Electrostatic discharge protection structure and forming method thereof
By designing the drains of multiple BJT structures in the electrostatic discharge protection structure, the problem of insufficient performance of the electrostatic discharge protection structure in the prior art for high current breakdown is solved, and higher current leakage capacity and reliability are achieved.
Patent Information
- Application Number
- CN202311256607.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-26
- Publication Date
- 2025-03-28
AI Technical Summary
The existing electrostatic discharge protection structures lack performance when facing high current breakdown, making it difficult to effectively discharge current, affecting the reliability of the chip.
An electrostatic discharge protection structure is designed, including a substrate, a gate structure, a source and a drain, wherein the drain is composed of a plurality of doped layers of different doped types to form a plurality of BJT structures to increase the device's equivalent resistance and current leakage capability.
By increasing the device equivalent resistance and sharing more current, the breakdown current of the electrostatic discharge protection structure is worth increasing, which in turn improves the protection capability and reliability of the electrostatic discharge protection structure.
Smart Images
Figure CN119730392A_ABST
Abstract
Description
Technical Field
[0001] The embodiments of the present invention relate to the field of semiconductor manufacturing, and in particular to an electrostatic discharge protection structure and a method for forming the same. Background Art
[0002] Integrated circuits are easily damaged by static electricity. In existing chip designs, electrostatic discharge (ESD) protection circuits are often used to reduce chip damage.
[0003] However, with the rapid growth of the semiconductor integrated circuit (IC) industry, semiconductor technology continues to move towards smaller process nodes driven by Moore's Law, making integrated circuits develop in the direction of smaller size, higher circuit precision and higher circuit complexity.
[0004] Therefore, the performance of the electrostatic protection structure in the prior art needs to be improved. Summary of the invention
[0005] The problem solved by the embodiments of the present invention is to provide an electrostatic discharge protection structure and a method for forming the same, so as to improve the performance of the electrostatic discharge protection structure.
[0006] To solve the above problems, the present invention provides an electrostatic discharge protection structure, comprising: a substrate; a gate structure located on the substrate; a source located in the substrate on one side of the gate structure; a drain located in the substrate on the other side of the gate structure, wherein the drain comprises a plurality of first doping layers and a second doping layer located between adjacent first doping layers, and the first doping layer and the second doping layer have different doping types.
[0007] Optionally, adjacent gate structures share the same source, and adjacent gate structures share the same drain.
[0008] Optionally, the electrostatic discharge protection structure further includes: an isolation structure located in the substrate between the gate structure and the source, and in the substrate between the gate structure and the drain.
[0009] Optionally, the electrostatic discharge protection structure further includes: a silicide blocking layer surrounding the drain and covering the side surface of the drain.
[0010] Optionally, the material of the silicide blocking layer includes one or both of silicon oxide and silicon nitride.
[0011] Optionally, the substrate includes an active area, and the gate structure, source and drain are all located in the active area; the substrate also includes: a pick-up area, the pick-up area includes a first pick-up area located at the periphery of the active area and surrounding the active area; the substrate also includes: a sealing area, the sealing area is located at the periphery of the active area and surrounds the active area.
[0012] Optionally, the pickup region further includes a second pickup region, the second pickup region is located between the gate structure closest to the first pickup region and the first pickup region, and the second pickup region is connected to the first pickup region.
[0013] Optionally, the electrostatic discharge protection structure further includes: a pickup area plug, located on the top of the pickup area, and the pickup area plug is connected to the pickup area.
[0014] Optionally, there are multiple pickup zone plugs, and the pickup zone plugs are arranged along the extension direction of the pickup zone.
[0015] Optionally, the doping ions in the first doping layer are N-type ions, and the doping ions in the second doping layer are P-type ions.
[0016] Optionally, the electrostatic discharge protection structure further includes: source-drain plugs, wherein the source-drain plugs include a first source-drain plug connected to the drain and a second source-drain plug connected to the source.
[0017] Optionally, the number of the first source-drain plugs and the number of the second source-drain plugs are both plural, and the first source-drain plugs are arranged along the extension direction of the drain, and the second source-drain plugs are arranged along the extension direction of the source.
[0018] Optionally, the first source-drain plug is located on the top of the outermost first doping layer.
[0019] Correspondingly, an embodiment of the present invention also provides a method for forming an electrostatic discharge protection structure, comprising: providing a substrate; forming a gate structure on the substrate; forming a source in the substrate on one side of the gate structure; forming a drain in the substrate on the other side of the gate structure, the drain comprising a plurality of first doping layers and a second doping layer located between adjacent first doping layers, the first doping layer and the second doping layer having different doping types.
[0020] Optionally, the steps of forming the first doping layer and the second doping layer include: forming multiple first doping layers in the substrate on the other side of the gate structure through a first doping treatment; forming a shielding layer on the first doping layer; after forming the shielding layer, forming a second doping layer in the substrate between adjacent first doping layers through a second doping treatment.
[0021] Optionally, both the first doping treatment and the second doping treatment are ion implantation processes.
