Isolation composite PNP tube, high-voltage electrostatic protection structure and electronic equipment

Abstract

The invention relates to the technical field of electrostatic protection, and particularly discloses an isolated composite PNP tube, a high-voltage electrostatic protection structure and electronic equipment, and the structure comprises a P-type substrate, a P-type epitaxial layer disposed on the P-type substrate, and an N-type buried layer disposed between the P-type substrate and the P-type epitaxial layer. A plurality of spaced active regions are arranged on the surface of the P-type epitaxial layer; the active area located in the outer side area is connected with a metal wire and then serves as a leading-out end of an isolation ground end, and the multiple active areas located in the center area are connected with metal wires and then serve as a collector electrode of the longitudinal PNP tube, a collector electrode of the transverse PNP tube and leading-out ends of a base electrode and an emitting electrode shared by the longitudinal PNP tube and the transverse PNP tube respectively. And the active region between the outer side region and the central region is connected with a metal wire and then is used as a leading-out end of the isolation port. When the isolation composite PNP tube provided by the invention is applied to a high-voltage electrostatic protection structure, the isolation composite PNP tube not only has relatively high high-voltage electrostatic protection capability, but also can effectively prevent a negative pulse from triggering a latch.

Description

Technical Field

[0001] The present invention relates to the technical field of electrostatic protection, and in particular to an isolated composite PNP tube, a high-voltage electrostatic protection structure and electronic equipment. Background Art

[0002] With the continuous development of modern integrated circuit technology, high-voltage MOS devices have been increasingly easily integrated into conventional CMOS processes. Since high-voltage MOS devices have high drive current and high breakdown voltage, they are widely used in high-voltage integrated circuits such as driver circuits, power management switches, and motor control systems. But the problem that follows is that these high-voltage MOS devices must be equipped with corresponding high-voltage anti-electrostatic discharge (ESD) devices in order to work safely and reliably. High-voltage ESD devices consume a lot of power because they work in a high-voltage state, and their ESD discharge capacity is generally weak. At the same time, it is also difficult to design the holding voltage of high-voltage ESD devices to be higher than the operating voltage. Therefore, such high-voltage ESD devices are often not used in high-voltage power supply pins, otherwise latch-up is likely to occur. In addition, in power management and motor drive circuits, negative pulses often appear on some pins. When a negative pulse appears on a pin, the high-voltage ESD device is likely to be affected by it, forming a PNPN latch structure with the N-type region of the negative pulse pin. Once latch-up occurs, the circuit will inevitably be damaged by the generated latch, causing the circuit to burn out instantly.

[0003] Therefore, how to provide a high-voltage electrostatic protection solution that has both strong high-voltage ESD protection capability and can effectively prevent negative pulses from triggering latch-up has become a technical problem that needs to be urgently solved by those skilled in the art. Summary of the invention

[0004] The present invention provides an isolated composite PNP tube, a high-voltage electrostatic protection structure and an electronic device, which solve the problem in the related art that the high-voltage ESD protection capability and the prevention of negative pulse triggering latch cannot be achieved at the same time.

[0005] As a first aspect of the present invention, an isolated composite PNP tube is provided, comprising: A P-type substrate, a P-type epitaxial layer disposed on the P-type substrate, and an N-type buried layer disposed between the P-type substrate and the P-type epitaxial layer; A plurality of active regions are sequentially arranged at intervals on the surface of the P-type epitaxial layer, and a field region is arranged between every two adjacent active regions, wherein both the active region and the field region extend along the surface of the P-type epitaxial layer toward the P-type substrate; Among them, the active area located in the outer area can be connected to the metal wire and can be used as the lead-out end of the isolated ground terminal. The multiple active areas located in the central area can be connected to the metal wire and can be used as the lead-out ends of the collector of the longitudinal PNP tube, the collector of the lateral PNP tube, and the base and emitter shared by the longitudinal PNP tube and the lateral PNP tube respectively. The active area located between the outer area and the central area can be connected to the metal wire and can be used as the lead-out end of the isolated port. The lead end of the collector of the longitudinal PNP tube is connected to the lead end of the collector of the lateral PNP tube, the lead end of the base shared by the longitudinal PNP tube and the lateral PNP tube is connected to the lead end of the emitter, the lead end of the isolated ground terminal is used to connect to the ground pin of the power supply circuit, and the lead end of the isolated port is used to connect to the high-voltage pin of the power supply circuit.

