Superjunction device termination structure

Abstract

This invention provides a superjunction device termination structure, which divides the first conductivity type epitaxial layer of the termination region into first to third regions. A second conductivity type main junction is formed in the top layer of the first conductivity type epitaxial layer in the first region, and a second conductivity type doped region is formed in the top layer of the first conductivity type epitaxial layer in the second region. The doping concentration of the doped region is less than that of the main junction. The top of the second conductivity type pillar below the bottom of the doped region is flush with or lower than the top of the second conductivity type pillar below the main junction. In the third region, the top height of the second conductivity type pillar closest to the cutoff ring doped region is lower than that of the second conductivity type pillar closest to the second region. Thus, not only is the electric field peak at the edge of the main junction introduced into the termination structure, but the surface electric field of the cutoff ring doped region and its surroundings is also effectively reduced, the distance between the cutoff ring doped region and the nearest second conductivity type pillar is reduced, and the termination area is effectively reduced. At the same time, it has no adverse effect on the device breakdown voltage and the overall electric field.

Description

Technical Field

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[0001] The present invention relates to the technical field of superjunction devices, and particularly to a terminal structure of a superjunction device. Background Art

[0002] In order to more effectively improve the breakdown voltage, based on the structure of a vertical double-diffused MOSFET (VDMOS) device, a superjunction device called CoolMOS is proposed in the prior art. It adopts the 3D-RESURF (3-Dimensions Reduced Surface Field) principle, enabling the alternately arranged P-type columns and N-type columns to deplete each other before breakdown to obtain a relatively high breakdown voltage, and reducing the on-resistance during forward conduction.

[0003] Please refer to Figure 1 , a CoolMOS superjunction device generally consists of a core active region I and a terminal region II located outside the core active region I. In the conventional process, the alternately arranged P-type columns (P-pillars) and N-type columns (N-pillars) in the core active region I and the terminal region II of the CoolMOS superjunction device are fabricated together through multiple epitaxial growths and ion implantations. Moreover, in order to improve the breakdown voltage of the device, a cutoff ring doping region 12 is usually set in the terminal region, and there is a certain distance D0 (abbreviated as the cutoff ring distance) left between the cutoff ring doping region 12 and the last P column in the terminal region II. Taking a 600V device as an example, the cutoff ring distance D0 can reach more than 10% of the entire terminal region length.

[0004] However, if the cutoff ring distance D0 is too large, it will lead to an increase in the terminal length of the device and waste of area. Especially for superjunction devices with small currents, the size of the terminal region directly affects the number of chips and ultimately the cost. For this reason, please refer to Figure 2 , in the prior art, the cutoff ring distance is directly reduced as much as possible (i.e., D1 < D0). However, this method is likely to cause problems such as too strong surface electric field of the device and adverse effects on reliability. Summary of the Invention

[0005] The purpose of the present invention is to provide a terminal structure of a superjunction device, which can reduce the terminal region length, decrease the device area, and reduce the product cost while ensuring the breakdown voltage performance and the overall electric field.

[0006] To address the aforementioned technical problems, this invention provides a superjunction device termination structure, comprising a first conductivity type epitaxial layer, wherein a plurality of alternating first conductivity type pillars and second conductivity type pillars are formed in the first conductivity type epitaxial layer, wherein the first conductivity type epitaxial layer comprises, in the lateral direction, a series of:

[0007] In the first region, a main junction of a second conductivity type is formed at the top of the first region, and the main junction is in contact with the top of the second conductivity type pillar below it;

[0008] The second region has a doped region of a second conductivity type formed at the top of the second region. The bottom of the doped region is in contact with the top of the second conductivity type pillar below it, and the doping concentration of the doped region is less than the doping concentration of the main junction. The top of the second conductivity type pillar below the bottom of the doped region is lower than or flush with the top of the second conductivity type pillar below the main junction.

