Bidirectional silicon controlled rectifier with symmetrical longitudinal structure

Abstract

The utility model discloses a bidirectional silicon controlled rectifier with a symmetrical longitudinal structure, which comprises an N-type silicon substrate, the N-type silicon substrate comprises an N-type silicon substrate front surface and an N-type silicon substrate back surface, and the N-type silicon substrate front surface and the N-type silicon substrate back surface are symmetrically provided with a front surface P-type short base region and a back surface P-type short base region. A front voltage dividing ring is arranged on the outer side of the front P-type short base region, a back voltage dividing ring is arranged on the outer side of the back P-type short base region, and the front voltage dividing ring and the back voltage dividing ring are symmetrically arranged on the front side of the N-type silicon substrate and the back side of the N-type silicon substrate relative to the N-type silicon substrate; according to the utility model, the structure is simple, the design is reasonable, forward off-state voltage is borne by the front P-type short base region and the front voltage dividing ring, reverse off-state voltage is borne by the back P-type short base region and the back voltage dividing ring, the voltage is completely symmetrical, a punch-through structure is not needed, and the production efficiency can be greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor technology, specifically to a bidirectional thyristor with a vertically symmetrical structure. Background Technology

[0002] A thyristor is a high-power semiconductor device mainly used in circuits such as controlled rectification, AC voltage regulation, and contactless switching. A thyristor controls the switching of a large current through a small current or voltage signal, and features high efficiency, long life and fast response.

[0003] The shortcomings of existing technology:

[0004] Currently, planar bidirectional thyristor structures all feature a punch-through structure, with a base window and voltage divider ring on the front side and a full-surface base region on the back side, exhibiting an asymmetrical longitudinal structure. The forward off-state voltage is primarily borne by the base region and voltage divider ring, while the reverse off-state voltage is mainly borne by the back-side base region and the punch-through. The punch-through structure requires a long diffusion process, resulting in low production efficiency. The asymmetrical longitudinal structure makes it difficult to balance parameters in both forward and reverse directions, increasing design complexity. Furthermore, the imbalance in forward and reverse parameters can increase the probability of failure on one side, reducing the overall reliability of the device. Utility Model Content

[0005] The purpose of this invention is to provide a bidirectional thyristor with a longitudinally symmetrical structure to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, this utility model provides the following technical solution: a longitudinally symmetrical bidirectional thyristor, comprising an N-type silicon substrate, wherein the N-type silicon substrate includes a front side and a back side, wherein a front P-type short base region and a back P-type short base region are symmetrically disposed on the front side and the back side of the N-type silicon substrate, a front voltage divider ring is disposed outside the front P-type short base region, and a back voltage divider ring is disposed outside the back P-type short base region, wherein the front voltage divider ring and the back voltage divider ring are symmetrically disposed about the front side and the back side of the N-type silicon substrate.

[0007] Preferably, the front P-type short base region is provided with a front N+ type emitter region, and the back P-type short base region is provided with a back N+ type emitter region, wherein the front N+ type emitter region and the back N+ type emitter region are centrally symmetrical about the N-type silicon substrate.

[0008] Preferably, a front N+ type cutoff ring is disposed on the outside of the front voltage divider ring on the front side of the N- type silicon substrate, and a back N+ type cutoff ring is disposed on the outside of the back voltage divider ring on the back side of the N- type silicon substrate.

[0009] Preferably, the front P-type short base region is provided with a first cathode electrode and a gate electrode, and the back P-type short base region is provided with a second cathode electrode. The first cathode electrode is provided with a front cathode short-circuit hole, and the second cathode electrode is provided with a back cathode short-circuit hole.

[0010] Preferably, the N-type silicon substrate has a front passivation layer on the front side and a back passivation layer on the back side.

[0011] Preferably, the junction depth of the front P-type short base region and the back P-type short base region is 60-65 μm, the distance between the front N+ type cutoff ring and the front voltage divider ring is 100-120 μm, and the distance between the back N+ type cutoff ring and the back voltage divider ring is 100-120 μm.

