponding to N-type semiconductors, they can be called N-pillars, and the regions between the N-pillars form P-pillars accordingly.

[0043] Furthermore, each of the first doped pillars 6 is positioned along a first direction (e.g., Figure 1 The vertical direction Y) shown extends and is spaced apart from each other, and each of the third doped pillars 8 is respectively along a second direction (e.g., the first direction intersects the second direction) intersecting the first direction. Figure 1 The second doped pillars 7 extend in the horizontal direction X and are spaced apart from each other, and each second doped pillar 7 is located between the first doped pillar 6 and the third doped pillar 8 and extends in a direction away from the substrate 1. In this embodiment, the extension direction of the second doped pillar 7 may be the first direction or slightly different from the first direction.

[0044] In this embodiment, the length (length in its extension direction) of each of the second doped pillars 7 decreases sequentially from the first doped pillar 6 towards the third doped pillar 8. For example, as... Figure 1 As shown, the length of each of the second doped pillars 7 is inversely proportional to the distance between it and the first doped pillar 6. For example, the farther the second doped pillar 7 is from the first doped pillar 6, the shorter its length.

[0045] Furthermore, the length of each of the third doped pillars 8 (its length in its extension direction / second direction) increases sequentially in the direction away from the substrate 1. For example, as... Figure 1As shown, the length of each of the third doped pillars 8 is proportional to the distance between it and the substrate 1. For example, the farther the third doped pillar 8 is from the substrate 1, the longer its length.

[0046] Furthermore, in this embodiment, a main junction region 3 and a cutoff region 5 are further disposed on the side of the epitaxial layer 2 away from the substrate 1, wherein the main junction region 3 and the cutoff region 5 are respectively located at opposite ends of the epitaxial layer 2 in the second direction. The main junction region 3 has a first doped pillar 6 and / or a second doped pillar 7 in contact with it below. That is, a first doped pillar 6, a second doped pillar 7, or both can be disposed below the main junction region 3. Figure 1 The image shows the first doped pillar 6 in contact with the main junction region 3. In another possible implementation, Figure 1 The first doped pillar 6, which is in contact with the main junction region 3 and is located near the side of the second doped pillar 7, can be replaced by the second doped pillar 7.

[0047] In addition, a surface doped region 4 located between the main junction region 3 and the cutoff region 5 may be provided on the side of the epitaxial layer 2 away from the substrate 1. The surface doped region 4 is in contact with the main junction region 3 and spaced apart from the cutoff region 5, for example, by the epitaxial layer 2 and the cutoff region 5.

[0048] Furthermore, see also Figure 1 and Figure 2 As shown, in this embodiment, the ends of each of the second doped pillars 7 near the substrate 1 can be aligned with each other. For example, in this embodiment, the alignment of the ends of each of the second doped pillars 7 near the substrate 1 can mean that the lines connecting the ends of each of the second doped pillars 7 near the substrate 1 are approximately on the same straight line, and this straight line is approximately parallel to the substrate 1. Furthermore, the height of the end of each of the second doped pillars 7 away from the substrate 1 decreases sequentially in the direction away from the first doped pillar 6, forming a stepped distribution, with the steps forming an angle of slightly less than 45 degrees with the substrate 1. For example, combined with... Figure 3 As shown, the line connecting the ends of each of the second doped pillars 7 away from the substrate 1 can form an angle θ with the substrate 1, the angle being less than 45 degrees. In this embodiment, it is preferable that the angle θ is slightly less than 45 degrees; for example, the angle θ can be between 42 degrees and 45 degrees, and as close to 45 degrees as possible.

[0049] In one possible implementation of this embodiment, for example Figure 1 As shown, the extension direction of the second doped pillar 7 can be the first direction, such that the second doped pillar 7 extends in a direction perpendicular to the substrate 1. In another possible real-time method, such asFigure 2 As shown, the extension direction of the second doped pillar 7 can also be inclined towards the direction of the main junction region 3. In this case, the extension direction of the second doped pillar 7 (e.g., Figure 2 The dashed arrow (direction) forms an angle of less than 90 degrees with the substrate, thereby causing the second doped pillar 7 to tilt towards the main junction region 3. In this embodiment, the main junction region 3, the cutoff region 5, and the surface doped region 4 may have the same second conductivity type as the first doped pillar 6, the second doped pillar 7, and the third doped pillar 8.