[0022] Optionally, the doping ions in the first doping layer are N-type ions, and the doping ions in the second doping layer are P-type ions.
[0023] Optionally, the method for forming the electrostatic discharge protection structure also includes: forming an isolation structure in the substrate between the gate structure and the source, and in the substrate between the gate structure and the drain; forming a silicide barrier layer surrounding the drain and covering the side surface of the drain on the top of the substrate; forming a first source-drain plug connected to the drain on the top of the drain, and forming a second source-drain plug connected to the source on the top of the source.
[0024] Optionally, in the step of providing a substrate, the substrate includes an active area, and the gate structure and the source are both located in the active area; in the step of forming the drain, the drain is located in the active area; in the step of providing a substrate, the substrate also includes a pick-up area, and the pick-up area includes a first pick-up area located at the periphery of the active area and surrounding the active area; the substrate also includes a sealing area, and the sealing area is located at the periphery of the active area and surrounds the active area.
[0025] Optionally, the pickup region further includes a second pickup region, the second pickup region is located between the gate structure closest to the first pickup region and the first pickup region, and the second pickup region is connected to the first pickup region.
[0026] Optionally, the method for forming the electrostatic discharge protection structure further includes: forming a pickup region plug on the top of the pickup region, and the pickup region plug is connected to the pickup region.
[0027] Compared with the prior art, the technical solution of the embodiment of the present invention has the following advantages:
[0028] In the electrostatic discharge protection structure provided by an embodiment of the present invention, the gate structure is located on the substrate, the source is located in the substrate on one side of the gate structure, and the drain is located in the substrate on the other side of the gate structure. The drain includes multiple first doping layers and a second doping layer located between adjacent first doping layers. The first doping layer and the second doping layer have different doping types, which means that multiple BJT (transistor) structures are arranged in the source. When the electrostatic discharge protection structure is triggered by a large current, the multiple BJT structures will be reverse biased (i.e., cut off). The multiple BJT structures can be used as voltage-dividing resistors to increase the device equivalent resistance of the electrostatic discharge protection structure, so that the multiple BJT structures can share more current, which means that the value of the breakdown current of the electrostatic discharge protection structure can be increased, thereby improving the electrostatic discharge protection structure's ability to discharge the breakdown current, and further improving the reliability of the electrostatic discharge protection structure. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 It is a structural schematic diagram of an embodiment of an electrostatic discharge protection structure of the present invention;
[0030] Figures 2 to 4 It is a schematic structural diagram corresponding to each step in an embodiment of a method for forming an electrostatic discharge protection structure of the present invention. DETAILED DESCRIPTION
[0031] In the prior art, if it is necessary to improve the protection capability of the electrostatic discharge protection structure, it is often achieved by increasing the area of the electrostatic discharge protection structure. However, as the process nodes of semiconductor integrated circuits become smaller and smaller, the area of the electrostatic discharge protection structure is subject to many restrictions. Therefore, the performance of the electrostatic discharge protection structure still needs to be improved.
[0032] In order to solve the above technical problems, an embodiment of the present invention provides an electrostatic discharge protection structure, including: a substrate; a gate structure located on the substrate; a source located in the substrate on one side of the gate structure; a drain located in the substrate on the other side of the gate structure, the drain including a plurality of first doping layers and a second doping layer located between adjacent first doping layers, the first doping layer and the second doping layer having different doping types.
[0033] The electrostatic discharge protection structure provided in an embodiment of the present invention includes a gate structure, and the drain includes multiple first doping layers and a second doping layer located between adjacent first doping layers. The first doping layer and the second doping layer have different doping types, which means that multiple BJT (transistor) structures are arranged in the drain. When the electrostatic discharge protection structure is triggered by a large current, the multiple BJT structures will be reverse biased (i.e., cut off). The multiple BJT structures can be used as voltage-dividing resistors to increase the device equivalent resistance of the electrostatic discharge protection structure, so that the multiple BJT structures can share more current, which means that the value of the breakdown current of the electrostatic discharge protection structure can be increased, thereby improving the electrostatic discharge protection structure's ability to discharge the breakdown current, and further improving the reliability of the electrostatic discharge protection structure.
[0034] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.
[0035] Figure 1 It is a structural schematic diagram of an embodiment of an electrostatic discharge protection structure of the present invention.
[0036] The electrostatic discharge protection structure includes: a substrate 100; a gate structure 110, located on the substrate 100; a source 108, located in the substrate 100 on one side of the gate structure 110; a drain 115, located in the substrate 100 on the other side of the gate structure 110, the drain 115 includes a plurality of first doping layers 114 and a second doping layer 113 located between adjacent first doping layers 114, and the first doping layer 114 and the second doping layer 113 have different doping types.
[0037] The substrate 100 is used to provide a process platform for forming an electrostatic discharge protection structure.
[0038] In this embodiment, the substrate 100 is used to form a metal-oxide-semiconductor (MOS) field effect transistor.