[0009] A third region is formed in which a stop ring doped region is formed at the top end of the third region away from the second region. A second conductivity type pillar in the third region is confined within the boundary of the stop ring doped region on the side away from the second region. The top height of the second conductivity type pillar in the third region is lower than or equal to the top height of the second conductivity type pillar in the second region. The top height of the second conductivity type pillar near the stop ring doped region is lower than the top height of the second conductivity type pillar near the boundary of the second region. A stop ring metal electrically connected to the stop ring doped region is also formed above the third region.

[0010] Optionally, the top height of the second conductive type pillar in the third region decreases in a stepped manner along the direction away from the second region.

[0011] Optionally, when the top height of the second conductive type pillars in the third region decreases in a stepped manner, the top height of each second conductive type pillar is different, or at least two second conductive type pillars have the same top height.

[0012] Optionally, the top height of the second conductive type pillar closest to the second region in the third region is the same as the top height of the second conductive type pillar in the second region; and / or, the bottom height of each second conductive type pillar in the first conductive type epitaxial layer is the same.

[0013] Optionally, the cutoff ring doped region is a first conductivity type region or a second conductivity type region, and the first conductivity type epitaxial layer outside the last second conductivity type pillar in the third region, together with the cutoff ring doped region and the cutoff ring metal, forms a cutoff ring structure.

[0014] Optionally, the first conductivity type epitaxial layer is a composite structure formed by stacking multiple epitaxial layers; the main junction is located in the topmost epitaxial layer of the composite structure, and / or the doped region is located in the topmost epitaxial layer, or the doped region is located in the top two epitaxial layers of the composite structure.

[0015] Optionally, the distance between the top of the second conductive type pillar in the third region and the top surface of the first conductive type epitaxial layer is equal to the stacking thickness of at least two epitaxial layers in the composite structure.

[0016] Optionally, the superjunction device termination structure further includes an interlayer dielectric layer, which covers the top surface of the first conductivity type epitaxial layer, and the stop ring metal is formed on a portion of the interlayer dielectric layer.

[0017] Optionally, the stop ring metal extends along the direction from the stop ring doped region to the second region above the top of at least one of the second conductivity type pillars in the third region.

[0018] Optionally, the superjunction device termination structure further includes a field oxide layer and a polysilicon layer. The field oxide layer is sandwiched between the top surface of the first conductivity type epitaxial layer and the interlayer dielectric layer, and covers the surface of a portion of the doped region and a portion of the third region. The polysilicon layer extends from a portion of the top surface of the doped region of the cutoff ring to a portion of the top surface of the field oxide layer, and the polysilicon layer is electrically connected to the cutoff ring metal.

[0019] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0020] The epitaxial layer of the first conductivity type in the terminal region is divided into three regions. A main junction of the second conductivity type is formed in the top layer of the epitaxial layer of the first conductivity type in the first region. A doped region of the second conductivity type is formed in the top layer of the epitaxial layer of the first conductivity type in the second region. The doping concentration of the doped region is less than that of the main junction. The top of the second conductivity type pillar below the bottom of the doped region is lower than or flush with the top of the second conductivity type pillar below the main junction (i.e., the junction depth of the doped region is greater than that of the main junction). In the third region, the top height of the second conductivity type pillar closest to the doped region of the cutoff ring is lower than that of the top of the second conductivity type pillar closest to the second region. Thus, not only can the electric field peak at the edge of the main junction be introduced into the terminal structure, but the surface electric field of the cutoff ring structure and its surroundings can also be effectively reduced. This is beneficial to reducing the distance between the doped region of the cutoff ring and the nearest second conductivity type pillar, allowing the cutoff ring metal to extend further inward beyond the last second conductivity type pillar, reducing the distance between the cutoff ring metal and the second region, thereby effectively reducing the terminal area, while having no adverse effect on the device breakdown voltage and the overall electric field. Attached Figure Description

[0021] Figure 1 and Figure 2 This is a cross-sectional structural diagram of a superjunction device in the prior art.

[0022] Figure 3 This is a cross-sectional schematic diagram of the terminal structure of a superjunction device according to an embodiment of the present invention.

