CN112928112B - Low-trigger high-maintenance bidirectional SCR protective device and process method thereof - Google Patents

Abstract

The invention provides a low-trigger high-maintenance bidirectional SCR protection device and a process method thereof. The device includes: a substrate, a first well and a first buried layer formed from outside to inside in the substrate; on the first buried layer The first deep well is formed; the second, third, fourth, and fifth wells are formed sequentially from outside to inside on the first deep well; the first and second body regions are respectively formed in the third and fifth wells; in the first The first active region formed in the well; the second and third active regions formed from outside to inside in the third well; the fourth active region formed in the first body region; the third well and the fourth well The fifth and sixth active regions are respectively formed at the junction of the fourth well and the fifth well; the seventh active region formed in the fifth well; the eighth active region formed in the second body region active area. The SCR device provided by the present invention can ensure the normal operation of the port and realize HBM ESD protection capability under positive and negative pressure.

Description

Low triggering and high sustaining bidirectional SCR protection device and process method thereof

Technical field

The invention belongs to the field of semiconductor devices, and in particular relates to a low-trigger and high-sustainment bidirectional SCR protection device and a process method thereof.

Background technique

As the size of semiconductor processes shrinks, the gap between device operating voltage and breakdown voltage becomes smaller and smaller, and the electrostatic discharge (ESD) problem of integrated circuits becomes more and more significant. Normally, the operating voltage of the IC port is between 0V and the power supply voltage, so the ESD structure of the ordinary device port only needs to ensure that the ESD device has no leakage current when the port voltage is between 0V and the power supply voltage. In order to achieve ESD protection of bidirectional ports, a bidirectional SCR structure is proposed.

Figure 1 is a cross-sectional structural diagram of an existing high trigger voltage bidirectional SCR device. The structure includes a P-type substrate (PSUB) 1, an N-type buried layer (BN+) 2, a deep N well (HVNWELL) 11, and a P well (PWELL). 3, 8, N well (NWELL) 7, P doped active region (P+) 4, 10, N doped active region (N+) 5, 9. In application, the P-doped active region 4 and the N-doped active region 5 are connected to PAD1, and the P-doped active region 10 and N-doped active region 9 are connected to PAD2. In application, PAD1 applies a forward TLP pulse relative to PAD2, P-doped active region 4 and P-well 3 serve as emitters, N-well 7 serves as the base, and P-well 8 and P-doped active region 10 serve as collectors. , forming a lateral PNP transistor. The deep N-type well (HVNWELL) 11 serves as the collector, the P-well 8 serves as the base, and the N-doped active region 9 serves as the emitter, forming a vertical NPN transistor. This horizontal PNP and vertical NPN constitute the silicon controlled structure SCR1. PAD1 applies a negative TLP pulse relative to PAD2, P-doped active region 9 and P-well 8 serve as emitters, N-well 7 serves as the base, P-well 3 and P-doped active region 4 serve as collectors, forming a lateral PNP triode. The deep N-type well (HVNWELL) 11 serves as the collector, the P-well 3 serves as the base, and the N-doped active region 5 serves as the emitter, forming a vertical NPN transistor. This horizontal PNP and vertical NPN constitute the thyristor structure SCR2. The equivalent circuit is shown in Figure 2.

When an ESD event occurs, if the voltage of port PAD1 is higher than PAD2 and reaches the breakdown voltage of the reverse PN junction formed by N well 7 and P well 8, the PN junction will undergo avalanche breakdown, the lateral PNP will conduct, and the P well 8 will Minority carrier electrons flow into N well 7, and minority carrier holes in N well 7 flow into P well 8, forming a forward current in the direction from N well 7 to P well 8. This current generates a voltage drop on the resistance of P well 8, so that Vertical NPN2 is turned on, and PNP and NPN2 form a positive feedback, causing the SCR1 structure to be triggered; when the voltage of port PAD1 is lower than PAD2, and the voltage reaches the reverse PN junction breakdown voltage formed by N well 7 and P well 3, the PN junction is struck Through, the transverse PNP is turned on, and the minority carrier holes flow from N well 7 into P well 3. The current generates a voltage drop on the resistance of P well 3, causing the vertical NPN1 to turn on. PNP and NPN1 form a positive feedback, causing the SCR2 structure to be triggered.