[0039] In this embodiment, the base 100 includes a substrate (not shown), which is a silicon substrate. In other embodiments, the material of the substrate may be other materials such as germanium, silicon germanium, silicon carbide, gallium arsenide or indium gallium, and the substrate may also be other types of substrates such as a silicon substrate on an insulator or a germanium substrate on an insulator.
[0040] In this embodiment, the substrate 100 includes an active region 100A, and the gate structure 110 , the source 108 , and the drain 115 are all located in the active region 100A.
[0041] The active region 100A is used to define the positions of the channel region and the source and drain doping regions.
[0042] The gate structure 110 is used to control the opening and closing of the conductive channel.
[0043] In this embodiment, the gate structure 110 is a device gate structure 110 , and the gate structure 110 includes a gate dielectric layer (not shown) and a gate electrode layer (not shown) covering the gate dielectric layer.
[0044] The gate dielectric layer is used to isolate the gate electrode layer from the substrate 100 in the active area 100A.
[0045] The material of the gate dielectric layer includes one or more of HfO2, ZrO2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, Al2O3, SiO2 and La2O3.
[0046] In this embodiment, the gate structure 110 is a metal gate structure 110, and therefore, the material of the gate electrode layer includes one or more of TiN, TaN, Ta, Ti, TiAl, W, Al, TiSiN and TiAlC. The gate electrode layer includes a work function layer and an electrode layer covering the work function layer, or may include only the work function layer.
[0047] Correspondingly, the gate dielectric layer includes a high-k gate dielectric layer. The material of the high-k gate dielectric layer is a high-k dielectric material, and the high-k dielectric material refers to a dielectric material having a relative dielectric constant greater than the relative dielectric constant of silicon oxide. Specifically, the material of the high-k gate dielectric layer can be selected from HfO2, ZrO2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO or Al2O3. As an example, the material of the high-k gate dielectric layer is HfO2.
[0048] In other embodiments, the gate structure may also be a polysilicon gate structure.
[0049] The drain 115 and the source 108 are used to provide a carrier source for the conductive channel when the device is working.
[0050] It should be noted that a plurality of BJT (transistor) structures are provided in the drain 115. When the electrostatic discharge protection structure is triggered by a large current, the plurality of BJT structures will be reverse biased (i.e., cut off). The plurality of BJT structures can be used as voltage-dividing resistors to increase the device equivalent resistance of the electrostatic discharge protection structure, thereby enabling the plurality of BJT structures to share more current, which means that the value of the breakdown current of the electrostatic discharge protection structure can be increased.
[0051] In this embodiment, adjacent gate structures 110 share the same source 108, and adjacent gate structures 110 share the same drain 115, so that the protection capability of the electrostatic discharge protection structure is improved, and the electrostatic discharge protection structure can further occupy a smaller area of the chip, thereby saving the chip area.
[0052] In this embodiment, the source 108 is doped with N-type ions, including P ions, As ions, Sb ions, etc. In other embodiments, the source may also be doped with P-type ions, including B ions, Ga ions, In ions, etc.
[0053] In this embodiment, the drain 115 includes a plurality of first doping layers 114 and a second doping layer 113 located between adjacent first doping layers 114 . The first doping layer 114 and the second doping layer 113 have different doping types.
[0054] As an example, the first doping layer 114 is doped with N-type ions, and the second doping layer 113 is doped with P-type ions, which means that a plurality of BJT (transistor) structures are arranged in the drain 115. After the electrostatic discharge protection structure is triggered by a large current, the plurality of BJT structures will be reverse biased (i.e., cut off). The plurality of BJT structures can be used as voltage divider resistors to increase the device equivalent resistance of the electrostatic discharge protection structure, thereby enabling the plurality of BJT structures to share more current, which means that the breakdown current value of the electrostatic discharge protection structure can be increased, thereby improving the protection capability of the electrostatic discharge protection structure.
[0055] In other embodiments, the first doping layer may be doped with P-type ions, and the second doping layer may be doped with N-type ions.
[0056] In this embodiment, the electrostatic discharge protection structure further includes: source-drain plugs (not shown), the source-drain plugs including a first source-drain plug 116 connected to the drain 115 and a second source-drain plug 118 connected to the source 108 .
[0057] The source-drain plugs are used to realize electrical connection between the drain 115 and the source 108 and an external circuit.
[0058] Specifically, there are plural first source-drain plugs 116 and plural second source-drain plugs 118 . The first source-drain plugs 116 are arranged along the extending direction of the drain 115 , and the second source-drain plugs 118 are arranged along the extending direction of the source 108 .
[0059] It should be noted that the number of the first source-drain plug 116 and the second source-drain plug 118 are both multiple, which is convenient for reducing the current value flowing through a single source-drain plug, thereby increasing the current discharge capability of the electrostatic discharge protection structure.
[0060] As an example, the first source-drain plug 116 is located on the top of the outermost first doping layer 114 .
