A bidirectional electrostatic protection device

Abstract

The application provides a bidirectional electrostatic protection device, which comprises a P-type substrate, an N-type well region, a first P-type well region, a second P-type well region, a first SN injection region, a second SN injection region, a first SP injection region, a second SP injection region, a first high injection energy high doping concentration P-type region, a second high injection energy high doping concentration P-type region, a first metal connecting line and a second metal connecting line. The high injection energy high doping concentration P-type region is introduced, a new current discharge path is embedded, the device realizes secondary hysteresis characteristics, the holding voltage is increased, the anti-latch-up performance is improved, the clamping voltage is reduced, the robustness is improved, and the bidirectional ESD protection requirement is met by adopting a completely symmetrical bidirectional structure design.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of semiconductor technology, and relates to a bidirectional electrostatic protection device. BACKGROUND

[0002] Electro-Static Discharge (ESD) is ubiquitous in the manufacturing, packaging, testing and use of chips, and accumulated static electricity is released in a current of several amperes or tens of amperes in nanoseconds to microseconds, with an instantaneous power of several or hundreds of watts, which is extremely destructive to chips in the circuit system. With the reduction of the process size of integrated circuits and the increase of the integration level, the ability of chips to resist ESD attacks is greatly reduced. According to statistics, more than 35% of chip failures are caused by ESD damage. Therefore, in the design of chips or systems, the design of the ESD protection module is directly related to the functional stability of the circuit system and the system reliability, and is extremely important for electronic products.

[0003] In the current research on ESD protection design, Silicon Controlled Rectifier (SCR) is the most commonly used one. The traditional SCR structure has a voltage snapback characteristic, has extremely strong current discharge capacity in unit area, and thus can achieve the smallest device area design under the same ESD resistance index, and is the most commonly used ESD protection device. However, this characteristic also makes the holding voltage (V h ) of the device low, and the latch-up effect occurs easily, resulting in the failure of the device to normally turn off. Therefore, improving the holding voltage of the SCR device to avoid the occurrence of latch-up is an important research direction. At the same time of improving the holding voltage, it is more meaningful to appropriately reduce the clamping voltage (V CL ) to improve the robustness of the device. In addition, for the protection of some Input / Output (I / O) ports, the device is also required to have bidirectional ESD protection capability SUMMARY

[0004] In view of the above problems, the present application proposes a bidirectional electrostatic protection device, which embeds a new current discharge path on the basis of the traditional SCR structure, realizes twice voltage snapback, and significantly improves the holding voltage of the device while reducing the clamping voltage.

[0005] To achieve the above-mentioned application purposes, the detailed technical solutions of the present application are as follows:

[0006] A bidirectional electrostatic protection device comprises: a P-type substrate 10, an N-type well region 20, a first P-type well region 31, a second P-type well region 32, a first SN implant region 41, a second SN implant region 42, a first SP implant region 51, a second SP implant region 52, a first high-energy high-doped P-type region 61, a second high-energy high-doped P-type region 62, a first metal connection line 71, and a second metal connection line 72.

[0007] The first P-type well region 31 is located on the left side of the P-type substrate 10, the second P-type well region 32 is located on the right side of the P-type substrate 10, and the N-type well region 20 is located in the middle of the P-type substrate 10 and is adjacent to the first P-type well region 31 and the second P-type well region 32 on the left and right sides, respectively. The first SP implant region 51 and the first SN implant region 41 are arranged from left to right on the top of the first P-type well region 31, and the two are adjacent and connected by the first metal connection line 71 as the anode or cathode of the device. The first high-energy high-doped P-type region 61 is located below the first SN implant region 41, and the upper boundary of the first high-energy high-doped P-type region 61 is adjacent to the lower boundary of the first SN implant region 41. The right boundary of the first high-energy high-doped P-type region 61 is aligned with the right boundary of the first SN implant region 41, and the left boundary of the first high-energy high-doped P-type region 61 is located to the right of the left boundary of the first SN implant region 41. The second SN implant region 42 and the second SP implant region 52 are arranged from left to right on the top of the second P-type well region 32, and the two are adjacent and connected by the second metal connection line 72 as the cathode or anode of the device. The second high-energy high-doped P-type region 62 is located below the second SN implant region 42, and the upper boundary of the second high-energy high-doped P-type region 62 is adjacent to the lower boundary of the second SN implant region 42. The left boundary of the second high-energy high-doped P-type region 62 is aligned with the left boundary of the second SN implant region 42, and the right boundary of the second high-energy high-doped P-type region 62 is located to the left of the right boundary of the second SN implant region 42.

