CN112928112A

CN112928112A - Low-trigger high-maintenance bidirectional SCR (selective catalytic reduction) protection device and process method thereof

Info

Publication number: CN112928112A
Application number: CN202110113617.4A
Authority: CN
Inventors: 杜明; 裴国旭; 李会羽; 董小雨
Original assignee: Shenzhen State Micro Electronics Co Ltd
Current assignee: Shenzhen State Micro Electronics Co Ltd
Priority date: 2021-01-27
Filing date: 2021-01-27
Publication date: 2021-06-08
Anticipated expiration: 2041-01-27
Also published as: CN112928112B

Abstract

The invention provides a low-trigger high-maintenance bidirectional SCR (selective catalytic reduction) protection device and a process method thereof, wherein the device comprises: the semiconductor device comprises a substrate, a first well and a first buried layer, wherein the first well and the first buried layer are formed in the substrate from outside to inside; a first deep well formed on the first buried layer; sequentially forming a second well, a third well, a fourth well and a fifth well on the first deep trap from outside to inside; first and second body regions formed in the third and fifth wells, respectively; a first active region formed in the first well; a second active region and a third active region formed from outside to inside in the third well; a fourth active region formed in the first body region; a fifth active region and a sixth active region respectively formed at the junction of the third well and the fourth well and at the junction of the fourth well and the fifth well; a seventh active region formed in the fifth well; and an eighth active region formed in the second body region. The SCR device provided by the invention can ensure that the port normally works under positive and negative pressure to realize HBM ESD protection capability.

Description

Low-trigger high-maintenance bidirectional SCR (selective catalytic reduction) protection device and process method thereof

Technical Field

The invention belongs to the field of semiconductor devices, and particularly relates to a low-trigger high-maintenance bidirectional SCR (selective catalytic reduction) protective device and a process method thereof.

Background

As the size of semiconductor processes is reduced, the difference between the device operating voltage and the breakdown voltage is smaller and smaller, and the problem of electrostatic discharge (ESD) of integrated circuits is more and more significant. Usually, the working voltage of the IC port is between 0V and the power supply voltage, so that the ESD structure of the ordinary device port only needs to ensure that there is no leakage current in the ESD device when the port voltage is between 0V and the power supply voltage. In order to realize the ESD protection of the bidirectional port, a bidirectional SCR structure is provided.

Fig. 1 is a cross-sectional structural diagram of a conventional bidirectional SCR device with a high trigger voltage, which includes a P-type substrate (PSUB)1, an N-type buried layer (BN +)2, a deep N-well (HVNWELL)11, P-wells (PWELL)3 and 8, an N-well (NWELL)7, P-doped active regions (P +)4 and 10, and N-doped active regions (N +)5 and 9. In application, the P-doped active region 4 and the N-doped active region 5 are connected to the PAD1, and the P-doped active region 10 and the N-doped active region 9 are connected to the PAD 2. In application, the PAD1 applies a forward TLP pulse relative to the PAD2, the P-doped active region 4 and the P-well 3 serve as emitters, the N-well 7 serves as a base, and the P-well 8 and the P-doped active region 10 serve as collectors, so that a lateral PNP transistor is formed. And a deep N-type well (HVNWELL)11 is used as a collector, a P-type well 8 is used as a base, and an N-doped active region 9 is used as an emitter, so that the vertical NPN triode is formed. The lateral PNP and vertical NPN form the thyristor structure SCR 1. The PAD1 applies a negative TLP pulse relative to the PAD2, the P-doped active region 9 and the P-well 8 serve as emitters, the N-well 7 serves as a base, and the P-well 3 and the P-doped active region 4 serve as collectors, thereby forming a lateral PNP triode. And a deep N-type well (HVNWELL)11 is used as a collector, a P-type well 3 is used as a base, and an N-doped active region 5 is used as an emitter, so that the vertical NPN triode is formed. The lateral PNP and vertical NPN form the thyristor structure SCR 2. The equivalent circuit is shown in fig. 2.

