SCR device layout structure with high maintaining voltage

Abstract

The utility model discloses a high-maintaining-voltage SCR (Selective Catalytic Reduction) device layout structure, which belongs to the technical field of electronic circuits and comprises a substrate. An N-type well region; the first N-type heavily doped region is longitudinally arranged in the N-type well region, and one side of the first N-type heavily doped region is connected with a first P-type heavily doped region; the third N-type heavily doped region is transversely arranged in the N-type well region, and the top or the bottom of the third N-type heavily doped region is connected with a third P-type heavily doped region; the P-type well region is adjacent to the N-type well region; the second N-type heavily doped region is longitudinally arranged in the P-type well region, and one side of the second N-type heavily doped region is connected with a second P-type heavily doped region; and the fourth N-type heavily doped region is transversely arranged in the P-type well region, and the top or the bottom of the fourth N-type heavily doped region is connected with a fourth P-type heavily doped region. Two SCR structures are formed on a substrate, the directions of electric fields generated by the two SCR structures have a certain angle when the two SCR structures work normally and bias, the current distribution of the SCR device after the SCR device is started is optimized, and the purpose of improving the maintaining voltage and the trigger current of the SCR device is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic circuits, is mainly used for electrostatic discharge protection, and particularly relates to a SCR device layout structure with a high maintenance voltage. Background Art

[0002] ESD (Electro Static Discharge), or ESD, is an ancient natural phenomenon. It exists in every corner of our daily lives. However, this commonplace electrical phenomenon can pose a fatal threat to sophisticated integrated circuits. Advances in integrated circuit manufacturing processes have reduced minimum line widths to submicron or even nanometer levels. While this has improved chip performance, it has also significantly reduced ESD resistance, making electrostatic damage more severe. ESD typically causes non-fatal damage to integrated circuits, reducing their lifespan and reliability, leading to degradation of system functionality. This significantly hinders the realization of large-scale, high-reliability integration.

[0003] The schematic diagram of the traditional silicon controlled thyristor (SCR) is shown in the following figure: Figure 1 As shown, due to its unique four-layer PNPN structure of P+, Nwell, Pwell, and N+, after an ESD transient voltage is triggered, the electron current and hole current generated by avalanche breakdown flow through the Nwell parasitic resistor and Pwell parasitic resistor, respectively, generating a voltage drop. When this voltage drop exceeds the forward conduction voltage of the parasitic PNP and NPN transistor emitter junctions, the strong positive feedback effect of the PNP and NPN transistors clamps the voltage across the device to a lower potential, dissipating the ESD current. Due to its extremely strong current robustness, SCRs have attracted much attention in the field of ESD protection devices.

[0004] However, the latch-up risk caused by the extremely low holding voltage (1-2V) of SCR devices limits their application in integrated circuits. How to improve the holding voltage of SCR devices has become a highly concerned issue in the design of ESD protection devices.

[0005] It should be noted that the information disclosed in the background technology section of this utility model is only intended to deepen the understanding of the general background technology of the utility model, and should not be regarded as an admission or in any form of implication that the information constitutes prior art already known to those skilled in the art. Utility Model Content

[0006] The purpose of the utility model is to provide a SCR device layout structure with a high holding voltage, so as to solve the problem of extremely low holding voltage of the SCR device.

[0007] In order to solve the above technical problems, the present invention provides a high holding voltage SCR device layout structure, comprising:

[0008] substrate;

[0009] An N-type well region is provided in the substrate;

[0010] a first N-type heavily doped region, longitudinally disposed in the N-type well region, wherein one side of the first N-type heavily doped region is connected to a first P-type heavily doped region;

[0011] a third N-type heavily doped region, disposed laterally in the N-type well region, wherein a top or bottom of the third N-type heavily doped region is connected to a third P-type heavily doped region;

[0012] A P-type well region, adjacent to the N-type well region;

[0013] a second N-type heavily doped region, longitudinally disposed in the P-type well region, wherein one side of the second N-type heavily doped region is connected to a second P-type heavily doped region;

[0014] A fourth N-type heavily doped region is laterally arranged in the P-type well region, and a top or a bottom of the fourth N-type heavily doped region is connected to a fourth P-type heavily doped region.