[0061] It should be noted that the first source drain plug 116 is located on the top of the outermost first doping layer 114 . In the process of forming the first source drain plug 116 , the process window for forming the first source drain plug 116 can be increased, thereby reducing the difficulty of the formation process.
[0062] In this embodiment, the material of the source / drain plugs includes one or both of tungsten and ruthenium.
[0063] In this embodiment, the substrate 100 further includes a pickup region 106 , wherein the pickup region 106 includes a first pickup region 102 located at the periphery of the active region 100A and surrounding the active region 100A.
[0064] The pickup region 106 is used as a bulk terminal and is used to be connected to a ground terminal.
[0065] The first pickup region 102 is located at the periphery of the active region 100A and surrounds the active region 100A, so that when the electrostatic discharge protection structure discharges current, the discharge current flows from the source 108 to the ground terminal through the first pickup region 102 .
[0066] In this embodiment, the electrostatic discharge protection structure further includes: a pickup region plug 160 , which is located on the top of the pickup region 106 , and the pickup region plug 160 is connected to the pickup region 106 .
[0067] The pickup region plug 160 connected to the pickup region 106 is used to realize electrical connection between the first pickup region 102 and the ground terminal, so as to facilitate the electrostatic discharge protection structure to discharge current.
[0068] Specifically, there are multiple pick-up area plugs 160 , and the pick-up area plugs 160 are arranged along the extension direction of the pick-up area 106 .
[0069] The first pickup region 102 is located at the periphery of the active region 100A and surrounds the active region 100A. That is, the first pickup region 102 surrounds the active region 100A. Therefore, the first pickup region 102 includes a first direction (eg, Figure 1 The first pickup area 102 is arranged along the Y direction, and the second pickup area 102 is arranged along the second direction (as shown in FIG. Figure 1The first pickup area 102 is arranged in the X direction, and the first direction and the second direction are perpendicular to each other.
[0070] like Figure 1 As shown, the pick-up area plugs 160 include pick-up area plugs 160 arranged along the first direction (i.e., pick-up area plugs 160 arranged longitudinally), and also include pick-up area plugs 160 arranged along the second direction (i.e., pick-up area plugs 160 arranged transversely). In other words, the pick-up area plugs 160 located on the first pick-up area 102 extending along the first direction are arranged along the first direction, and the pick-up area plugs 160 located on the first pick-up area 102 extending along the second direction are arranged along the second direction.
[0071] There are multiple pickup area plugs 160, and they are arranged along the extension direction of the pickup area 106, so that when the electrostatic discharge protection structure discharges current, it is easy to reduce the current value flowing through a single pickup area plug 160, thereby making the electrostatic discharge protection structure more effective in discharging current.
[0072] In this embodiment, the pickup region 106 further includes a second pickup region 103 . The second pickup region 103 is located between the gate structure 110 closest to the first pickup region 102 and the first pickup region 102 . The second pickup region 103 is connected to the first pickup region 102 .
[0073] It should be noted that the second pickup area 103 is located between the gate structure 110 closest to the first pickup area 102 and the first pickup area 102, shortening the distance between the drain 115 and the first pickup area 102. When a voltage is applied to the drain 115 to turn on the parasitic NPN transistor (BJT), the generated current can flow out from the closer second pickup area 103, thereby further increasing the path for the electrostatic discharge protection structure to discharge the current, so that the discharge current can flow from the drain 115 to the ground via the second pickup area 103.
[0074] In this embodiment, the electrostatic discharge protection structure further includes: an isolation structure (not shown) located in the substrate 100 between the gate structure 110 and the source 108 , and in the substrate 100 between the gate structure 110 and the drain 115 .
[0075] An isolation structure is provided in the substrate 100 between the gate structure 110 and the source 108, and between the gate structure 110 and the drain 115, which is beneficial to increase the resistance between the gate structure 110 and the drain 115, and increase the resistance between the gate structure 110 and the source 108, and correspondingly further increases the value of the breakdown current, thereby further improving the protection capability of the electrostatic discharge protection structure.
[0076] Specifically, the material of the isolation structure may be a dielectric material such as silicon oxide, silicon nitride or silicon oxynitride. As an example, the material of the isolation structure is silicon oxide.
[0077] In this embodiment, the electrostatic discharge protection structure further includes a silicide block (SAB) 112 surrounding the drain 115 and covering the side surface of the drain 115 .
[0078] It should be noted that the silicide blocking layer 112 covers the side surface of the drain 115, which is beneficial to reduce the probability of the discharge current of the electrostatic discharge protection structure flowing out laterally through the surface of the drain 115, so that the discharge current of the electrostatic discharge protection structure can flow to the ground end through the drain 115 and the pickup area 106, thereby improving the discharge current effect of the electrostatic discharge protection structure.
[0079] Therefore, the silicide blocking layer 112 has an insulating function.
