Super junction device and forming method thereof

Abstract

The invention provides a super junction device and a forming method thereof, and the device comprises the steps: after an epitaxial layer is formed on a substrate, at least two deep trenches and deep trench epitaxial layers located in the deep trenches are formed in the epitaxial layer, the deep trench epitaxial layers comprise a first deep trench epitaxial layer located in the deep trenches, and a second deep trench epitaxial layer located in the deep trenches; the first deep groove epitaxial layer is located on the surface of the substrate, the second deep groove epitaxial layer is located on the surface of the first deep groove epitaxial layer, the third deep groove epitaxial layer is located on the surface of the second deep groove epitaxial layer, first doped ions are arranged in the first deep groove epitaxial layer, second doped ions are arranged in the second deep groove epitaxial layer, and the type of the first doped ions is opposite to that of the second doped ions. The first deep trench epitaxial layer has a first transverse width value in the extending direction perpendicular to the deep trench, the second deep trench epitaxial layer has a second transverse width value in the extending direction perpendicular to the deep trench, and the first doping ions have a first doping concentration value in the first deep trench epitaxial layer; the second doping ion has a second doping concentration value in the second deep trench epitaxial layer, and the product of the first transverse width value and the first doping concentration value is equal to the product of the second transverse width value and the second doping concentration value; the deep trench of the super junction device is enabled to maintain the same N and P doping matching from the top to the bottom, and the super junction device can be more easily applied to an MOSFET device of which the BV exceeds 1000V.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing technology, and in particular to a super junction device and a method for forming the same. Background Art

[0002] In the field of power semiconductors, as electronic devices' requirements for power conversion efficiency, switching speed, and voltage resistance continue to increase, traditional power devices have gradually exposed some limitations, which provides the background for the birth and development of superjunction devices.

[0003] Traditional power MOSFETs (metal-oxide semiconductor field-effect transistors) in high-voltage applications typically require a thicker drift region to achieve high voltage resistance. This results in higher on-resistance, which in turn increases device power consumption in the on-state, affecting overall energy efficiency. Superjunction devices cleverly resolve this contradiction through their unique structural design.

[0004] The fundamental concept behind superjunction devices stems from the exploration of optimizing the electric field distribution in traditional power devices. In traditional structures, the high withstand voltage requirement causes the electric field to be primarily concentrated near the device surface, which can easily lead to breakdown. Superjunction devices employ alternating P-type and N-type columnar regions within the device. In the blocking state, these regions interact to evenly distribute the electric field, effectively expanding the depletion layer. This significantly reduces the drift region thickness and on-resistance while maintaining high withstand voltage.

[0005] However, the performance of existing superjunction devices is poor. Summary of the Invention

[0006] The technical problem solved by the present invention is to provide a super junction device and a method for forming the same, so that the deep trench of the super junction device maintains the same N and P doping matching from top to bottom, avoiding the problem of difference in charge balance between the top and bottom of the deep trench, so that the super junction device can be more easily applied to MOSFET devices with a BV exceeding 1000V.

[0007] In order to solve the above problems, the present invention provides a super junction device, comprising a substrate; an epitaxial layer located on the surface of the substrate; at least two deep trenches located in the epitaxial layer, the deep trenches penetrating the epitaxial layer; a deep trench epitaxial layer located in the deep trenches, the deep trench epitaxial layer filling the deep trenches, wherein the deep trench epitaxial layer comprises a first deep trench epitaxial layer located in the deep trenches, a second deep trench epitaxial layer located on the surface of the first deep trench epitaxial layer, and a third deep trench epitaxial layer located on the surface of the second deep trench epitaxial layer, the first deep trench epitaxial layer having a first dopant ion, and the second deep trench epitaxial layer having a first dopant ion. It has a second doping ion, the type of the first doping ion is opposite to the type of the second doping ion, the first deep trench epitaxial layer has a first lateral width value in the extension direction perpendicular to the deep trench, the second deep trench epitaxial layer has a second lateral width value in the extension direction perpendicular to the deep trench, the first doping ion has a first doping concentration value in the first deep trench epitaxial layer, the second doping ion has a second doping concentration value in the second deep trench epitaxial layer, and the product of the first lateral width value and the first doping concentration value is equal to the product of the second lateral width value and the second doping concentration value.

[0008] Optionally, the first deep trench epitaxial layer is located on the side wall surface of the deep trench and the bottom surface of the deep trench; or the first deep trench epitaxial layer is located on the side wall surface of the deep trench and part of the bottom surface of the deep trench, part of the bottom surface of the deep trench is exposed between the first deep trench epitaxial layer on the side wall surface of the deep trench, the second deep trench epitaxial layer is located on the surface of the first deep trench epitaxial layer and part of the bottom surface of the deep trench is exposed between the first deep trench epitaxial layer, part of the bottom surface of the deep trench is exposed between the second deep trench epitaxial layer, and the third deep trench epitaxial layer is located on the surface of the second deep trench epitaxial layer and part of the bottom surface of the deep trench is exposed between the second deep trench epitaxial layer.