[0015] Preferably, the N-type well region has a first longitudinal segment and a first transverse segment that are opposite to each other, and ends of the first longitudinal segment and the first transverse segment are connected with a first preset angle therebetween.

[0016] Preferably, the N-type well region is L-shaped, and the first preset angle is 90 degrees.

[0017] Preferably, the P-type well region has a second longitudinal segment and a second transverse segment opposite to each other, and ends of the second longitudinal segment and the second transverse segment are connected with a second preset angle therebetween.

[0018] Preferably, the P-type well region is in an inverted L-shape, and the second preset angle is 90 degrees.

[0019] Preferably, the P-type well region and the N-type well region are assembled into a rectangle.

[0020] Preferably, the first N-type heavily doped region and the first P-type heavily doped region are short-circuited by metal and then led out as the anode terminal of the first SCR structure, and the second N-type heavily doped region and the second P-type heavily doped region are short-circuited by metal and then led out as the cathode terminal of the first SCR structure.

[0021] Preferably, the third N-type heavily doped region and the third P-type heavily doped region are short-circuited by metal and then led out as the anode terminal of the second SCR structure, and the fourth N-type heavily doped region and the fourth P-type heavily doped region are short-circuited by metal and then led out as the cathode terminal of the second SCR structure.

[0022] Preferably, a first diode is further included, wherein a cathode of the first diode is connected to an anode terminal of the first SCR structure via metal.

[0023] Preferably, a second diode is further included, wherein the cathode of the second diode is connected to the anode terminal of the second SCR structure through metal.

[0024] In the high holding voltage SCR device layout structure provided by the present invention, two SCR structures are formed on a substrate. When the two SCR structures are biased in normal operation, the directions of the electric fields generated by the two SCR structures have a certain angle, for example, the electric field directions are perpendicular to each other. When a high potential is induced at the anode terminal of either SCR structure due to an external ESD event, the N-type well region and the P-type well region breakdown to generate a large number of electron-hole pairs. However, some of these carriers are extracted by the electric field generated by the other SCR structure, thereby inhibiting the turn-on of the SCR structure. Moreover, the extraction of carriers by the other SCR structure weakens the large injection effect of the N-type well region and the P-type well region, thereby achieving the effect of increasing the trigger current and the holding voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Those skilled in the art will appreciate that the accompanying drawings are provided for a better understanding of the present invention and do not constitute any limitation on the scope of the present invention.

[0026] Figure 1 This is a schematic diagram of the traditional SCR device layout structure;

[0027] Figure 2 This is a schematic diagram of the layout structure of a high holding voltage SCR device according to an embodiment of the present invention;

[0028] Figure 3 This is a wiring diagram of a high holding voltage SCR device layout structure according to an embodiment of the present invention.

[0029] In the attached figure:

[0030] 11. Substrate; 21. N-type well region; 211. First longitudinal segment; 212. First transverse segment; 31. P-type well region; 311. Second longitudinal segment; 312. Second transverse segment; 41. First N-type heavily doped region; 42. Second N-type heavily doped region; 43. Third N-type heavily doped region; 44. Fourth N-type heavily doped region; 51. First P-type heavily doped region; 52. Second P-type heavily doped region; 53. Third P-type heavily doped region; 54. Fourth P-type heavily doped region; 61. First diode; 62. Second diode. DETAILED DESCRIPTION

[0031] To further clarify the objectives, advantages, and features of the present invention, the present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are highly simplified and not drawn to scale, and are intended solely to facilitate and clearly illustrate the objectives of the embodiments of the present invention. Furthermore, the structures shown in the drawings are often portions of the actual structures. In particular, different drawings may require different emphases and may use different scales.