When an ESD event occurs, if the voltage of a port PAD1 is higher than that of a PAD2, and after the reverse PN junction breakdown voltage formed by an N well 7 and a P well 8 is reached, avalanche breakdown occurs on the PN junction, a transverse PNP is conducted, minority electrons of the P well 8 flow into the N well 7, minority holes of the N well 7 flow into the P well 8, the current direction is formed to be a forward current from the N well 7 to the P well 8, the current generates a voltage drop on the resistance of the P well 8, so that a longitudinal NPN2 is conducted, and the PNP and the NPN2 form positive feedback to cause the SCR1 structure to be triggered; when the voltage of the port PAD1 is lower than the PAD2 and the voltage reaches the breakdown voltage of a reverse PN junction formed by the N well 7 and the P well 3, the PN junction is broken down, the transverse PNP is conducted, minority holes flow into the P well 3 from the N well 7, and the current generates voltage drop on the resistance of the P well 3, so that the longitudinal NPN1 is conducted, and the PNP and the NPN1 form positive feedback to trigger the SCR2 structure.

From the structure, the triggering of the SCR1 structure requires that the voltage between the ports PAD1 and PAD2 exceeds the reverse breakdown voltage of the PN junction between the N well 7 and the P well 8, and since the doping concentrations of the two wells constituting the PN junction are both low, the reverse breakdown voltage is high and may be higher than the breakdown voltage of the gate oxide layer of the device inside the chip, so that the ESD protection function cannot be achieved. Due to the symmetry of the structure, the breakdown voltage of the SCR2 is equal to that of the SCR1, the breakdown voltage is 30-50V in a common BCD process, and if the breakdown voltage is higher than the breakdown voltage of a gate oxide layer of a device in a chip, the SCR device cannot play an ESD protection role, and the reliability of the whole chip is affected.

SCR is one of the highest current density ESD protection devices, typically 50mA/um, but if 15KV HBM protection capability is achieved, SCR requires at least 200um device width. In a conventional layout method of the bidirectional SCR structure, the active region is in a strip shape, as shown in fig. 3. Under the condition of discharging large ESD current, the electric field density at the sharp corner of the long strip-shaped active region is high, and large current is easy to gather at the edge of the sharp corner, so that the SCR is easy to fail in advance. In addition, the middle finger of the multi-interdigital SCR has a larger parasitic substrate resistance than the fingers on both sides, so that a failure phenomenon caused by non-uniform conduction is easily generated, and a large chip area is consumed by a multi-interdigital layout drawing method.

Disclosure of Invention

The embodiment of the invention aims to provide a low-trigger high-maintenance bidirectional SCR (silicon controlled rectifier) protective device capable of realizing HBM (hybrid vehicle body) protection capability, and aims to solve the problems that the conventional SCR ESD protective device consumes a large chip area, is low in maintenance voltage, and is easy to generate circuit latch and non-uniform conductivity of layout multi-interdigital when high HBM protection level is realized.

The embodiment of the invention is realized in such a way that a low-trigger high-maintenance bidirectional SCR protective device comprises:

the semiconductor device comprises a substrate, a first buried layer and a first well, wherein the first buried layer and the first well are formed in the substrate, the first buried layer is in a circular shape and is positioned in the first well, and the first well is in an annular shape;

a first deep well formed by epitaxial growth and doping on the first buried layer, and a second well, a third well, a fourth well and a fifth well sequentially formed from outside to inside on the first deep well; a first body region and a second body region formed in the third well and the fifth well, respectively; the second well, the third well, the fourth well and the first body region are annular; the first deep trap, the fifth trap and the second body region are circular;

a first active region formed in the first well; a third active region formed in the first body region; a sixth active region formed at a boundary of the fourth well and the fifth well; an eighth active region formed in the second body region; the first active region, the third active region and the sixth active region are annular, and the eighth active region is circular;

a second active region and a fourth active region formed from outside to inside in the third well; a fifth active region formed at a boundary of the third well and the fourth well; a seventh active region formed in the fifth well; the second active region, the fourth active region and the fifth active region are annular and sequentially comprise the first active region, the second active region, the third active region, the fourth active region, the fifth active region, the sixth active region, the seventh active region and the eighth active region from outside to inside;

the doping types of the first well, the third well and the fifth well are the same and are opposite to the doping types of the second well and the fourth well;

the doping types of the first active region, the third active region, the fifth active region and the eighth active region are the same and are opposite to the doping types of the second active region, the fourth active region, the sixth active region and the seventh active region;

the substrate, the first well and the first active region are the same as the doping types of the first body region and the second body region; the doping types of the first buried layer, the first deep trap, the second trap and the second active region are the same.