[0023] Figure 4 It is relative to Figure 3 Potential distribution diagram of the terminal structure of a superjunction device where the height of the top of the P-type pillar near the doped region of the middle stop ring does not decrease.

[0024] Figure 5 yes Figure 3 The potential distribution diagram of the superjunction device terminal structure is shown.

[0025] Figure 6 yes Figure 4 and Figure 5 The diagram shows a comparison of the surface electric field distribution curves of the superjunction device terminal structure.

[0026] Figure 7 It is relative Figure 4 Potential distribution diagram of the terminal structure of a superjunction device with increased doping concentration of P-type pillars.

[0027] Figure 8 It is relative Figure 3 Potential distribution diagram of the terminal structure of a superjunction device with increased doping concentration of P-type pillars.

[0028] Figure 9 yes Figure 7 and Figure 8 The diagram shows a comparison of the surface electric field distribution curves of the superjunction device terminal structure.

[0029] Figure 10 This is a cross-sectional schematic diagram of the terminal structure of a superjunction device according to another embodiment of the present invention. Detailed Implementation

[0030] The technical solution proposed by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer from the following description. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the present invention. In this document, "and / or" means either one or both.

[0031] Please refer to Figure 3One embodiment of the present invention provides a superjunction device termination structure, which is formed in the termination region II of the superjunction device and has a first conductivity type (e.g., N-type) epitaxial layer 201. The first conductivity type epitaxial layer 201 can be formed on a first conductivity type substrate 200 by multiple epitaxial processes. The first conductivity type substrate 200 can be a semiconductor layer doped with a first conductivity type dopant on a substrate (not shown) well known to those skilled in the art, such as a silicon substrate, a silicon-on-insulator substrate, or a silicon-germanium substrate. The doping concentration of the first conductivity type epitaxial layer 201 is lower or higher than that of the first conductivity type substrate 200.

[0032] In the superjunction device termination structure of this embodiment, the first conductivity type epitaxial layer 201 includes a first region II-1, a second region II-2, and a third region II-3 arranged laterally. Furthermore, each of the first region II-1, the second region II-2, and the third region II-3 contains a plurality of alternating first conductivity type pillars (i.e., the first conductivity type epitaxial layer 201 sandwiched between adjacent second conductivity type pillars 202) and second conductivity type pillars (e.g., P-type) 202 (i.e.,... Figure 3 (P-pillars in the example). In this embodiment, the bottom height (also known as the bottom depth) of all second conductive type pillars 202 in the first region II-1, the second region II-2, and the third region II-3 is the same (i.e., consistent).

[0033] In this structure, a main junction 204 of a second conductivity type is formed at the top of the first region II-1, and the main junction 204 is in contact with the tops of a plurality of second conductivity type pillars 202 below it. The main junction 204 can be formed by ion implantation and diffusion on the top surfaces of the second conductivity type pillars 202 and the top surfaces of the first conductivity type epitaxial layer 201 in the first region II-1, with the top surfaces of the second conductivity type pillars 202 and the first conductivity type pillars in the first region II-1 being flush with the top surfaces of the first conductivity type epitaxial layer 201.

[0034] A doped region 205 of a second conductivity type is formed at the top of the second region II-2. The bottom of the doped region 205 is in contact with the tops of multiple second conductivity type pillars 202 below it. The sidewalls of the doped region 205 are in contact with the main junction 204. The doping concentration of the second conductivity type ions (e.g., P-type ions) in the doped region 205 is less than the doping concentration of the second conductivity type ions in the main junction 204. The top height of the second conductivity type pillars 202 below the bottom of the doped region 205 is lower than or equal to the top height of the second conductivity type pillars 202 below the main junction 204 (i.e., the junction depth H1 of the doped region 205 is greater than or equal to the junction depth of the main junction 204). The doped region 205 can be formed directly by a single second conductivity type ion implantation process on the entire top of the second region II-2, without the formation of second conductivity type pillars 202 on the entire top of the second region II-2.