[0012] Preferably, the junction depth of the front pressure dividing ring and the back pressure dividing ring is 60~65um.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] This is a vertically symmetrical bidirectional thyristor. A front-side P-type short base region and a back-side P-type short base region are symmetrically arranged on the front and back sides of an N-type silicon substrate. A front voltage divider ring is located outside the front P-type short base region, and a back voltage divider ring is located outside the back P-type short base region. The forward off-state voltage is borne by the front P-type short base region and the front voltage divider ring, while the reverse off-state voltage is borne by the back P-type short base region and the back voltage divider ring. The voltages are completely symmetrical, eliminating the need for a punch-through structure and significantly improving production efficiency. The vertically symmetrical structure reduces the complexity of mask design and the adjustment requirements for photolithography and doping processes. It enables more uniform process parameter control during wafer fabrication, thereby improving production yield. Furthermore, the vertically symmetrical structure improves the balance of forward and reverse electrical performance parameters, reduces design complexity, and ensures high consistency between the positive and negative half-cycle trigger voltages and holding currents, guaranteeing the stability of bidirectional conduction in AC circuits. Attached Figure Description

[0015] Figure 1 This is a front view of the thyristor chip of this utility model;

[0016] Figure 2 This is a schematic diagram of the back of the thyristor chip of this utility model;

[0017] Figure 3 This is a schematic diagram of the AB cross-section of this utility model;

[0018] Figure 4 This is a schematic diagram of the forward and reverse off-state voltages of the thyristor according to this utility model;

[0019] In the figure: 1. N-type silicon substrate; 101. Front side of N-type silicon substrate; 102. Back side of N-type silicon substrate; 2. Front side P-type short base region; 3. Back side P-type short base region; 4. Front side voltage divider ring; 5. Back side voltage divider ring; 6. Front side N+ type emitter region; 7. Back side N+ type emitter region; 8. Front side N+ type cutoff ring; 9. Back side N+ type cutoff ring; 10. First cathode electrode; 11. Gate electrode; 12. Second cathode electrode; 13. Front side cathode short-circuit hole; 14. Back side cathode short-circuit hole; 15. Front side passivation layer; 16. Back side passivation layer. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0021] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0022] In the description of this patent, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integrated connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "several" means two or more, unless otherwise explicitly specified.

[0024] Example

[0025] Please see Figure 1-4As shown, this utility model provides a longitudinally symmetrical bidirectional thyristor technology solution: It includes an N-type silicon substrate 1 with a resistivity of 30~40 Ω·cm. The N-type silicon substrate 1 includes a front side 101 and a back side 102. A front P-type short base region 2 and a back P-type short base region 3 are symmetrically arranged on the front side 101 and the back side 102. The junction depth of the front P-type short base region 2 and the back P-type short base region 3 is 60-65 μm. A front voltage divider ring 4 is arranged outside the front P-type short base region 2. The front N+ type cutoff ring 8 is 10 μm away from the front voltage divider ring 4. A back voltage divider ring 5 is provided on the outer side of the back P-type short base region 3, with a distance of 0-120um between the back N+ type cutoff ring 7 and the back voltage divider ring 5. The front voltage divider ring 4 and the back voltage divider ring 5 are symmetrically arranged about the N-type silicon substrate 1 on the front side 101 and the back side 102 of the N-type silicon substrate. The junction depth of the front voltage divider ring 4 and the back voltage divider ring 5 is 60~65um. The forward off-state voltage is borne by the front P-type short base region 2 and the front voltage divider ring 4, and the reverse off-state voltage is borne by the back P-type short base region 3 and the back voltage divider ring 5. The voltage is completely symmetrical, and no through-structure is required, which can greatly improve production efficiency.