Another objective of an embodiment of the present invention is to provide a process method for a low-trigger high-sustain bidirectional SCR protective device, the process method including the following steps:

forming a first buried layer and a first well in a substrate, wherein the first buried layer is round and is positioned in the first well, and the first well is annular;

doping the first buried layer to form a first deep well;

forming a first well on the substrate through doping, and sequentially forming a second well, a third well, a fourth well and a fifth well on the first buried layer from outside to inside, wherein the first well, the second well, the third well and the fourth well are all annular; the fifth trap is circular;

forming a first body region and a second body region in the third well and the fifth well respectively; the first body region is annular, and the second body region is circular;

forming a first active region in the first well; forming a third active region in the first body region; forming a fifth active region at the junction of the third well and the fourth well; forming an eighth active region in the second body region; the first active region, the third active region and the fifth active region are annular, and the eighth active region is circular;

forming a second active region and a fourth active region in the third well from outside to inside; a sixth active region formed at a boundary of the fourth well and the fifth well; a seventh active region formed in the fifth well;

the second active region, the fourth active region, the sixth active region and the seventh active region are annular, and are sequentially a first active region, the second active region, the third active region, the fourth active region, the fifth active region, the sixth active region, the seventh active region and the eighth active region from outside to inside;

The embodiment of the invention provides a low-trigger high-maintenance bidirectional SCR (silicon controlled rectifier) protective device capable of realizing HBM (hybrid just-bridge) protective capability, which can effectively reduce the trigger voltage of an SCR structure, ensure that a port normally works under positive and negative pressure and also can meet the ESD (electro-static discharge) protective design requirement.

Drawings

FIG. 1 is a cross-sectional view of a conventional high trigger positive pressure tolerant SCR device;

FIG. 2 is an equivalent circuit schematic diagram of a conventional high trigger positive voltage tolerant SCR device;

FIG. 3 is a schematic diagram of a layout of a conventional high-trigger positive pressure resistant SCR device;

fig. 4 is a first cross-sectional structural diagram of a low-trigger high-maintenance bidirectional SCR protective device capable of implementing 15KV HBM protection capability according to an embodiment of the present invention;

fig. 5 is a second cross-sectional structural diagram of a low-trigger high-maintenance bidirectional SCR protective device capable of implementing 15KV HBM protection capability according to an embodiment of the present invention;

fig. 6 is a schematic layout drawing of a low-trigger high-maintenance bidirectional SCR protective device capable of realizing 15KV HBM protection capability according to an embodiment of the present invention.

Fig. 7 is a schematic flow chart of a process method of a low-trigger high-maintenance bidirectional SCR protective device capable of realizing 15KV HBM protection capability according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

The embodiment of the invention is realized in such a way that, as shown in fig. 4, the low-triggering high-maintenance bidirectional SCR protective device comprises:

a substrate 1, a first buried layer 30 and

first wells

2 and 29 formed in the substrate 1, wherein the first buried layer 30 is circular and is located inside the

first wells

2 and 29, and the

first wells

2 and 29 are annular;

a first deep well 4 formed by epitaxial growth and doping on the first buried layer 30, and

second wells

5 and 27,

third wells

6 and 22,

fourth wells

12 and 20, and a fifth well 14 formed on the first deep well 4 in sequence from outside to inside;

first body regions

10, 25 and second body regions 17 formed in the

third wells

6, 22 and the fifth well 14, respectively; the

second well

5, 27, the third well 6, 22, the

fourth well

12, 20 and the

first body region

10, 25 are ring-shaped; the first deep well 4, the fifth well 14 and the second body region 17 are circular;

a first

active region

3, 28 formed in the

first well

2, 29; a third

active region

8, 24 formed in said

first body region

10, 25; sixth

active regions

13, 19 formed at the intersections of the

fourth wells

12, 20 and the fifth well 14; an eighth active region 16 formed in the second body region 17; the first

active region

3, 28, the third

active region

8, 24, the sixth

active region

13, 19 are ring-shaped, and the eighth active region 16 is circular;