[0035] The lateral span of the doped region 205 is greater than that of the main junction 204, meaning that the number of second conductive type pillars 202 connected to the bottom of the doped region 205 is greater than the number of second conductive type pillars 202 connected to the bottom of the main junction 204.

[0036] A stop ring doped region 206 is formed in the top end of the third region II-3 away from the second region II-2. The second conductivity type pillar 202 in the third region II-3 is confined within the outer boundary of the stop ring doped region 206 (i.e., the side boundary of the stop ring doped region 206 away from the second region II-2). The top height of at least one second conductivity type pillar 202 in the third region II-3 closest to the second region II can be lower than or flush with the top height of the second conductivity type pillar 202 in the second region II-2. Figure 3 In the third region II-3, H2 ≥ H1. The top height of the second conductivity type pillar 202 near the stop ring doped region 206 is lower than the top height of the second conductivity type pillar 202 near the boundary of the second region II-2, i.e. Figure 3 H3 > H2. Furthermore, a stop ring metal 211c is formed above the third region II-3, and the stop ring metal 211c is electrically connected to the stop ring doped region 206.

[0037] Optionally, the top height of the second conductive type pillar 202 in the third region II-3 decreases in a stepped manner along the direction away from the second region II-2, that is, the distance between the top of the second conductive type pillar 202 in the third region II-3 and the top surface of the first semiconductor type epitaxial layer 201 increases in a stepped manner.

[0038] In this embodiment, the first conductivity type epitaxial layer 201 is a composite structure (not shown) formed by stacking multiple epitaxial layers of basically the same thickness. The main junction 204 is located in the topmost epitaxial layer of the composite structure, and the doped region 205 is located in the topmost epitaxial layer of the composite structure, or the doped region 205 is located in the top two epitaxial layers of the composite structure. The top heights of the first two second conductivity type pillars 202 in the third region II-3 are the same, and the distance between them and the top surface of the first conductivity type epitaxial layer 201 is the thickness of two epitaxial layers of the composite structure. The top heights of the latter three second conductivity type pillars 202 are the same, and the distance between them and the top surface of the first conductivity type epitaxial layer 201 is the thickness of three epitaxial layers of the composite structure.

[0039] The stop-ring doped region 206 can be a first conductivity type region, where the doping concentration of impurities of the first conductivity type is higher than that of the first conductivity type epitaxial layer 201. It can be formed using the same ion implantation process as the source / drain regions of the core region. In this case, the bottom depth of the stop-ring doped region 206 can be shallower than the bottom depth of the main junction 204. Alternatively, the stop-ring doped region 206 can be a second conductivity type region, which can be formed using the same ion implantation process as the main junction 204 or the doped region 205. In this case, the bottom depth of the stop-ring doped region 206 can be the same as the bottom depth of the main junction 204 or the doped region 205. Both approaches reduce the number of photomasks required for ion implantation, simplify the process, and lower costs.

[0040] Furthermore, the stop ring doped region 206 can also be formed by implanting first-conductivity-type ions or second-conductivity-type ions into the first-conductivity-type epitaxial layer at the bottom of the contact hole after etching out the contact hole for fabricating the conductive plug 210e. In this case, the bottom depth of the stop ring doped region 206 can be shallower than the bottom depth of the main junction 204, or even shallower than the depth of the source / drain regions in the core region. Alternatively, the bottom depth of the stop ring doped region 206 can be the same as or slightly greater than the bottom depth of the main junction 204 or the doped region 205. In this embodiment, the first conductive epitaxial layer 201 outside the last second conductive type pillar 202 (i.e., the second conductive type pillar 202 closest to the stop ring doped region 206) in the third region II-3, the stop ring doped region 206, and the stop ring metal 211c together form a stop ring structure. The stop ring doped region 206 is not connected to any of the second conductive type pillars 202 in the third region II-3. Its function is: (1) to form an ohmic contact with the conductive plug 210e connected to the stop ring metal 211c, ensuring the current-voltage characteristics of the formed stop ring structure; (2) to make the first conductive type epitaxial layer 201 outside the last second conductive type pillar 202 in the third region II-3 and the stop ring metal 211c at the same potential, which plays the role of a stop electric field, thereby improving the breakdown voltage of the device.

