Bidirectional low-capacity longitudinal structure SCR characteristic transient voltage suppression device
By setting trenches between SCR structures and filling them with insulating and conductive materials to form a longitudinal current path, the problems of weak electrostatic discharge capability and limited packaging of transverse SCR products are solved, achieving higher electrostatic protection capability and packaging flexibility.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- WILL SEMICON (SHANGHAI) CO LTD
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-12
AI Technical Summary
Existing bidirectional SCR products have a lateral structure, weak electrostatic discharge capability, and limited packaging, which cannot meet the higher requirements for transient voltage suppression devices under high signal transmission rates.
The design employs a bidirectional low-capacitance longitudinal structure. By setting trenches between the SCR structures and filling them with insulating and conductive materials, a first SCR structure is formed from the front to the back of the device, and a second SCR structure is formed from the back to the front, thus enabling the longitudinal flow of current.
It improves the electrostatic discharge capability of transient voltage suppression devices, removes packaging limitations, and meets the protection requirements under high signal transmission rates.
Smart Images
Figure CN122028508A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor technology, specifically to a transient voltage suppression device with bidirectional low capacitance vertical structure SCR characteristics. Background Technology
[0002] As the signal transmission rate of electronic products continues to increase and the manufacturing processes of back-end IC devices become increasingly advanced, the ability of electronic products to withstand ESD (electrostatic discharge) and EOS (electrical overstress) is weakening. This necessitates the addition of transient voltage suppression devices (TVS) to protect the back-end ICs of electronic products, while also placing higher demands on TVS devices, requiring lower clamping voltages and smaller capacitances. However, due to process limitations, current bidirectional SCR products are all lateral structures (current flows laterally). Lateral structure SCR products have only usable side areas during operation, resulting in weaker maximum anti-static capability. Furthermore, due to the lateral structure, the positive and negative terminals can only be led out from the same side, thus significantly limiting packaging options. Summary of the Invention
[0003] To address or mitigate the problems existing in the prior art, this application provides a bidirectional low-capacitance longitudinal structure SCR transient voltage suppression device, comprising: a first SCR structure from the front to the back of the device and a second SCR structure from the back to the front. Both the first SCR structure and the second SCR structure include a first epitaxial layer and a second epitaxial layer, which are disposed on the substrate from bottom to top. A first groove, a second groove, and a third groove are provided between the first SCR structure and the second SCR structure. The first groove is located close to the first SCR structure, and the third groove is located close to the second SCR structure. The first groove and the third groove are filled with insulating material, and the second groove is filled with conductive material. The first trench, the second trench, and the third trench are spaced apart from each other. The first trench and the second trench penetrate the second epitaxial layer and the first epitaxial layer and extend into the substrate; the third trench penetrates the second epitaxial layer and extends into the first epitaxial layer. One end of each of the first SCR structure and the second SCR structure is connected to the first input / output interface, and the other end of each of the first SCR structure and the second SCR structure is connected to the second input / output interface.
[0004] As a preferred embodiment of this application, it includes: A fourth trench is provided on the side of the first SCR structure away from the first trench, and the fourth trench penetrates the second epitaxial layer and the first epitaxial layer and extends into the substrate; The second SCR structure has a fifth trench, a sixth trench, and a seventh trench on the side away from the first trench; the fifth trench, the sixth trench, and the seventh trench are spaced apart from each other, the sixth trench and the seventh trench penetrate the second epitaxial layer and the first epitaxial layer and extend into the substrate; the fifth trench penetrates the second epitaxial layer and extends into the first epitaxial layer; The fifth groove is positioned close to the second SCR structure; The fifth and seventh trenches are filled with insulating material; the sixth trench is filled with conductive material.
[0005] As a preferred embodiment of this application, the first SCR structure includes a P-type first injection region, an N-type second epitaxial layer, an N-type second injection region, a P-type first epitaxial layer, and an N-type substrate disposed between a first input / output interface and a second input / output interface; The second SCR structure includes a P-type first epitaxial layer, an N-type second epitaxial layer, a P-type well region, and an N-type third injection region disposed between the second input / output interface and the first input / output interface; The first injection region and the well region are disposed in the second epitaxial layer, and the third injection region is disposed in the well region; The second injection region is disposed in the first epitaxial layer.
[0006] In a preferred embodiment of this application, there are multiple second and sixth trenches.
[0007] In a preferred embodiment of this application, an N-type fourth injection region and an N-type fifth injection region are symmetrically arranged on both sides of the well region; The fourth injection region is disposed between the third trench and the well region; The fifth injection region is located between the fifth trench and the well region.