From this structure, triggering the SCR1 structure requires that the voltage between ports PAD1 and PAD2 exceed the reverse breakdown voltage of the PN junction between N well 7 and P well 8. Since the doping concentrations of the two wells that constitute the PN junction are both It is relatively low, so the reverse breakdown voltage is high, which may be higher than the breakdown voltage of the gate oxide layer of the device inside the chip, so it cannot play the role of ESD protection. Due to the symmetry of the structure, the breakdown voltage of SCR2 is equal to the breakdown voltage of SCR1. This breakdown voltage is 30 to 50V in the general BCD process. If the breakdown voltage is higher than the breakdown voltage of the gate oxide layer of the device inside the chip, it will This will cause the SCR device to fail to provide ESD protection, affecting the reliability of the entire chip.

SCR is one of the ESD protection devices with the highest current density. The current density is usually 50mA/um. However, if the HBM protection capability of 15KV is achieved, the SCR requires a device width of at least 200um. In the conventional layout method of the bidirectional SCR structure, the active area adopts a long strip shape, as shown in Figure 3. When discharging large ESD currents, the electric field density is large at the sharp corners of the long active area, and large currents tend to accumulate at the edges of the sharp corners, which makes the SCR prone to early failure. In addition, since the middle finger of a multi-finger SCR will have a greater parasitic substrate resistance than the fingers on both sides, it is easy to cause failures caused by non-uniform conduction, and the multi-finger layout method will consume a lot of time. Larger chip area.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a low-trigger and high-maintenance bidirectional SCR protection device that can achieve HBM protection capabilities, aiming to solve the problem that existing SCR ESD protection devices consume large chip areas and maintain voltage when achieving high HBM level protection levels. Low, prone to circuit latch-up and non-uniform conductivity problems with multiple fingers in the layout.

The embodiment of the present invention is implemented in this way. A low trigger and high sustain bidirectional SCR protection device includes:

A substrate, a first buried layer and a first well formed in the substrate, the first buried layer is circular and is located inside the first well, and the first well is annular;

A first deep well formed on the first buried layer by growth epitaxy and doping, and a second well, a third well, a fourth well and a third well formed sequentially from outside to inside on the first deep well. Five wells; first body regions and second body regions respectively formed in the third well and the fifth well; the second well, the third well, the fourth well and the third well The integrated region is annular; the first deep well, the fifth well 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 the interface of the fourth well and the fifth well Active region; 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 third active region Eight active areas are 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 the junction of the third well and the fourth well; in the The seventh active region formed in the fifth well; the second active region, the fourth active region, and the fifth active region are ring-shaped, and are the first active region in order from outside to inside. active area, the second active area, the third active area, the fourth active area, the fifth active area, the sixth active area, the seventh active area area and the eighth active area;

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

The first active region, the third active region, the fifth active region, and the eighth active region have the same doping type, and are of the same doping type as the second active region, the third active region, and the third active region. The doping types of the fourth active region, the sixth active region, and the seventh active region are opposite;

The substrate, the first well, the first active region, the first body region and the second body region have the same doping type; the first buried layer, the first deep The type well, the second well and the second active region have the same doping type.

Another object of the embodiment of the present invention is to provide a process method for a low trigger and high sustain bidirectional SCR protection device. The process method includes the following steps:

Form a first buried layer and a first well in the substrate, the first buried layer is circular and is located inside the first well, the first well is annular;

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

A first well is formed on the substrate by doping, and a second well, a third well, a fourth well and a fifth well are sequentially formed on the first buried layer from outside to inside. The second well, the third well, and the fourth well are all annular; the fifth well is circular;

A first body region and a second body region are formed 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 interface of the third well and the fourth well; An eighth active region is formed 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;

A second active region and a fourth active region are formed in the third well from outside to inside; a sixth active region is formed at the interface of the fourth well and the fifth well; The seventh active region formed in the five wells;