[0050] Furthermore, in this embodiment, the spacing between adjacent first doped pillars 6 is different from the spacing between adjacent second doped pillars 7. The spacing between adjacent third doped pillars 8 corresponds to the thickness of each outer edge in the outer edge fabrication process of the epitaxial layer 2. The doping concentration of the second doped pillar 7 can be lower than the doping concentration of the first doped pillar 6, and the doping concentration of the third doped pillar 8 can be lower than the doping concentration of the second doped pillar 7. In addition, the second doped pillar 7 can be a columnar structure formed by sequentially connecting multiple doped units (e.g., ...). Figure 1 and Figure 2 As shown), it can also be multiple circular island doped units stacked sequentially (such as...). Figure 4 The columnar structure is formed as shown. In another possible embodiment, the second doped column 7 and the third doped column 8 can be spaced apart from each other or partially connected, for example, a portion of the second doped column 7 and a portion of the third doped column 8 are connected.

[0051] In summary, the superjunction power device provided in this application takes into account that the breakdown voltage of the drift region of the superjunction structure is directional, for example... Figure 5 As shown, the highest breakdown voltage can be obtained when the electric field in the breakdown voltage direction is perpendicular to the electric field direction of the PN pillar. For the termination of superjunction power devices, the substrate and edge of the device are at the same potential. The electric field direction of the active region (such as the main junction region 3) surface relative to the outer edge of the device and below the substrate gradually transitions from the horizontal direction to the vertical direction, and the electric field distribution is fan-shaped. To achieve higher termination efficiency, the P pillars and N pillars in the termination region are most suitable in a fan-shaped distribution. In the embodiments of this application, if the doped pillars (including the first doped pillar 6, the second doped pillar 7, and the third doped pillar 8) are P pillars, then the portion between the epitaxial layers 2 between the doped pillars is an N pillar; conversely, if the doped pillars are N pillars, then the portion between the epitaxial layers 2 between the doped pillars is a P pillar.

[0052] Research revealed that a fan-shaped distribution of P-pillars and N-pillars places extremely high demands on manufacturing process capabilities. Therefore, in this embodiment, the height of the P-pillars and N-pillars near the substrate in the terminal region gradually decreases from the main junction region (active region) towards the cutoff region, and they are vertically distributed. Simultaneously, the P-pillars and N-pillars near the surface of the terminal region (formed based on the third doped pillar 8) are designed to gradually widen and are arranged horizontally. This ensures that the terminal region falls in both the horizontal and vertical directions along the highest breakdown voltage directions of the superjunction structure's P-pillars and N-pillars. The transition region between the vertical and horizontal electric fields, i.e., the stepped region formed by the P-pillars and N-pillars (corresponding to the region of the second doped pillar 7), represents the vector sum of the two directions. Considering manufacturing process fluctuations, appropriately reducing the tilt angle of the transition region (i.e., setting it to slightly below 45 degrees) relative to the substrate can further guarantee the breakdown voltage margin.

[0053] In this example, the inventors experimentally verified that the superjunction power device exhibits better voltage withstand performance when the tilt angle is between 42 and 45 degrees (greater than or equal to 42 degrees and less than or equal to 45 degrees). Specifically, generally speaking, the voltage withstand capability of a superjunction power device is determined by the voltage withstand capability of the active region and the terminal region along its longitudinal direction. The active region voltage withstand capability is primarily determined by the length L of the PN junction pillar; the longer L is, the higher the voltage withstand capability. As an example, for instance... Figure 9 As shown, the N+ of the lower electrode D of the device is the same as that of the device edge D', meaning the breakdown voltage of S-D' must be greater than the voltage of the active region; otherwise, the breakdown voltage of the device will be low. Therefore, it can be seen that the longer the lateral superjunction structure, the higher the lateral breakdown voltage in the terminal region near the surface. Secondly, in the region where the breakdown voltage transitions between the active and terminal regions, the direction of the electric field transitions from vertical to horizontal. To achieve a relatively high breakdown voltage, the tilt angle should be as close to 42 degrees as possible within the aforementioned range, which results in better breakdown voltage compared to approaching 45 degrees. However, if the tilt angle is too small, it will increase the terminal length of the entire superjunction power device, leading to waste. Based on this, after extensive experiments and data verification by the inventors of this application, the preferred tilt angle is 42 degrees to best balance the terminal length and breakdown voltage effect of the superjunction power device. Therefore, in this embodiment, the preferred tilt angle is 42 degrees.