[0080] As an example, the material of the silicide blocking layer 112 includes silicon oxide and silicon nitride. The material of the silicide blocking layer 112 includes silicon oxide or silicon nitride, which is conducive to forming a silicide blocking layer 112 in a high resistance state, and accordingly, it is conducive to keeping the area covered by the silicide blocking layer 112 in a high resistance state, thereby reducing the probability of the discharge current flowing out laterally through the surface of the drain 115.
[0081] In this embodiment, the substrate 100 further includes a sealing area 101 , which is located at the periphery of the active area 100A and surrounds the active area 100A.
[0082] Specifically, the sealing area 101 is used to protect the active area 100A and the pickup area 106 in the electrostatic discharge protection structure, thereby reducing the risk of damage to the active area 100A and the pickup area in the electrostatic discharge protection structure.
[0083] Accordingly, an embodiment of the present invention also provides a method for forming an electrostatic discharge protection structure. Figures 2 to 4 It is a schematic structural diagram corresponding to each step in an embodiment of a method for forming an electrostatic discharge protection structure of the present invention.
[0084] refer to Figure 2 , providing a substrate 200 , on which a gate structure 210 is formed, and in which a source 208 is formed on one side of the gate structure 210 .
[0085] The substrate 200 is used to provide a process platform for forming an electrostatic discharge protection structure.
[0086] In this embodiment, the substrate 200 is used to form a metal-oxide-semiconductor (MOS) field effect transistor.
[0087] In this embodiment, the base 200 includes a substrate (not shown), which is a silicon substrate. In other embodiments, the material of the substrate may be other materials such as germanium, silicon germanium, silicon carbide, gallium arsenide or indium gallium, and the substrate may also be other types of substrates such as a silicon substrate on an insulator or a germanium substrate on an insulator.
[0088] In this embodiment, the substrate 200 includes an active region 200A, and the gate structure 210 , the source 208 , and the subsequently formed drain are all located in the active region 200A.
[0089] The active region 200A is used to define the positions of the channel region and the source and drain doping regions.
[0090] The gate structure 210 is used to control the opening and closing of the conductive channel.
[0091] In this embodiment, the gate structure 210 is a device gate structure 210 , and the gate structure 210 includes a gate dielectric layer (not shown) and a gate electrode layer (not shown) covering the gate dielectric layer.
[0092] The gate dielectric layer is used to isolate the gate electrode layer from the substrate 200 in the active area 200A.
[0093] The material of the gate dielectric layer includes one or more of HfO2, ZrO2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO, Al2O3, SiO2 and La2O3.
[0094] In this embodiment, the gate structure 210 is a metal gate structure 210, and therefore, the material of the gate electrode layer includes one or more of TiN, TaN, Ta, Ti, TiAl, W, Al, TiSiN and TiAlC. The gate electrode layer includes a work function layer and an electrode layer covering the work function layer, or may include only the work function layer.
[0095] Correspondingly, the gate dielectric layer includes a high-k gate dielectric layer. The material of the high-k gate dielectric layer is a high-k dielectric material, and the high-k dielectric material refers to a dielectric material having a relative dielectric constant greater than the relative dielectric constant of silicon oxide. Specifically, the material of the high-k gate dielectric layer can be selected from HfO2, ZrO2, HfSiO, HfSiON, HfTaO, HfTiO, HfZrO or Al2O3. As an example, the material of the high-k gate dielectric layer is HfO2.
[0096] In other embodiments, the gate structure may also be a polysilicon gate structure.
[0097] The source 208 is used to provide a carrier source for the conductive channel when the device is working.
[0098] In this embodiment, adjacent gate structures 210 share the same source 208 , so that the protection capability of the electrostatic discharge protection structure is improved and the electrostatic discharge protection structure can further occupy a smaller chip area, thereby saving chip area.
[0099] In this embodiment, the source 208 is doped with N-type ions, including P ions, As ions, Sb ions, etc. In other embodiments, the source may also be doped with P-type ions, including B ions, Ga ions, In ions, etc.
[0100] In this embodiment, in the step of providing the substrate 200 , an isolation structure (not shown) is further formed in the substrate 200 , and the isolation structure is located between the gate structure 210 and the source 208 .
[0101] The isolation structure is located between the gate structure 210 and the source 208, and also between the gate structure 210 and the subsequently formed drain, which is beneficial to increase the resistance between the gate structure 210 and the drain, and increase the resistance between the gate structure 210 and the source 208, and correspondingly further increases the value of the breakdown current, thereby further improving the protection capability of the electrostatic discharge protection structure.
[0102] Specifically, the material of the isolation structure may be a dielectric material such as silicon oxide, silicon nitride or silicon oxynitride. As an example, the material of the isolation structure is silicon oxide.
[0103] In this embodiment, in the step of providing the substrate 200 , the substrate 200 further includes a pickup region 206 , and the pickup region 206 includes a first pickup region 202 located at the periphery of the active region 200A and surrounding the active region 200A.
[0104] The pickup region 206 is used as a bulk terminal and is used to be connected to a ground terminal.