[0008] In a preferred embodiment of this application, the insulating material is silicon dioxide and the conductive material is tungsten metal.
[0009] Compared with the prior art, the present application provides a bidirectional low-capacitance vertical structure SCR transient voltage suppression device, including: a first SCR structure from the front to the back of the device and a second SCR structure from the back to the front; a first trench, a second trench and a third trench are provided between the first SCR structure and the second SCR structure to form a bidirectional low-capacitance vertical structure SCR transient voltage suppression device. The present application solves the technical problems of weak electrostatic discharge capability and limited packaging of the bidirectional low-capacitance horizontal structure SCR transient voltage suppression device in the prior art. Attached Figure Description
[0010] Non-limiting and non-exhaustive embodiments of the invention are described by way of example with reference to the following figures, wherein: Figure 1 This image shows a cross-sectional view of a bidirectional low-capacitance longitudinal structure SCR transient voltage suppression device provided in an embodiment of this application. Detailed Implementation
[0011] To make the above and other features and advantages of the present invention clearer, the invention will be further described below with reference to the accompanying drawings. It should be understood that the specific embodiments given herein are for the purpose of explanation to those skilled in the art and are exemplary only, not restrictive.
[0012] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.
[0013] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0014] In the embodiments of this application, the main difference between N-type doping and P-type doping lies in the type of impurity, the conductive carriers, and the type of semiconductor formed.
[0015] N-type doping is achieved by incorporating pentavalent elements (such as phosphorus or arsenic) into a semiconductor. These elements provide additional electrons, giving the semiconductor good electronic conductivity and a negative charge. In N-type semiconductors, the primary charge carriers are electrons.
[0016] P-type doping is achieved by incorporating trivalent elements (such as boron). These elements create holes in the semiconductor, which carry a positive charge, causing the P-type semiconductor to exhibit electrical conductivity. In P-type semiconductors, the dominant charge carriers are holes.
[0017] It should be noted that SCR structure is short for silicon controlled rectifier, also known as thyristor.
[0018] The core of an SCR is a "sandwich" structure consisting of four semiconductor layers and three PN junctions (J1, J2, J3). The semiconductor layers of the SCR are PNPN, with the anode being the outermost P-type semiconductor and the cathode being the outermost N-type semiconductor. Specifically, it includes three PN junctions: J1 is the PN junction closest to the anode; J2 is the middle NP junction (reverse junction); and J3 is the PN junction closest to the cathode.
[0019] like Figure 1 As shown, this application provides a bidirectional low-capacitance longitudinal structure SCR transient voltage suppression device, including: a first SCR structure from the front to the back of the device and a second SCR structure from the back to the front; Both the first and second SCR structures include a P-type first epitaxial layer 2 and an N-type second epitaxial layer 3, which are sequentially disposed above the substrate 1 from bottom to top. Both the substrate 1 and the first epitaxial layer 2 are heavily doped. The second epitaxial layer 3 is a high-resistivity epitaxial layer, designed to reduce the capacitance of the product.
[0020] A first trench 4, a second trench 5, and a third trench 6 are disposed between the first SCR structure and the second SCR structure. The first trench 4 is disposed close to the first SCR structure, and the third trench 6 is disposed close to the second SCR structure. The second trench 5 is disposed between the first trench 4 and the third trench 6. The first trench 4 and the third trench 6 are filled with insulating material, and the second trench 5 is filled with conductive material. The insulating material is silicon dioxide, and the conductive material is tungsten. The second trench 5 and the sixth trench 9 form ohmic contacts with the substrate 1 and the first epitaxial layer 2, respectively.
[0021] The first trench 4, the second trench 5, and the third trench 6 are spaced apart from each other. The first trench 4 and the second trench 5 penetrate the second epitaxial layer 3 and the first epitaxial layer 2 and extend into the substrate 1; the third trench 6 penetrates the second epitaxial layer 3 and extends into the first epitaxial layer 2. One end of the first SCR structure and the second SCR structure are both connected to the first input / output interface IO1, and the other end of the first SCR structure and the second SCR structure are both connected to the second input / output interface IO2. The first SCR structure and the second SCR structure are connected in reverse parallel to form a bidirectional low-capacitance longitudinal structure SCR characteristic transient voltage suppression device.