[0054] Based on the above, this application also provides a method for manufacturing a superjunction power device, which will be described exemplarily below.

[0055] Step S1: Multiple epitaxial material layers 21 with a set thickness are formed on the substrate 1 by multiple epitaxial doping, wherein each epitaxial doping includes the following steps S11-S12.

[0056] Step S11, for example Figure 6As shown, a selective implantation masking film 9 is formed on the currently formed outer edge material layer 21. The selective implantation masking film 9 includes a plurality of first doping windows, a plurality of second doping windows, and a plurality of third doping windows, with the plurality of second doping windows located between the plurality of first doping windows and the plurality of third doping windows.

[0057] Step S12, as follows Figure 7 As shown, impurity implantation is performed through the first, second, and third doping windows of the selected implantation masking film 9 to form a plurality of first doped units 61, a plurality of second doped units 71, and a plurality of third doped units 81 on the outer edge material layer 21, respectively. For example, the first doped unit 61 can be formed by doping with impurities of a second conductivity type through the first doping window, the second doped unit 71 can be formed by doping with impurities of a second conductivity type through the second doping window, and the third doped unit can be formed by doping with impurities of a second conductivity type through the third doping window. During impurity implantation, the concentration of impurities implanted through the second doping window is lower than the concentration of impurities implanted through the first doping window, and the concentration of impurities implanted through the third doping window is lower than the concentration of impurities implanted through the second doping window. This allows the doping concentration of the second doped pillar 7 obtained after doping to be lower than the doping concentration of the first doped pillar 6, and the doping concentration of the third doped pillar 8 to be lower than the doping concentration of the second doped pillar 7.

[0058] Specifically, for any two adjacent outer edge material layers 21, the number of second doped units 71 formed in the outer edge material layer 21 closer to the substrate 1 is greater than the number of second doped units 71 formed in the epitaxial material layer 21 farther from the substrate 1, and the number of third doped units 81 formed in the outer edge material layer 21 closer to the substrate 1 is less than the number of third doped units 81 formed in the epitaxial material layer 21 farther from the substrate 1. Based on this, in two adjacent outer edge material layers 21, the number of second doped windows in the selective implantation masking film 9 used in the outer edge material layer 21 closer to the substrate 1 is greater than the number of second doped windows in the selective implantation masking film 9 used in the epitaxial material layer 21 farther from the substrate 1, and the number of third doped windows in the selective implantation masking film 9 used in the outer edge material layer 21 closer to the substrate 1 is less than the number of third doped windows in the selective implantation masking film 9 used in the epitaxial material layer 21 farther from the substrate 1.

[0059] After impurity implantation, the selective implantation masking film 9 on the outer edge material layer 21 can be removed, allowing for the next epitaxial doping process. The selective implantation masking film 9 can be formed by coating photoresist onto the outer edge material layer 21 and then performing a photolithography process to create a selective implantation masking film of the desired shape. By repeating the processes S11 and S12 multiple times, a film like... Figure 8 The epitaxial layer 2 shown is formed by multiple outer material layers 21 with multilayer doping.

[0060] Step S2 involves annealing or diffusion processing on the multilayer epitaxial material layer 21 formed on the substrate 1 to form an epitaxial layer 2 having at least two first doped pillars 6, at least two second doped pillars 7, and at least two third doped pillars 8. In this embodiment, the substrate 1 and the epitaxial layer 2 have a first conductivity type, and the first doped pillars 6, second doped pillars 7, and third doped pillars 8 have a second conductivity type different from the first conductivity type. Specifically, multiple first doped units 61 arranged in a first direction and located in the same column can form the first doped pillar 6 after diffusion connection; multiple second doped units 71 extending in the same direction can form the second doped pillar 7 after diffusion connection; and multiple third doped units 81 arranged in a second direction and located in the same row can form the third doped pillar 8 after diffusion connection.