[0006] Further, a first active region, a second active region, a third active region, a fourth active region, a fifth active region, a sixth active region, a seventh active region, an eighth active region and a ninth active region are sequentially arranged on the surface of the P-type epitaxial layer. Deep P-well regions are arranged at the positions of the first active region and the ninth active region, P-well regions are arranged in the deep P-well regions, and P+ injection diffusion regions are arranged in the P-well regions, and the positions of the first active region and the ninth active region are connected to metal wires as lead-out terminals of the isolated ground terminals; A deep N-well region is disposed at the positions of the second active region and the eighth active region, an N-well region is disposed in the deep N-well region, and an N+ implantation diffusion region is disposed in the N-well region, and the positions of the second active region and the eighth active region are connected to metal wires as lead-out ends of isolation ports; Deep P-well regions are arranged at the positions of the third active region to the seventh active region, wherein P-well regions are arranged in the deep P-well regions corresponding to the third active region and the seventh active region, and P+ injection diffusion regions are arranged in the P-well regions, and the positions of the third active region and the seventh active region are connected to metal wires to serve as the lead-out terminal of the collector of the vertical PNP; N-well regions are arranged in the deep P-well regions corresponding to the fourth active region to the sixth active region, and N+ injection diffusion regions are arranged in the N-well regions corresponding to the fourth active region and the sixth active region, and the positions of the fourth active region and the sixth active region are connected to metal wires to serve as the lead-out terminal of the base shared by the vertical PNP tube and the horizontal PNP tube; the position of the fifth active region is connected to a metal wire to serve as the lead-out terminal of the collector of the horizontal PNP tube and the lead-out terminal of the emitter shared by the vertical PNP tube and the horizontal PNP tube.

[0007] Further, a first P-type drift region, a second P-type drift region, a third P-type drift region, a fourth P-type drift region and a fifth P-type drift region are arranged at intervals in the N-well region corresponding to the fifth active region, a P+ injection diffusion region is arranged in each of the first P-type drift region, the second P-type drift region, the third P-type drift region, the fourth P-type drift region and the fifth P-type drift region, and the P+ injection diffusion regions corresponding to the first P-type drift region, the third P-type drift region and the fifth P-type drift region are connected to metal wires and serve as the lead-out end of the collector of the lateral PNP tube; The P+ injection diffusion regions corresponding to the second P-type drift region and the fourth P-type drift region are connected to metal wires and serve as the lead-out ends of the emitter shared by the vertical PNP tube and the horizontal PNP tube.

[0008] Furthermore, a thin oxide layer is provided between the first P-type drift region and the second P-type drift region, between the second P-type drift region and the third P-type drift region, between the third P-type drift region and the fourth P-type drift region, and between the fourth P-type drift region and the fifth P-type drift region, and the thickness of the thin oxide layer is 800 angstroms to 1200 angstroms.

[0009] Furthermore, an outer oxide layer is arranged above the field area and the active area, wherein the outer oxide layer at the position corresponding to the P+ injection diffusion area of ​​each active area and the outer oxide layer at the position corresponding to the N+ injection diffusion area are removed to form contact holes, and a metal wire is arranged in each of the contact holes.

[0010] Furthermore, the thickness of the outer oxide layer is 7000 angstroms to 12000 angstroms.

[0011] Furthermore, a field oxide layer is provided in each field region, and the thickness of the field oxide layer is 5500 angstroms to 7000 angstroms.

[0012] As another aspect of the present invention, a high-voltage electrostatic protection structure is provided, which includes: a plurality of the above-mentioned isolated composite PNP tubes connected in series, each of which includes a lateral PNP tube and a longitudinal PNP tube, the collector of the lateral PNP tube is connected to the collector of the longitudinal PNP tube to form a collector connection end, the lateral PNP tube and the longitudinal PNP tube share an emitter and a base, and the emitter and the base are connected to form an emitter-base connection end; Each two adjacent isolated composite PNP tubes are connected in series by connecting the collector connection end of one of the isolated composite PNP tubes to the emitter and base connection ends of the other isolated composite PNP tube; The emitter and base connection ends of the isolated composite PNP tube at the head end are used to connect the high voltage pin of the power circuit, and the collector connection end of the isolated composite PNP tube at the tail end is used to connect the ground pin of the power circuit; The isolated port of each isolated composite PNP tube is used to connect to the high voltage pin of the power supply circuit.

[0013] Furthermore, each of the isolated composite PNP tubes comprises a multi-finger structure, the number of fingers of each isolated composite PNP tube ranges from 8 to 12, and the total width is at least 1000 μm.

[0014] As another aspect of the present invention, an electronic device is provided, which includes: a power supply circuit and the high-voltage electrostatic protection structure described above, the high-voltage pin of the power supply circuit is connected to the emitter and base connection terminals of the isolated composite PNP tube of the high-voltage electrostatic protection structure, the high-voltage pin of the power supply circuit can also be connected to the isolation port of each isolated composite PNP tube of the high-voltage electrostatic protection structure, and the ground pin of the power supply circuit is connected to the collector connection terminal of the isolated composite PNP tube of the high-voltage electrostatic protection structure.

[0015] The isolated composite PNP tube provided by the present invention has a base N well surrounded by a deep P well, a deep N well at the isolation end, and an N buried layer. The high voltage pin of the power supply circuit is connected to the emitter P+ of the isolated composite PNP tube, but its base N well is surrounded as described above. Therefore, the emitter P+ and the base N well cannot form a PNPN latch structure with a negative pulse PN junction (i.e., a PN junction formed by a P-type ground and an N-type region at the negative pulse pin), thereby avoiding failure of the circuit in the event of an extreme negative pulse, and greatly improving the reliability of the circuit. Therefore, the isolated composite PNP tube provided by the present invention can not only play an effective protective role when used in a high voltage electrostatic protection structure, but also prevent the occurrence of latching triggered by a negative pulse, thereby improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present invention, but do not constitute a limitation of the present invention.