[0009] Optionally, the epitaxial layer contains third doping ions, and the type of the third doping ions is the same as or opposite to the type of the first doping ions.

[0010] Optionally, the third deep trench epitaxial layer has fourth doping ions, and a type of the fourth doping ions is opposite to or the same as a type of the second doping ions.

[0011] Optionally, it also includes: a body region located in the deep trench epitaxial layer, the top surface of the body region is flush with the top surface of the deep trench epitaxial layer, the body region has fifth doping ions, and the type of the fifth doping ions is the same as the type of the second doping ions.

[0012] Optionally, it also includes: a gate structure located on the surface of the epitaxial layer between adjacent deep trenches, the gate structure including a gate oxide layer located on the surface of the epitaxial layer between adjacent deep trenches and a gate layer located on the surface of the gate oxide layer, and the gate structure also extends to the surface of part of the body region in the adjacent deep trench epitaxial layer.

[0013] Optionally, it also includes: a first heavily doped region and a second heavily doped region located in the body region, the first heavily doped region being located between the second heavily doped region and the gate structure and the first heavily doped region being located in the body region on both sides of the gate structure, the first heavily doped region having a sixth doping ion, the second heavily doped region having a seventh doping ion, the type of the sixth doping ion being opposite to the type of the seventh doping ion, and the type of the sixth doping ion being opposite to the type of the fifth doping ion.

[0014] Optionally, the bottom of the deep trench exposes the surface of the substrate or the bottom of the deep trench extends into a portion of the substrate.

[0015] Optionally, at least two of the deep trenches have the same depth and at least two of the deep trenches have the same etching angle, where the etching angle is the inclination angle of the sidewall of the deep trench relative to the substrate, and the etching angle near the top of the deep trench ranges from 85° to 90°.

[0016] Correspondingly, the present invention also provides a method for forming a super junction device, comprising the steps of: providing a substrate; forming an epitaxial layer on the surface of the substrate; etching the epitaxial layer to form at least two deep trenches in the epitaxial layer, wherein the deep trenches penetrate the epitaxial layer; forming a deep trench epitaxial layer in the deep trenches, wherein the deep trench epitaxial layer fills the deep trenches, wherein the deep trench epitaxial layer comprises a first deep trench epitaxial layer formed in the deep trenches, a second deep trench epitaxial layer formed on the surface of the first deep trench epitaxial layer, and a third deep trench epitaxial layer formed on the surface of the second deep trench epitaxial layer, wherein the first deep trench epitaxial layer has first doped ions, and the deep trench epitaxial layer has a first doped ion. The second deep trench epitaxial layer has second doping ions, the type of the first doping ions is opposite to the type of the second doping ions, the first deep trench epitaxial layer has a first lateral width value in the extension direction perpendicular to the deep trench, the second deep trench epitaxial layer has a second lateral width value in the extension direction perpendicular to the deep trench, the first doping ions have a first doping concentration value in the first deep trench epitaxial layer, the second doping ions have a second doping concentration value in the second deep trench epitaxial layer, and the product of the first lateral width value and the first doping concentration value is equal to the product of the second lateral width value and the second doping concentration value.

[0017] Optionally, the first deep trench epitaxial layer is formed on the side wall surface of the deep trench and the bottom surface of the deep trench; or the first deep trench epitaxial layer is formed on the side wall surface of the deep trench and part of the bottom surface of the deep trench, and part of the bottom surface of the deep trench is exposed between the first deep trench epitaxial layer on the side wall surface of the deep trench; the second deep trench epitaxial layer is formed on the surface of the first deep trench epitaxial layer and part of the bottom surface of the deep trench is exposed between the first deep trench epitaxial layer, and part of the bottom surface of the deep trench is exposed between the second deep trench epitaxial layer; the third deep trench epitaxial layer is formed on the surface of the second deep trench epitaxial layer and part of the bottom surface of the deep trench is exposed between the second deep trench epitaxial layer.

[0018] Optionally, the third deep trench epitaxial layer has fourth doping ions, and a type of the fourth doping ions is opposite to or the same as a type of the second doping ions.

[0019] Optionally, it also includes: forming a body region in the deep trench epitaxial layer, the top surface of the body region is flush with the top surface of the deep trench epitaxial layer, the body region has fifth doping ions, and the type of the fifth doping ions is the same as the type of the second doping ions.

[0020] Optionally, a gate structure is formed on the surface of the epitaxial layer between adjacent deep trenches, wherein the gate structure includes a gate oxide layer formed on the surface of the epitaxial layer between adjacent deep trenches and a gate layer formed on the surface of the gate oxide layer, and the gate structure also extends to the surface of part of the body region in the epitaxial layer adjacent to the deep trenches.

[0021] Optionally, it also includes: a first heavily doped region and a second heavily doped region formed in the body region, the first heavily doped region is formed between the second heavily doped region and the gate structure and the first heavily doped region is formed in the body region on both sides of the gate structure, the first heavily doped region has a sixth doping ion, the second heavily doped region has a seventh doping ion, the type of the sixth doping ion is opposite to the type of the seventh doping ion, and the type of the sixth doping ion is opposite to the type of the fifth doping ion.

