Bidirectional withstand voltage high voltage electrostatic protection device structure

Abstract

This invention discloses a bidirectional withstand voltage high-voltage electrostatic discharge (ESD) protection device structure comprising a ring-shaped high-voltage N-well and a P-type deep well. The P-type deep well is surrounded by the ring-shaped high-voltage N-well with a gap between them. The ring-shaped high-voltage N-well contains a first P-type diffusion region and a first N-type diffusion region, with the first N-type diffusion region close to the P-type deep well. Above the P-type deep well, a ring-shaped high-voltage P-well and a high-voltage N-well are formed, with the high-voltage N-well surrounded by the ring-shaped high-voltage P-well with a gap between them. A second P-type diffusion region is formed within the ring-shaped high-voltage P-well. The high-voltage N-well contains a second N-type diffusion region and a third P-type diffusion region, with the third P-type diffusion region located inside the second N-type diffusion region. The first P-type diffusion region and the first N-type diffusion region share a common lead-out port A, and the second N-type diffusion region and the third P-type diffusion region share a common lead-out port B. This invention allows for flexible changes to the grounding method and application voltage of Port A and Port B without affecting the ESD protection capability of the ESD protection device.

Description

Technical Field

[0001] This invention relates to the structural design of semiconductor devices, specifically to a bidirectional high-voltage electrostatic protection device structure. Background Technology

[0002] Static electricity is widespread in nature and can be generated in various ways, such as through contact, friction, and induction between electrical appliances. Frictional charging and static electricity from the human body are two major hazards in the electronics industry, often causing instability or even damage to electronic and electrical products.

[0003] As the feature size of semiconductor integrated circuit manufacturing processes shrinks, the size of chip cells also decreases, making the chip's anti-static capability increasingly important. Static electricity often causes permanent damage to semiconductor components and computer systems, thus affecting the circuit function of integrated circuits and causing electronic products to malfunction. Therefore, it is necessary to set up electrostatic protection structures to protect chips from damage caused by electrostatic discharge.

[0004] Electrostatic discharge (ESD) protection structures are typically placed between the input / output pads and ground. When static electricity occurs in the input / output pads, the ESD protection structure is triggered and discharges the static electricity, thereby protecting the internal circuitry.

[0005] Among electrostatic discharge (ESD) protection structures, the SCR (Silicon Controlled Rectifier) ​​boasts the highest performance-to-area ratio, offering advantages such as small size and high ESD protection. For example... Figure 1 The diagram shows a cross-sectional view of a common existing SCR structure. The grounding terminal is located in the P-well, and the electrostatic terminal is located in the N-well. The sides of the P-well and N-well are in contact. Both the N-well and P-well have N-type diffusion regions and P-type diffusion regions. There is a gap between the two diffusion regions in the same well. Figure 2 yes Figure 1 The equivalent circuit diagram.

[0006] The inherent disadvantage of the SCR structure is its low turn-back voltage. Especially in high-voltage applications, its turn-back voltage is generally much lower than VDD, which may cause the chip to burn out after being accidentally turned on during normal power-on. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a bidirectional high voltage electrostatic protection device structure that can avoid the accidental situation of chip burnout caused by low return voltage in existing high voltage electrostatic protection structures.

[0008] To address the above problems, the present invention provides a bidirectional high-voltage electrostatic protection device structure, wherein: The structure consists of a first annular high-voltage well of a first conductivity type and a deep well of a second conductivity type, wherein the deep well is surrounded by the first annular high-voltage well and a gap is left between them. The first annular high-voltage trap contains a first diffusion region of a first conductivity type and a second diffusion region of a second conductivity type, and the first diffusion region is close to the deep trap, and a field oxygen isolation is formed between the first diffusion region and the second diffusion region. A second annular high-voltage well of the second conductivity type and a third high-voltage well of the first conductivity type are formed above the deep well. The third high-voltage well is surrounded by the second annular high-voltage well and a gap is left between them. The second annular high-voltage trap contains a third diffusion region of a second conductivity type, and the third diffusion region is isolated from the first diffusion region in the first annular high-voltage trap by field oxygen isolation. The third high-pressure trap contains a fourth diffusion region of a first conductivity type and a fifth diffusion region of a second conductivity type. The fifth diffusion region is located within the fourth diffusion region and a field oxygen isolation is formed between them. The fourth diffusion region is also isolated from the third diffusion region in the second annular high-pressure trap.

[0009] Furthermore, the first and second diffusion regions within the first annular high-pressure trap are connected to Port A, and the fourth and fifth diffusion regions within the third high-pressure trap are connected to Port B.

[0010] Furthermore, Port A is a grounding terminal, and Port B is an electrostatic terminal.

[0011] Furthermore, Port B is a grounding terminal, and Port A is an electrostatic terminal.

[0012] Furthermore, the structure is an SCR structure that is entirely located above an N-type buried layer or an N-type silicon substrate.