The second active area, the fourth active area, the sixth active area, and the seventh active area are annular, and from outside to inside, they are the first active area, the second active area, and the second active area. active area, the third active area, the fourth active area, the fifth active area, the sixth active area, the seventh active area and the eighth active area district;

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

The first active region, the third active region, the fifth active region, and the eighth active region have the same doping type, and are of the same doping type as the second active region, the third active region, and the third active region. The doping types of the fourth active region, the sixth active region, and the seventh active region are opposite;

The substrate, the first well, the first active region and the first body region and the second body region have the same doping type; the first buried layer, the first deep well The doping type of the second well and the second active region is the same.

Embodiments of the present invention provide a low-trigger high-maintenance bidirectional SCR protection device that can achieve HBM protection capabilities, which can effectively reduce the trigger voltage of the SCR structure and ensure that the port operates normally under positive and negative pressures, and can also meet ESD protection design requirements.

Description of the drawings

Figure 1 is a cross-sectional structural diagram of a traditional high-trigger positive-voltage SCR device;

Figure 2 is the equivalent circuit schematic diagram of a traditional high-trigger positive-voltage SCR device;

Figure 3 is a schematic diagram of the layout method of a traditional high-trigger positive-voltage SCR device;

Figure 4 is a first cross-sectional structural diagram of a low-trigger high-maintenance bidirectional SCR protection device capable of achieving 15KV HBM protection provided by an embodiment of the present invention;

Figure 5 is a second cross-sectional structural diagram of a low-trigger high-sustainment bidirectional SCR protection device capable of achieving 15KV HBM protection provided by an embodiment of the present invention;

Figure 6 is a schematic diagram of the layout of a low-trigger high-sustainment bidirectional SCR protection device capable of achieving 15KV HBM protection provided by an embodiment of the present invention.

FIG. 7 is a schematic flow chart of a process method for a low-trigger high-sustainment bidirectional SCR protection device capable of realizing 15KV HBM protection capability provided by an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

The embodiment of the present invention is implemented as follows. As shown in Figure 4, the low trigger and high sustain bidirectional SCR protection device includes:

Substrate 1, a first buried layer 30 and first wells 2, 29 formed in the substrate 1. The first buried layer 30 is circular and located inside the first wells 2, 29. Wells 2 and 29 are annular;

The first deep well 4 is formed on the first buried layer 30 by growth epitaxy and doping, and the second wells 5, 27 and third wells are sequentially formed on the first deep well 4 from outside to inside. 6, 22, fourth wells 12, 20 and fifth well 14; first body regions 10, 25 and second body region 17 respectively formed in the third wells 6, 22 and the fifth well 14; The second wells 5, 27, the third wells 6, 22, the fourth wells 12, 20 and the first body regions 10, 25 are annular; the first deep well 4, the The fifth well 14 and the second body region 17 are circular;

First active regions 3, 28 formed in the first wells 2, 29; third active regions 8, 24 formed in the first body regions 10, 25; in the fourth well 12 , 20 and the fifth well 14; the eighth active region 16 formed in the second body region 17; the first active region 3, 28. The third active areas 8 and 24 and the sixth active areas 13 and 19 are annular, and the eighth active area 16 is circular;

The second active regions 7, 26 and the fourth active regions 9, 23 are formed from outside to inside in the third wells 6, 22; The fifth active regions 11, 21 formed at the junction of 20; the seventh active regions 15, 18 formed in the fifth well 14; the second active regions 7, 26, the fourth active region The source areas 9 and 23 and the fifth active areas 11 and 21 are annular, and from the outside to the inside are the first active areas 3 and 28, the second active areas 7 and 26, and the The third active area 8, 24, the fourth active area 9, 23, the fifth active area 11, 21, the sixth active area 13, 19, the seventh active area 15, 18 and the eighth active area 16;

The first wells 2, 29, the third wells 6, 22, and the fifth well 14 have the same doping type, and are the same as those of the second wells 5, 27, and the fourth wells 12, 20. The doping type is opposite;

The first active regions 3, 28, the third active regions 8, 24, the fifth active regions 11, 21, and the eighth active region 16 have the same doping type, and are the same as the doping types. The doping types of the second active regions 7 and 26, the fourth active regions 9 and 23, the sixth active regions 13 and 19, and the seventh active regions 15 and 18 are opposite;

The substrate 1, the first wells 2 and 29, the first active regions 3 and 28 have the same doping type as the first body regions 10 and 25 and the second body region 17; The first buried layer 30 , the first deep well 4 , the second wells 5 and 27 and the second active regions 7 and 26 have the same doping type.