[0017] Figure 1 This is a cross-sectional structural diagram of the isolated composite PNP tube provided by the present invention.

[0018] Figure 2 This is a circuit schematic diagram of the high-voltage electrostatic protection structure provided by the present invention. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0020] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0022] Conventional high-voltage pin ESD protection generally uses a high-voltage NMOS tube with the same working voltage as its ESD protection device. As we all know, high-voltage NMOS devices have high breakdown voltage, so they consume large power under high voltage and have weak electrostatic discharge capabilities. In addition, the holding voltage of high-voltage NMOS is low and cannot be used on power pins. If high-voltage PMOS or high-voltage PNP is used for ESD protection, although the discharge capability and holding voltage are improved, when a negative pulse appears in the N-type region connected to one of the other pins, the P-type region of the high-voltage PMOS or high-voltage PNP connected to the high-voltage pin, its N-type substrate or base, as well as the P-type ground and the aforementioned N-type negative pulse region, form a PNPN latch structure, causing the circuit to burn out instantly.

[0023] Based on this, an isolated composite PNP tube is provided in this embodiment. Figure 1 is a cross-sectional view of an isolated composite PNP tube provided according to an embodiment of the present invention, Figure 1 As shown, including: A P-type substrate 200, a P-type epitaxial layer 202 disposed on the P-type substrate 200, and an N-type buried layer 201 disposed between the P-type substrate 200 and the P-type epitaxial layer 202; A plurality of active regions are sequentially arranged at intervals on the surface of the P-type epitaxial layer 202, and a field region is arranged between every two adjacent active regions, and both the active region and the field region extend along the surface of the P-type epitaxial layer 202 toward the direction of the P-type substrate 200; Among them, the active area located in the outer area can be connected to the metal wire and can be used as the lead-out end of the isolated ground terminal. The multiple active areas located in the central area can be connected to the metal wire and can be used as the lead-out ends of the collector of the longitudinal PNP tube, the collector of the lateral PNP tube, and the base and emitter shared by the longitudinal PNP tube and the lateral PNP tube respectively. The active area located between the outer area and the central area can be connected to the metal wire and can be used as the lead-out end of the isolated port. The lead end of the collector of the longitudinal PNP tube is connected to the lead end of the collector of the lateral PNP tube, the lead end of the base shared by the longitudinal PNP tube and the lateral PNP tube is connected to the lead end of the emitter, the lead end of the isolated ground terminal is used to connect to the ground pin of the power supply circuit, and the lead end of the isolated port is used to connect to the high-voltage pin of the power supply circuit.

[0024] The isolated composite PNP tube provided by the embodiment of the present invention has a base N well surrounded by a deep P well, a deep N well at the isolation end, and an N buried layer. The high voltage pin of the power supply circuit is connected to the emitter P+ of the isolated composite PNP tube, but its base N well is surrounded as described above. Therefore, the emitter P+ and the base N well cannot form a PNPN latch structure with the negative pulse PN junction (i.e., a PN junction formed by the P-type ground and the N-type region at the negative pulse pin), thereby avoiding the failure of the circuit in the event of an extreme negative pulse, and greatly improving the reliability of the circuit. Therefore, the isolated composite PNP tube provided by the present invention can not only play an effective protective role when used in a high voltage electrostatic protection structure, but also prevent the occurrence of negative pulse triggering latching, thereby improving reliability.

[0025] In the embodiment of the present invention, Figure 1 As shown, a first active region 213, a second active region 214, a third active region 215, a fourth active region 216, a fifth active region 217, a sixth active region 218, a seventh active region 219, an eighth active region 220 and a ninth active region 221 are sequentially arranged on the surface of the P-type epitaxial layer 202. A deep P-well region 203 is disposed at the positions of the first active region 213 and the ninth active region 221, a P-well region 205 is disposed in the deep P-well region 203, and a P+ injection diffusion region 207 is disposed in the P-well region 205. The positions of the first active region 213 and the ninth active region 221 are connected to the metal wire 212 and serve as the lead-out terminal of the isolated ground terminal; A deep N-well region 204 is disposed at the positions of the second active region 214 and the eighth active region 220, an N-well region 206 is disposed in the deep N-well region 204, and an N+ implantation diffusion region 208 is disposed in the N-well region 206. The positions of the second active region 214 and the eighth active region 220 are connected to the metal wire 212 and serve as the lead-out end of the isolation port; A deep P-well region 203 is provided at the positions of the third active region 215 to the seventh active region 219, wherein a P-well region 205 is provided in the deep P-well region 203 corresponding to the third active region 215 and the seventh active region 219, and a P+ injection diffusion region 207 is provided in the P-well region 205, and the positions of the third active region 215 and the seventh active region 219 are connected to the metal wire 212 and serve as the lead-out end of the collector of the vertical PNP; in the deep P-well region 203 corresponding to the fourth active region 216 to the sixth active region 218, a P-well region 205 is provided in the deep P-well region 203 corresponding to the third active region 215 and the seventh active region 219, and a P+ injection diffusion region 207 is provided in the P-well region 205; the positions of the third active region 215 and the seventh active region 219 are connected to the metal wire 212 and serve as the lead-out end of the collector of the vertical PNP; N-well regions 206 are provided, and N+ injection diffusion regions 208 are provided in the N-well regions 206 corresponding to the fourth active region 216 and the sixth active region 218; the positions of the fourth active region 216 and the sixth active region 218 are connected to metal wires 212 and serve as the lead-out end of the base shared by the longitudinal PNP tube and the lateral PNP tube; the position of the fifth active region 217 is connected to the metal wire 212 and serves as the lead-out end of the collector of the lateral PNP tube and the lead-out end of the emitter shared by the longitudinal PNP tube and the lateral PNP tube.

