SCR device layout structure with high maintaining voltage
By designing two SCR structures with mutually perpendicular electric field directions in the SCR device layout, the problem of low sustaining voltage of SCR devices is solved, trigger current and sustaining voltage are improved, latch-up risk is reduced, and application in integrated circuits is enhanced.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JIEFANG SEMICON (SHANGHAI) CO LTD
- Filing Date
- 2024-10-28
- Publication Date
- 2026-05-01
AI Technical Summary
The low sustaining voltage of SCR devices leads to latch-up risk, limiting their application in integrated circuits.
Design a high sustaining voltage SCR device layout structure by forming two SCR structures on the substrate, making their electric field directions perpendicular to each other when they are under normal operating bias, and using another SCR structure to extract carriers to suppress turn-on, thereby weakening the large injection effect of the N-type well region and the P-type well region.
This improves the trigger current and sustaining voltage of SCR devices, reduces latch-up risk, and enhances their application capabilities in integrated circuits.
Smart Images
Figure CN121968720A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic circuit technology, mainly for electrostatic discharge protection, and particularly to a layout structure of an SCR device with high sustaining voltage. Background Technology
[0002] ESD (Electro Static Discharge) is an ancient natural phenomenon. ESD is present in every aspect of daily life. However, this seemingly commonplace electrical phenomenon poses a fatal threat to delicate integrated circuits. With advancements in integrated circuit manufacturing processes, the minimum linewidth has decreased to the sub-micron or even nanometer level. While this has led to improved chip performance, it has also significantly reduced the chip's resistance to ESD, making electrostatic damage more severe. Most ESD incidents cause non-fatal damage to integrated circuits, reducing their lifespan and reliability, and ultimately leading to system functional degradation. This poses a significant obstacle to achieving large-scale, highly reliable integration.
[0003] A schematic diagram of the layout structure of a traditional silicon controlled thyristor (SCR) is shown below. Figure 1 As shown, due to its unique four-layer PNPN structure (P+, Nwell, Pwell, N+), after an ESD transient voltage trigger, the electron and hole currents generated by avalanche breakdown flow through the parasitic resistances of Nwell and Pwell, respectively, producing a voltage drop. When this voltage drop exceeds the forward conduction voltage of the emitter junctions of the parasitic PNP and NPN transistors, the strong positive feedback effect of the PNP and NPN transistors clamps the voltage across the device to a lower potential, discharging the ESD current. Due to its extremely strong current robustness, SCR has attracted much attention in the field of ESD protection devices.
[0004] However, the extremely low sustaining voltage (1-2V) of SCR devices introduces a latch-up risk that limits their application in integrated circuits. Improving the sustaining voltage of SCR devices has become a significant concern in ESD protection device design.
[0005] It should be noted that the information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention
[0006] The purpose of this invention is to provide an SCR device layout structure with high sustaining voltage to solve the problem of extremely low sustaining voltage in SCR devices.
[0007] To address the aforementioned technical problems, this invention provides a high sustaining voltage SCR device layout structure, comprising:
[0008] Substrate;
[0009] An N-type well region is disposed in the substrate;
[0010] A first N-type heavily doped region is vertically disposed in the N-type well region, and a first P-type heavily doped region is connected to one side of the first N-type heavily doped region.
[0011] The third N-type heavily doped region is laterally disposed in the N-type well region, and the top or bottom of the third N-type heavily doped region is connected to the third P-type heavily doped region.
[0012] The P-type well region is adjacent to the N-type well region;
[0013] A second N-type heavily doped region is vertically disposed in the P-type well region, and a second P-type heavily doped region is connected to one side of the second N-type heavily doped region.
[0014] The fourth N-type heavily doped region is laterally disposed in the P-type well region, and the top or bottom of the fourth N-type heavily doped region is connected to the fourth P-type heavily doped region.