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 wells 2 and 29, the third wells 6 and 22, and the fifth well 14 are all P wells, and the second wells 5 and 27 and the fourth wells 12 and 20 are all N wells. ;

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

The first active regions 3 and 28, the third active regions 8 and 24, the fifth active regions 11 and 21, and the eighth active region 16 are all P-doped active regions;

The second active regions 7 and 26, the fourth active regions 9 and 23, the sixth active regions 13 and 19, and the seventh active regions 15 and 18 are all N-doped active regions. district.

Embodiments of the present invention provide a low-trigger high-maintenance bidirectional SCR protection device that can achieve HBM protection capabilities, which can effectively reduce the trigger voltage of the SCR structure and ensure that the port operates normally under positive and negative pressures, and can also meet ESD protection design requirements.

The implementation of the present invention is described in detail below with reference to specific embodiments:

Figure 4 shows the cross-sectional structure of an SCR ESD protection device with ground-breaking high-maintenance HBM protection capability provided by an embodiment of the present invention. For convenience of explanation, only the parts related to the present invention are shown.

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

P-type substrate (PSUB) 1, P-wells (PWELL) 2, 29 formed by growth epitaxy and doping in P-type substrate 1, P-doped active materials formed by doping in P-wells 2, 29 Regions (P+) 3, 28, P-type substrate 1 are connected to ground potential through P wells 2, 29 and P-doped active regions 3, 28 to form isolation.

In the embodiment of the present invention, the P well (PWELL) 2 and the P doped active region (P+) 3 are respectively the same as the P well (PWELL) 29 and the P doped active region (P+) 28 from the perspective of the layout. A closed ring, as shown in Figure 6.

The structure also 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 formed by epitaxial growth and doping on the N-type buried layer 30 , and N-wells (NWELL) 5, 12, 20, 27 formed by doping in the N-type deep well (HVNWELL) 4.

It can be 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 to the N-type deep well 4 and the N-wells 5, 12, 20, and 27, and the potential is floating.

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 respectively form a closed ring shape when viewed from above.

P-wells (Deep-PWELL) 6 and 22 formed by doping in the N-type deep well 4 are respectively doped with P-body regions (P-body) 10 and 25 formed in the P-wells 6 and 22. In the P-body region The P-doped active regions (P+) 8 and 24 formed by doping in (P-body) 10 and 25, and the N-doped active regions (N+) 7 and 9 formed by doping in P wells 6 and 22. 23, 26.

In application, as shown in Figure 5, P wells 6 and 22 are connected to PAD2 through P body regions 10 and 25 and P-doped active regions 8 and 24, and N-doped active regions 7, 9, 23 and 26 are connected at the same time. PAD2.

In the embodiment of the present invention, P well (Deep-PWELL) 6, N-doped active region (N+) 7, P-body region (P-body) 10, P-doped active region 8, N-doped active region Region (N+) 9 and P well (Deep-PWELL) 22, N-doped active region (N+) 26, P-body region (P-body) 25, P-doped active region (P+) 24, N-doped The active area (N+) 23 is a closed ring when viewed from the top of the layout.

The structure also includes: a P-well (Deep-PWELL) 14 formed by doping in the N-type epitaxial layer (BN+) 30, a P-body region (P-body) 17 formed by doping in the P-well 14, and a P-body region (P-body) 17 formed by doping in the P-well 14. The P active region (P+) 16 is doped in the region 17, and the N-doped active regions (N+) 15 and 18 are doped in the P well 14. When used, the P well 14 passes through the P body region ( P-body) 17 and P-doped active region 16 are connected to the potential of port PAD1, and N-doped active regions 15 and 18 are also connected to port PAD1.