[0105] The first pickup region 202 is located at the periphery of the active region 200A and surrounds the active region 200A, so that when the electrostatic discharge protection structure discharges current, the discharge current flows from the source 208 to the ground terminal through the first pickup region 202 .
[0106] In this embodiment, the first pickup area 202 is located at the periphery of the active area 200A and surrounds the active area 200A. That is, the first pickup area 202 surrounds the active area 200A. Therefore, the first pickup area 202 includes a first direction (such as Figure 2 The first pickup area 202 is arranged along the Y direction, and the second pickup area 202 is arranged along the second direction (as shown in FIG. Figure 2 The first pickup area 202 is arranged in the X direction, and the first direction and the second direction are perpendicular to each other.
[0107] In this embodiment, the pickup region 206 further includes a second pickup region 203 . The second pickup region 203 is located between the gate structure 210 closest to the first pickup region 202 and the first pickup region 202 . The second pickup region 203 is connected to the first pickup region 202 .
[0108] It should be noted that the second pickup area 203 is located between the gate structure 210 closest to the first pickup area 202 and the first pickup area 202, shortening the distance between the drain and the first pickup area 202. When a voltage is applied to the drain to turn on the parasitic NPN transistor (BJT), the generated current can flow out from the closer second pickup area 203, thereby further increasing the path for the electrostatic discharge protection structure to discharge the current, so that the discharge current can flow from the drain to the ground via the second pickup area 203.
[0109] In this embodiment, the substrate 200 further includes a sealing area 201 . The sealing area 201 is located at the periphery of the active area 200A and surrounds the active area 200A and the pickup area 206 .
[0110] Specifically, the sealing area 201 is used to protect the active area 200A and the pickup area 206 in the electrostatic discharge protection structure, thereby reducing the risk of damage to the active area 200A and the pickup area 206 in the electrostatic discharge protection structure.
[0111] refer to Figure 3 A drain 215 is formed in the substrate 200 on the other side of the gate structure 210. The drain 215 includes a plurality of first doping layers 214 and a second doping layer 213 located between adjacent first doping layers 214. The first doping layer 214 and the second doping layer 213 have different doping types.
[0112] It should be noted that the drain 215 includes multiple first doping layers 214 and second doping layers 213 located between adjacent first doping layers 214. The first doping layers 214 and the second doping layers 213 have different doping types. That is to say, multiple BJT (transistor) structures are arranged in the drain 215. When the electrostatic discharge protection structure is triggered by a large current, the multiple BJT structures will be reverse biased (i.e., cut off). The multiple BJT structures can be used as voltage divider resistors to increase the device equivalent resistance of the electrostatic discharge protection structure, thereby enabling the multiple BJT structures to share more current, which means that the value of the breakdown current of the electrostatic discharge protection structure can be increased.
[0113] It should also be noted that the drain 215 is used to provide a carrier source for the conductive channel when the device is working.
[0114] In this embodiment, adjacent gate structures 210 share the same drain 215 , so that the protection capability of the electrostatic discharge protection structure is improved and the electrostatic discharge protection structure can further occupy a smaller chip area, thereby saving chip area.
[0115] In this embodiment, the isolation structure is located between the gate structure 210 and the drain 215, which is beneficial to increase the resistance between the gate structure 210 and the drain 215, and accordingly, further increases the value of the breakdown current, thereby further improving the protection capability of the electrostatic discharge protection structure.
[0116] In this embodiment, the drain 215 includes a plurality of first doping layers 214 and a second doping layer 213 located between adjacent first doping layers 214 . The first doping layer 214 and the second doping layer 213 have different doping types.
[0117] As an example, the first doping layer 214 is doped with N-type ions, and the second doping layer 213 is doped with P-type ions, which means that a plurality of BJT (transistor) structures are arranged in the drain 215. After the electrostatic discharge protection structure is triggered by a large current, the plurality of BJT structures will be reverse biased (i.e., cut off). The plurality of BJT structures can be used as voltage divider resistors to increase the device equivalent resistance of the electrostatic discharge protection structure, thereby enabling the plurality of BJT structures to share more current, which means that the breakdown current value of the electrostatic discharge protection structure can be increased, thereby improving the protection capability of the electrostatic discharge protection structure.
[0118] In other embodiments, the first doping layer may be doped with P-type ions, and the second doping layer may be doped with N-type ions.
[0119] In this embodiment, the steps of forming the first doping layer 214 and the second doping layer 213 include: forming multiple first doping layers 214 in the substrate 200 on the other side of the gate structure 210 through a first doping treatment; forming a blocking layer (not shown) on the first doping layer 214; after forming the blocking layer, forming a second doping layer 213 in the substrate 200 between adjacent first doping layers 214 through a second doping treatment.
[0120] The shielding layer protects the first doping layer 214 , thereby reducing the probability that the doping ions in the second doping process will damage the first doping layer 214 .
[0121] In this embodiment, both the first doping treatment and the second doping treatment are ion implantation processes.