[0022] Optionally, the bottom of the deep trench exposes the surface of the substrate or the bottom of the deep trench extends into a portion of the substrate.

[0023] Optionally, the method for forming the deep trench epitaxial layer includes: forming an initial first deep trench epitaxial layer on the surface of the epitaxial layer and in the deep trench; forming an initial second deep trench epitaxial layer on the surface of the initial first deep trench epitaxial layer; forming an initial third deep trench epitaxial layer on the surface of the initial second deep trench epitaxial layer, the initial third deep trench epitaxial layer, the initial second deep trench epitaxial layer and the initial third deep trench epitaxial layer filling the deep trench; planarizing the initial third deep trench epitaxial layer, the initial second deep trench epitaxial layer and the initial first deep trench epitaxial layer until the surface of the epitaxial layer is exposed, and forming a deep trench epitaxial layer in the deep trench, the deep trench epitaxial layer including the first deep trench epitaxial layer, the second deep trench epitaxial layer and the third deep trench epitaxial layer.

[0024] Optionally, the bottom of the deep trench exposes the surface of the substrate or the bottom of the deep trench extends into a portion of the substrate.

[0025] Optionally, at least two of the deep trenches have the same depth and at least two of the deep trenches have the same etching angle, where the etching angle is the inclination angle of the sidewall of the deep trench relative to the substrate, and the etching angle near the top of the deep trench ranges from 85° to 90°.

[0026] Optionally, after forming the deep trench epitaxial layer, the method further includes: performing heat treatment on the deep trench epitaxial layer, wherein the first deep trench epitaxial layer and the epitaxial layer form a drift region, and the second deep trench epitaxial layer and the third deep trench epitaxial layer form a depletion region assisting the drift region.

[0027] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0028] In the technical solution of the super junction device of the present invention, after an epitaxial layer is formed on a substrate, at least two deep trenches are formed in the epitaxial layer, wherein the deep trench penetrates the epitaxial layer, and the deep trench epitaxial layer is located in the deep trench, wherein the deep trench epitaxial layer includes a first deep trench epitaxial layer located in the deep trench, a second deep trench epitaxial layer located on the surface of the first deep trench epitaxial layer, and a third deep trench epitaxial layer located on the surface of the second deep trench epitaxial layer, the first deep trench epitaxial layer has a first doped ion, the second deep trench epitaxial layer has a second doped ion, the type of the first doped ion is opposite to the type of the second doped ion, the first deep trench epitaxial layer has a first lateral width value in a direction perpendicular to the extension direction of the deep trench, and the second deep trench epitaxial layer has a first lateral width value in a direction perpendicular to the extension direction of the deep trench, and the second deep trench epitaxial layer has a first lateral width value in a direction perpendicular to the extension direction of the deep trench. The deep trench has a second lateral width value in the extension direction, the first doping ion has a first doping concentration value in the first deep trench epitaxial layer, the second doping ion has a second doping concentration value in the second deep trench epitaxial layer, and the product of the first lateral width value and the first doping concentration value is equal to the product of the second lateral width value and the second doping concentration value; the product of the first lateral width value and the first doping concentration value is equal to the product of the second lateral width value and the second doping concentration value to ensure that the deep trench maintains the same N and P doping matching from top to bottom, avoids the problem of difference in charge balance between the top and bottom of the deep trench, and makes it easier to apply super junction devices to MOSFET devices with a BV exceeding 1000V. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of a super junction device in one embodiment;

[0030] Figure 2 It is a schematic diagram of the structure of a deep trench;

[0031] Figures 3 to 7 1 is a structural schematic diagram of a formation process of a super junction device according to an embodiment of the present invention;

[0032] Figure 8 FIG. 4 is a schematic structural diagram of a super junction device in another embodiment of the present invention. DETAILED DESCRIPTION

[0033] The electrical performance of existing superjunction devices still needs to be improved. This will be described in detail below with reference to the accompanying drawings.

[0034] Please refer to Figure 1Taking an N-type super junction MOSFET as an example, it includes a highly doped N-type substrate 102, an N-type epitaxial layer / N-type drift region 101, a P-type pillar region (P-pillar, PPL) 103 that assists in depleting the N-type drift region, a gate dielectric layer 104, gate polysilicon 105, a P-type body region 106, a P-type heavily doped implant 107, and an N-type heavily doped implant 108.