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

The structure also includes: P-doped active regions (P+) 11, 21 formed by simultaneously implanting P wells 6, 22 and N wells 12, 20 at the junctions of P wells 6, 22 and N wells 12, 20, and The formed N-doped active regions (N+) 13 and 19 are simultaneously implanted into the N wells 12 and 20 and the P well 14 at the junctions of the N wells 12 and 20 and the P well 14. In application, P-wells (Deep-PWELL) 6 and 22 are connected to the potential of port PAD2 through P-body regions (P-body) 10 and 25 and P-doped active regions 8 and 24, and N-doped active regions 7 and 24 are connected to the port PAD2 potential. 9, 23, and 26 are also connected to port PAD2.

In the embodiment of the present invention, the P-doped active region (P+) 11 and the N-doped active region (N+) 13 are respectively connected with the P-doped active region (P+) 21 and the N-doped active region (N+). 19The layout is a closed ring when viewed from above.

Among them, the implanted wells and body regions from outside to inside are: P wells 2 and 29, deep N wells 4, N wells 5 and 27, P wells 6 and 22, P body regions 10 and 25, N wells 12, 20, P well 14, P body region 17.

In application, when PAD1 applies a forward ESD pulse relative to PAD2, P well 14 serves as the emitter, deep N well 4 and N wells 12 and 20 serve as bases, and P wells 6 and 22 serve as collectors to form a lateral triode PNP. . Deep N well 4 serves as the collector, P wells 6 and 22 serve as bases, and N-doped active regions 9 and 23 serve as emitters, forming a vertical transistor NPN1; deep N well 4 serves as the collector, and P wells 6 and 22 serve as bases. pole, N-doped active regions 7 and 26 serve as emitters to form a vertical transistor NPN2. The transverse transistor PNP, the vertical transistor NPN1, and the vertical transistor NPN2 form a silicon-controlled structure SCR to discharge the ESD current.

In application, when PAD1 applies a negative ESD pulse relative to PAD2, P wells 6 and 22 serve as emitters, deep N well 4 and N wells 12 and 20 serve as bases, and P well 14 serves as a collector, forming a lateral triode PNP. . The deep N well 4 serves as the collector, the P well 14 serves as the base, and the N-doped active region 15 serves as the emitter, forming a vertical NPN transistor NPN3; the deep N well 4 serves as the collector, the P well 14 serves as the base, and the N-doped active region 15 serves as the emitter. The active area 18 serves as an emitter, forming a vertical NPN transistor NPN4. Horizontal PNP, vertical NPN3, and vertical NPN4 form a thyristor structure SCR to discharge ESD current. In addition, the P-doped active regions (P+) 11 and 21 and the N-wells 12 and 20 form a forward diode D1, with the N-wells 12 and 20 serving as collectors, the P-well 14 serving as the base, and the N-doped active regions The lateral transistors NPN5 formed by 15 and 18 as emitters are connected in series to form a surface parasitic path.

When the device is working, when the voltage reaches the sum of the BVCES of NPN5 and the threshold voltage of D1, the surface parasitic path first opens to discharge the ESD current. When enough minority carriers are injected into the N-well and P-well, the SCR path in the body opens as the main The discharge path discharges ESD current.

In this structure, since the P-doped active regions 11 and 21 have high doping concentrations, 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 region 13 The PN junction formed by , 19 has a low reverse breakdown voltage, allowing this SCR structure to be triggered at low voltage, thereby providing ESD protection. In addition, different SCR trigger junctions are used to apply a forward bias voltage to PAD1 relative to PAD2 and a negative bias voltage to PAD1 relative to PAD2. While achieving a bidirectional SCR discharge path, it can also be applied to asymmetric bidirectional power supplies. voltage situation.

As an embodiment of the present invention, the device can adopt the BCD process, and its structural trigger voltage is much lower than the breakdown voltage of the gate oxide layer of the internal device of the chip. Therefore, it can play an ESD protection role and can be used in the Human-Body Model (HBM). ) ESD protection capability is 15KV.