[0008] As a preferred mode, a third SN implant region 43 is arranged above the N-type well region 20 and has the same width as the N-type well region 20.

[0009] As a preferred mode, a fourth SN implant region 44 and a fifth SN implant region 45 are arranged above the left and right boundaries of the N-type well region 20, respectively. The left boundary of the fourth SN implant region 44 is aligned with the left boundary of the N-type well region 20, and the right boundary of the fifth SN implant region 45 is aligned with the right boundary of the N-type well region 20.

[0010] As a preferred mode, the third SP injection region 53 is arranged at the right boundary above the first P-type well region 31, and the right boundary of the third SP injection region 53 is in boundary alignment with the first P-type well region 31; and the fourth SP injection region 54 is arranged at the left boundary above the second P-type well region 32, and the left boundary of the fourth SP injection region 54 is in alignment with the left boundary of the second P-type well region 32.

[0011] As a preferred mode, the doping type of the bidirectional electrostatic protection device structure is changed to the opposite doping type, that is, the P-type doping is changed to N-type doping, and the N-type doping is changed to P-type doping.

[0012] As a preferred mode, the high injection energy refers to a junction depth greater than that of the first SN injection region 41 and the second SN injection region 42 after injection.

[0013] As a preferred mode, the high doping concentration refers to a concentration at least two orders of magnitude higher than that of the first P-type well region 31 and the second P-type well region 32 and lower than that of the first SN injection region 41 and the second SN injection region 42.

[0014] The beneficial effects of the present application are:

[0015] (1) The present application introduces a high injection energy and high doping concentration P-type region, embeds a new current discharge path, and enables the device to achieve a secondary hysteresis characteristic, increase the holding voltage, improve the anti-latch-up performance, reduce the clamping voltage, and improve the robustness.

[0016] (2) The present application adopts a completely symmetrical structure design, which can meet the needs of bidirectional ESD protection and make the bidirectional electrical structure and characteristics completely consistent. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a cross-sectional view of a bidirectional SCR electrostatic protection device in the prior art;

[0018] Figure 2 is a bidirectional electrostatic protection device ESD design window provided by Embodiment 1 of the present application;

[0019] Figure 3 is a cross-sectional view of a bidirectional electrostatic protection device provided by Embodiment 1 of the present application;

[0020] Figure 4 is a bidirectional electrostatic protection device current discharge path schematic diagram provided by Embodiment 1 of the present application;

[0021] Figure 5 is an equivalent circuit diagram of a bidirectional electrostatic protection device provided by Embodiment 1 of the present application;

[0022] Figure 6 is a bidirectional electrostatic protection device and a conventional SCR and a conventional high holding voltage SCR test curve comparison diagram provided by Embodiment 1 of the present application;

[0023] Figure 7 A bidirectional electrostatic protection device cross-sectional view provided for Embodiment 2 of the present application;

[0024] Figure 8 A bidirectional electrostatic protection device cross-sectional view provided for Embodiment 3 of the present application;

[0025] Figure 9 A bidirectional electrostatic protection device cross-sectional view provided for Embodiment 4 of the present application;

[0026] In the figure, 10 is a P-type substrate, 20 is an N-type well region, 31 is a first P-type well region, 32 is a second P-type well region, 41 is a first SN implantation region, 42 is a second SN implantation region, 43 is a third SN implantation region, 44 is a fourth SN implantation region, 45 is a fifth SN implantation region, 51 is a first SP implantation region, 52 is a second SP implantation region, 53 is a third SP implantation region, 54 is a fourth SP implantation region, 61 is a first high implantation energy and high doping concentration P-type region, 62 is a second high implantation energy and high doping concentration P-type region, 71 is a metal connection line A, and 72 is a metal connection line B. DETAILED DESCRIPTION

[0027] The embodiments of the present application will be described in detail with specific examples. Other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of this specification. The present application can also be implemented or applied in other different embodiments, and various modifications or changes can be made to the details in this specification without departing from the spirit of the present application.