second

active regions

7, 26 and fourth

active regions

9, 23 formed from the outside to the inside in the

third wells

6, 22; fifth

active regions

11, 21 formed at the junctions of the

third wells

6, 22 and the

fourth wells

12, 20; seventh

active regions

15, 18 formed in the fifth well 14; the second

active regions

7, 26, the fourth

active regions

9, 23, and the fifth

active regions

11, 21 are annular, and the first

active regions

3, 28, the second

active regions

7, 26, the third

active regions

8, 24, the fourth

active regions

9, 23, the fifth

active regions

11, 21, the sixth

active regions

13, 19, the seventh

active regions

15, 18, and the eighth active regions 16 are sequentially arranged from outside to inside;

the doping types of the

first well

2, 29, the

third well

6, 22 and the fifth well 14 are the same and opposite to the doping types of the

second well

5, 27 and the

fourth well

12, 20;

the doping types of the first

active region

3, 28, the third

active region

8, 24, the fifth

active region

11, 21 and the eighth active region 16 are the same and opposite to the doping types of the second

active region

7, 26, the fourth

active region

9, 23, the sixth

active region

13, 19 and the seventh

active region

15, 18;

the substrate 1, the

first well

2, 29, the first

active region

3, 28, the

first body region

10, 25, and the second body region 17 are doped in the same type; the doping type of the first buried layer 30, the first deep well 4, the

second well

5, 27 and the second

active region

7, 26 are the same.

In one embodiment, the substrate 1 is a P-type substrate 1;

the first buried layer 30 is an N-type buried layer;

the first deep well 4 is an N well;

the

first well

2, 29, the

third well

6, 22 and the fifth well 14 are all P-wells, and the

second well

5, 27 and the

fourth well

12, 20 are all N-wells;

the

first body regions

10, 25 and the second body region 17 are both P-type body regions;

the first

active region

3, 28, the third

active region

8, 24, the fifth

active region

11, 21, and the eighth active region 16 are all P-doped active regions;

the second

active regions

7, 26, the fourth

active regions

9, 23, the sixth

active regions

13, 19, and the seventh

active regions

15, 18 are all N-doped active regions.

The embodiment of the invention provides a low-trigger high-maintenance bidirectional SCR (silicon controlled rectifier) protective device capable of realizing HBM (hybrid diode management) protective capability, which can effectively reduce the trigger voltage of an SCR structure, ensure that a port normally works under positive and negative pressure and also can meet the ESD (electro-static discharge) protection design requirement.

The following detailed description of the implementation of the present invention is made with reference to specific embodiments:

fig. 4 shows a cross-sectional structure of a high-maintenance SCR ESD protection device with HBM protection capability provided by an embodiment of the present invention, and only the part relevant to the present invention is shown for convenience of illustration.

As an embodiment of the present invention, the low-trigger high-sustain bidirectional SCR protective device includes:

the P-type substrate (PSUB)1, P Wells (PWELL)2 and 29 formed in the P-type substrate 1 through epitaxial growth and doping, P doped active regions (P +)3 and 28 formed in the

P wells

2 and 29 through doping, and the P-type substrate 1 is connected to the ground potential through the

P wells

2 and 29 and the P doped

active regions

3 and 28 to form isolation.

In the embodiment of the present invention, the P-well (PWELL)2 and the P-doped active region (P +)3, and the P-well (PWELL)29 and the P-doped active region (P +)28 are both a closed ring from the layout plan view, as shown in fig. 6.

The structure further includes: an N-type buried layer (BN +)30 formed by diffusion or ion implantation in the P-type substrate 1 and an N-type deep well (HVNWELL)4 epitaxially and doped grown on the N-type buried layer 30, and N-wells (NWELL)5, 12, 20, 27 doped in the N-type deep well (HVNWELL) 4.

It is understood that the N-type deep well (HVNWELL)4 is grown on the N-type buried layer (BN +)30 and the P-type substrate (PSUB) 1.

The N-type buried layer 30 is connected with the N-type deep well 4 and the N-

type wells

5, 12, 20 and 27, and the electric potential is floated.

In the embodiment of the present invention, the N-well (NWELL)5 and the N-well (NWELL)12, and the N-well (NWELL)27 and the N-well (NWELL)20 are both a closed ring from the layout top view.

P-wells (Deep-PWELL)6, 22 doped in the N-type Deep well 4, P-body regions (P-body)10, 25 doped in the P-

wells

6, 22, P-doped active regions (P +)8, 24 doped in the P-body regions (P-body)10, 25, and N-doped active regions (N +)7, 9, 23, 26 doped in the P-

wells

6, 22, respectively.