In addition, since both the N-doped active area and the P-doped active area in the layout adopt a ring structure, as shown in Figure 6, unlike the conventional layout method in Figure 3, the SCR layout structure in the patent does not contain sharp edges. Areas prone to failure risks, such as corners and edges, can greatly improve the robustness of SCR. The patent of this invention only uses a single ring structure to achieve the ESD protection capability of 15KV HBM, greatly saving the chip area.

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

Another object of the embodiment of the present invention is to provide a process method for realizing a low-trigger high-sustainment bidirectional SCR protection device with 15KV HBM protection capability, which includes the following steps:

A first buried layer 30 and first wells 2 and 29 are formed in the substrate 1. The first buried layer 30 is circular and is located inside the first wells 2 and 29. The first wells 2 and 29 are annular;

A first deep well 4 is formed on the first buried layer 30 by growth epitaxy and doping, and second wells 5, 27, third wells 6, 22. The fourth wells 12, 20 and the fifth well 14; the first body regions 10, 25 and the second body region 17 are respectively formed in the third wells 6, 22 and the fifth well 14; The second wells 5 and 27, the third wells 6 and 22, the fourth wells 12 and 20 and the first body regions 10 and 25 are annular; the first deep well 4 and the fifth well The well 14 and the second body region 17 are circular;

First active regions 3, 28 are formed in the first wells 2, 29; third active regions 8, 24 are formed in the first body regions 10, 25; and in the fourth wells 12, 20 Sixth active regions 13 and 19 are formed at the interface with the fifth well 14; an eighth active region 16 is formed in the second body region 17; the first active regions 3 and 28, the The third active areas 8 and 24, the sixth active areas 13 and 19 are annular, and the eighth active area 16 is circular;

Second active regions 7, 26 and fourth active regions 9, 23 are formed in the third wells 6, 22 from outside to inside; in the third wells 6, 22 and the fourth wells 12, 20 The fifth active regions 11 and 21 are formed at the junction of , 23. The fifth active areas 11 and 21 are annular, and from outside to inside are the first active areas 3 and 28, the second active areas 7 and 26, and the third Active areas 8 and 24, the fourth active areas 9 and 23, the fifth active areas 11 and 21, the sixth active areas 13 and 19, and the seventh active areas 15 and 18 and the eighth active region 16;

The first wells 2, 29, the third wells 6, 22, and the fifth well 14 have the same doping type, and are the same as those of the second wells 5, 27, and the fourth wells 12, 20. The doping type is opposite;

The first active regions 3, 28, the third active regions 8, 24, the fifth active regions 11, 21, and the eighth active region 16 have the same doping type, and are the same as the doping types. The doping types of the second active regions 7 and 26, the fourth active regions 9 and 23, the sixth active regions 13 and 19, and the seventh active regions 15 and 18 are opposite;

The substrate 1, the first wells 2 and 29, the first active regions 3 and 28 have the same doping type as the first body regions 10 and 25 and the second body region 17; The first buried layer 30 , the first deep well 4 , the second wells 5 and 27 and the second active regions 7 and 26 have the same doping type.

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 wells 2 and 29, the third wells 6 and 22, and the fifth well 14 are all P wells, and the second wells 5 and 27 and the fourth wells 12 and 20 are all N wells. ;

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

The first active regions 3 and 28, the third active regions 8 and 24, the fifth active regions 11 and 21, and the eighth active region 16 are all P-doped active regions;

The second active regions 7 and 26, the fourth active regions 9 and 23, the sixth active regions 13 and 19, and the seventh active regions 15 and 18 are all N-doped active regions. district.

The implementation of the present invention is described in detail below with reference to specific embodiments:

FIG. 7 shows a schematic process flow diagram of a low-trigger high-sustainment SCR ESD protection device with 15KV HBM protection capability provided by an embodiment of the present invention. For convenience of explanation, only the parts related to the present invention are shown.