[0122] The ion implantation process has the characteristics of high controllability of doping depth. By adopting the ion implantation process to form the first doping layer 214 and the second doping layer 213, the thickness of the first doping layer 214 can be consistent with the thickness of the second doping layer 213. The first doping layer 214 and the second doping layer 213 have a larger contact area perpendicular to the surface normal of the substrate 200, thereby improving the performance of the BJT (transistor) structure.
[0123] It should be noted that, in the step of forming the drain, the drain 215 is also located in the active region 200A.
[0124] Continue to refer Figure 3 After forming the drain 215 , the method for forming the electrostatic discharge protection structure further includes: forming a silicide blocking layer 212 in the substrate 200 that surrounds the drain 215 and covers the side surface of the drain 215 .
[0125] It should be noted that the silicide blocking layer 212 covers the side surface of the drain 215, which is beneficial to reducing the probability of the discharge current of the electrostatic discharge protection structure flowing out laterally through the surface of the drain 215, thereby making the discharge current of the electrostatic discharge protection structure flow to the ground end through the drain 215 and the pickup area 206 better, thereby making the discharge current of the electrostatic discharge protection structure better.
[0126] Therefore, the silicide blocking layer 212 has an insulating function.
[0127] As an example, the material of the silicide blocking layer 212 includes silicon oxide and silicon nitride. The material of the silicide blocking layer 212 includes silicon oxide or silicon nitride, which is conducive to forming a silicide blocking layer 212 in a high resistance state, and accordingly, it is conducive to keeping the area covered by the silicide blocking layer 212 in a high resistance state, thereby reducing the probability of the discharge current flowing out laterally through the surface of the drain 215.
[0128] refer to Figure 4 After forming the silicide blocking layer 212, the method for forming the electrostatic discharge protection structure further includes: forming a first source-drain plug 216 connected to the drain 215 on the top thereof, and forming a second source-drain plug 218 connected to the source 208 on the top thereof, wherein the first source-drain plug 216 and the second source-drain plug 218 constitute source-drain plugs (not shown).
[0129] The source-drain plugs are used to realize electrical connection between the drain 215 and the source 208 and an external circuit.
[0130] Specifically, there are plural first source-drain plugs 216 and plural second source-drain plugs 218 . The first source-drain plugs 216 are arranged along the extending direction of the drain 215 , and the second source-drain plugs 218 are arranged along the extending direction of the source 208 .
[0131] It should be noted that the number of the first source-drain plug 216 and the second source-drain plug 218 are both multiple, which is convenient for reducing the current value flowing through a single source-drain plug, thereby increasing the current discharge capability of the electrostatic discharge protection structure.
[0132] In this embodiment, in the step of forming the first source drain plug 216 , the first source drain plug 216 is formed on the top of the outermost first doping layer 214 , thereby increasing the process window for forming the first source drain plug 216 and reducing the difficulty of the formation process.
[0133] In this embodiment, the material of the source / drain plugs includes one or both of tungsten and ruthenium.
[0134] Continue to refer Figure 4 The method for forming the electrostatic discharge protection structure further includes: forming a pickup region plug 260 on the top of the pickup region 206 , and the pickup region plug 260 is connected to the pickup region 206 .
[0135] Specifically, the pickup region plug 260 connected to the pickup region 206 is used to realize electrical connection between the first pickup region 202 and the ground terminal, thereby facilitating the electrostatic discharge protection structure to discharge current.
[0136] Specifically, there are multiple pick-up area plugs 260 , and the pick-up area plugs 260 are arranged along the extension direction of the pick-up area 206 .
[0137] In this embodiment, the pickup region plug 260 includes a first direction (eg Figure 4 The pickup area plugs 260 are arranged along the second direction (as shown in the Y direction) (i.e., the pickup area plugs 260 are arranged longitudinally), and the pickup area plugs 260 are arranged along the second direction (as shown in the Y direction) Figure 4In other words, the pick-up area plugs 260 located on the first pick-up area 202 extending along the first direction are arranged along the first direction, and the pick-up area plugs 260 located on the first pick-up area 202 extending along the second direction are arranged along the second direction.
[0138] There are multiple pickup area plugs 260, and they are arranged along the extension direction of the pickup area, so that when the electrostatic discharge protection structure discharges current, it is easy to reduce the current value flowing through a single pickup area plug 260, thereby making the electrostatic discharge protection structure more effective in discharging current.
[0139] It should be noted that the pickup region plug 260 and the source / drain plug may be formed in the same step or may be formed in separate steps.
[0140] 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 protection scope of the present invention shall be subject to the scope defined by the claims.
Claims
1. An electrostatic discharge protection structure, characterized in that: include: substrate; A gate structure, located on the substrate; A source electrode is located in the substrate on one side of the gate structure; The drain is located in the substrate on the other side of the gate structure, and the drain includes a plurality of first doping layers and a second doping layer located between adjacent first doping layers, and the first doping layer and the second doping layer have different doping types.
2. The electrostatic discharge protection structure according to claim 1, characterized in that: The adjacent gate structures share the same source, and the adjacent gate structures share the same drain.