In use, as shown in fig. 5, the P-

wells

6, 22 are connected to the PAD2 through the P-

body regions

10, 25, the P-doped

active regions

8, 24, and the N-doped

active regions

7, 9, 23, 26 are simultaneously connected to the PAD 2.

In the embodiment of the invention, a P-well (Deep-PWELL)6, an N-doped active region (N +)7, a P-body (P-body)10, a P-doped active region 8, an N-doped active region (N +)9, a P-well (Deep-PWELL)22, an N-doped active region (N +)26, a P-body (P-body)25, a P-doped active region (P +)24 and an N-doped active region (N +)23 are all in a closed ring shape from the top view of a layout.

The structure further includes: a P-well (Deep-PWELL)14 doped in the N-type epitaxial layer (BN +)30, a P-body (P-body)17 doped in the P-well 14, a P-active (P +)16 doped in the P-body 17, and N-doped active (N +)

regions

15, 18 doped in the P-well 14, wherein, in application, the P-well 14 is connected to a port PAD1 potential through the P-body (P-body)17 and the P-doped active region 16, and the N-doped

active regions

15, 18 are also connected to a port PAD 1.

In the embodiment of the present invention, the N-doped active region (N +)15 and the N-doped active region (N +)18 are in a closed ring shape from the layout plan view.

The structure further includes: p-doped active regions (P +)11, 21 are implanted into the P-

wells

6, 22 and the N-

wells

12, 20 at the intersection of the P-

wells

6, 22 and the N-

wells

12, 20 simultaneously, and N-doped active regions (N +)13, 19 are implanted into the N-

wells

12, 20 and the P-well 14 at the intersection of the N-

wells

12, 20 and the P-well 14 simultaneously. In application, the P-wells (Deep-PWELL)6, 22 are connected to the port PAD2 potential through the P-body (P-body)10, 25, the P-doped

active regions

8, 24, and the N-doped

active regions

7, 9, 23, 26 are also connected to the port PAD 2.

In the embodiment of the invention, the P-doped active region (P +)11 and the N-doped active region (N +)13 are respectively in a closed ring shape with the P-doped active region (P +)21 and the N-doped active region (N +)19 from the layout overlooking angle.

Wherein, the injected trap and the body region are sequentially as follows from outside to inside: p-

wells

2, 29, deep N-well 4, N-

wells

5, 27, P-

wells

6, 22, P-

body regions

10, 25, N-

wells

12, 20, P-well 14, P-body region 17.

In use, when PAD1 applies a positive ESD pulse with respect to PAD2, P-well 14 acts as the emitter, deep N-well 4 and N-

wells

12, 20 act as the bases, and P-

wells

6, 22 act as the collectors, forming a lateral triode PNP. The deep N well 4 is used as a collector, the

P wells

6 and 22 are used as bases, and the N-doped

active regions

9 and 23 are used as emitters to form a longitudinal triode NPN 1; the deep N well 4 is used as a collector, the

P wells

6 and 22 are used as bases, the N-doped

active regions

7 and 26 are used as emitters to form a vertical triode NPN2, and the lateral triode PNP, the vertical triode NPN1 and the vertical triode NPN2 form a silicon controlled rectifier structure SCR to discharge ESD current.

In use, when PAD1 applies a negative ESD pulse with respect to PAD2, P-

wells

6, 22 act as emitters, deep N-well 4 and N-

wells

12, 20 act as bases, and P-well 14 acts as a collector, forming a lateral triode PNP. The deep N well 4 is used as a collector, the P well 14 is used as a base, the N-doped active region 15 is used as an emitter, and a longitudinal NPN triode NPN3 is formed; the deep N-well 4 serves as a collector, the P-well 14 serves as a base, and the N-doped active region 18 serves as an emitter, forming a vertical NPN transistor NPN 4. The transverse PNP, the longitudinal NPN3 and the longitudinal NPN4 form a silicon controlled rectifier structure SCR to discharge ESD current. In addition, the P-doped active regions (P +)11, 21 and the N-

wells

12, 20 form a forward diode D1, and are connected in series with a lateral triode NPN5 formed by using the N-

wells

12, 20 as collectors, the P-well 14 as a base, and the N-doped

active regions

15, 18 as emitters, to form a surface parasitic path.

