High-surge bidirectional ESD protection device
The high-surge bidirectional ESD protection device designed with NPN structure and isolation ring solves the problems of insufficient surge capability and leakage current in the existing technology, and achieves higher transient voltage impulse protection and heat dissipation performance.
Patent Information
- Application Number
- CN202423270925.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-30
- Publication Date
- 2025-12-12
- Estimated Expiration
- 2034-12-30
AI Technical Summary
Existing bidirectional surge devices have insufficient surge capability when faced with high-energy transient voltage impacts, and the single-chip structure is prone to forward leakage problems.
The high-surge bidirectional ESD protection device adopts an NPN structure, which includes a P-type substrate and symmetrically distributed N+ expansion regions. Combined with an oxide barrier layer and an isolation ring structure, it forms a punch-through breakdown through depletion layer expansion to improve protection capability and prevent leakage.
It significantly improves the surge capability and protection effect of the device, while avoiding forward leakage and enhancing the heat dissipation channel and voltage clamping capability of the device.
Smart Images
Figure CN223666689U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to ESD protection devices, specifically a high surge bidirectional ESD protection device. Background Technology
[0002] In the field of electronic equipment protection, bidirectional protection technology plays a crucial role. It is mainly used to prevent damage to circuits caused by transient voltages such as electrostatic discharge (ESD). From a technical implementation perspective, bidirectional protection typically has two main structures: one is implemented by connecting two unidirectional chips in series, and the other is by using single-chip epitaxy technology to form an NPN (or PNP) structure.
[0003] A significant advantage of a bidirectional protection structure consisting of two unidirectional chips connected in series is its excellent symmetry, eliminating the need to distinguish directions. This structure is relatively simple to design and apply, meeting the needs of various applications. However, a bidirectional protection structure implemented with a single chip requires specific epitaxial resistivity and thickness to determine the required voltage. Although this structure has relatively poor symmetry, its lower on-state impedance helps reduce residual voltage, making it more suitable for low-voltage devices.
[0004] However, both structures have significant drawbacks. To improve device performance, high-density substrates are typically used to reduce on-state impedance. But this results in a thinner epitaxial layer, which fails to provide an effective heat dissipation path for the device. This limits the device's surge capability, making it perform poorly when faced with high-energy transient voltage surges. Utility Model Content
[0005] The purpose of this invention is to solve the technical problem of low surge capability of current bidirectional surge devices and to provide a high surge bidirectional ESD protection device.
[0006] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows:
[0007] A high surge bidirectional ESD protection device includes a P-type substrate and two N+ expansion regions symmetrically distributed on the upper and lower sides of the P-type substrate.
[0008] The two N+ expansion regions are located in the middle of the upper and lower surfaces of the P-type substrate, respectively;
[0009] An oxide barrier layer is provided on both the upper and lower surfaces of the P-type substrate;
[0010] An electrode is provided on the oxide barrier layer, and the electrode penetrates the oxide barrier layer and is connected to the N+ expansion region.
[0011] Furthermore, the P-type substrate has an upper isolation ring and a lower isolation ring symmetrically distributed on its side;
[0012] The upper isolation ring is connected to the lower isolation ring, and the upper isolation ring and the lower isolation ring are respectively connected to the oxide barrier layer located on the upper surface of the P-type substrate and the oxide barrier layer located on the lower surface of the P-type substrate.
[0013] Furthermore, the thickness of the P-type substrate is 160–180 μm.
[0014] Furthermore, the thickness of the oxide barrier layer is 1.5–2.0 μm.
[0015] Furthermore, the depth of the N+ expansion region is 15–30 μm.
[0016] Furthermore, the protection voltage between the two electrodes is 5–60V.
[0017] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0018] 1. The high surge bidirectional ESD protection device provided by this utility model adopts an NPN structure as its main structure, which consists of an N+ expansion region, a P-type substrate, and an N+ expansion region from top to bottom. The NPN consists of a forward junction and a reverse junction. When a surge flows in, the depletion layer of the reverse junction expands under a strong electric field. Since the base region concentration is relatively light, the depletion layer expands quickly. Before reaching the base region width required for avalanche breakdown, the depletion layer expands to another N+ region, forming a punch-through breakdown. Since punch-through breakdown has a higher surge capability and a lower clamping voltage than the avalanche effect, the protection capability of the device is greatly improved.
[0019] 2. The high surge bidirectional ESD protection device provided by this utility model avoids the problem of positive leakage between the P-type substrate and the N+ expansion region of the device due to the presence of an upper isolation ring and a lower isolation ring. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the present utility model;
[0021] Figure 2 for Figure 1 Top view.