[0028] As described in the background, the related art uses a traditional bidirectional SCR structure as an electrostatic protection device, which has a low holding voltage and causes a latch-up problem. The inventor has found that the reason for this problem is that the base width of the parasitic PNP and NPN transistors in the SCR structure is narrow and the doping concentration is low, which easily causes a large injection effect and results in a high transistor amplification factor, thus a low holding voltage.

[0029] To solve the above technical problem, the present application provides a bidirectional electrostatic protection device, which has a design window as shown in Figure 2 On the basis of the traditional bidirectional SCR device, a high implantation energy and high doping concentration structure region is introduced to embed a new current discharge path, slow down the opening of the parasitic NPN transistor, suppress the positive feedback effect, and form two different current discharge paths in succession, which not only increases the holding voltage but also reduces the clamping voltage, and further improves the anti-latch-up capability and robustness of the SCR device.

[0030] Embodiment 1:

[0031] Example 1 provides a bidirectional electrostatic discharge protection device, such as Figure 3 As shown, it includes: a P-type substrate 10, an N-type well region 20, a first P-type well region 31, a second P-type well region 32, a first SN implantation region 41, a second SN implantation region 42, a first SP implantation region 51, a second SP implantation region 52, a first high implantation energy high doping concentration P-type region 61, a second high implantation energy high doping concentration P-type region 62, a first metal interconnect 71, and a second metal interconnect 72;

[0032] The first P-type well region 31 is located on the upper left side of the P-type substrate 10, the second P-type well region 32 is located on the upper right side of the P-type substrate 10, and the N-type well region 20 is located in the middle of the P-type substrate 10, with its left and right sides adjacent to the first P-type well region 31 and the second P-type well region 32, respectively. A first SP implantation region 51 and a first SN implantation region 41 are respectively provided above the first P-type well region 31 from left to right. These two regions are adjacent to each other and connected by a first metal connection line 71, serving as the anode or cathode of the device. A first high-injection-energy, high-doped-concentration P-type region 61 is located below the first SN implantation region 41, with its upper boundary adjacent to the lower boundary of the first SN implantation region 41, and its right boundary adjacent to the lower boundary of the first SN implantation region 41. The right boundary of the first high-injection-energy, high-doped-concentration P-type region 61 is aligned, and the left boundary of the first high-injection-energy, high-doped-concentration P-type region 61 is located to the right of the left boundary of the first SN injection region 41. The second SN injection region 42 and the second SP injection region 52 are respectively provided from left to right above the second P-type well region 32. The two are adjacent to each other and connected by the second metal connection line 72 as the cathode or anode of the device. The second high-injection-energy, high-doped-concentration P-type region 62 is located below the second SN injection region 42, and the upper boundary of the second high-injection-energy, high-doped-concentration P-type region 62 is adjacent to the lower boundary of the second SN injection region 42. The left boundary of the second high-injection-energy, high-doped-concentration P-type region 62 is aligned with the left boundary of the second SN injection region 42, and the right boundary of the second high-injection-energy, high-doped-concentration P-type region 62 is located to the left of the right boundary of the second SN injection region 42.

[0033] Furthermore, in the structure of the bidirectional electrostatic protection device, the doping types are correspondingly reversed, that is, P-type doping becomes N-type doping while N-type doping becomes P-type doping.

[0034] Specifically, high injection energy refers to a junction depth after injection that is greater than the junction depth of the first SN injection region 41 and the second SN injection region 42.

[0035] Specifically, a high doping concentration refers to a concentration that is at least two orders of magnitude higher than that of the first P-type well region 31 and the second P-type well region 32, but lower than that of the first SN injection region 41 and the second SN injection region 42.

[0036] Its working principle is as follows Figure 4 As shown, with the help ofFigure 5 Equivalent circuit diagram analysis, taking metal connection line A71 as the anode with applied voltage and metal connection line B72 as the cathode grounded as an example, when the PN junction formed by the N-type well region 20 and the second P-type well region 32 undergoes avalanche breakdown, the parasitic PNP transistor conducts, and current flows to the second P-type well region 32, generating a voltage drop across the well region resistance. The voltage drop across the Zener diode formed by the second high-energy, high-doped P-type region 62 and the second SN-implanted region 42 is equal to the voltage drop across the entire well region resistance, while the voltage drop across the parasitic NPN emitter junction is equal to the voltage drop across a portion of the well region resistance. Therefore, the Zener diode conducts only partially, forming the first current discharge path, and the curve exhibits a first hysteresis. Because the original SCR path is suppressed, a higher sustaining voltage than the traditional SCR structure is obtained. As the voltage increases, when the current increases to the point where the voltage drop across a portion of the well region resistance is sufficient to turn on the parasitic NPN transistor, the original SCR current discharge path turns on, and the curve exhibits a second hysteresis, achieving a lower clamping voltage than traditional high sustaining voltage devices. Figure 6 The device test curves are shown, clearly demonstrating the electrical performance of the proposed electrostatic discharge protection device, indicating that the device has anti-latch-up capability and higher robustness.