When the device works, when the voltage reaches the sum of the BVCES of the NPN5 and the threshold voltage of the D1, the surface parasitic path is started to discharge ESD current, and after enough minority carriers are injected into the N trap and the P trap, the SCR path in the body is started to be used as a main discharge path to discharge ESD current.

In the structure, due to the fact that the P-doped

active regions

11 and 21 have high doping concentration, PN junctions formed by the

N wells

12 and 20 and the P-doped

active regions

11 and 21 and the P well 14 and the N-doped

active regions

13 and 19 have low reverse breakdown voltage, so that the SCR structure can be triggered at low voltage, and an ESD protection effect is achieved. In addition, the condition of applying positive bias to PAD1 relative to PAD2 and the condition of applying negative bias to PAD1 relative to PAD2 respectively adopt different SCR trigger junctions, and the method is suitable for the condition of asymmetric bidirectional power supply voltage while realizing a bidirectional SCR discharge path.

As an embodiment of the present invention, the device may adopt a BCD process, and the structure trigger voltage of the device is much lower than the breakdown voltage of the gate oxide layer of the device inside the chip, so that the device can play a role of ESD protection, and the ESD protection capability is 15KV under a Human Body Model (HBM).

In addition, as the N-doped active region and the P-doped active region in the layout both adopt annular structures, as shown in fig. 6, different from the conventional layout drawing method in fig. 3, the SCR layout structure in the invention patent does not contain regions which are easy to generate failure risks, such as sharp corner edges, and the like, and the robustness of the SCR can be greatly improved. The invention realizes the ESD protection capability of the 15KV HBM by only adopting a single annular structure, thereby greatly saving the area of a chip.

The embodiment of the invention provides a low-trigger high-maintenance bidirectional SCR (silicon controlled rectifier) protective device capable of realizing 15KV HBM (heterojunction with metal) protective capability, which can effectively reduce the trigger voltage of an SCR structure, ensure that a port normally works under positive and negative pressure and also can meet the ESD (electro-static discharge) protection design requirement.

Another objective of an embodiment of the present invention is to provide a process method for implementing a low-trigger high-maintenance bidirectional SCR protective device with 15KV HBM protection capability, including the following steps:

forming a first buried layer 30 and

first wells

2 and 29 in a substrate 1, wherein the first buried layer 30 is circular and is located inside the

first wells

2 and 29, and the

first wells

2 and 29 are annular;

forming a first deep well 4 on the first buried layer 30 by epitaxial growth and doping, and forming

second wells

5 and 27,

third wells

6 and 22,

fourth wells

12 and 20 and a fifth well 14 on the first deep well 4 from outside to inside in sequence; forming

first body regions

10, 25 and second body regions 17 in the

third well

6, 22 and the fifth well 14, respectively; the

second well

5, 27, the

third well

6, 22, the

fourth well

12, 20 and the

first body region

forming a first

active region

3, 28 in said first well 2, 29; forming a third

active region

8, 24 in said

first body region

10, 25; forming sixth

active regions

13, 19 at the intersections of the

fourth wells

12, 20 and the fifth well 14; forming an eighth active region 16 in the second body region 17; the first

active region

3, 28, the third

active region

8, 24, the sixth

active region

13, 19 are ring-shaped, and the eighth active region 16 is circular;

forming a second

active region

7, 26 and a fourth

active region

9, 23 in the

third well

6, 22 from outside to inside; forming fifth

active regions

11, 21 at the interface of the

third well

6, 22 and the

fourth well

12, 20; forming seventh

active regions

15, 18 in the fifth well 14; the second

active regions

7, 26, the fourth

active regions

9, 23, and the fifth

active regions

11, 21 are annular, and the first

active regions

3, 28, the second

active regions

7, 26, the third

active regions

8, 24, the fourth

active regions

9, 23, the fifth

active regions

11, 21, the sixth

active regions

13, 19, the seventh

active regions

the doping types of the

first well

2, 29, the

third well

second well

5, 27 and the

fourth well

12, 20;

the doping types of the first

active region

3, 28, the third

active region

8, 24, the fifth

active region

7, 26, the fourth

active region

9, 23, the sixth

active region

13, 19 and the seventh

active region

15, 18;

the substrate 1, the

first well

2, 29, the first

active region

3, 28, the

first body region

second well

5, 27 and the second

active region

7, 26 are the same.