[0026] Specifically, a P-type epitaxial layer 202 is provided above the P-type substrate 200, and the isolation composite PNP tube is made in the P-type epitaxial layer. An N-type buried layer 201 is provided between the P-type substrate 200 and the P-type epitaxial layer 202. On the surface of the P-type epitaxial layer 202, a first active area 213, a second active area 214, a third active area 215, a fourth active area 216, a fifth active area 217, a sixth active area 218, a seventh active area 219, an eighth active area 220, and a ninth active area 221 are provided in sequence. On both sides of each active area, a field area is provided, and on the field area is a field oxide layer 209 with a thickness of 5500 to 7000 angstroms, which serves as isolation between every two active areas.

[0027] In the embodiment of the present invention, deep P-well regions 203 are provided at the first active region 213 and the ninth active region 221, serving as the isolated ground terminal of the isolated composite PNP transistor. Inside the deep P-well region 203, P+ injection diffusion regions 207 and P-well regions 205 are provided to increase the impurity concentration at the location, and form a good ohmic contact through contact holes and metal wires, serving as the lead-out terminal of the isolated ground terminal. Deep N-well regions 204 are provided at the second active region 214 and the eighth active region 220, serving as the isolated port of the isolated composite PNP transistor. The deep N-well region 204 diffuses downward from the P-type epitaxial surface by 5 to 6 microns, and contacts and communicates with the N-type buried layer 201. Inside the deep N-well region 204, N+ injection diffusion regions 208 and N-well regions 206 are provided to increase the impurity concentration at the location, and form a good ohmic contact through contact holes and metal wires, serving as the lead-out terminal of the isolated port.

[0028] In the embodiment of the present invention, a large deep P-well region 203 is provided below the third active region 215 to the seventh active region 219. Inside the deep P-well 203 at the third active region 215 and the seventh active region 219, a P+ injection diffusion region 207 and a P-well region 205 are provided to increase the impurity concentration therein, and to form a good ohmic contact through contact holes and metal wires, serving as the collector lead-out terminal of the vertical PNP in the isolated composite PNP tube.

[0029] In the embodiment of the present invention, a large N-well region 206 is provided below the fourth active region 216 to the sixth active region 218. The N-well region 206 is located inside the deep P-well region 203, that is, the lateral and longitudinal dimensions of the N-well region 206 are smaller than the deep P-well region 203. N+ implantation diffusion regions 208 are provided inside the N-well region 206 at the fourth active region 216 and the sixth active region 218 to increase the impurity concentration therein and form a good ohmic contact through the contact hole and the metal wire, which serves as the base lead-out terminal of the isolated composite PNP transistor.

[0030] In the embodiment of the present invention, a first P-type drift region, a second P-type drift region, a third P-type drift region, a fourth P-type drift region and a fifth P-type drift region are arranged at intervals in the N-well region 206 corresponding to the fifth active region 217, and a P+ injection diffusion region is arranged in each of the first P-type drift region, the second P-type drift region, the third P-type drift region, the fourth P-type drift region and the fifth P-type drift region, and the P+ injection diffusion regions corresponding to the first P-type drift region, the third P-type drift region and the fifth P-type drift region are connected to metal wires and serve as the lead-out end of the collector of the lateral PNP tube; The P+ injection diffusion regions corresponding to the second P-type drift region and the fourth P-type drift region are connected to metal wires and serve as the lead-out ends of the emitter shared by the vertical PNP tube and the horizontal PNP tube.

[0031] Furthermore, a thin oxide layer 211 is disposed between the first P-type drift region and the second P-type drift region, between the second P-type drift region and the third P-type drift region, between the third P-type drift region and the fourth P-type drift region, and between the fourth P-type drift region and the fifth P-type drift region, and the thickness of the thin oxide layer 211 is 800 angstroms to 1200 angstroms.

[0032] Specifically, in the embodiment of the present invention, five P-type drift regions 222 are arranged at intervals at the position of the fifth active region 217. A thin oxide layer 211 with a thickness of 800 to 1200 angstroms is provided between every two P-type drift regions 222 to prevent the P-type drift regions 222 from short-circuiting each other when the surface is metallized. A P+ injection diffusion region 207 is provided inside each P-type drift region 222 to increase the impurity concentration on the surface. Among them, the P+ injection diffusion region 207 in the first, third, and fifth P-type drift regions 222 forms a good ohmic contact through the contact hole and the metal wire, serving as the collector lead-out terminal of the lateral PNP tube in the isolated composite PNP tube. The P+ injection diffusion region 207 in the second and fourth P-type drift regions 222 forms a good ohmic contact through the contact hole and the metal wire, serving as the emitter lead-out terminal of the isolated composite PNP tube.