[0013] Furthermore, the first conductivity type is N-type and the second conductivity type is P-type, or the first conductivity type is P-type and the second conductivity type is N-type.

[0014] The high-voltage electrostatic discharge (ESD) protection device structure of this invention allows for flexible changes to the grounding methods and application voltages of Port A and Port B without affecting the ESD protection capability. Simultaneously, the second annular high-voltage trap located between the first and third annular high-voltage traps within the deep trap serves as an isolation and withstand voltage, preventing direct penetration between the first and third annular high-voltage traps and the formation of a drain path. Attached Figure Description

[0015] Figure 1This is a cross-sectional schematic diagram of an existing SCR structure; Figure 2 The equivalent circuit of the existing SCR structure; Figure 3 This is a schematic diagram of the high-voltage electrostatic protection structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the AA cross-section of the high-voltage electrostatic protection structure according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the electrostatic current flow direction of the high-voltage electrostatic protection structure in an embodiment of the present invention when Port B is grounded and static electricity flows into Port A; Figure 6 for Figure 5 The equivalent circuit; Figure 7 This is a schematic diagram of the electrostatic current flow direction of the high-voltage electrostatic protection structure in an embodiment of the present invention when Port A is grounded and static electricity flows into Port B; Figure 8 for Figure 7 The equivalent circuit. Detailed Implementation

[0016] The embodiments of the present invention are described below with reference to the accompanying drawings and specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Specific details are set forth in the following description to provide a thorough understanding of the present invention; however, the present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be based on different viewpoints and applications. Those skilled in the art can make various similar extensions and substitutions without departing from the spirit of the present invention.

[0017] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element 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 application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0018] The semiconductor conductivity type in this application includes an opposite first conductivity type and a second conductivity type, that is, when the first conductivity type is N-type, the second conductivity type is P-type; when the first conductivity type is P-type, the second conductivity type is N-type.

[0019] Figure 3The diagram shows a top view of the high-voltage electrostatic protection device structure provided in the embodiments of this application. Figure 4 A schematic diagram of the AA cross-section of the high voltage electrostatic protection device structure provided in the embodiment of this application is shown.

[0020] The structure of the high-voltage electrostatic protection device in this application is described below, taking N-type as the first conductivity type and P-type as the second conductivity type as an example. (See figure) Figure 2 As shown, the bidirectional high voltage electrostatic protection device structure of this embodiment is an SCR structure located entirely above the N-type buried layer (NBL) 100, but it can also be located above the N-type silicon substrate.

[0021] like Figure 3 , Figure 4 As shown, the electrostatic discharge (ESD) protection device structure of this embodiment comprises an annular high-voltage N-well 101 and a P-type deep well 102. The P-type deep well 102 is surrounded by the annular high-voltage N-well 101, and a gap is left between the P-type deep well 102 and the annular high-voltage N-well 101. A first P-type diffusion region 201 and a first N-type diffusion region 202 are formed within the annular high-voltage N-well 101, with the first N-type diffusion region 202 close to the P-type deep well 102. An annular high-voltage P-well 103 and a high-voltage N-well 104 are formed above the P-type deep well 102, with the high-voltage N-well 104 surrounded by the annular high-voltage P-well 103, and a gap is left between the high-voltage N-well 104 and the annular high-voltage P-well 103. A second P-type diffusion region 203 is formed within the annular high-voltage P-well 103. The high-voltage N-well 104 contains a second N-type diffusion region 204 and a third P-type diffusion region 205, with the third P-type diffusion region 205 located inside the second N-type diffusion region 204.

[0022] like Figure 4 As shown, an oxygen field isolation is formed between the first P-type diffusion region 201 and the first N-type diffusion region 202, an oxygen field isolation is formed between the second P-type diffusion region 203 and the first N-type diffusion region 202 in the annular high-pressure N-well 101, an oxygen field isolation is formed between the second N-type diffusion region 204 and the third P-type diffusion region 205, and an oxygen field isolation is also formed between the second N-type diffusion region 204 and the second P-type diffusion region 203 in the annular high-pressure P-well 103.

[0023] like Figure 4 As shown, the first P-type diffusion region 201 and the first N-type diffusion region 202 in the annular high-pressure N-well 101 are connected to Port A, and the second N-type diffusion region 204 and the third P-type diffusion region 205 in the high-pressure N-well 104 are connected to Port B.