[0032] As used in the present invention, the singular forms "a", "an" and "the" include plural objects, the term "or" is generally used in a sense including "and / or", the term "several" is generally used in a sense including "at least one", and the term "at least two" is generally used in a sense including "two or more". In addition, the terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", and "third" may explicitly or implicitly include one or at least two of such features. The term "proximal end" generally refers to the end closest to the operator, and the term "distal end" generally refers to the end closest to the patient. "One end" and "the other end" as well as "proximal end" and "distal end" generally refer to two corresponding parts, which include not only endpoints. The terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be internal communication between two elements or an interaction relationship between two elements. In addition, as used in the present invention, an element is generally provided on another element, which generally only means that there is a connection, coupling, cooperation or transmission relationship between the two elements, and the connection, coupling, cooperation or transmission between the two elements can be direct or indirect through an intermediate element, and it cannot be understood to indicate or imply a spatial positional relationship between the two elements, that is, one element can be in any position such as inside, outside, above, below, or to the side of another element, unless the content clearly indicates otherwise. For those skilled in the art, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

[0033] The inventors have found that the holding voltage of SCR devices is relatively low, and the latch-up risk thus exists, which limits their application in integrated circuits.

[0034] Based on this, the core idea of ​​the present invention is to propose a new SCR device layout structure to optimize the current distribution of the SCR device after it is turned on, so as to achieve the purpose of increasing the holding voltage and trigger current of the SCR device.

[0035] For details, please refer to Figure 2-Figure 3 , which is a schematic diagram of an embodiment of the present utility model. Figure 2 As shown, a high holding voltage SCR device layout structure includes:

[0036] substrate 11;

[0037] An N-type well region 21 is provided in the substrate 11;

[0038] A first N-type heavily doped region 41 is longitudinally disposed in the N-type well region 21 , wherein one side of the first N-type heavily doped region 41 is connected to a first P-type heavily doped region 51 ;

[0039] A third N-type heavily doped region 43 is laterally disposed in the N-type well region 21 , and a top or bottom of the third N-type heavily doped region 43 is connected to a third P-type heavily doped region 53 ;

[0040] A P-type well region 31 adjacent to the N-type well region 21;

[0041] A second N-type heavily doped region 42 is longitudinally disposed in the P-type well region 31 , and one side of the second N-type heavily doped region 42 is connected to a second P-type heavily doped region 52 ;

[0042] The fourth N-type heavily doped region 44 is laterally disposed in the P-type well region 31 . The top or bottom of the fourth N-type heavily doped region 44 is connected to the fourth P-type heavily doped region 54 .

[0043] Two SCR structures are formed on the substrate 11. The first SCR structure is formed by the N-type well region 21, the P-type well region 31, the first N-type heavily doped region 41, the second N-type heavily doped region 42, the first P-type heavily doped region 51, and the second P-type heavily doped region 52. The second SCR structure is formed by the N-type well region 21, the P-type well region 31, the third N-type heavily doped region 43, the fourth N-type heavily doped region 44, the third P-type heavily doped region 53, and the fourth P-type heavily doped region 54. The two SCR structures share the N-type well region 21 and the P-type well region 31. The two SCR structures are in the positive During normal operating bias, the direction of the generated electric field has a certain angle, for example, the electric field directions are perpendicular to each other. When a high potential is induced at the anode terminal of any SCR structure due to an external ESD event, the N-type well region 21 and the P-type well region 31 are broken down to generate a large number of electron-hole pairs. However, some of these carriers will be extracted by the electric field generated by the other SCR structure, thereby inhibiting the turn-on of the SCR structure. In addition, due to the extraction of carriers by the other SCR structure, the large injection effect of the N-type well region 21 and the P-type well region 31 is weakened, thereby achieving the effect of increasing the trigger current and the holding voltage.