[0033] In an embodiment of the present invention, an outer oxide layer 210 is arranged above the field area and the active area, wherein the outer oxide layer at the position corresponding to the P+ injection diffusion area of ​​each active area and the outer oxide layer at the position corresponding to the N+ injection diffusion area are removed to form contact holes, and a metal wire 212 is arranged in each of the contact holes.

[0034] Specifically, the thickness of the outer oxide layer is 7000 angstroms to 12000 angstroms.

[0035] In the embodiment of the present invention, a field oxide layer 209 is disposed in each field region, and the thickness of the field oxide layer 209 is 5500 angstroms to 7000 angstroms.

[0036] In the embodiment of the present invention, an outer oxide layer 210 covering the entire wafer surface is provided above all field oxide layers and active regions, and the thickness is 7000 angstroms to 12000 angstroms. The outer oxide layer 210 is removed at the corresponding positions of the P+ injection diffusion region 207 and the N+ injection diffusion region 208 of each active region to form a contact hole directly reaching the silicon surface; at the position of each contact hole, a metal wire 212 is provided to contact the silicon surface, and each port of the isolated composite PNP tube is led out respectively, forming a complete isolated composite PNP tube structure.

[0037] When the isolated composite PNP tube of the embodiment of the present invention is applied to Figure 2In the high-voltage electrostatic protection structure shown, the metal wires of the longitudinal PNP collector 207 at the third active region 215 and the seventh active region 219 of the isolated composite PNP tube and the metal wires of the transverse PNP collector 207 at the first, third, and fifth P-type drift regions 222 in the fifth active region 217 are short-circuited together. At the same time, the metal wires of the isolated composite PNP base 208 at the fourth active region 216 and the sixth active region 218 and the metal wires of the isolated composite PNP emitter 207 at the second and fourth P-type drift regions 222 in the fifth active region 217 are short-circuited together. The metal wires of the isolated composite PNP1 to the isolated composite PNP4 are short-circuited in the same way, and the isolated composite PNP1 to the isolated composite PNP4 are connected in series.

[0038] In the embodiment of the present invention, the breakdown voltage from the isolation end of the isolated composite PNP tube to the ground end is greater than 100V (i.e., the breakdown voltage of the deep N-well region 204 and the deep P-well region 203). The breakdown voltage from the emitter P-type drift region 222 of the isolated composite PNP tube to the lateral PNP collector P-type drift region 222 is 15-20V; the breakdown voltage from the emitter P-type drift region 222 of the isolated composite PNP to the vertical PNP collector deep P-well 203 is also 15-20V. Therefore, the breakdown voltage from the emitter of the isolated composite PNP tube to the collector short-circuit end of the vertical PNP and the horizontal PNP is 15-20V.

[0039] like Figure 2 As shown in the figure, the isolated composite PNP2~isolated composite PNP4 connected in series with the isolated composite PNP1 tube have the same structure and connection method as the isolated composite PNP1, and the breakdown voltage of each port is also the same as the isolated composite PNP1. Figure 2 The ESD voltage is introduced into the high-voltage pin 100. At this time, since the breakdown voltage of each isolated port connected to the high-voltage pin 100 to the ground is greater than 100V, the ESD voltage will break down the emitter and collector short-circuited ends of the isolated composite PNP1 with a lower breakdown voltage (15~20V), and then the ESD energy reaches the emitter and base short-circuited ends of the isolated composite PNP2. Similarly, the ESD energy breaks down the emitter and collector short-circuited ends of the isolated composite PNP2 with a lower breakdown voltage. By analogy, the ESD energy gradually breaks down the emitter and collector short-circuited ends of the isolated composite PNP3 and the isolated composite PNP4, and finally reaches the ground pin 121, completing the discharge of the ESD energy introduced from the high-voltage pin 100 to the ground pin 121. It should be noted that Figure 1The structure of the isolated composite PNP tube of the present invention adds a P-type drift region 222 of a high-voltage PMOS at the emitter, the purpose of which is to increase the emitter junction depth and reduce the vertical base width to increase the amplification factor and electrostatic discharge of the vertical PNP. Because the electrostatic discharge capacity of the vertical PNP is stronger than that of the horizontal PNP. In addition, in order to properly discharge more ESD energy in the vertical direction, the distance between the collector P-type drift region and the emitter P-type drift region of the horizontal PNP can also be appropriately increased to reduce the amplification factor of the horizontal PNP and reduce the horizontal ESD discharge, thereby making the discharge path of the ESD energy in the isolated composite PNP more reasonable.