[0024] Figure 5 The diagram shows the current flow direction when Port B is the grounding terminal and Port A is the electrostatic terminal. Figure 6This is the equivalent circuit. When Port B is grounded, static electricity enters the high-voltage electrostatic protection device structure of this embodiment from Port A. First, it will cause the annular high-voltage N-well 101 (HVNW) below the high-voltage Port A to break down through the longitudinal junction of the N-type buried layer 100 and the P-type deep well 102 (Deep Pwell). This will trigger the opening of the parasitic N-type buried layer 100 / P-type deep well 102 / high-voltage N-well 104 NPN structure. When this NPN structure is turned on, the potential of the annular high-voltage N-well 101 (HVNW) below Port A will decrease, causing the diode formed by the first P-type diffusion region 201 in the annular high-voltage N-well 101 (HVNW) and the annular high-voltage N-well 101 (HVNW) to become forward biased. This triggers the PNP structure of the first P-type diffusion region 201 / annular high-voltage N-well 101 / P-type deep well 102 in the annular high-voltage N-well 101 (HVNW) to be turned on. Ultimately, this causes the PNPN silicon controlled ballast (SCR) of the first P-type diffusion region 201 / annular high-voltage N-well 101 / P-type deep well 102 / high-voltage N-well 104 to turn on and discharge the electrostatic current, which flows out from Port B.

[0025] Figure 7 The diagram shows the current flow direction with Port A as the ground terminal and Port B as the electrostatic terminal. Figure 8 This is the equivalent circuit. When Port A is grounded, static electricity enters the high-voltage electrostatic protection device structure of this embodiment from Port B. First, it causes the vertical junction formed by the high-voltage N-well 104 and the lower P-type deep well 102 to break down, thereby triggering the NPN structure of parasitic high-voltage N-well 104 / P-type deep well 102 / N-type buried layer 100 to turn on. After this NPN structure turns on, the potential of the high-voltage N-well 104 below Port B drops, causing the diode formed by the third P-type diffusion region 205 in the high-voltage N-well 104 and the high-voltage N-well 104 to become forward biased, triggering the PNP structure of the third P-type diffusion region 205 / high-voltage N-well 104 / P-type deep well 102 in the high-voltage N-well 104 to turn on, ultimately causing the silicon controlled ballast (SCR) of the third P-type diffusion region 205 / high-voltage N-well 104 / P-type deep well 102 / N-type buried layer 100 to turn on and discharge the static current, which flows out from Port A.

[0026] The annular high-voltage P-trap 103 is located inside the P-type deep trap 102 and between the annular high-voltage N-trap 101 and the high-voltage N-trap 104. It can play the role of isolation and withstand voltage, preventing the annular high-voltage N-trap 101 and the high-voltage N-trap 104 from directly penetrating and forming a leakage path.

[0027] The high-voltage electrostatic protection device structure in this embodiment can flexibly change the grounding method and application voltage of Port A and Port B without affecting the electrostatic protection capability of the device.

[0028] The present invention has been described in detail above through specific embodiments. These embodiments are merely preferred embodiments of the present invention, and the present invention is not limited to the above-described implementation methods. Equivalent substitutions and improvements made by those skilled in the art without departing from the principles of the present invention should be considered within the scope of the technology protected by the present invention.

Claims

1. A bidirectional withstand voltage high-voltage electrostatic protection device structure, characterized in that, The structure consists of a first annular high-voltage well of a first conductivity type and a deep well of a second conductivity type, wherein the deep well is surrounded by the first annular high-voltage well and a gap is left between them. The first annular high-voltage trap contains a first diffusion region of a first conductivity type and a second diffusion region of a second conductivity type, and the first diffusion region is close to the deep trap, and a field oxygen isolation is formed between the first diffusion region and the second diffusion region. A second annular high-voltage well of the second conductivity type and a third high-voltage well of the first conductivity type are formed above the deep well. The third high-voltage well is surrounded by the second annular high-voltage well and a gap is left between them. The second annular high-voltage trap contains a third diffusion region of a second conductivity type, and the third diffusion region is isolated from the first diffusion region in the first annular high-voltage trap by field oxygen isolation. The third high-pressure trap contains a fourth diffusion region of a first conductivity type and a fifth diffusion region of a second conductivity type. The fifth diffusion region is located within the fourth diffusion region and a field oxygen isolation is formed between them. The fourth diffusion region is also isolated from the third diffusion region in the second annular high-pressure trap.

2. The structure of the bidirectional withstand voltage high-voltage electrostatic protection device according to claim 1, characterized in that, The first and second diffusion regions within the first annular high-pressure trap are connected to Port A, and the fourth and fifth diffusion regions within the third high-pressure trap are connected to Port B.

3. The structure of the bidirectional withstand voltage high-voltage electrostatic protection device according to claim 2, characterized in that, Port A is the grounding terminal, and Port B is the electrostatic terminal.

4. The structure of the bidirectional withstand voltage high-voltage electrostatic protection device according to claim 2, characterized in that, Port B is the grounding terminal, and Port A is the electrostatic terminal.

5. The structure of the bidirectional withstand voltage high-voltage electrostatic protection device according to claim 1, characterized in that, The structure is an SCR structure that is entirely located above an N-type buried layer or an N-type silicon substrate.

6. The structure of the bidirectional withstand voltage high-voltage electrostatic protection device according to claim 1, characterized in that, The first conductivity type is N-type and the second conductivity type is P-type, or the first conductivity type is P-type and the second conductivity type is N-type.

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