[0061] Thus, in the epitaxial layer 2 formed by the above method, each of the first doped pillars 6 is along the first direction (e.g., Figure 1 The vertical direction Y) shown extends and is spaced apart from each other, and each of the third doped pillars 8 is respectively along a second direction (e.g., the first direction intersects the second direction) intersecting the first direction. Figure 1 The second doped pillars 7 extend in the horizontal direction X and are spaced apart from each other, and each second doped pillar 7 is located between the first doped pillar 6 and the third doped pillar 8 and extends in a direction away from the substrate 1. The length of each second doped pillar 7 (length along its extension direction) decreases sequentially from the first doped pillar 6 to the third doped pillar 8. The length of each third doped pillar 8 (length in its extension direction / second direction) increases sequentially in a direction away from the substrate 1.

[0062] Based on the above process, this embodiment may also include the following step S3.

[0063] Step S3: A main junction region 3 and a cutoff region 5 are formed at opposite ends of the epitaxial layer 2 on the side away from the substrate 1, such that the main junction region 3 is in contact with the first doped pillar 6 and / or the second doped pillar 7. A surface doped region 4 is formed between the main junction region 3 and the cutoff region 5, such that the surface doped region 4 is in contact with the main junction region 3 and spaced apart from the cutoff region 5. The resulting superjunction power device structure is as follows: Figure 1, Figure 2 ,or Figure 4 As shown.

[0064] In summary, the superjunction power device and its manufacturing method provided in this application involve vertically distributing the P-pillars and N-pillars near the substrate in the terminal region from the main junction region (active region) to the cutoff region, while simultaneously designing the P-pillars and N-pillars near the surface of the terminal region (formed based on the third doped pillar 8) to gradually widen and be arranged horizontally. This ensures that the terminal region falls in both the horizontal and vertical directions along the highest breakdown voltage directions of the P-pillars and N-pillars of the superjunction structure. The transition region between the vertical and horizontal electric fields, i.e., the stepped region formed by the P-pillars and N-pillars (corresponding to the region of the second doped pillar 7), represents the vector sum of the two directions. Considering the fluctuations in the manufacturing process, appropriately reducing the tilt angle of the transition region, i.e., the stepped region formed by the P-pillars and N-pillars, relative to the substrate can further guarantee the breakdown voltage margin.

[0065] Meanwhile, by combining multilayer epitaxial processes with selectively implanted masking films of different shapes to form a non-uniform impurity implantation region, and then by performing appropriate annealing or diffusion processes, superjunction structures in the first and second directions (such as vertical and horizontal directions) are formed in the terminal region of the superjunction power device, thereby improving the terminal efficiency of the superjunction power device.

[0066] For illustrative purposes, the foregoing description has been made with reference to specific embodiments. However, the foregoing illustrative discussions are not intended to be exhaustive or to limit the present application to the precise forms disclosed. Numerous modifications and variations are possible in accordance with the foregoing teachings. These embodiments were chosen and described to best illustrate the principles of the present application and its practical application, thereby enabling those skilled in the art to best utilize the present application and to employ various embodiments with different modifications to suit a particular intended application.

Claims

1. A superjunction power device, characterized in that, Includes a substrate and an epitaxial layer disposed on the substrate; wherein: The epitaxial layer is provided with at least two first doped pillars, at least two second doped pillars, and at least two third doped pillars. The substrate and the epitaxial layer have a first conductivity type, and the first doped pillars, the second doped pillars, and the third doped pillars have a second conductivity type. Each of the first doped pillars extends along a first direction and is spaced apart from each other; each of the third doped pillars extends along a second direction intersecting the first direction and is spaced apart from each other; and each of the second doped pillars is located between the first doped pillars and the third doped pillars and extends in a direction away from the substrate. The length of each of the second doped pillars decreases sequentially from the first doped pillar to the second doped pillar; The length of each of the third doped pillars increases sequentially in the direction away from the substrate; The epitaxial layer has a main junction region and a cutoff region on the side away from the substrate. Below the main junction region, there is a second doped pillar in contact with the main junction region. The line connecting the ends of the second doped pillars away from the substrate forms an angle with the substrate. The angle is greater than or equal to 42 degrees and less than or equal to 45 degrees. The extension direction of the second doped pillar forms an angle of less than 90 degrees with the substrate, so that the second doped pillar is tilted towards the main junction region. The second doped pillar is a columnar structure formed by connecting multiple doped units in sequence or a columnar structure composed of multiple circular island doped units stacked in sequence.