[0037] Example 2:

[0038] like Figure 7 As shown, the difference between the device structure of this embodiment and that of embodiment 1 is that a third SN injection region 43 of the same width is provided above the N-type well region 20.

[0039] The working principle of this embodiment is largely the same as that of Embodiment 1, except that when a voltage is applied with metal connection line A71 as the anode and metal connection line B72 as the cathode grounded, the breakdown condition of the device changes to avalanche breakdown of the PN junction formed by the third SN injection region 43 and the second P-type well region 32 because the doping concentration of the third SN injection region 43 is greater than that of the N-type well region 20. Similarly, when a voltage is applied with metal connection line B72 as the anode and metal connection line A71 as the cathode grounded, the breakdown condition of the device changes to avalanche breakdown of the PN junction formed by the third SN injection region 43 and the first P-type well region 31 because the doping concentration of the third SN injection region 43 is greater than that of the N-type well region 20. This results in a relatively low trigger voltage.

[0040] Example 3:

[0041] like Figure 8 As shown, the difference between the device structure of this embodiment and that of Embodiment 1 is that a fourth SN injection region 44 and a fifth SN injection region 45 are respectively provided on the left and right boundaries above the N-type well region 20. The left boundary of the fourth SN injection region 44 is aligned with the left boundary of the N-type well region 20, and the right boundary of the fifth SN injection region 45 is aligned with the right boundary of the N-type well region 20.

[0042] The working principle of this embodiment is basically the same as that of Embodiment 1, except that when a voltage is applied with the metal connecting wire A71 as an anode and the metal connecting wire B72 as a cathode ground, since the doping concentration of the fifth SN injection region 45 is greater than that of the N-type well region 20, the breakdown condition of the device becomes that the PN junction formed by the fifth SN injection region 45 and the second P-type well region 32 occurs avalanche breakdown. Similarly, when a voltage is applied with the metal connecting wire B72 as an anode and the metal connecting wire A71 as a cathode ground, since the doping concentration of the fourth SN injection region 44 is greater than that of the N-type well region 20, the breakdown condition of the device becomes that the PN junction formed by the fourth SN injection region 44 and the second P-type well region 32 occurs avalanche breakdown, so that a relatively low trigger voltage is obtained.

[0043] Embodiment 4:

[0044] As shown in FIG. 5, the device structure of this embodiment is different from that of Embodiment 3 in that a third SP injection region 53 is arranged at the right boundary above the first P-type well region 31, and the right boundary of the third SP injection region 53 is aligned with the boundary of the first P-type well region 31; and a fourth SP injection region 54 is arranged at the left boundary above the second P-type well region 32, and the left boundary of the fourth SP injection region 54 is aligned with the left boundary of the second P-type well region 32. Figure 9 The working principle of this embodiment is basically the same as that of Embodiment 3, except that when a voltage is applied with the metal connecting wire A71 as an anode and the metal connecting wire B72 as a cathode ground, since the doping concentration of the fourth SP injection region 54 is greater than that of the second P-type well region 32, the breakdown condition of the device becomes that the PN junction formed by the fifth SN injection region 45 and the fourth SP injection region 54 occurs avalanche breakdown, so that a lower trigger voltage is further obtained. Similarly, when a voltage is applied with the metal connecting wire B72 as an anode and the metal connecting wire A71 as a cathode ground, since the doping concentration of the third SP injection region 53 is greater than that of the first P-type well region 31, the breakdown condition of the device becomes that the PN junction formed by the fourth SN injection region 44 and the third SP injection region 53 occurs avalanche breakdown, so that a lower trigger voltage is further obtained.