[0035] The inventors have found that in the above embodiments, for super junction (SJ) MOSFET devices using deep trench (DT), the higher the voltage, the deeper the deep trench depth needs to be. However, when the deep trench depth H exceeds 40 μm (e.g. Figure 2 Due to the etching angle (~89.4°), the top and bottom dimensions of the deep trench have a large deviation (the top dimension is approximately 3.05 μm, and the bottom dimension is approximately 2.0 μm). This causes a difference in charge balance between the top and bottom of the deep trench superjunction (when the P-type pillar region 103 of the deep trench is uniformly doped and the N-type epitaxial layer / N-type drift region 101 is uniformly doped, the top of the superjunction has more P-type pillar regions 103 (large deep trench opening) and fewer N-type epitaxial layer / N-type drift region 101, while the bottom has fewer P-type pillar regions 103 (small deep trench opening) and more N-type epitaxial layer / N-type drift region 101). When the P-type pillar region 103 and the N-type epitaxial layer / N-type drift region 101 are uniformly doped, it is difficult to simultaneously meet the charge balance requirements of the superjunction at both the top and bottom. This makes the superjunction (superjunction, DT) using deep trench (DT) difficult to meet the charge balance requirements of the superjunction at both the top and bottom. SJ) MOSFET device technology is difficult to apply to devices with a BV exceeding 1000V.

[0036] The inventors have found through research that after an epitaxial layer is formed on a substrate, at least two deep trenches are formed in the epitaxial layer, wherein the deep trenches penetrate the epitaxial layer, and the deep trench epitaxial layer is located in the deep trenches, wherein the deep trench epitaxial layer includes a first deep trench epitaxial layer located in the deep trench, a second deep trench epitaxial layer located on the surface of the first deep trench epitaxial layer, and a third deep trench epitaxial layer located on the surface of the second deep trench epitaxial layer, the first deep trench epitaxial layer has a first doping ion, the second deep trench epitaxial layer has a second doping ion, the type of the first doping ion is opposite to the type of the second doping ion, the first deep trench epitaxial layer has a first lateral width value in a direction perpendicular to the extension direction of the deep trench, and the second deep trench epitaxial layer has a first lateral width value in a direction perpendicular to the extension direction of the deep trench, and the second deep trench epitaxial layer has a first lateral width value in a direction perpendicular to the extension direction of the deep trench. The groove has a second lateral width value in the extension direction, the first doping ion has a first doping concentration value in the first deep trench epitaxial layer, the second doping ion has a second doping concentration value in the second deep trench epitaxial layer, and the product of the first lateral width value and the first doping concentration value is equal to the product of the second lateral width value and the second doping concentration value; the product of the first lateral width value and the first doping concentration value is equal to the product of the second lateral width value and the second doping concentration value to ensure that the deep trench maintains the same N and P doping matching from top to bottom, avoids the problem of difference in charge balance between the top and bottom of the deep trench, and makes it easier to apply deep trench super junction devices to MOSFET devices with a BV exceeding 1000V.

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] First, please refer to Figure 3 , providing a substrate 200 , forming an epitaxial layer 201 on the surface of the substrate 200 , etching the epitaxial layer 201 , forming at least two deep trenches 209 in the epitaxial layer 201 , and the deep trenches 209 penetrate the epitaxial layer 201 .

[0039] In this embodiment, two deep trenches 209 are taken as an example.

[0040] In some embodiments, the number of the deep trenches 209 can be other numbers, which can be selected according to actual needs.

[0041] In this embodiment, the substrate 200 is a silicon substrate 200 .

[0042] In some embodiments, the substrate 200 may also be made of materials such as silicon germanium and germanium.

[0043] In this embodiment, an epitaxial growth process is adopted to form an initial epitaxial layer 201 on the surface of the substrate 200 , and ion doping is performed on the initial epitaxial layer 201 to form the epitaxial layer 201 . The epitaxial layer 201 has third doping ions.

[0044] In this embodiment, the epitaxial layer 201 is a high-resistance layer with low doping.

[0045] In this embodiment, an N-type super junction device is taken as an example, that is, the third doping ion is N-type.

[0046] In some embodiments, a P-type super junction device may also be formed, and the type of doping ions in the device may be changed accordingly according to actual needs.

[0047] In this embodiment, the concentration of the third doping ion is less than 5e14cm -3 .

[0048] In this embodiment, a patterned layer (not shown in the figure) is formed on the surface of the epitaxial layer 201 , and the epitaxial layer 201 is etched using the patterned layer as a mask to form at least two deep trenches 209 in the epitaxial layer 201 , wherein the deep trenches 209 penetrate the epitaxial layer 201 .

[0049] In this embodiment, the bottom of the deep trench 209 extends to a portion of the thickness of the substrate 200. Figure 5 The bottom of the deep trench 209 extends to the depth of the substrate 200 to be y, where y≥0um. This is to enable the subsequently formed first deep trench epitaxial layer 202 to be in direct contact with the substrate 200, thereby reducing the connection resistance. If y<0, there will be a low-doped high-resistance layer, namely the epitaxial layer 201, between the first deep trench epitaxial layer 202 and the substrate 200, which increases the resistance between the subsequently formed first deep trench epitaxial layer 202 and the substrate 200, thereby increasing the on-resistance of the device.

[0050] In some embodiments, the bottom of the deep trench 209 is flush with the surface of the substrate 200 .

[0051] In this embodiment, the two deep trenches 209 have the same depth, and the two deep trenches 209 have the same etching angle. The etching angle α near the top of the deep trench 209 ranges from 85° to 90°, where the etching angle is the inclination angle of the side wall of the deep trench 209 relative to the substrate 200.