[0026] A front-side P-type short base region 2 is provided with a front-side N+ type emitter region 6, and a back-side P-type short base region 3 is provided with a back-side N+ type emitter region 7. The front-side N+ type emitter region 6 and the back-side N+ type emitter region 7 are centrally symmetrical about the N-type silicon substrate 1. A front-side N+ type cutoff ring 8 is provided on the front side 101 of the N-type silicon substrate outside the front-side voltage divider ring 4, and a back-side N+ type cutoff ring 9 is provided on the back side 102 of the N-type silicon substrate outside the back-side voltage divider ring 5. The potential barriers of the front-side N+ type cutoff ring 8 and the back-side N+ type cutoff ring 9 can limit the expansion of the electric field, limit carrier drift, and reduce high-temperature leakage. The vertically symmetrical structure reduces the complexity of mask design and the adjustment requirements of photolithography and doping processes. It enables more uniform process parameter control during wafer manufacturing, thereby improving production yield. In addition, the vertically symmetrical structure can improve the balance of forward and reverse electrical performance parameters, reduce design complexity, and ensure high consistency of positive and negative half-cycle trigger voltage and holding current. This ensures the stability of bidirectional conduction in AC circuits, avoids system collapse caused by unipolar failure, and improves overall reliability.

[0027] A first cathode electrode 10 and a gate electrode 11 are provided on the front P-type short base region 2, and a second cathode electrode 12 is provided on the back P-type short base region 3. The first cathode electrode 10 is provided with a front cathode short-circuit hole 13, and the second cathode electrode 12 is provided with a back cathode short-circuit hole 14. A front passivation layer 15 is provided on the front side 101 of the N-type silicon substrate, and a back passivation layer 16 is provided on the back side 102 of the N-type silicon substrate.

[0028] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model. The scope of protection of this utility model is defined by the appended claims and their equivalents.

Claims

1. A longitudinally symmetrical bidirectional thyristor, comprising an N-type silicon substrate (1), characterized in that: The N-type silicon substrate (1) includes an N-type silicon substrate front side (101) and an N-type silicon substrate back side (102). The N-type silicon substrate front side (101) and the N-type silicon substrate back side (102) are symmetrically provided with a front P-type short base region (2) and a back P-type short base region (3). A front voltage divider ring (4) is provided outside the front P-type short base region (2), and a back voltage divider ring (5) is provided outside the back P-type short base region (3). The front voltage divider ring (4) and the back voltage divider ring (5) are symmetrically provided about the N-type silicon substrate (1) on the front side (101) and the back side (102).

2. The longitudinally symmetrical bidirectional thyristor according to claim 1, characterized in that: The front P-type short base region (2) is provided with a front N+ type emitter region (6), and the back P-type short base region (3) is provided with a back N+ type emitter region (7). The front N+ type emitter region (6) and the back N+ type emitter region (7) are centrally symmetrical about the N-type silicon substrate (1).

3. The longitudinally symmetrical bidirectional thyristor according to claim 2, characterized in that: A front N+ type cutoff ring (8) is provided on the outside of the front voltage divider ring (4) on the front side (101) of the N-type silicon substrate, and a back N+ type cutoff ring (9) is provided on the outside of the back voltage divider ring (5) on the back side (102) of the N-type silicon substrate.

4. The longitudinally symmetrical bidirectional thyristor according to claim 1, characterized in that: The front P-type short base region (2) is provided with a first cathode electrode (10) and a gate electrode (11), and the back P-type short base region (3) is provided with a second cathode electrode (12). The first cathode electrode (10) is provided with a front cathode short-circuit hole (13), and the second cathode electrode (12) is provided with a back cathode short-circuit hole (14).

5. The longitudinally symmetrical bidirectional thyristor according to claim 1, characterized in that: The front side (101) of the N-type silicon substrate is provided with a front passivation layer (15), and the back side (102) of the N-type silicon substrate is provided with a back passivation layer (16).

6. The longitudinally symmetrical bidirectional thyristor according to claim 3, characterized in that: The junction depth of the front P-type short base region (2) and the back P-type short base region (3) is 60-65um. The distance between the front N+ type cutoff ring (8) and the front voltage divider ring (4) is 100-120um. The distance between the back N+ type cutoff ring (9) and the back voltage divider ring (5) is 100-120um.

7. The longitudinally symmetrical bidirectional thyristor according to claim 1, characterized in that: The front pressure dividing ring (4) and the back pressure dividing ring (5) have a junction depth of 60~65um.

Images