As an embodiment of the present invention, with reference to Figure 5, the process flow of the low trigger high sustain bidirectional SCR protection device includes the following steps:

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

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

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

In step S103, the deep N well (HVNWELL) 4 forms P wells (Deep-PWELL) 6, 14, and 22 through inversion doping, and the P well (PWELL) 2 and 29 are formed by doping on the P substrate. Of course, there are many Two P-wells can be formed at the same time;

In the embodiment of the present invention, the deep N well (HVNWELL) on the P substrate becomes P well (Deep-PWELL) 6, 14, and 22 after inversion doping, and the P well (Deep-PWELL) 6 and P well The well (PWELL) 22 is a closed ring shape when viewed from the top of the layout; the P well (PWELL) 2 and P well (PWELL) 29 on the P substrate are both a closed ring shape when viewed from the top of the layout.

In step S104, dope the deep N well to form N wells (NWELL) 5, 12, 20, and 27;

In the embodiment of the present invention, the N-type buried layer 30 is connected to the deep N-well 4 and the N-wells 5, 12, 20, and 27, and the potential is floating.

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 respectively form a closed ring shape when viewed from above.

In step S105, P-type body regions 10, 17, and 25 are formed in the P wells 6, 14, and 22 by doping.

In the embodiment of the present invention, the P-body region (P-body) 10 and the P-body region (P-body) 25 are both in the shape of a closed ring when viewed from above.

In step S106, P-doped active regions (P+) 3, 28 are formed in P wells (PWELL) 2, 29 by doping, and P-doped active regions (P+) 3, 28 are formed in P-body regions (P-body) 10, 17, 25 by doping. P-doped active regions (P+) 8, 16, 24 are simultaneously added to P wells 6, 22 and N wells 12, 20 at the junctions of P wells (Deep-PWELL) 6, 22 and N wells (NWELL) 12, 20. 20 is implanted to form P-doped active regions 11 and 21.

In the embodiment of the present invention, the P-doped active region (P+) 3, P-doped active region (P+) 8, and P-doped active region (P+) 11 are respectively connected with the P-doped active region (P+). 28. The P-doped active region (P+) 24 and the P-doped active region (P+) 21 are both a closed ring shape when viewed from above.

In step 107, N-doped active regions 7, 9, 15, 18, 23, 26 are formed in P-wells (Deep-PWELL) 6, 14, and 22. Between P-well (Deep-PWELL) 14 and The junction of the N wells (NWELL) 12 and 20 is simultaneously implanted into the P well 14 and the N wells 12 and 20 to form N-doped active regions (N+) 13 and 19.

In the embodiment of the present invention, N-doped active region (N+) 7, N-doped active region (N+) 9, N-doped active region (N+) 13, N-doped active region (N+) 15 , respectively with N-doped active region (N+) 26, N-doped active region (N+) 23, N-doped active region (N+) 19, and N-doped active region (N+) 18 as viewed from the layout. The angles are all in a closed ring.

Among them, the implanted wells and body regions from outside to inside are: P wells 2 and 29, deep N wells 4, N wells 5 and 27, P wells 6 and 22, P body regions 10 and 25, N wells 12, 20, P well 14, P body region 17.

P substrate 1 is connected to ground potential through P wells 2, 29 and P doped active regions 3, 28 to form isolation.

When used, the P well 14 is connected to the potential of the port PAD1 through the P-body region (P-body) 17 and the P-doped active region 16, and the N-doped active regions 15 and 18 are also connected to the port PAD1. P-wells (Deep-PWELL) 6, 22 are connected to the port PAD2 potential through P-body regions (P-body) 10, 25, P-doped active regions 8, 24, and N-doped active regions 7, 9, 23, 26 is also connected to port PAD2.

In application, when PAD1 applies a forward ESD pulse relative to PAD2, P well 14 serves as the emitter, deep N well 4 and N wells 12 and 20 serve as bases, and P wells 6 and 22 serve as collectors, forming a lateral transistor PNP . Deep N well 4 serves as the collector, P wells 6 and 22 serve as bases, and N-doped active regions 9 and 23 serve as emitters, forming a vertical transistor NPN1; deep N well 4 serves as the collector, and P wells 6 and 22 serve as bases. pole, N-doped active regions 7 and 26 serve as emitters, forming a vertical transistor NPN2. Horizontal PNP, vertical NPN1, and vertical NPN2 form a thyristor structure SCR to discharge ESD current.