[0052] A deep trench epitaxial layer is formed in the deep trench 209. For the process of filling the deep trench 209 with the deep trench epitaxial layer, please refer to Figures 4 and 5 .

[0053] Please refer to Figure 4 An initial first deep trench epitaxial layer 202' is formed on the surface of the epitaxial layer 201 and in the deep trench 209; an initial second deep trench epitaxial layer 203' is formed on the surface of the initial first deep trench epitaxial layer 202'; and an initial third deep trench epitaxial layer 301' is formed on the surface of the initial second deep trench epitaxial layer 203'. The initial first deep trench epitaxial layer 202', the initial second deep trench epitaxial layer 203' and the initial third deep trench epitaxial layer 301' fully fill the deep trench 209.

[0054] In this embodiment, the initial first deep trench epitaxial layer 202 ′, the initial second deep trench epitaxial layer 203 ′, and the initial third deep trench epitaxial layer 301 ′ are formed in the deep trench 209 by using epitaxial growth processes.

[0055] Please refer to Figure 5 , the initial third deep trench epitaxial layer 301', the initial second deep trench epitaxial layer 203' and the initial first deep trench epitaxial layer 202' are planarized until the surface of the epitaxial layer 201 is exposed, and a deep trench epitaxial layer is formed in the deep trench 209, and the deep trench epitaxial layer includes the first deep trench epitaxial layer 202, the second deep trench epitaxial layer 203 and the third deep trench epitaxial layer 301.

[0056] In this embodiment, the first deep trench epitaxial layer 202 has a first doping ion, and the second deep trench epitaxial layer 203 has a second doping ion, the type of the first doping ion is opposite to the type of the second doping ion, the first deep trench epitaxial layer 202 has a first lateral width value w1 in the extension direction perpendicular to the deep trench 209, and the second deep trench epitaxial layer 203 has a second lateral width value w2 in the extension direction perpendicular to the deep trench 209, the first doping ion has a first doping concentration value in the first deep trench epitaxial layer 202, and the second doping ion has a second doping concentration value in the second deep trench epitaxial layer 203, and the product of the first lateral width value w1 and the first doping concentration value is equal to the product of the second lateral width value w2 and the second doping concentration value.

[0057] In this embodiment, the product of the first lateral width value w1 and the first doping concentration value is equal to the product of the second lateral width value w2 and the second doping concentration value, so that the deep trench 209 (super junction) of the super junction device maintains the same N and P doping matching from top to bottom, avoiding the problem of the difference between the top charge balance and the bottom charge balance of the existing single DT-SJ. This allows the single DT-SJ ​​to be applied to devices with a BV exceeding 1000V, and can achieve uniform electric field distribution in the vertical direction of the device, improve the voltage resistance of the device, reduce the on-resistance of the device, and thus improve the overall performance of the super junction device.

[0058] Specifically, the first doping ion is an N-type ion, the second doping ion is a P-type ion, and the concentration range of the first doping ion is 1e14 cm -3 to 5e16cm -3 , the concentration range of the second dopant ion is 1e14 cm -3 to 5e16cm -3 .

[0059] In this embodiment, the third deep trench epitaxial layer 301 has fourth doping ions. The type of the fourth doping ions is opposite to or the same as the type of the second doping ions. For an N-type super junction device, the type of the fourth doping ions is preferably N-type.

[0060] In this embodiment, the concentration of the fourth doping ion is less than 5e14 cm -3 .

[0061] In this embodiment, the first deep trench epitaxial layer 202 is formed on the sidewall surfaces of the deep trench 209 and the bottom surface of the deep trench 209 .

[0062] Please refer to Figure 6 , also including: forming a body region 206 in the deep trench epitaxial layer, the top surface of the body region 206 is flush with the top surface of the deep trench epitaxial layer, and the body region 206 has a fifth doping ion, and the type of the fifth doping ion is the same as the type of the second doping ion.

[0063] In this embodiment, the type of the fifth doping ion is P type.

[0064] Please continue to refer to Figure 6, and also includes forming a gate structure on the surface of the epitaxial layer 201 between adjacent deep trenches 209, wherein the gate structure includes a gate oxide layer 204 formed on the surface of the epitaxial layer 201 between adjacent deep trenches 209 and a gate layer 205 formed on the surface of the gate oxide layer 204, and the gate oxide layer 204 also extends to the surface of part of the body region 206 in the adjacent deep trench epitaxial layer.

[0065] In this embodiment, after the body region 206 is formed by an ion implantation process, a thermal implantation process is performed on the body region 206 to thermally oxidize the gate oxide layer, deposit an initial gate layer 205, and etch the gate layer 205 to form a gate structure.

[0066] Please continue to refer to Figure 6 , also including: a first heavily doped region 208 and a second heavily doped region 207 formed in the body region 206, the first heavily doped region 208 being formed between the second heavily doped region 207 and the gate structure and the first heavily doped region 208 being formed in the body region 206 on both sides of the gate structure, the first heavily doped region 208 having a sixth doping ion, the second heavily doped region 207 having a seventh doping ion, the type of the sixth doping ion being opposite to the type of the seventh doping ion, and the type of the sixth doping ion being opposite to the type of the fifth doping ion.