[0040] On the contrary, when ESD energy is introduced from the ground pin 121. At this time, the PN junction formed by the isolation end and the ground end of the isolation composite PNP1~isolation composite PNP4 is in forward bias. The isolation ends of the isolation composite PNP1~isolation composite PNP4 are all connected to the high-voltage pin 100. Therefore, the ESD energy is discharged in parallel to the high-voltage pin through the four isolation end PN junctions of the isolation composite PNP1~isolation composite PNP4, thereby completing its discharge from the ground pin 121 to the high-voltage pin 100. It should be understood that the electrostatic discharge capacity of the forward PN junction is very strong, and the structure of the present invention is that four large-area forward PN junctions are discharged in parallel at the same time, and its discharge capacity is multiplied. Therefore, the high-voltage electrostatic protection structure of the present invention can realize the discharge of forward and reverse ESD energy from the high-voltage pin to the ground pin. After testing, the high-voltage electrostatic protection structure of the present invention has a forward and reverse ESD discharge level of more than 8000V in the human body model. It should also be noted here that when a negative pulse appears in the N-type region connected to the remaining pins, the emitter and base PN junctions of the isolated composite PNP tube of the present invention are surrounded and isolated by the collector deep P well, the isolation end deep N well and the N-type buried layer, and therefore will not form a PNPN latch structure with the negative pulses in the N-type regions of the remaining pins, thereby avoiding damage to the circuit under special abnormal circumstances and greatly improving the reliability of the circuit.

[0041] It should be noted that the photolithography layers and process of the isolated composite PNP tube of the present invention are compatible with existing high-voltage MOS tubes, that is, no additional platemaking and process costs will be generated. Therefore, the isolated composite PNP tube of the present invention can be applied to high-voltage electrostatic protection structures without increasing costs. While improving the high-voltage electrostatic protection capability, it can also effectively prevent the occurrence of latch structures.

[0042] As another embodiment of the present invention, a high-voltage electrostatic protection structure is provided, wherein: Figure 2As shown, it includes: a plurality of the above-mentioned isolated composite PNP tubes connected in series, each of which includes a lateral PNP tube and a longitudinal PNP tube, the collector of the lateral PNP tube is connected to the collector of the longitudinal PNP tube to form a collector connection end, the lateral PNP tube and the longitudinal PNP tube share an emitter and a base, and the emitter and the base are connected to form an emitter-base connection end; Each two adjacent isolated composite PNP tubes are connected in series by connecting the collector connection end of one of the isolated composite PNP tubes to the emitter and base connection ends of the other isolated composite PNP tube; The emitter and base connection ends of the isolated composite PNP tube at the head end are used to connect the high voltage pin of the power circuit, and the collector connection end of the isolated composite PNP tube at the tail end is used to connect the ground pin of the power circuit; The isolated port of each isolated composite PNP tube is used to connect to the high voltage pin of the power supply circuit.

[0043] In the embodiment of the present invention, each of the isolated composite PNP tubes comprises a multi-finger structure, the number of fingers of each isolated composite PNP tube ranges from 8 to 12, and the total width is at least 1000 μm.

[0044] Specifically, Figure 2 As shown, the emitter 102 of the first isolated composite PNP tube PNP1 is connected to the port of the high voltage pin 100. The base 103 and the emitter 102 of the first isolated composite PNP tube PNP1 are short-circuited together, and the collector of the longitudinal PNP in the first isolated composite PNP tube PNP1 and the collector of the lateral PNP in the first isolated composite PNP tube PNP1 are short-circuited together. The isolation port 101 of the first isolated composite PNP tube PNP1 is connected to the high voltage pin 100.

[0045] In the embodiment of the present invention, the collector short-circuit ends of the longitudinal PNP and the transverse PNP in the first isolated composite PNP tube PNP1 are connected to the emitter 107 of the second isolated composite PNP tube PNP2. The base 108 and the emitter 107 of the second isolated composite PNP tube PNP2 are short-circuited together, and the collector of the longitudinal PNP in the second isolated composite PNP tube PNP2 and the collector of the transverse PNP in the second isolated composite PNP tube PNP2 are short-circuited together. The isolation port 106 of the second isolated composite PNP tube PNP2 is also connected to the high-voltage pin 100.

[0046] Similarly, the connection mode of the third isolated composite PNP tube PNP3 and the fourth isolated composite PNP tube PNP4 is the same as that of the second isolated composite PNP tube PNP2, that is, the base and the emitter are short-circuited, and the longitudinal PNP collector and the lateral PNP collector in each are short-circuited. The isolation ports of the third isolated composite PNP tube PNP3 and the fourth isolated composite PNP tube PNP4 are both connected to the high-voltage pin 100. The collector short-circuit end of the fourth isolated composite PNP tube PNP4 is connected to the ground wire pin 121, thereby forming a complete high-voltage electrostatic protection structure to prevent negative pulses from triggering latches.