[0044] In one embodiment, the substrate 11 is a P-type substrate. It is understandable that the above-mentioned layout structure is also applicable to various snapback ESD devices, such as NPN, N-type LDMOS, etc.

[0045] Among them, the longitudinal arrangement of the above-mentioned first N-type heavily doped region 41 and the second N-type heavily doped region 42 does not strictly mean that they are arranged in the vertical direction, and they can also be arranged at a certain angle to the vertical direction. Similarly, the transverse arrangement of the third N-type heavily doped region 43 and the fourth N-type heavily doped region 44 does not strictly mean that they are arranged in the vertical direction, and they can also be arranged at a certain angle to the horizontal direction, so that the electric field direction or current flow direction of the PN structure formed by the first N-type heavily doped region 41 and the first P-type heavily doped region 51 and the PN structure formed by the third N-type heavily doped region 43 and the third P-type heavily doped region 53 have a certain angle. The same is true for the PN structure in the P-type well region 31, and the electric field direction of the two PN structures formed in the P-type well region 31 can be parallel to the electric field direction of the PN structure in the N-type well region 21.

[0046] Illustratively, the N-type well region 21 has a first longitudinal segment 211 and a first transverse segment 212 that are opposite to each other, with the ends of the first longitudinal segment 211 and the first transverse segment 212 connected and a first preset angle therebetween. The P-type well region 31 has a second longitudinal segment 311 and a second transverse segment 312 that are opposite to each other, with the ends of the second longitudinal segment 311 and the second transverse segment 312 connected and a second preset angle therebetween.

[0047] More preferably, the N-type well region 21 is L-shaped, and the first preset angle is 90 degrees. The P-type well region 31 is inverted L-shaped, and the second preset angle is 90 degrees. Alternatively, the N-type well region 21 is inverted L-shaped, and the P-type well region 31 is L-shaped.

[0048] Specifically, the P-type well region 31 and the N-type well region 21 are assembled into a rectangle. Obviously, the transverse section and the longitudinal section between the N-type well region 21 and the P-type well region 31 are connected to each other. The first preset angle of the N-type well region 21 and the second preset angle of the P-type well region 31 can also be appropriately adjusted. For example, the first preset angle and the second preset angle are both 30 degrees, 45 degrees, or 60 degrees, so that the two are assembled into a parallelogram.

[0049] The L-shaped N-type well region 21 and the inverted L-shaped P-type well region 31 are located in the substrate 11 and are wrapped by the substrate 11. The two are adjacent to each other on the left and right. The N-type well region 21 is located on the left side of the P-type well region 31. The first N-type heavily doped region 41 and the first P-type heavily doped region 51 are located on the left side of the inside of the N-type well region 21. The two are adjacent to each other on the left and right. The first N-type heavily doped region 41 is located on the left side of the first P-type heavily doped region 51. The third N-type heavily doped region 43 and the third P-type heavily doped region 53 are adjacent to each other from top to bottom. Both are located on the right side of the inside of the N-type well region 21. On the lower side, the third N-type heavily doped region 43 is located on the lower side of the third P-type heavily doped region 53; the second N-type heavily doped region 42 and the second P-type heavily doped region 52 are located on the right side inside the P-type well region 31, and the two are adjacent to each other on the left and right. Specifically, the second N-type heavily doped region 42 is located on the left side of the second P-type heavily doped region 52; the fourth N-type heavily doped region 44 and the fourth P-type heavily doped region 54 are adjacent to each other from top to bottom, and both are located on the upper left side inside the P-type well region 31, and the fourth N-type heavily doped region 44 is located on the lower side of the fourth P-type heavily doped region 54.