[0041] The interactions between the various structures in the superjunction device termination structure of this embodiment result in a distance D2 (D2 is less than) between the cutoff ring doped region 206 and the last P-pillar in the third region II-3. Figure 2D1 in the process can be reduced to the minimum distance allowed by the process and device performance, or even D2 can be equal to 0. In this case, the inner boundary of the stop ring doped region 206 is basically aligned with the outer boundary of the last P pillar in the third region II-3. Alternatively, if D2 is less than 0, the inner boundary of the stop ring doped region 206 extends beyond the outer boundary of the last P pillar in the third region II-3. Thus, while ensuring device performance (i.e., without adverse effects on device breakdown voltage and overall electric field), the stop ring metal 211c extends further inward beyond the last second conductivity type pillar 202, reducing the distance between the stop ring metal 211c and the second region II-2, which is beneficial for further reduction in device size and area.

[0042] In this embodiment, the superjunction device terminal structure further includes a field oxide layer 207, a gate oxide layer (not shown), polysilicon layers 208b and 208c, an interlayer dielectric layer 209, conductive plugs 210a to 210e, and a gate metal 211b.

[0043] In this design, the field oxide layer 207 covers the top of a portion of the doped region 205 and extends to the top surface of the first conductivity type epitaxial layer 201 in a portion of the third region II-3. Polysilicon layers 208b and 208c are formed by deposition and etching of the same polysilicon layer and are separate from each other. Polysilicon layer 208b extends from a portion of the top of the main junction 204 through the top of the doped region 205 exposed by the field oxide layer 207 and one sidewall of the field oxide layer 207 to a portion of the top of the field oxide layer 207. Polysilicon layer 208c extends from a portion of the top of the stop ring doped region 206 through the other sidewall of the field oxide layer 207 to a portion of the top of the field oxide layer 207. The field oxide layer 207 may include materials such as silicon dioxide and silicon oxynitride. Polysilicon layers 208b and 208c may be P-type doped polysilicon or N-type doped polysilicon.

[0044] The interlayer dielectric layer 209 can be at least one of tetraethyl orthosilicate, borosilicate glass, phosphosilicate glass, fluorosilicone glass, etc. The interlayer dielectric layer 209 covers the top surface of the first conductivity type epitaxial layer 201 and buries the main junction 204, polysilicon layer 208b, field oxide layer 207, polysilicon layer 208c and stop ring doped region 206 within it.

[0045] The gate metal 211b and the stop ring metal 211c are formed by deposition and etching of the same metal layer. The gate metal 211b is electrically connected to the polysilicon layer 208b through a conductive plug 210c, and the stop ring metal 211c is electrically connected to the polysilicon layer 208c through a conductive plug 210d, and to the stop ring doped region 206 through a conductive plug 210e. In other embodiments of the present invention, the conductive plugs 210d and 210e can be omitted, and the stop ring metal 211c is directly in electrical contact with the polysilicon layer 208c and the stop ring doped region 206.

[0046] Optionally, the stop ring metal 211c extends along the direction from the stop ring doped region 206 to the second region II-2 above the top of at least one second conductivity type pillar 202 in the third region II-3. For example Figure 3 The diagram shows the stop ring metal 211c extending above the top of the last two second-conductivity type pillars 202 in the third region II-3. Figure 10 The diagram shows the stop ring metal 211c extending above the tops of the last three second-conductivity type pillars 202 in the third region II-3. It should be noted that the third region II-3 is limited by the length of the stop ring metal 211c; the longer the stop ring metal 211c (i.e., the longer the extension towards the second region), the longer the lateral length of the third region II-3 needs to be, and the lower the top height of the second-conductivity type pillars 202 in the third region II-3 needs to be. However, the minimum top height must meet the device's withstand voltage requirements.