In one embodiment, the substrate 1 is a P-type substrate 1;

the first buried layer 30 is an N-type buried layer;

the first deep well 4 is an N well;

the

first well

2, 29, the

third well

6, 22 and the fifth well 14 are all P-wells, and the

second well

5, 27 and the

fourth well

12, 20 are all N-wells;

the

first body regions

10, 25 and the second body region 17 are both P-type body regions;

the first

active region

3, 28, the third

active region

8, 24, the fifth

active region

11, 21, and the eighth active region 16 are all P-doped active regions;

the second

active regions

7, 26, the fourth

active regions

9, 23, the sixth

active regions

13, 19, and the seventh

active regions

15, 18 are all N-doped active regions.

fig. 7 is a process flow diagram of a low-trigger high-maintenance SCR ESD protection device with 15KV HBM protection capability according to an embodiment of the present invention, and for convenience of illustration, only the relevant parts of the device are shown.

As an embodiment of the present invention, with reference to fig. 5, a process flow of the low-triggering high-maintenance bidirectional SCR protective device includes the following steps:

in step S101, an N-type buried layer (BN +)30 is formed in a P-type substrate (PSUB)1 by diffusion;

in an embodiment of the present invention, the N-type buried layer (BN +)30 is circular.

In step S102, a deep N well (HVNWELL)4 is doped on the N-type buried layer 30;

in step S103, the Deep N-well (HVNWELL)4 is doped by inversion to form P-wells (Deep-PWELL)6, 14, 22, and P-wells (PWELL)2, 29 are doped on the P-substrate, although multiple P-wells may be formed simultaneously;

in the embodiment of the invention, the Deep N well (HVNWELL) on the P substrate becomes the P well (Deep-PWELL)6, 14, 22 after inversion doping, and the P well (Deep-PWELL)6 and the P Well (PWELL)22 are both a closed ring from the layout overlooking angle; the P-well (PWELL)2 and the P-well (PWELL)29 on the P-substrate are both a closed ring from the layout overlooking perspective.

In step S104, N Wells (NWELL)5, 12, 20, 27 are doped on the deep N well;

in the embodiment of the invention, the N-type buried layer 30, the deep N-well 4 and the N-

wells

5, 12, 20 and 27 are connected together, and the electric potential is floated.

In step S105, P-

type body regions

10, 17, 25 are formed by doping in the P-

wells

6, 14, 22.

In the embodiment of the present invention, the P-body region (P-body)10 and the P-body region (P-body)25 are both a closed ring from the layout top view.

In step S106, P-doped active regions (P +)3, 28 are formed in the P-wells (PWELL)2, 29 by doping, P-doped active regions (P +)8, 16, 24 are formed in the P-body regions (P-body)10, 17, 25 by doping, and P-doped

active regions

11, 21 are formed by implanting into the P-

wells

6, 22 and the N-

wells

12, 20 at the same time at the junctions of the P-wells (Deep-PWELL)6, 22 and the N-wells (NWELL)12, 20.

In the embodiment of the invention, the P-doped active region (P +)3, the P-doped active region (P +)8 and the P-doped active region (P +)11 are respectively in a closed ring shape with the P-doped active region (P +)28, the P-doped active region (P +)24 and the P-doped active region (P +)21 from the layout overlooking angle.

In step 107, N-doped

active regions

7, 9, 15, 18, 23, 26 are doped in the P-wells (Deep-PWELL)6, 14, 22, and N-doped active regions (N +)13, 19 are implanted into the P-well 14 and the N-

wells

12, 20 at the intersection of the P-well (Deep-PWELL)14 and the N-wells (NWELL)12, 20.

In the embodiment of the invention, the N-doped active region (N +)7, the N-doped active region (N +)9, the N-doped active region (N +)13, the N-doped active region (N +)15 are respectively in a closed ring shape with the N-doped active region (N +)26, the N-doped active region (N +)23, the N-doped active region (N +)19 and the N-doped active region (N +)18 from the layout overlooking angle.

Wherein, for the injected trap and the body region, the following steps are performed from outside to inside in sequence: p-

wells

2, 29, deep N-well 4, N-

wells

5, 27, P-

wells

6, 22, P-

body regions

10, 25, N-

wells

12, 20, P-well 14, P-body region 17.