[0050] Specifically, the first N-type heavily doped region 41 and the first P-type heavily doped region 51 are short-circuited by metal and then lead out to serve as the anode terminal of the first SCR structure. The second N-type heavily doped region 42 and the second P-type heavily doped region 52 are short-circuited by metal and then lead out to serve as the cathode terminal of the first SCR structure. The third N-type heavily doped region 43 and the third P-type heavily doped region 53 are short-circuited by metal and then lead out to serve as the anode terminal of the second SCR structure. The fourth N-type heavily doped region 44 and the fourth P-type heavily doped region 54 are short-circuited by metal and then lead out to serve as the cathode terminal of the second SCR structure.

[0051] like Figure 3 As shown, the first diode 61 is further included, the cathode of the first diode 61 is connected to the anode terminal of the first SCR structure through metal, and the second diode 62 is further included, the cathode of the second diode 62 is connected to the anode terminal of the second SCR structure through metal.

[0052] By introducing the first diode 61 and the second diode 62 , the voltage difference between the anode terminals of the two SCR structures caused by factors such as ESD events can be effectively blocked, thereby preventing current from being generated between the anode terminals of the two SCR structures.

[0053] The above description is only a description of the preferred embodiment of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of protection of the technical solution of the present invention.

Claims

1. A high holding voltage SCR device layout structure, characterized in that: include: substrate; An N-type well region is provided in the substrate; a first N-type heavily doped region, longitudinally disposed in the N-type well region, wherein one side of the first N-type heavily doped region is connected to a first P-type heavily doped region; a third N-type heavily doped region, disposed laterally in the N-type well region, wherein a top or bottom of the third N-type heavily doped region is connected to a third P-type heavily doped region; A P-type well region, adjacent to the N-type well region; a second N-type heavily doped region, longitudinally disposed in the P-type well region, wherein one side of the second N-type heavily doped region is connected to a second P-type heavily doped region; A fourth N-type heavily doped region is laterally arranged in the P-type well region, and a top or a bottom of the fourth N-type heavily doped region is connected to a fourth P-type heavily doped region.

2. The high holding voltage SCR device layout structure according to claim 1, characterized in that: The N-type well region has a first longitudinal section and a first transverse section that are opposite to each other. Ends of the first longitudinal section and the first transverse section are connected with each other and a first preset angle is formed therebetween.

3. The high holding voltage SCR device layout structure according to claim 2, characterized in that: The N-type well region is L-shaped, and the first preset angle is 90 degrees.

4. The high holding voltage SCR device layout structure according to claim 1, characterized in that: The P-type well region has a second longitudinal section and a second transverse section that are opposite to each other. Ends of the second longitudinal section and the second transverse section are connected with a second preset angle therebetween.

5. The high holding voltage SCR device layout structure according to claim 4, characterized in that: The P-type well region is in an inverted L-shape, and the second preset angle is 90 degrees.

6. The high holding voltage SCR device layout structure according to claim 3 or 5, characterized in that: The P-type well region and the N-type well region are assembled into a rectangle.

7. The high holding voltage SCR device layout structure according to claim 1, characterized in that: The first N-type heavily doped region and the first P-type heavily doped region are short-circuited by metal and then led out as the anode terminal of the first SCR structure. The second N-type heavily doped region and the second P-type heavily doped region are short-circuited by metal and then led out as the cathode terminal of the first SCR structure.

8. The high holding voltage SCR device layout structure according to claim 1, characterized in that: The third N-type heavily doped region and the third P-type heavily doped region are short-circuited by metal and then led out as the anode terminal of the second SCR structure. The fourth N-type heavily doped region and the fourth P-type heavily doped region are short-circuited by metal and then led out as the cathode terminal of the second SCR structure.

9. The high holding voltage SCR device layout structure according to claim 7, characterized in that: A first diode is also included, wherein a cathode of the first diode is connected to an anode terminal of the first SCR structure through metal.

10. The high holding voltage SCR device layout structure according to claim 8, characterized in that: A second diode is also included, wherein a cathode of the second diode is connected to an anode terminal of the second SCR structure through metal.

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