[0047] It should be understood that the purpose of the superjunction device termination structure in this embodiment is to protect the core element in the core active region I. Therefore, the superjunction device termination structure and the core element in the core active region I are formed on the same first conductivity type epitaxial layer 201. The specific structural form of the core element in the core active region I can be designed as needed. Optionally, the core element in the core active region I also adopts a superjunction structure, that is, the superjunction structure of the core active region I also has a plurality of alternating first conductivity type pillars and second conductivity type pillars 202, and the superjunction structure of the core active region I is formed together with the superjunction device termination structure in the termination region II. The distribution density of the second conductivity type pillars 202 in the core active region I can be greater than the distribution density of the second conductivity type pillars 202 in the termination region II, and the linewidth of the second conductivity type pillars 201 in the core active region I can be smaller than the linewidth of the second conductivity type pillars 202 in the termination region II. The top view shape of the second conductivity type pillars 203 in the core active region I can be the same as or different from the top view shape of the second conductivity type pillars 202 in the termination region II. For example, the first and second conductive type pillars 202 in the core active region I are arranged in parallel and in a strip-like pattern, while the first and second conductive type pillars 202 in the terminal region II are arranged in a ring and surround the periphery of the core active region I; as another example, the first and second conductive type pillars 202 in both the core active region I and the terminal region II are arranged in a strip-like pattern.

[0048] In this embodiment, a second conductivity type well 203 is also formed on the top of each second conductivity type pillar 202. Simultaneously with the formation of polysilicon layers 208b and 208c, a polysilicon gate 208a is also formed in the core active region I. Simultaneously with the formation of gate metal 211b and stop-ring metal 211c, a source metal 211a is also formed in the core active region I. The source metal 211a is electrically connected to the source and drain regions located on both sides of the polysilicon gate 208a in the core active region I through corresponding conductive plugs 210a, and is electrically connected to the main junction 204 through conductive plugs 210b.

[0049] To better illustrate the technical effects of the superjunction device termination structure in this embodiment, we conducted simulation tests on this structure and similar structures.

[0050] First, make Figure 3 In the third region II-3, the P-pillars are of equal height and their tops are suspended (i.e., the top of the P-pillars is at a required distance from the top surface of the first conductivity type epitaxial layer 201). Figure 3 The approximate structure of the superjunction device termination structure shown is described below. Figure 3 After simulation testing of the structure, it was found that... Figure 5 The structure shown (i.e.) Figure 3 The equipotential lines near the stop ring doped region of the structure are compared to Figure 4 The equipotential lines at the same location are sparse and more concentrated towards the interior, and from Figure 6 It can be seen from this that Figure 5 The peak value of the surface electric field near the doped region of the cutoff ring in the structure shown is smaller than that of the peak value to the right of the solid line. Figure 4 The peak value of the surface electric field near the doped region of the cutoff ring in the approximate structure shown is... Figure 5 The electric field of the structure shown at other locations and Figure 4 The electric fields at the same locations in the approximate structure shown are basically the same and do not change much.

[0051] Secondly, when Figure 3 When the structure is in a p-biased state (i.e., the p-column concentration is too high due to process errors, for example, 10% higher), it also makes... Figure 3 In the third region II-3, the P-pillars are of equal height and their tops are suspended (i.e., the top of the P-pillars is at a required distance from the top surface of the first conductivity type epitaxial layer 201). Figure 3 The approximate structure of the superjunction device termination structure shown is described below. Figure 3 After simulation testing of the structure, it was found that... Figure 8 The structure shown (i.e.) Figure 3 The structure in the p-biased state has a higher equipotential line ratio near the cutoff ring doped region than the structure in the p-biased state. Figure 7 The equipotential lines at the same location are sparse and more concentrated towards the interior, and from Figure 9 It can be seen from this that Figure 8 The peak value of the surface electric field near the doped region of the cutoff ring in the structure shown is smaller than that of the peak value to the right of the solid line. Figure 7 The peak value of the surface electric field near the doped region of the cutoff ring in the approximate structure shown is... Figure 8 The electric field of the structure shown at other locations and Figure 7 The electric fields at the same locations in the approximate structure shown are basically the same and do not change much.