The P-substrate 1 is isolated from ground potential by the P-

wells

2, 29 and the P-doped

active regions

3, 28.

In application, the P-well 14 is connected to the port PAD1 potential through the P-body 17, the P-doped active region 16, and the N-doped

active regions

15, 18 are also connected to the port PAD 1. The P-wells (Deep-PWELL)6, 22 are connected to the port PAD2 potential through P-body (P-body)10, 25, P-doped

active regions

8, 24, and N-doped

active regions

7, 9, 23, 26 are also connected to the port PAD 2.

wells

12, 20 act as the bases, and P-

wells

P wells

6 and 22 are used as bases, and the N-doped

active regions

9 and 23 are used as emitters to form a longitudinal triode NPN 1; the deep N-well 4 is used as collector, the P-

wells

6, 22 are used as base, the N-doped

active regions

7, 26 are used as emitter, and the vertical triode NPN2 is formed. The transverse PNP, the longitudinal NPN1 and the longitudinal NPN2 form a silicon controlled rectifier structure SCR to discharge ESD current.

In use, when PAD1 applies a negative ESD pulse with respect to PAD2, P-

wells

6, 22 act as emitters, deep N-well 4 and N-

wells

12, 20 act as bases, and P-well 14 acts as a collector, forming a lateral triode PNP. The deep N well 4 is used as a collector, the P well 14 is used as a base, the N-doped active region 15 is used as an emitter, and a longitudinal NPN triode NPN3 is formed; the deep N-well 4 serves as a collector, the P-well 14 serves as a base, and the N-doped active region 18 serves as an emitter, forming a vertical NPN transistor NPN 4. The lateral triode PNP, the longitudinal triode NPN3 and the longitudinal NPN4 form a silicon controlled rectifier structure SCR to discharge ESD current. In addition, the P-doped active regions (P +)11, 21 and the N-

wells

12, 20 as collectors, the P-well 14 as a base, and the N-doped

active regions

15, 18 as emitters, to form a surface parasitic path.

In the structure, due to the fact that the P-doped

active regions

11 and 21 have high doping concentration, PN junctions formed by the

N wells

12 and 20 and the P-doped

active regions

11 and 21 and the P well 14 and the N-doped

active regions

As an embodiment of the present invention, the device may adopt a BCD process, and has a structure in which when the PAD1 applies a positive ESD pulse with respect to the PAD2, the trigger voltage is 17V, and the sustain voltage is 14V; the trigger voltage is 22V and the sustain voltage is 18.5V when PAD1 applies a negative ESD pulse with respect to PAD 2. The ESD protection capability under Human Body Model (HBM) is 15 KV.

The embodiment of the invention provides a low-trigger high-maintenance SCR ESD protection device meeting the 15KV HBM protection capability, which can effectively reduce the trigger voltage of an SCR structure, improve the maintenance voltage of the SCR structure, ensure that a port normally works under different positive and negative pressures, and meet the ESD protection design requirements.

The present invention is not limited to the above preferred embodiments, and any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A low-trigger high-sustain bidirectional SCR protective device, the device comprising:

2. The low-trigger high-maintenance bidirectional SCR protective device of claim 1, wherein the substrate is a P-type substrate;

the first buried layer is an N-type buried layer;

the first deep trap is an N trap;

the first well, the third well and the fifth well are all P wells, and the second well and the fourth well are all N wells;

the first body region and the second body region are both P-type body regions;

the first active region, the third active region, the fifth active region and the eighth active region are all P-doped active regions;

the second active region, the fourth active region, the sixth active region and the seventh active region are all N-doped active regions.

3. The device of claim 1, wherein the active regions, the wells, and the buried layers are formed by ion implantation or diffusion.

4. The low-trigger high-maintenance bidirectional SCR protective device of claim 2, wherein the substrate is isolated by the first well and the first active region being connected to ground potential.

5. A process method for a low-triggering high-maintenance bidirectional SCR protective device is characterized by comprising the following steps:

doping the first buried layer to form a first deep well;

6. The process of claim 5, wherein the substrate is a P-type substrate;

the first buried layer is an N-type buried layer;

the first deep trap is an N trap;

the first body region and the second body region are both P-type body regions;

7. The process of claim 5, wherein the active region is formed by ion implantation or diffusion.

8. The process of claim 6, wherein the substrate is isolated by the first well and the first active region being tied to ground potential.