[0045] In summary, the present application proposes a bidirectional electrostatic protection device. On the basis of a traditional SCR structure, a high injection energy and high doping concentration P-type region is introduced to embed a new current discharge path, so that the device realizes a secondary hysteresis characteristic, increases the holding voltage, improves the anti-latch-up performance, reduces the clamping voltage, and improves the robustness. Furthermore, the trigger voltage characteristics of the device are further designed through embodiments, so that the application is applied in a wider field.

[0046]

[0047] ​The above examples only illustrate the principles of the present application and its efficacy, and are not intended to limit the application. Any modification or change on the above examples made by any person skilled in the art, without departing from the spirit and scope of the present application, shall be covered by the claims of the present application.

Claims

1. A bidirectional electrostatic protection device, characterized in that Comprise: P-type substrate (10), N-type well region (20), first P-type well region (31), second P-type well region (32), first SN injection region (41), second SN injection region (42), first SP injection region (51), second SP injection region (52), first high injection energy high doping concentration P-type region (61), second high injection energy high doping concentration P-type region (62), first metal connecting line (71), second metal connecting line (72); Wherein, the first P-type well region (31) is located in the left region above the P-type substrate (10), the second P-type well region (32) is located in the right region above the P-type substrate (10), and the N-type well region (20) is located in the middle of the P-type substrate (10) and is adjacent to the first P-type well region (31) and the second P-type well region (32) on the left and right sides respectively; the first SP injection region (51) and the first SN injection region (41) are provided from left to right above the first P-type well region (31) respectively, and the two are adjacent and connected by the first metal connecting line (71) as anode or cathode of the device, the first high injection energy high doping concentration P-type region (61) is located below the first SN injection region (41) and the upper boundary of the first high injection energy high doping concentration P-type region (61) is adjacent to the lower boundary of the first SN injection region (41), the right boundary of the first high injection energy high doping concentration P-type region (61) is aligned with the right boundary of the first SN injection region (41), and the left boundary of the first high injection energy high doping concentration P-type region (61) is located to the right of the left boundary of the first SN injection region (41); the second SN injection region (42) and the second SP injection region (52) are provided from left to right above the second P-type well region (32) respectively, and the two are adjacent and connected by the second metal connecting line (72) as cathode or anode of the device, the second high injection energy high doping concentration P-type region (62) is located below the second SN injection region (42) and the upper boundary of the second high injection energy high doping concentration P-type region (62) is adjacent to the lower boundary of the second SN injection region (42), the left boundary of the second high injection energy high doping concentration P-type region (62) is aligned with the left boundary of the second SN injection region (42), and the right boundary of the second high injection energy high doping concentration P-type region (62) is located to the left of the right boundary of the second SN injection region (42).

2. The bidirectional electrostatic protection device of claim 1, wherein: The third SN injection region (43) with the same width as the N-type well region (20) is provided above the N-type well region (20).

3. The bidirectional electrostatic protection device of claim 1, wherein: The fourth SN injection region (44) and the fifth SN injection region (45) are provided above the N-type well region (20) on the left and right boundaries respectively, the left boundary of the fourth SN injection region (44) is aligned with the left boundary of the N-type well region (20), and the right boundary of the fifth SN injection region (45) is aligned with the right boundary of the N-type well region (20).

4. The bidirectional electrostatic protection device of claim 3, wherein: The third SP injection region (53) is provided above the right boundary of the first P-type well region (31), and the right boundary of the third SP injection region (53) is aligned with the right boundary of the first P-type well region (31); the fourth SP injection region (54) is provided above the left boundary of the second P-type well region (32), and the left boundary of the fourth SP injection region (54) is aligned with the left boundary of the second P-type well region (32).

5. The bidirectional electrostatic protection device of claim 1 or 2 or 3, wherein: The doping type of the bidirectional electrostatic protection device structure is changed to the opposite doping, that is, the P-type doping is changed to N-type doping, and the N-type doping is changed to P-type doping.

6. The bidirectional electrostatic protection device of claim 1 or 2 or 3, wherein: The high implantation energy refers to a junction depth after implantation that is greater than the junction depths of the first SN implantation region (41) and the second SN implantation region (42).

7. The bidirectional electrostatic protection device of claim 1 or 2 or 3, wherein: The high doping concentration refers to a concentration that is at least two orders of magnitude higher than the first P-type well region (31) and the second P-type well region (32) and lower than the first SN implantation region (41) and the second SN implantation region (42).

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