[0022] Explanation of reference numerals in the attached figures: 1-P-type substrate, 2-N+ expansion region, 3-Oxide barrier layer, 4-Electrode, 5-Upper isolation ring, 6-Lower isolation ring. Detailed Implementation
[0023] The technical solutions of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.
[0024] like Figure 1 and Figure 2 As shown, a high-surge bidirectional ESD protection device includes a P-type substrate 1 with a thickness of 160-180 μm, and two N+ expansion regions symmetrically distributed on the upper and lower sides of the P-type substrate 1, with a depth of 15-30 μm; the two N+ expansion regions are located in the middle of the upper and lower surfaces of the P-type substrate 1, respectively; an oxide barrier layer 3 with a thickness of 1.5-2.0 μm is provided on both the upper and lower surfaces of the P-type substrate 1; an electrode 4 is provided on the oxide barrier layer 3, and the electrode 4 penetrates the oxide barrier layer 3 and is connected to the N+ expansion region.
[0025] To prevent forward leakage between the P-type substrate 1 and the N+ expansion region of the device due to dicing or overfilling of adhesive during die mounting, the side of the P-type substrate 1 is provided with an upper isolation ring 5 and a lower isolation ring 6 symmetrically distributed vertically. The upper isolation ring 5 and the lower isolation ring 6 are connected, and the upper isolation ring 5 and the lower isolation ring 6 are respectively connected to the oxide barrier layer 3 located on the upper surface of the P-type substrate 1 and the oxide barrier layer 3 located on the lower surface of the P-type substrate 1.
[0026] The protection voltage between the two electrodes 4 is 5-60V. In actual operation, when a surge flows in, the NPN transistor consists of a forward junction and a reverse junction. Under a strong electric field, the depletion layer of the reverse junction expands. Because the base region concentration is relatively low, the depletion layer expands rapidly. Before reaching the base region width required for avalanche breakdown, the depletion layer expands into another N+ region, forming a punch-through breakdown.
[0027] The specific preparation method of the high surge bidirectional ESD protection device provided by this utility model is as follows:
[0028] On the upper and lower surfaces of a P-type substrate 1 with a thickness of 170±10μm, a high-density oxide barrier layer 3 with a thickness of 1.5 to 2.0μm is grown.
[0029] The diffusion regions of the upper isolation ring 5 and the lower isolation ring 6 are etched on the side of the P-type substrate 1 by photolithography, and the diffusion regions are doped with high-energy injection or liquid phosphorus source; the connection of the upper isolation ring 5 and the lower isolation ring 6 is achieved by high-temperature push junction, with a push junction temperature of 1350℃ and an annealing time of 10-30 hours.
[0030] Bilateral phosphorus doping was performed on the middle of the upper and lower surfaces of the P-type substrate 1, followed by annealing and push-junction to form an N+ expansion region. The push-junction temperature was 1250℃ and the push-junction depth was 15-30µm.
[0031] Photolithography creates apertures, and metal is sputtered to form two electrodes 4, one above the other. Since the device is symmetrical, the two electrodes 4 can be interchanged.
[0032] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the protection scope of the claims.
Claims
1. A high-surge bidirectional ESD protection device, characterized in that: It includes a P-type substrate (1) and two N+ expansion regions symmetrically distributed on the upper and lower sides of the P-type substrate (1); The two N+ expansion regions are located in the middle of the upper and lower surfaces of the P-type substrate (1), respectively; The P-type substrate (1) has an oxide barrier layer (3) on both its upper and lower surfaces; An electrode (4) is provided on the oxide barrier layer (3), and the electrode (4) penetrates the oxide barrier layer (3) and is connected to the N+ expansion region.
2. The high surge bidirectional ESD protection device according to claim 1, characterized in that: The P-type substrate (1) is provided with an upper isolation ring (5) and a lower isolation ring (6) symmetrically distributed on its side. The upper isolation ring (5) is connected to the lower isolation ring (6), and the upper isolation ring (5) and the lower isolation ring (6) are respectively connected to the oxide barrier layer (3) located on the upper surface of the P-type substrate (1) and the oxide barrier layer (3) located on the lower surface of the P-type substrate (1).
3. The high surge bidirectional ESD protection device according to claim 1, characterized in that: The thickness of the P-type substrate (1) is 160-180 μm.
4. The high surge bidirectional ESD protection device according to claim 1, characterized in that: The thickness of the oxide barrier layer (3) is 1.5 to 2.0 μm.
5. The high surge bidirectional ESD protection device according to claim 1, characterized in that: The depth of the N+ expansion region is 15–30 μm.
6. The high surge bidirectional ESD protection device according to claim 1, characterized in that: The protection voltage between the two electrodes (4) is 5-60V.