[0067] In this embodiment, a first heavily doped region 208 is formed by selective implantation as a source terminal, and then a second heavily doped region 207 is formed by selective implantation and activated.

[0068] In this embodiment, the type of the seventh doping ion is P-type, and the type of the sixth doping ion is N-type.

[0069] It should be noted that Figure 6 The smallest primitive cell design is in the A box, and the rest except the terminal region are repeating units of the primitive cell.

[0070] Please refer to Figure 7 , performing heat treatment on the deep trench epitaxial layer.

[0071] In this embodiment, after heat treatment, the first deep trench epitaxial layer 202 and the epitaxial layer 201 form a drift region 202-1, and the second deep trench epitaxial layer 203 and the third deep trench epitaxial layer 301 form a depletion region 203-1 assisting the drift region 202-1. 202-1 serves as a deep trench N-type pillar region (NPL), and 203-1 serves as a deep trench P-type pillar region (PPL).

[0072] Correspondingly, the present invention also provides a super junction device, please refer to Figure 6 , comprising a substrate 200; an epitaxial layer 201 located on the surface of the substrate 200; at least two deep trenches 209 located in the epitaxial layer 201, the deep trenches 209 penetrating the epitaxial layer 201; a deep trench epitaxial layer located in the deep trenches 209, the deep trench epitaxial layer filling the deep trenches 209, wherein the deep trench epitaxial layer comprises a first deep trench epitaxial layer 202 located in the deep trenches 209, a second deep trench epitaxial layer 203 located on the surface of the first deep trench epitaxial layer 202, and a third deep trench epitaxial layer 301 located on the surface of the second deep trench epitaxial layer 203, wherein the first deep trench epitaxial layer 202 has a first dopant ion, and the second deep trench epitaxial layer 201 has a first dopant ion. 03 has a second doping ion, the type of the first doping ion is opposite to the type of the second doping ion, the first deep trench epitaxial layer 202 has a first lateral width value w1 in the extension direction perpendicular to the deep trench 209, the second deep trench epitaxial layer 203 has a second lateral width value w2 in the extension direction perpendicular to the deep trench 209, the first doping ion has a first doping concentration value in the first deep trench epitaxial layer 202, the second doping ion has a second doping concentration value in the second deep trench epitaxial layer 203, the product of the first lateral width value w1 and the first doping concentration value is equal to the product of the second lateral width value w2 and the second doping concentration value.

[0073] In this embodiment, the first deep trench epitaxial layer 202 is located on the sidewall surfaces of the deep trench 209 and the bottom surface of the deep trench 209 .

[0074] In this embodiment, the epitaxial layer 201 has third doping ions in it. The type of the third doping ions is opposite to or the same as that of the first doping ions, preferably the same.

[0075] In this embodiment, the third deep trench epitaxial layer 301 has fourth doping ions therein, and the type of the fourth doping ions is opposite to or the same as the type of the second doping ions, preferably opposite to each other.

[0076] In this embodiment, it also includes: a body region 206 located in the deep trench epitaxial layer, the top surface of the body region 206 is flush with the top surface of the deep trench epitaxial layer, and the body region 206 has fifth doping ions, and the type of the fifth doping ions is the same as the type of the second doping ions.

[0077] In this embodiment, it also includes: a gate structure located on the surface of the epitaxial layer 201 between adjacent deep trenches 209, the gate structure including a gate oxide layer 204 located on the surface of the epitaxial layer 201 between adjacent deep trenches 209 and a gate layer 205 located on the surface of the gate oxide layer, and the gate structure also extends to the surface of part of the body region 206 in the adjacent deep trench epitaxial layer.

[0078] In this embodiment, it also includes: a first heavily doped region 208 and a second heavily doped region 207 located in the body region 206, the first heavily doped region 208 is located between the second heavily doped region 207 and the gate structure, and the first heavily doped region 208 is located in the body region 206 on both sides of the gate structure, the first heavily doped region 208 has a sixth doping ion, the second heavily doped region 207 has a seventh doping ion, the type of the sixth doping ion is opposite to the type of the seventh doping ion, and the type of the sixth doping ion is opposite to the type of the fifth doping ion.

[0079] In this embodiment, the bottom of the deep trench 209 extends into a portion of the substrate 200 .

[0080] In this embodiment, the depths of at least two of the deep trenches 209 are equal, and at least two of the deep trenches 209 have the same etching angle, where the etching angle is the inclination angle of the sidewall of the deep trench 209 relative to the substrate 200, and the etching angle near the top of the deep trench 209 ranges from 85° to 90°.