[0015] Preferably, the N-type well region has a first longitudinal segment and a first transverse segment, the ends of the first longitudinal segment and the first transverse segment are connected and there is a first preset angle between them.
[0016] Preferably, the N-type trap region is L-shaped, and the first preset angle is 90 degrees.
[0017] Preferably, the P-shaped well region has a second longitudinal segment and a second transverse segment, the ends of which are connected and there is a second preset angle between them.
[0018] Preferably, the P-type trap region is inverted L-shaped, and the second preset angle is 90 degrees.
[0019] Preferably, the P-type well region and the N-type well region are combined to form a rectangle.
[0020] Preferably, the first N-type heavily doped region and the first P-type heavily doped region are shorted by a metal and brought out as the anode of the first SCR structure, and the second N-type heavily doped region and the second P-type heavily doped region are shorted by a metal and brought out as the cathode of the first SCR structure.
[0021] Preferably, the third N-type heavily doped region and the third P-type heavily doped region are shorted by a metal and brought out as the anode of the second SCR structure, and the fourth N-type heavily doped region and the fourth P-type heavily doped region are shorted by a metal and brought out as the cathode of the second SCR structure.
[0022] Preferably, it further includes a first diode, the cathode of which is connected to the anode of the first SCR structure via a metal.
[0023] Preferably, it further includes a second diode, the cathode of which is connected to the anode of the second SCR structure via a metal.
[0024] In the high sustaining voltage SCR device layout structure provided by this invention, two SCR structures are formed on the substrate. When the two SCR structures are under normal operating bias, the electric field directions generated by them have a certain angle, for example, the electric field directions are perpendicular to each other. When either SCR structure generates a high potential at its anode due to an external ESD event, the N-type well region and P-type well region break down and generate a large number of electron-hole pairs. However, some of the charge carriers are drawn away by the electric field generated by the other SCR structure, thereby suppressing the turn-on of the SCR structure. Furthermore, due to the extraction of charge carriers by the other SCR structure, the large injection effect of the N-type well region and P-type well region is weakened, thereby achieving the effect of improving the trigger current and sustaining voltage. Attached Figure Description
[0025] Those skilled in the art will understand that the accompanying drawings are provided to better understand the invention and do not constitute any limitation on the scope of the invention. Wherein:
[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 an SCR device with high sustaining voltage according to an embodiment of the present invention;
[0028] Figure 3 This is a wiring diagram of the layout structure of a high sustaining voltage SCR device according to an embodiment of the present invention.
[0029] In the attached image:
[0030] 11. Substrate; 21. N-type well region; 211. First vertical segment; 212. First horizontal segment; 31. P-type well region; 311. Second vertical segment; 312. Second horizontal segment; 41. First heavily doped N-type region; 42. Second heavily doped N-type region; 43. Third heavily doped N-type region; 44. Fourth heavily doped N-type region; 51. First heavily doped P-type region; 52. Second heavily doped P-type region; 53. Third heavily doped P-type region; 54. Fourth heavily doped P-type region; 61. First diode; 62. Second diode. Detailed Implementation
[0031] To make the objectives, advantages, and features of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, and are only used to facilitate and clarify the explanation of the embodiments of this invention. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and may sometimes use different scales.
[0032] As used in this invention, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; the term “at least two” is generally used to mean “two or more”; furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, features defined with "first," "second," and "third" may explicitly or implicitly include one or at least two of those features. The term "proximal" typically refers to the end closer to the operator, and the term "distal" typically refers to the end closer to the patient. "One end" and "the other end," as well as "proximal" and "distal," generally refer to two corresponding parts, including not only endpoints. The terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections or electrical connections; they can be direct connections or indirect connections through an intermediate medium; they can be internal connections between two elements or interactions between two elements. Furthermore, as used in this invention, the placement of one element on another element generally only indicates 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. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of another element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.
[0033] The inventors discovered that the SCR device has a low sustaining voltage, and the resulting latch-up risk limits its application in integrated circuits.