[0047] In an embodiment of the present invention, the high-voltage electrostatic protection structure is specifically composed of four low-voltage isolated composite PNP tubes connected in series. Its electrostatic discharge capability is the same as the ESD level of a single isolated composite PNP tube. As is well known, the discharge capability of low-voltage PNP is very strong, so the discharge capability of the high-voltage electrostatic protection structure of the present invention is relatively strong. Moreover, since the holding voltage of the PNP tube is relatively high (almost the same as its breakdown voltage), the holding voltage of the structure of the present invention is equal to the sum of the holding voltages of the four low-voltage isolated composite PNP tubes. Therefore, the holding voltage of the high-voltage electrostatic protection structure of the present invention is relatively high (about 60~80V), which can be used in high-voltage pins and power pins. In addition, when a negative pulse appears in the N-type region connected to the remaining pins, since the high-voltage pin is connected to the emitter and base of the isolated composite PNP tube of the present invention, it is all surrounded by the collector deep P well, and the deep N well and N buried layer of the isolation end, and cannot form a PNPN latch structure with the negative pulse N-type region of the remaining pins, which also protects the circuit very well.

[0048] In summary, the high-voltage electrostatic protection structure of the present invention has the following advantages: (1) The structure can perform bidirectional discharge of ESD energy from the high-voltage pin to the ground pin. (2) The electrostatic discharge capability of the high-voltage electrostatic protection structure is very strong. (3) The maintenance voltage of the high-voltage electrostatic protection structure is equal to the sum of the maintenance voltages of the four isolated composite PNPs, that is, 60~80V. Therefore, the structure can meet the use of high-voltage power supply. (4) When abnormal negative pulses appear on the other pins, the high-voltage pins connected to the high-voltage electrostatic protection structure will not form a latch structure with the other pins, thereby improving the reliability and safety of the circuit under extreme conditions, extending the service life of the circuit, and complying with the national energy-saving and environmental protection policy. Therefore, the high-voltage electrostatic protection structure of the present invention can fully realize good electrostatic protection for the high-voltage pins (including power pins) of the circuit, and has high reliability against negative pulses.

[0049] It should be understood that, for the convenience of explanation, the present invention only exemplifies the high-voltage electrostatic protection structure when the high-voltage pin is 60~80V. For those skilled in the art, it is easy to increase or decrease the number of isolated composite PNP tubes to obtain high-voltage ESD protection structures of different voltage levels. At the same time, for the convenience of explanation, the present invention only exemplifies the structure with 2 emitter fingers in the isolated composite PNP tube. For those skilled in the art, it is easy to increase the number of emitter and collector fingers to obtain structures with different ESD discharge capabilities. The high-voltage electrostatic protection structure proposed in the present invention can be applied not only between the high-voltage pin and the ground pin described in the present invention, but also between the remaining different functional pins.

[0050] It should be noted that the electrostatic discharge principle of the high-voltage electrostatic protection structure of the present invention can be specifically referred to the relevant description in the above-mentioned isolated composite PNP tube, which will not be repeated here.

[0051] As another embodiment of the present invention, an electronic device is provided, which includes: a power supply circuit and the high-voltage electrostatic protection structure described above, the high-voltage pin of the power supply circuit is connected to the emitter and base connection terminals of the isolated composite PNP tube of the high-voltage electrostatic protection structure, the high-voltage pin of the power supply circuit can also be connected to the isolation port of each isolated composite PNP tube of the high-voltage electrostatic protection structure, and the ground pin of the power supply circuit is connected to the collector connection terminal of the isolated composite PNP tube of the high-voltage electrostatic protection structure.

[0052] The electronic device of the embodiment of the present invention adopts the high-voltage electrostatic protection structure mentioned above and can be applied to high-voltage power supply circuits. It can play a role in electrostatic protection under high voltage of the power supply circuit, improve the reliability and safety of the power supply circuit under extreme conditions, and extend the service life of the power supply circuit.

[0053] The specific working principle of the electronic device of the present invention can be referred to the specific description of the high-voltage electrostatic protection structure above, which will not be repeated here.

[0054] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An isolated composite PNP tube, characterized in that: include: A P-type substrate, a P-type epitaxial layer disposed on the P-type substrate, and an N-type buried layer disposed between the P-type substrate and the P-type epitaxial layer; A plurality of active regions are sequentially arranged at intervals on the surface of the P-type epitaxial layer, and a field region is arranged between every two adjacent active regions, wherein both the active region and the field region extend along the surface of the P-type epitaxial layer toward the P-type substrate; Among them, the active area located in the outer area can be connected to the metal wire and can be used as the lead-out end of the isolated ground terminal. The multiple active areas located in the central area can be connected to the metal wire and can be used as the lead-out ends of the collector of the longitudinal PNP tube, the collector of the lateral PNP tube, and the base and emitter shared by the longitudinal PNP tube and the lateral PNP tube respectively. The active area located between the outer area and the central area can be connected to the metal wire and can be used as the lead-out end of the isolated port. The lead end of the collector of the longitudinal PNP tube is connected to the lead end of the collector of the lateral PNP tube, the lead end of the base shared by the longitudinal PNP tube and the lateral PNP tube is connected to the lead end of the emitter, the lead end of the isolated ground terminal is used to connect to the ground pin of the power supply circuit, and the lead end of the isolated port is used to connect to the high-voltage pin of the power supply circuit.