[0081] Second embodiment

[0082] The difference between this embodiment and the first embodiment is that the first deep trench epitaxial layer 202 is located on the sidewall surface of the deep trench 209 and a portion of the bottom surface of the deep trench 209, a portion of the bottom surface of the deep trench 209 is exposed between the first deep trench epitaxial layer 202 on the sidewall surface of the deep trench 209, and the second deep trench epitaxial layer 203 is located on the surface of the first deep trench epitaxial layer 202 and a portion of the bottom surface of the deep trench 209 is exposed between the first deep trench epitaxial layer 202. Part of the bottom surface of the deep trench 209 is exposed between the second deep trench epitaxial layer 203, and the third deep trench epitaxial layer 301 is located on the surface of the second deep trench epitaxial layer 203 and the bottom surface of the deep trench 209 is exposed between the second deep trench epitaxial layer 203, that is, the bottoms of the first deep trench epitaxial layer 202, the second deep trench epitaxial layer 203 and the third deep trench epitaxial layer 301 are in contact with the substrate 200 at the same time. For details, please see Figure 8 .

[0083] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the scope defined by the claims.

Claims

1. A super junction device, characterized in that: include: substrate; an epitaxial layer located on the surface of the substrate; at least two deep trenches located in the epitaxial layer, the deep trenches penetrating the epitaxial layer; a deep trench epitaxial layer located in the deep trench, the deep trench epitaxial layer filling the deep trench, wherein the deep trench epitaxial layer includes a first deep trench epitaxial layer located in the deep trench, a second deep trench epitaxial layer located on a surface of the first deep trench epitaxial layer, and a third deep trench epitaxial layer located on a surface of the second deep trench epitaxial layer; the first deep trench epitaxial layer has a first doping ion, the second deep trench epitaxial layer has a second doping ion, the type of the first doping ion is opposite to the type of the second doping ion, the first deep trench epitaxial layer has a first lateral width value in an extension direction perpendicular to the deep trench, the second deep trench epitaxial layer has a second lateral width value in an extension direction perpendicular to the deep trench, the first doping ion has a first doping concentration value in the first deep trench epitaxial layer, the second doping ion has a second doping concentration value in the second deep trench epitaxial layer, and the product of the first lateral width value and the first doping concentration value is equal to the product of the second lateral width value and the second doping concentration value.

2. The super junction device according to claim 1, wherein: The first deep trench epitaxial layer is located on the sidewall surface of the deep trench and the bottom surface of the deep trench; or the first deep trench epitaxial layer is located on the sidewall surface of the deep trench and a portion of the bottom surface of the deep trench, and a portion of the bottom surface of the deep trench is exposed between the first deep trench epitaxial layer on the sidewall surface of the deep trench, the second deep trench epitaxial layer is located on the surface of the first deep trench epitaxial layer and the first deep trench epitaxial layer to expose a portion of the bottom surface of the deep trench, and a portion of the bottom surface of the deep trench is exposed between the second deep trench epitaxial layers, and the third deep trench epitaxial layer is located on the surface of the second deep trench epitaxial layer and the second deep trench epitaxial layer to expose the bottom surface of the deep trench.

3. The super junction device according to claim 1, wherein: The epitaxial layer has third doping ions therein, and a type of the third doping ions is the same as or opposite to a type of the first doping ions.

4. The super junction device according to claim 1, wherein: The third deep trench epitaxial layer has fourth doping ions therein, and a type of the fourth doping ions is opposite to or the same as a type of the second doping ions.

5. The super junction device according to claim 1, wherein: Also includes: A body region is located in the deep trench epitaxial layer, a top surface of the body region is flush with the top surface of the deep trench epitaxial layer, and the body region has fifth doping ions, and the type of the fifth doping ions is the same as the type of the second doping ions.

6. The super junction device according to claim 5, wherein: Also includes: A gate structure is located on the surface of the epitaxial layer between adjacent deep trenches, and the gate structure includes a gate oxide layer located on the surface of the epitaxial layer between adjacent deep trenches and a gate layer located on the surface of the gate oxide layer. The gate structure also extends to the surface of part of the body region in the epitaxial layer adjacent to the deep trench.

7. The super junction device according to claim 6, wherein: Also includes: A first heavily doped region and a second heavily doped region are located in the body region, the first heavily doped region is located between the second heavily doped region and the gate structure and the first heavily doped region is located in the body region on both sides of the gate structure, the first heavily doped region has a sixth doping ion, the second heavily doped region has a seventh doping ion, the type of the sixth doping ion is opposite to the type of the seventh doping ion, and the type of the sixth doping ion is opposite to the type of the fifth doping ion.

8. The super junction device according to claim 1, wherein: The bottom of the deep trench exposes the surface of the substrate or the bottom of the deep trench extends into a portion of the substrate.

9. The super junction device according to claim 1, wherein: At least two of the deep trenches have the same depth and at least two of the deep trenches have the same etching angle, where the etching angle is the inclination angle of the sidewall of the deep trench relative to the substrate, and the etching angle near the top of the deep trench ranges from 85° to 90°.