[0034] Based on this, the core idea of this invention is to propose a novel SCR device layout structure and optimize the current distribution of the SCR device after it is turned on, thereby improving the SCR device's holding voltage and trigger current.
[0035] For details, please refer to Figures 2-3This is a schematic diagram of an embodiment of the present invention. Figure 2 As shown, a layout structure for a high sustaining voltage SCR device includes:
[0036] Substrate 11;
[0037] An N-type well region 21 is disposed in the substrate 11;
[0038] A first N-type heavily doped region 41 is longitudinally disposed in the N-type well region 21, and a first P-type heavily doped region 51 is connected to one side of the first N-type heavily doped region 41.
[0039] The third N-type heavily doped region 43 is laterally disposed in the N-type well region 21, and the top or bottom of the third N-type heavily doped region 43 is connected to the third P-type heavily doped region 53.
[0040] P-type well region 31 is adjacent to N-type well region 21;
[0041] The second N-type heavily doped region 42 is longitudinally disposed in the P-type well region 31, and a second P-type heavily doped region 52 is connected to one side of the second N-type heavily doped region 42.
[0042] A fourth N-type heavily doped region 44 is laterally disposed in the P-type well region 31, and a fourth P-type heavily doped region 54 is connected to the top or bottom of the fourth N-type heavily doped region 44.
[0043] Two SCR structures are formed on substrate 11. The first SCR structure is formed by an N-type well region 21, a P-type well region 31, a first heavily doped N-type region 41, a second heavily doped N-type region 42, a first heavily doped P-type region 51, and a second heavily doped P-type region 52. The second SCR structure is formed by an N-type well region 21, a P-type well region 31, a third heavily doped N-type region 43, a fourth heavily doped N-type region 44, a third heavily doped P-type region 53, and a fourth heavily doped P-type 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... When the operating bias voltage is normal, the direction of the generated electric field has a certain angle, for example, the electric field directions are perpendicular to each other. When any SCR structure generates a high potential at the anode due to an external ESD event, the N-type well region 21 and the P-type well region 31 break down and generate a large number of electron-hole pairs. However, some of the charge carriers will be drawn away by the electric field generated by the other SCR structure, thereby suppressing the turn-on of the SCR structure. Furthermore, due to the extraction of charge 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 maintaining the voltage.
[0044] In one embodiment, substrate 11 is a P-type substrate. It is understood that the above layout structure is also applicable to various hysteresis ESD devices, such as NPN, N-type LDMOS, etc.
[0045] The longitudinal arrangement of the 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; 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; they can also be arranged at a certain angle to the horizontal direction. As long as there is a certain angle between 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, the same applies to the PN structure in the P-type well region 31. 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] For example, the N-type well region 21 has a first longitudinal segment 211 and a first transverse segment 212, the ends of which are connected and have a first preset angle between them. The P-type well region 31 has a second longitudinal segment 311 and a second transverse segment 312, the ends of which are connected and have a second preset angle between them.
[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 combined to form a rectangle. Obviously, the horizontal and vertical segments between the N-type well region 21 and the P-type well region 31 are interconnected. 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 combined to form a parallelogram.
[0049] The L-shaped N-type well region 21 and the inverted L-shaped P-type well region 31 are located in and enclosed by the substrate 11, and are adjacent to each other on the left and right sides. The N-type well region 21 is located to the left of the P-type well region 31. The first heavily doped N-type region 41 and the first heavily doped P-type region 51 are located inside the N-type well region 21 on the left side, and are adjacent to each other on the left and right sides. The first heavily doped N-type region 41 is located to the left of the first heavily doped P-type region 51. The third heavily doped N-type region 43 and the third heavily doped P-type region 53 are adjacent vertically, and are both located inside the N-type well region 21 on the right side. On the lower side, the third N-type heavily doped region 43 is located below 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 inside the P-type well region 31 on the right side, and the two are adjacent to each other on the left and right sides. Specifically, the second N-type heavily doped region 42 is located to the left 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 on the upper left side inside the P-type well region 31, and the fourth N-type heavily doped region 44 is located below 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 shorted by a metal connection and brought out as the anode of the first SCR structure. The second N-type heavily doped region 42 and the second P-type heavily doped region 52 are shorted by a metal connection and brought out as the cathode of the first SCR structure. The third N-type heavily doped region 43 and the third P-type heavily doped region 53 are shorted by a metal connection and brought out as the anode of the second SCR structure. The fourth N-type heavily doped region 44 and the fourth P-type heavily doped region 54 are shorted by a metal connection and brought out as the cathode of the second SCR structure.