[0022] As a preferred embodiment of this application, a fourth trench 7 is provided on the side of the first SCR structure away from the first trench 4, and the fourth trench 7 penetrates the second epitaxial layer 3 and the first epitaxial layer 2 and extends into the substrate 1; The second SCR structure has a fifth trench 8, a sixth trench 9, and a seventh trench 10 on the side away from the first trench 4; the fifth trench 8, the sixth trench 9, and the seventh trench 10 are spaced apart from each other, the sixth trench 9 and the seventh trench 10 penetrate the second epitaxial layer 3 and the first epitaxial layer 2 and extend into the substrate 1; the fifth trench 8 penetrates the second epitaxial layer 3 and extends into the first epitaxial layer 2; The first trench 4, second trench 5, fourth trench 7, sixth trench 9, and seventh trench 10 have the same depth and all extend into the substrate 1. The second trench 5 and sixth trench 9 are used to bypass the NP junction between the substrate 1 and the first epitaxial layer 2; otherwise, a PNPN structure cannot be formed between the second input / output interface IO2 and the first input / output interface IO1. The first trench 4, fourth trench 7, and seventh trench 10 are mainly used to isolate the first SCR structure and the second SCR structure.
[0023] The third trench 6 and the fifth trench 8 have the same depth and both extend into the first epitaxial layer 2. This is to prevent current from flowing directly from the second trench 5 and the sixth trench 9 through the second epitaxial layer 3, the well region 14 and the third injection region 15 in sequence.
[0024] The fifth groove 8 is positioned close to the second SCR structure; The fifth trench 8 and the seventh trench 10 are filled with insulating material; the sixth trench 9 is filled with conductive material, wherein the insulating material is silicon dioxide and the conductive material is tungsten metal.
[0025] As a preferred embodiment of this application, the first SCR structure includes a P-type first injection region 11, an N-type second epitaxial layer 3, an N-type second injection region 12, a P-type first epitaxial layer 2, and an N-type substrate 1 disposed between a first input / output interface and a second input / output interface; the second injection region 12 is used to adjust the breakdown voltage between the first input / output interface IO1 and the second input / output interface IO2.
[0026] The second SCR structure includes a P-type first epitaxial layer 2, an N-type second epitaxial layer 3, a P-type well region 14, and an N-type third injection region 15 disposed between the second input / output interface and the first input / output interface; The first injection region 11 and the well region 14 are disposed in the second epitaxial layer 3, and the third injection region 15 is disposed in the well region 14; The second injection region 12 is disposed in the first epitaxial layer 2; In a preferred embodiment of this application, an N-type fourth injection region 13 and an N-type fifth injection region 16 are symmetrically arranged on both sides of the well region 14; The fourth injection region 13 is disposed between the third trench 6 and the well region 14; the fourth injection region 13 is connected to the well region 14; The fifth injection region 16 is disposed between the fifth trench 8 and the well region 14. The fifth injection region 16 is connected to the well region 14. The fourth injection region 13 and the fifth injection region 16 are used to adjust the breakdown voltage between the second input / output interface IO2 and the first input / output interface IO1.
[0027] It should be noted that this application uses epitaxial growth technology on substrate 1, trench isolation technology, and conductive material filling technology to make a bidirectional lateral structure SCR transient voltage suppression device into a bidirectional longitudinal structure SCR transient voltage suppression device, specifically as follows: a heavily doped low-resistivity substrate 1 is selected, then a first epitaxial layer 2 is grown on substrate 1, then a second implantation region 12 is implanted in the first epitaxial layer 2, then a high-resistivity second epitaxial layer 3 is grown on the first epitaxial layer 2, then ion implantation is performed in the second epitaxial layer 3 to form a well region 14, then ion implantation is performed in the well region 14 to form a third implantation region 15, and a fourth implantation region 13 and a fifth implantation region 16 are symmetrically formed on both sides of the well region 14, and a first implantation region 11 is formed in the second epitaxial layer 3. Finally, a first trench 4, a second trench 5, a third trench 6, a fourth trench 7, a fifth trench 8, a sixth trench 9, and a seventh trench 10 are made. The second trench 5 and the sixth trench 9 are filled with tungsten metal, which is respectively connected to the substrate 1 and the first epitaxial layer 2. Finally, silicon dioxide is filled through the first trench 4, the third trench 6, the fourth trench 7, the fifth trench 8 and the seventh trench 10. The first trench 4 isolates the well region 14 and the first injection region 11, the first trench 4 isolates the first injection region 11 and the second trench 5, and the third trench 6 isolates the second trench 5 and the well region 14, thus forming a bidirectional low-capacitance longitudinal structure SCR characteristic transient voltage suppression device.