[0052] This illustrates that the superjunction device termination structure of this embodiment divides the first conductivity type epitaxial layer of the termination region into first to third regions. A second conductivity type main junction is formed in the top layer of the first conductivity type epitaxial layer in the first region, and a second conductivity type doped region is formed in the top layer of the first conductivity type epitaxial layer in the second region. The doping concentration of the doped region is less than that of the main junction. The top of the second conductivity type pillar below the bottom of the doped region is lower than or flush with the top of the second conductivity type pillar below the main junction (i.e., the junction depth of the doped region is greater than or equal to the junction depth of the main junction). In the third region, the top height of the second conductivity type pillar closest to the cutoff ring doped region is lower than that of the second conductivity type pillar closest to the second region. This not only introduces the electric field peak at the edge of the main junction into the termination structure, but also effectively reduces the surface electric field of the cutoff ring doped region and its surroundings. This is beneficial for reducing the distance between the cutoff ring doped region and the nearest second conductivity type pillar, thereby effectively reducing the termination area, while having no adverse effect on the device breakdown voltage and overall electric field.

[0053] It should be noted that, Figure 3 Although the diagram shows the lateral extension of the main junction 204 such that its bottom contacts the tops of four P-pillars (i.e., second conductivity type pillars 202), and the lateral extension of the doped region 205 such that its bottom contacts the tops of seven P-pillars (i.e., second conductivity type pillars 202), the technical solution of this invention is not limited to this. The lateral extension lengths of the main junction 204 and the doped region 205 depend on the device design requirements; that is, the number of P-pillars contacted by the bottom of the main junction 204 and the number of P-pillars contacted by the bottom of the doped region 205 both depend on the device design requirements and are not limited thereto. Figure 3 Examples are provided. Furthermore, Figure 3 In the structure shown, each step height in the third region II-3 has two or three P-pillars with equal top height, and there are five P-pillars in the third region II-3. However, the technical solution of the present invention is not limited to this. In other embodiments of the present invention, the number of P-pillars in the third region II-3 can be more or less according to the device design requirements, and the top heights of the P-pillars in the third region II-3 can all be different, such as... Figure 10 As shown, the number of P-pillars with the same top height at each step can also be more than 3.

[0054] It should also be understood that the superjunction device termination structure of the present invention can be manufactured based on any known suitable manufacturing method for superjunction device termination structures. During the manufacturing process, it is necessary to ensure that no P-pillars are formed in the region of the second region II-2 used to form the doped region 205, and that the top height of the P-pillars in the third region II-3 is distributed in a stepped manner, and that no P-type doped region is formed above the top of the P-pillars in the third region II-3.

[0055] Specifically, for example, the first conductivity type epitaxial layer 201 is formed by multiple epitaxial growth layers. After each first conductivity type epitaxial layer is formed, a second conductivity type ion implantation is performed on that epitaxial layer. Different ion implantation masks are selected according to the required top height of each P-pillar in the second region II-2 and the third region II-3 to mask the tops of the corresponding P-pillars in the second region II-2 and the third region II-3, ultimately forming second conductivity type pillars of different heights required in the first to third regions. Then, ion implantation can be performed using masks corresponding to the main junction, the doped region, and the cutoff ring doped region, respectively, to form the main junction 204, the doped region 205, and the cutoff ring doped region 206. After completing the corresponding ion implantation steps, a high-temperature annealing process is performed. Subsequently, through polysilicon layer deposition and etching, gate 208a, polysilicon layers 208b and 208c are formed. Then, an interlayer dielectric layer 209 is deposited, and the required conductive plugs 210a to 210e are formed through a contact via process. Following this, through metal deposition and etching, source metal 211a, gate metal 211b, and stop-ring metal 211c are formed. Thus, the superjunction device terminal device required by this invention is finally obtained.