In application, when PAD1 applies a negative ESD pulse relative to PAD2, P wells 6 and 22 serve as emitters, deep N well 4 and N wells 12 and 20 serve as bases, and P well 14 serves as a collector, forming a lateral triode PNP. . The deep N well 4 serves as the collector, the P well 14 serves as the base, and the N-doped active region 15 serves as the emitter, forming a vertical NPN transistor NPN3; the deep N well 4 serves as the collector, the P well 14 serves as the base, and the N-doped active region 15 serves as the emitter. The active area 18 serves as an emitter, forming a vertical NPN transistor NPN4. The horizontal transistor PNP and the vertical transistors NPN3 and vertical NPN4 form a thyristor structure SCR to discharge the ESD current. In addition, the P-doped active regions (P+) 11 and 21 and the N-wells 12 and 20 form a forward diode D1, with the N-wells 12 and 20 serving as collectors, the P-well 14 serving as the base, and the N-doped active regions The lateral transistors NPN5 formed by 15 and 18 as emitters are connected in series to form a surface parasitic path.

When the device is working, when the voltage reaches the sum of the BVCES of NPN5 and the threshold voltage of D1, the surface parasitic path first opens to discharge the ESD current. When enough minority carriers are injected into the N-well and P-well, the SCR path in the body opens as the main The discharge path discharges ESD current.

In this structure, since the P-doped active regions 11 and 21 have high doping concentrations, 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 region 13 The PN junction formed by , 19 has a low reverse breakdown voltage, allowing this SCR structure to be triggered at low voltage, thereby providing ESD protection. In addition, different SCR trigger junctions are used to apply a forward bias voltage to PAD1 relative to PAD2 and a negative bias voltage to PAD1 relative to PAD2. While achieving a bidirectional SCR discharge path, it can also be applied to asymmetric bidirectional power supplies. voltage situation.

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

The embodiment of the present invention provides a low-trigger and high-sustainment SCR ESD protection device that meets the 15KV HBM protection capability, which can effectively reduce the trigger voltage of the SCR structure, increase the sustaining voltage of the SCR structure, and ensure that the port operates normally under different positive and negative voltages. It can also meet ESD protection design requirements.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. Inside.

Claims (8)

1. A low-trigger high-maintenance bi-directional SCR protective device, the device comprising:

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 circular and is positioned in the first well, and the first well is annular;

a first deep well formed on the first buried layer through growth epitaxy and doping, and a second well, a third well, a fourth well and a fifth well which are sequentially formed on the first deep well from outside to inside; 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 well, the fifth well 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 an intersection 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 an interface 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 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 are sequentially arranged 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 doping types of the substrate, the first well and the first active region are the same as those of the first body region and the second body region; the doping types of the first buried layer, the first deep well, the second well and the second active region are the same.

2. The low-trigger high-maintenance bi-directional 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 well is an N well;

the first well, the third well and the fifth well are P-wells, and the second well and the fourth well are 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 each active region, each well, and each buried layer are formed by ion implantation or diffusion.

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

5. The process method of the low-triggering high-maintenance bidirectional SCR protection device is characterized by comprising the following steps of:

forming a first buried layer and a first well in a substrate, wherein the first buried layer is circular 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 by doping, and forming a second well, a third well, a fourth well and a fifth well on the first buried layer from outside to inside in sequence, wherein the first well, the second well, the third well and the fourth well are all annular; the fifth well is round;

forming a first body region and a second body region in the third well and the fifth well respectively; the first body area is annular, and the second body area 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 area, the third active area and the fifth active area are annular, and the eighth active area 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 an intersection 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 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 doping types of the substrate, the first well and the first active region are the same as those of the first body region and the second body region; the doping types of the first buried layer, the first deep well, the second well and the second active region are the same.

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 well is an N well;

the first well, the third well and the fifth well are P-wells, and the second well and the fourth well are 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.

7. The method 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 from ground by the first well and the first active region.