2. The superjunction power device according to claim 1, characterized in that, The main junction region and the cutoff region are located at opposite ends of the epitaxial layer in the second direction; wherein, a first doped pillar is located below the main junction region and contacts the main junction region.

3. The superjunction power device according to claim 2, characterized in that, The epitaxial layer also has a surface doped region located between the main junction region and the cutoff region on the side away from the substrate. The surface doped region is in contact with the main junction region and is spaced apart from the cutoff region.

4. The superjunction power device according to any one of claims 1-3, characterized in that, The ends of each of the second doped pillars near the substrate are aligned with each other.

5. The superjunction power device according to claim 3, characterized in that, The main junction region, the cutoff region, and the surface doped region have a second conductivity type; The spacing between the first doped pillars is different from the spacing between the second doped pillars. The doping concentration of the second doped pillars is lower than that of the first doped pillars. The doping concentration of the third doped pillars is lower than that of the second doped pillars.

6. A method for manufacturing a superjunction power device, characterized in that, The method includes: Multiple epitaxial material layers, each with a predetermined thickness, are formed on a substrate through multiple epitaxial doping processes. Each epitaxial doping step includes the following steps: A selective implantation masking film is formed on the currently formed outer edge material layer. The selective implantation masking film includes a plurality of first doping windows, a plurality of second doping windows, and a plurality of third doping windows, wherein the plurality of second doping windows are located between the plurality of first doping windows and the plurality of third doping windows. Impurity implantation is performed through the first doping window, second doping window, and third doping window of the selected implantation masking film to form a plurality of first doped units, a plurality of second doped units, and a plurality of third doped units on the outer edge material layer, respectively; wherein, for any two adjacent outer edge material layers, the number of second doped units formed in the outer edge material layer closer to the substrate is greater than the number of second doped units formed in the outer epitaxial material layer farther from the substrate, and the number of third doped units formed in the outer edge material layer closer to the substrate is less than the number of third doped units formed in the outer epitaxial material layer farther from the substrate; Annealing or diffusion processes are performed on the multilayer epitaxial material layers formed on the substrate to form an epitaxial layer having at least two first doped pillars, at least two second doped pillars, and at least two third doped pillars; The substrate and the epitaxial layer have a first conductivity type, and the first doped pillar, the second doped pillar, and the third doped pillar have a second conductivity type. A main junction region and a cutoff region are provided on the side of the epitaxial layer away from the substrate. A second doped pillar is provided below the main junction region and in contact with the main junction region. The line connecting the ends of each second doped pillar away from the substrate forms an angle with the substrate. The angle is greater than or equal to 42 degrees and less than or equal to 45 degrees. The extension direction of the second doped pillar forms an angle of less than 90 degrees with the substrate, causing the second doped pillar to tilt towards the main junction region. The second doped pillar is a columnar structure formed by connecting multiple doped units in sequence or a columnar structure composed of multiple circular island doped units stacked in sequence.

7. The method for manufacturing a superjunction power device according to claim 6, characterized in that, The method further includes: A main junction region and a cutoff region are formed at opposite ends on the side of the epitaxial layer away from the substrate, such that the main junction region is in contact with the first doped pillar and / or the second doped pillar, and a surface doped region is formed between the main junction region and the cutoff region, such that the surface doped region is in contact with the main junction region and spaced apart from the cutoff region. The main junction region, the cutoff region, and the surface doped region have a second conductivity type.

8. The method for manufacturing a superjunction power device according to claim 6 or 7, characterized in that, The concentration of impurity implanted through the second doping window is less than the concentration of impurity implanted through the first doping window, and the concentration of impurity implanted through the third doping window is less than the concentration of impurity implanted through the second doping window.

9. The method for manufacturing a superjunction power device according to claim 6 or 7, characterized in that, In two adjacent outer edge material layers, the number of second doped windows in the selective implantation masking film used in the outer edge material layer closer to the substrate is greater than the number of second doped windows in the selective implantation masking film used in the epitaxial material layer farther from the substrate, and the number of third doped windows in the selective implantation masking film used in the outer edge material layer closer to the substrate is less than the number of third doped windows in the selective implantation masking film used in the epitaxial material layer farther from the substrate.

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