3. The electrostatic discharge protection structure according to claim 1, characterized in that: The electrostatic discharge protection structure further includes an isolation structure located in the substrate between the gate structure and the source electrode, and in the substrate between the gate structure and the drain electrode.
4. The electrostatic discharge protection structure according to claim 1 or 3, characterized in that: The electrostatic discharge protection structure further includes: a silicide blocking layer surrounding the drain and covering the side surface of the drain.
5. The electrostatic discharge protection structure according to claim 4, characterized in that: The material of the silicide blocking layer includes one or both of silicon oxide and silicon nitride.
6. The electrostatic discharge protection structure according to claim 1, characterized in that: The substrate comprises an active region, and the gate structure, the source electrode and the drain electrode are all located in the active region; The substrate further comprises: a pickup region, wherein the pickup region comprises a first pickup region located at the periphery of the active region and surrounding the active region; The substrate further includes a sealing area, which is located at the periphery of the active area and surrounds the active area.
7. The electrostatic discharge protection structure according to claim 6, characterized in that: The pickup region further includes a second pickup region, wherein the second pickup region is located between the gate structure closest to the first pickup region and the first pickup region, and the second pickup region is connected to the first pickup region.
8. The electrostatic discharge protection structure according to any one of claims 6 to 7, characterized in that: The electrostatic discharge protection structure further includes: a pickup region plug, which is located on the top of the pickup region and is connected to the pickup region.
9. The electrostatic discharge protection structure according to any one of claims 8, characterized in that: There are multiple plugs in the pickup area, and the plugs in the pickup area are arranged along the extension direction of the pickup area.
10. The electrostatic discharge protection structure according to claim 1, characterized in that: The doping ions in the first doping layer are N-type ions, and the doping ions in the second doping layer are P-type ions.
11. The electrostatic discharge protection structure according to claim 1, characterized in that: The electrostatic discharge protection structure further includes: source-drain plugs, wherein the source-drain plugs include a first source-drain plug connected to the drain and a second source-drain plug connected to the source.
12. The electrostatic discharge protection structure according to claim 11, characterized in that: There are plural numbers of the first source-drain plugs and the second source-drain plugs, and the first source-drain plugs are arranged along the extending direction of the drain, and the second source-drain plugs are arranged along the extending direction of the source.
13. The electrostatic discharge protection structure according to claim 11, characterized in that: The first source-drain plug is located on the top of the outermost first doping layer.
14. A method for forming an electrostatic discharge protection structure, characterized in that: include Providing a substrate, wherein a gate structure is formed on the substrate, and a source electrode is formed in the substrate on one side of the gate structure; A drain is formed in the substrate at the other side of the gate structure, wherein the drain includes a plurality of first doping layers and a second doping layer located between adjacent first doping layers, wherein the first doping layer and the second doping layer have different doping types.
15. The method for forming an electrostatic discharge protection structure according to claim 14, wherein: The steps of forming the first doping layer and the second doping layer include: forming multiple first doping layers in the substrate on the other side of the gate structure through a first doping treatment; forming a shielding layer on the first doping layer; after forming the shielding layer, forming a second doping layer in the substrate between adjacent first doping layers through a second doping treatment.
16. The electrostatic discharge protection structure according to claim 15, characterized in that: The doping ions in the first doping layer are N-type ions, and the doping ions in the second doping layer are P-type ions.
17. The method for forming an electrostatic discharge protection structure according to claim 14, wherein: In the step of providing a substrate, an isolation structure is also formed in the substrate, and the isolation structure is located between the gate structure and the source; In the step of forming the drain, the isolation structure is located between the gate structure and the drain; After forming the drain electrode, the method for forming the electrostatic discharge protection structure further includes: forming a silicide barrier layer in the substrate surrounding the drain electrode and covering the side surface of the drain electrode; A first source-drain plug connected to the drain is formed on the top of the drain, and a second source-drain plug connected to the source is formed on the top of the source, wherein the first source-drain plug and the second source-drain plug constitute source-drain plugs.
18. The method for forming an electrostatic discharge protection structure according to claim 14, wherein: In the step of providing a substrate, the substrate includes an active area, and the gate structure and the source electrode are both located in the active area; In the step of forming the drain, the drain is located in the active area; In the step of providing a substrate, the substrate further comprises a pickup region, and the pickup region comprises a first pickup region located at the periphery of the active region and surrounding the active region; The substrate further includes a sealing area, which is located at the periphery of the active area and surrounds the active area.
19. The method for forming an electrostatic discharge protection structure according to claim 18, wherein: The pickup region further includes a second pickup region, wherein the second pickup region is located between the gate structure closest to the first pickup region and the first pickup region, and the second pickup region is connected to the first pickup region.
20. The method for forming an electrostatic discharge protection structure according to any one of claims 18 to 19, characterized in that: The method for forming the electrostatic discharge protection structure further includes: forming a pickup region plug on the top of the pickup region, and the pickup region plug is connected to the pickup region.