10. A method for forming a super junction device, characterized in that: Including steps: providing a substrate; forming an epitaxial layer on the surface of the substrate; Etching the epitaxial layer to form at least two deep trenches in the epitaxial layer, wherein the deep trenches penetrate the epitaxial layer; A deep trench epitaxial layer is formed in the deep trench, and the deep trench epitaxial layer completely fills the deep trench, wherein the deep trench epitaxial layer includes a first deep trench epitaxial layer formed in the deep trench, a second deep trench epitaxial layer formed on a surface of the first deep trench epitaxial layer, and a third deep trench epitaxial layer formed on a surface of the second deep trench epitaxial layer, the first deep trench epitaxial layer has a first doping ion, the second deep trench epitaxial layer has a second doping ion, a type of the first doping ion is opposite to a type of the second doping ion, the first deep trench epitaxial layer has a first lateral width value in a direction perpendicular to an extension of the deep trench, the second deep trench epitaxial layer has a second lateral width value in a direction perpendicular to an extension of the deep trench, the first doping ion has a first doping concentration value in the first deep trench epitaxial layer, the second doping ion has a second doping concentration value in the second deep trench epitaxial layer, and a product of the first lateral width value and the first doping concentration value is equal to a product of the second lateral width value and the second doping concentration value.

11. The method for forming a super junction device according to claim 10, wherein: The first deep trench epitaxial layer is formed on the sidewall surface of the deep trench and the bottom surface of the deep trench; or the first deep trench epitaxial layer is formed on the sidewall surface of the deep trench and a portion of the bottom surface of the deep trench, and a portion of the bottom surface of the deep trench is exposed between the first deep trench epitaxial layer on the sidewall surface of the deep trench; the second deep trench epitaxial layer is formed on the surface of the first deep trench epitaxial layer and the portion of the bottom surface of the deep trench is exposed between the first deep trench epitaxial layer, and a portion of the bottom surface of the deep trench is exposed between the second deep trench epitaxial layer; the third deep trench epitaxial layer is formed on the surface of the second deep trench epitaxial layer and the portion of the bottom surface of the deep trench is exposed between the second deep trench epitaxial layer.

12. The method for forming a super junction device according to claim 10, wherein: The third deep trench epitaxial layer has fourth doping ions therein, and a type of the fourth doping ions is opposite to or the same as a type of the second doping ions.

13. The method for forming a super junction device according to claim 10, wherein: Also includes: A body region is formed in the deep trench epitaxial layer, wherein a top surface of the body region is flush with a top surface of the deep trench epitaxial layer, and the body region has fifth doping ions, and a type of the fifth doping ions is the same as a type of the second doping ions.

14. The method for forming a super junction device according to claim 13, wherein: It also includes forming a gate structure on the surface of the epitaxial layer between adjacent deep trenches, wherein the gate structure includes a gate oxide layer formed on the surface of the epitaxial layer between adjacent deep trenches and a gate layer formed on the surface of the gate oxide layer, and the gate structure also extends to the surface of part of the body region in the epitaxial layer adjacent to the deep trench.

15. The method for forming a super junction device according to claim 14, wherein: Also includes: A first heavily doped region and a second heavily doped region are formed in the body region, the first heavily doped region is formed between the second heavily doped region and the gate structure, and the first heavily doped region is formed in the body region on both sides of the gate structure, the first heavily doped region has a sixth doping ion, the second heavily doped region has a seventh doping ion, the type of the sixth doping ion is opposite to the type of the seventh doping ion, and the type of the sixth doping ion is opposite to the type of the fifth doping ion.

16. The method for forming a super junction device according to claim 10, wherein: The bottom of the deep trench exposes the surface of the substrate or the bottom of the deep trench extends into a portion of the substrate.

17. The method for forming a super junction device according to claim 10, wherein: The method for forming the deep trench epitaxial layer includes: forming an initial first deep trench epitaxial layer on the surface of the epitaxial layer and in the deep trench; forming an initial second deep trench epitaxial layer on a surface of the initial first deep trench epitaxial layer; forming an initial third deep trench epitaxial layer on the surface of the initial second deep trench epitaxial layer, wherein the initial third deep trench epitaxial layer, the initial second deep trench epitaxial layer and the initial third deep trench epitaxial layer fully fill the deep trench; The initial third deep trench epitaxial layer, the initial second deep trench epitaxial layer and the initial first deep trench epitaxial layer are planarized until the surface of the epitaxial layer is exposed, and a deep trench epitaxial layer is formed in the deep trench, and the deep trench epitaxial layer includes the first deep trench epitaxial layer, the second deep trench epitaxial layer and the third deep trench epitaxial layer.

18. The method for forming a super junction device according to claim 10, wherein: The bottom of the deep trench exposes the surface of the substrate or the bottom of the deep trench extends into a portion of the substrate.

19. The method for forming a super junction device according to claim 10, wherein: At least two of the deep trenches have the same depth and at least two of the deep trenches have the same etching angle, where the etching angle is the inclination angle of the sidewall of the deep trench relative to the substrate, and the etching angle near the top of the deep trench ranges from 85° to 90°.

20. The method for forming a super junction device according to claim 10, wherein: After forming the deep trench epitaxial layer, the method further includes: performing heat treatment on the deep trench epitaxial layer, wherein the first deep trench epitaxial layer and the epitaxial layer form a drift region, and the second deep trench epitaxial layer and the third deep trench epitaxial layer form a depletion region assisting the drift region.

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