[0056] The other process steps of the superjunction device termination device required by the present invention are the same as the process steps of the existing conventional superjunction device termination structure, and will not be described in detail here.

[0057] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A superjunction device termination structure, comprising a first conductivity type epitaxial layer, wherein a plurality of alternating first conductivity type pillars and second conductivity type pillars are formed in the first conductivity type epitaxial layer; characterized in that, The first conductivity type epitaxial layer comprises, in the lateral direction, the following sequentially arranged elements: In the first region, a main junction of a second conductivity type is formed at the top of the first region, and the main junction is in contact with the top of the second conductivity type pillar below it; The second region has a doped region of a second conductivity type formed at its top. The bottom of the doped region of the second conductivity type is in contact with the top of a plurality of second conductivity type pillars below it. The doping concentration of the doped region of the second conductivity type is less than the doping concentration of the main junction. The top of the second conductivity type pillars below the bottom of the doped region of the second conductivity type is lower than or flush with the top of the second conductivity type pillars below the main junction. A third region is formed in which a stop ring doped region is formed at the top end of the third region away from the second region. A second conductivity type pillar in the third region is confined within the boundary of the stop ring doped region on the side away from the second region. The top height of the second conductivity type pillar in the third region is lower than or equal to the top height of the second conductivity type pillar in the second region. The top height of the second conductivity type pillar near the stop ring doped region is lower than the top height of the second conductivity type pillar near the boundary of the second region. A stop ring metal electrically connected to the stop ring doped region is also formed above the third region.

2. The superjunction device termination structure as described in claim 1, characterized in that, The top height of the second conductive type pillar in the third region decreases in a stepped manner along the direction away from the second region.

3. The superjunction device termination structure as described in claim 2, characterized in that, When the top height of the second conductive type pillars in the third region decreases in a stepped manner, the top height of each second conductive type pillar is different, or at least two second conductive type pillars have the same top height.

4. The superjunction device termination structure as described in claim 1, characterized in that, The top height of the second conductive type pillar closest to the second region in the third region is the same as the top height of the second conductive type pillar in the second region; and / or, the bottom height of each second conductive type pillar in the first conductive type epitaxial layer is the same.

5. The superjunction device termination structure as described in claim 1, characterized in that, The cutoff ring doped region is either a first conductivity type region or a second conductivity type region. The first conductivity type epitaxial layer outside the last second conductivity type pillar in the third region, together with the cutoff ring doped region and the cutoff ring metal, forms a cutoff ring structure.

6. The superjunction device termination structure according to any one of claims 1-5, characterized in that, The first conductivity type epitaxial layer is a composite structure formed by stacking multiple epitaxial layers; the main junction is located in the topmost epitaxial layer of the composite structure, and / or, the doped region of the second conductivity type is located in the topmost epitaxial layer, or, the doped region of the second conductivity type is located in the top two epitaxial layers of the composite structure.

7. The superjunction device termination structure as described in claim 6, characterized in that, The distance between the top of the second conductive type pillar in the third region and the top surface of the first conductive type epitaxial layer is equal to the stacking thickness of at least two epitaxial layers in the composite structure.

8. The superjunction device termination structure according to any one of claims 1-5, characterized in that, It also includes an interlayer dielectric layer that covers the top surface of the first conductivity type epitaxial layer, and the stop ring metal is formed on a portion of the interlayer dielectric layer.

9. The superjunction device termination structure as described in claim 8, characterized in that, The stop ring metal extends along the direction from the stop ring doped region to the second region above the top of at least one of the second conductivity type pillars in the third region.

10. The superjunction device termination structure as described in claim 8, characterized in that, It also includes a field oxide layer and a polysilicon layer. The field oxide layer is sandwiched between the top surface of the first conductivity type epitaxial layer and the interlayer dielectric layer, and covers the surface of a portion of the second conductivity type doped region and a portion of the third region. The polysilicon layer extends from a portion of the top surface of the stop ring doped region to a portion of the top surface of the field oxide layer, and the polysilicon layer is electrically connected to the stop ring metal.

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