2. The isolated composite PNP tube according to claim 1, characterized in that: A first active region, a second active region, a third active region, a fourth active region, a fifth active region, a sixth active region, a seventh active region, an eighth active region and a ninth active region are sequentially arranged on the surface of the P-type epitaxial layer. Deep P-well regions are arranged at the positions of the first active region and the ninth active region, P-well regions are arranged in the deep P-well regions, and P+ injection diffusion regions are arranged in the P-well regions, and the positions of the first active region and the ninth active region are connected to metal wires as lead-out terminals of the isolated ground terminals; A deep N-well region is disposed at the positions of the second active region and the eighth active region, an N-well region is disposed in the deep N-well region, and an N+ implantation diffusion region is disposed in the N-well region, and the positions of the second active region and the eighth active region are connected to metal wires as lead-out ends of isolation ports; Deep P-well regions are arranged at the positions of the third active region to the seventh active region, wherein P-well regions are arranged in the deep P-well regions corresponding to the third active region and the seventh active region, and P+ injection diffusion regions are arranged in the P-well regions, and the positions of the third active region and the seventh active region are connected to metal wires to serve as the lead-out terminal of the collector of the vertical PNP; N-well regions are arranged in the deep P-well regions corresponding to the fourth active region to the sixth active region, and N+ injection diffusion regions are arranged in the N-well regions corresponding to the fourth active region and the sixth active region, and the positions of the fourth active region and the sixth active region are connected to metal wires to serve as the lead-out terminal of the base shared by the vertical PNP tube and the horizontal PNP tube; the position of the fifth active region is connected to a metal wire to serve as the lead-out terminal of the collector of the horizontal PNP tube and the lead-out terminal of the emitter shared by the vertical PNP tube and the horizontal PNP tube.

3. The isolated composite PNP tube according to claim 2, characterized in that: A first P-type drift region, a second P-type drift region, a third P-type drift region, a fourth P-type drift region and a fifth P-type drift region are arranged at intervals in the N-well region corresponding to the fifth active region, a P+ injection diffusion region is arranged in each of the first P-type drift region, the second P-type drift region, the third P-type drift region, the fourth P-type drift region and the fifth P-type drift region, and the P+ injection diffusion regions corresponding to the first P-type drift region, the third P-type drift region and the fifth P-type drift region are connected to metal wires and serve as the lead-out end of the collector of the lateral PNP tube; The P+ injection diffusion regions corresponding to the second P-type drift region and the fourth P-type drift region are connected to metal wires and serve as the lead-out ends of the emitter shared by the vertical PNP tube and the horizontal PNP tube.

4. The isolated composite PNP tube according to claim 3, characterized in that: A thin oxide layer is disposed between the first P-type drift region and the second P-type drift region, between the second P-type drift region and the third P-type drift region, between the third P-type drift region and the fourth P-type drift region, and between the fourth P-type drift region and the fifth P-type drift region, and the thickness of the thin oxide layer is 800 angstroms to 1200 angstroms.

5. The isolated composite PNP tube according to claim 1, characterized in that: An outer oxide layer is arranged above the field area and the active area, wherein the outer oxide layer corresponding to the P+ injection diffusion area in each active area and the outer oxide layer corresponding to the N+ injection diffusion area are removed to form contact holes, and a metal line is arranged in each of the contact holes.

6. The isolated composite PNP tube according to claim 5, characterized in that: The thickness of the outer oxide layer is 7000 angstroms to 12000 angstroms.

7. The isolated composite PNP tube according to claim 1, characterized in that: A field oxide layer is arranged in each field region, and the thickness of the field oxide layer is 5500 angstroms to 7000 angstroms.

8. A high voltage electrostatic protection structure, characterized in that: include: A plurality of isolated composite PNP tubes according to any one of claims 1 to 7 connected in series, each of which comprises a lateral PNP tube and a longitudinal PNP tube, the collector of the lateral PNP tube is connected to the collector of the longitudinal PNP tube to form a collector connection end, the lateral PNP tube and the longitudinal PNP tube share an emitter and a base, and the emitter and the base are connected to form an emitter-base connection end; Each two adjacent isolated composite PNP tubes are connected in series by connecting the collector connection end of one of the isolated composite PNP tubes to the emitter and base connection ends of the other isolated composite PNP tube; The emitter and base connection ends of the isolated composite PNP tube at the head end are used to connect the high voltage pin of the power circuit, and the collector connection end of the isolated composite PNP tube at the tail end is used to connect the ground pin of the power circuit; The isolated port of each isolated composite PNP tube is used to connect to the high voltage pin of the power supply circuit.

9. The high voltage electrostatic protection structure according to claim 8, characterized in that: Each of the isolated composite PNP tubes comprises a multi-finger structure, the number of fingers of each isolated composite PNP tube ranges from 8 to 12, and the total width is at least 1000 μm.

10. An electronic device, characterized in that: include: A power supply circuit and a high-voltage electrostatic protection structure as described in claim 8 or 9, wherein the high-voltage pin of the power supply circuit is connected to the emitter and base connection terminals of the isolated composite PNP tube of the high-voltage electrostatic protection structure, the high-voltage pin of the power supply circuit can also be connected to the isolation port of each isolated composite PNP tube of the high-voltage electrostatic protection structure, and the ground pin of the power supply circuit is connected to the collector connection terminal of the isolated composite PNP tube of the high-voltage electrostatic protection structure.

Images