[0028] Specific current paths and structures are as follows: Figure 1 As shown: As shown by arrow 17, the current path from the first input / output interface IO1 to the second input / output interface IO2 is: first injection region 11, N-type second epitaxial layer 3, N-type second injection region 12, P-type first epitaxial layer 2 and N-type substrate 1; As shown by arrows 18 and 19, the current path from the second input / output interface IO2 to the second input / output interface IO1 is as follows: N-type substrate 1, tungsten metal in the second trench 5 and the sixth trench 9, P-type first epitaxial layer 2, N-type second epitaxial layer 3, N-type fourth implantation region 13 and N-type fifth implantation region 16, P-type well region 14 and N-type third implantation region 15.
[0029] The technical features of the above implementation schemes can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above implementation schemes are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0030] Although the invention has been described in conjunction with embodiments, those skilled in the art will understand that the above description and drawings are exemplary and not restrictive, and the invention is not limited to the disclosed embodiments. Various modifications and variations are possible without departing from the spirit of the invention.
Claims
1. A bidirectional low-capacitance longitudinal structure SCR characteristic transient voltage suppression device, characterized in that, include: The first SCR structure from the front to the back of the device and the second SCR structure from the back to the front; Both the first SCR structure and the second SCR structure include a first epitaxial layer and a second epitaxial layer, which are disposed on the substrate from bottom to top. A first groove, a second groove, and a third groove are provided between the first SCR structure and the second SCR structure. The first groove is located close to the first SCR structure, and the third groove is located close to the second SCR structure. The first groove and the third groove are filled with insulating material, and the second groove is filled with conductive material. The first trench, the second trench, and the third trench are spaced apart from each other, and the first trench and the second trench penetrate the second epitaxial layer and the first epitaxial layer and extend into the substrate; The third trench penetrates the second epitaxial layer and extends into the first epitaxial layer; One end of the first SCR structure and the second SCR structure are both connected to the first input / output interface, and the other end of the first SCR structure and the second SCR structure are both connected to the second input / output interface. The first SCR structure and the second SCR structure are connected in reverse parallel to form a bidirectional low-capacitance longitudinal structure SCR characteristic transient voltage suppression device.
2. The transient voltage suppression device with bidirectional low capacitance longitudinal structure SCR characteristics as described in claim 1, characterized in that, include: A fourth trench is provided on the side of the first SCR structure away from the first trench, and the fourth trench penetrates the second epitaxial layer and the first epitaxial layer and extends into the substrate; The second SCR structure has a fifth trench, a sixth trench, and a seventh trench on the side away from the first trench; the fifth trench, the sixth trench, and the seventh trench are spaced apart from each other, the sixth trench and the seventh trench penetrate the second epitaxial layer and the first epitaxial layer and extend into the substrate; the fifth trench penetrates the second epitaxial layer and extends into the first epitaxial layer; The fifth groove is positioned close to the second SCR structure; The fifth and seventh trenches are filled with insulating material; the sixth trench is filled with conductive material.
3. A bidirectional low-capacitance longitudinal structure SCR characteristic transient voltage suppression device as described in claim 1 or 2, characterized in that, The first SCR structure includes a P-type first implantation region, an N-type second epitaxial layer, an N-type second implantation region, a P-type first epitaxial layer, and an N-type substrate disposed between a first input / output interface and a second input / output interface; The second SCR structure includes a P-type first epitaxial layer, an N-type second epitaxial layer, a P-type well region, and an N-type third injection region disposed between the second input / output interface and the first input / output interface; The first injection region and the well region are disposed in the second epitaxial layer, and the third injection region is disposed in the well region; The second injection region is disposed in the first epitaxial layer.
4. The transient voltage suppression device with bidirectional low capacitance longitudinal structure SCR characteristics as described in claim 3, characterized in that, There are multiple second and sixth trenches.
5. The transient voltage suppression device with bidirectional low capacitance longitudinal structure SCR characteristics as described in claim 3, characterized in that, The well region is symmetrically provided with an N-type fourth injection region and an N-type fifth injection region on both sides; The fourth injection region is disposed between the third trench and the well region; The fifth injection region is located between the fifth trench and the well region.
6. The transient voltage suppression device with bidirectional low capacitance longitudinal structure SCR characteristics as described in claim 3, characterized in that, The insulating material is silicon dioxide, and the conductive material is tungsten metal.