[0051] like Figure 3 As shown, it also includes a first diode 61, the cathode of which is connected to the anode of the first SCR structure via a metal connection. It also includes a second diode 62, the cathode of which is connected to the anode of the second SCR structure via a metal connection.
[0052] By introducing the first diode 61 and the second diode 62, the voltage difference between the anodes of the two SCR structures caused by ESD events and other factors can be effectively blocked, thus preventing current from flowing between the anodes of the two SCR structures.
[0053] The above description is only a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the present invention.
Claims
1. A layout structure for an SCR device with high sustaining voltage, characterized in that, include: Substrate; An N-type well region is disposed in the substrate; A first N-type heavily doped region is vertically disposed in the N-type well region, and a first P-type heavily doped region is connected to one side of the first N-type heavily doped region. The third N-type heavily doped region is laterally disposed in the N-type well region, and the top or bottom of the third N-type heavily doped region is connected to the third P-type heavily doped region. The P-type well region is adjacent to the N-type well region; A second N-type heavily doped region is vertically disposed in the P-type well region, and a second P-type heavily doped region is connected to one side of the second N-type heavily doped region. The fourth N-type heavily doped region is laterally disposed in the P-type well region, and the top or bottom of the fourth N-type heavily doped region is connected to the fourth P-type heavily doped region.
2. The SCR device layout structure with high sustaining voltage according to claim 1, characterized in that, The N-type well region has a first longitudinal segment and a first transverse segment, the ends of which are connected and there is a first preset angle between them.
3. The SCR device layout structure with high sustaining voltage according to claim 2, characterized in that, The N-type trap region is L-shaped, and the first preset angle is 90 degrees.
4. The SCR device layout structure with high sustaining voltage according to claim 1, characterized in that, The P-type well region has a second longitudinal segment and a second transverse segment, the ends of which are connected and there is a second preset angle between them.
5. The SCR device layout structure with high sustaining voltage according to claim 4, characterized in that, The P-type trap region is inverted L-shaped, and the second preset angle is 90 degrees.
6. The SCR device layout structure with high sustaining voltage according to claim 3 or 5, characterized in that, The P-type well region and the N-type well region are combined to form a rectangle.
7. The SCR device layout structure with high sustaining voltage according to claim 1, characterized in that, The first N-type heavily doped region and the first P-type heavily doped region are shorted by a metal and brought out as the anode of the first SCR structure, and the second N-type heavily doped region and the second P-type heavily doped region are shorted by a metal and brought out as the cathode of the first SCR structure.
8. The SCR device layout structure with high sustaining voltage according to claim 1, characterized in that, The third N-type heavily doped region and the third P-type heavily doped region are shorted by a metal and brought out as the anode of the second SCR structure, and the fourth N-type heavily doped region and the fourth P-type heavily doped region are shorted by a metal and brought out as the cathode of the second SCR structure.
9. The SCR device layout structure with high sustaining voltage according to claim 7, characterized in that, It also includes a first diode, the cathode of which is connected to the anode of the first SCR structure via a metal.
10. The SCR device layout structure with high sustaining voltage according to claim 8, characterized in that, It also includes a second diode, the cathode of which is connected to the anode of the second SCR structure via a metal.