Electrostatic discharge structure

Abstract

An electrostatic discharge structure includes a first region, a first ring structure, a second ring structure, and a third ring structure. The first ring structure surrounds the first region and has a second region and a third region. The second ring structure surrounds the first ring structure and has a fourth region and a fifth region. The third ring structure surrounds the second ring structure. A distance between the second and fourth regions is different from a distance between the third and fifth regions.

Description

Technical Field

[0001] This invention relates to an electrostatic discharge structure, and more particularly to an electrostatic discharge structure having multiple electrostatic discharge elements. Background Technology

[0002] Electrostatic discharge (ESD) damage has become one of the most significant reliability issues for integrated circuit (IC) products. Especially as dimensions continue to shrink to sub-micron levels, the gate oxide layer of metal-oxide-semiconductor (MOS) semiconductors becomes increasingly thin, making ICs more susceptible to ESD damage. In general industry standards, the input / output (I / O) pins of IC products must pass human body mode ESD tests exceeding 2000 volts and mechanical mode ESD tests exceeding 200 volts. Therefore, ESD protection components must be placed near all I / O pads in IC products to protect the internal core circuitry from ESD current. Summary of the Invention

[0003] An embodiment of the present invention provides an electrostatic discharge structure, including a first region, a first ring structure, a second ring structure, and a third ring structure. The first ring structure surrounds the first region and has a second region and a third region. The second ring structure surrounds the first ring structure and has a fourth region and a fifth region. The third ring structure surrounds the second ring structure. The distance between the second and fourth regions is different from the distance between the third and fifth regions.

[0004] In some embodiments, the distance between the outer side of the first ring structure and the inner side of the second ring structure is related to the conduction impedance of the electrostatic discharge element. A larger distance between the outer side of the first ring structure and the inner side of the second ring structure corresponds to a larger conduction impedance of the electrostatic discharge element. Conversely, a smaller distance between the outer side of the first ring structure and the inner side of the second ring structure corresponds to a smaller conduction impedance of the electrostatic discharge element. When an electrostatic discharge event occurs, the electrostatic discharge element with a large conduction impedance conducts earlier than the electrostatic discharge element with a small conduction impedance. Attached Figure Description

[0005] Figure 1 This is a schematic diagram of the electrostatic discharge structure of the present invention.

[0006] Figure 2A This is another schematic diagram of the electrostatic discharge structure of the present invention.

[0007] Figure 2B This is a schematic diagram of the region allocation of the electrostatic discharge structure of the present invention.

[0008] Figure 2C This is a schematic diagram of the electrical contact end of the electrostatic discharge structure of the present invention.

[0009] Figure 3A for Figure 2B A cross-sectional view of the electrostatic discharge structure along the dashed line AA'.

[0010] Figure 3B for Figure 2B A cross-sectional view of the electrostatic discharge structure along the dashed line BB'.

[0011] Figure 4A for Figure 3A A schematic diagram of the types of the first electrostatic discharge element.

[0012] Figure 4B for Figure 3B A schematic diagram of the types of the second electrostatic discharge element.

[0013] Symbol Explanation

[0014] 100, 200: Electrostatic discharge structure

[0015] 110, 210, 221~228, 231~238, 241, 242: Areas

[0016] 110C, 210C: Center point

[0017] 120, 130, 140, 220, 230, 240: Ring structure

[0018] 120A~120C, 130A~130C, 140A~140C, 220A~220H, 230A~230H, 240A~240H: Inner Point

[0019] 120D~120F, 130D~130F, 220I~220P, 230I~230P: Outer edge points

[0020] D1~D8: Direction

[0021] DS1~DS3: Width

[0022] 211, 212: Doped regions

[0023] W1, W2: Trap

[0024] 310: Base

[0025] IO_1~IO_4: Input / output pins

[0026] 321, 322A, 322B, 323A, 323B: Isolation Structure Detailed Implementation

[0027] To make the objectives, features, and advantages of this invention more apparent and understandable, embodiments are provided below in conjunction with the accompanying drawings for detailed description. This specification provides different embodiments to illustrate the technical features of different implementations of the invention. The configuration of the elements in the embodiments is for illustrative purposes only and is not intended to limit the invention. Furthermore, the repetition of some reference numerals in the embodiments is for simplification and does not imply any correlation between different embodiments.

[0028] Figure 1 This is a schematic diagram of the electrostatic discharge structure of the present invention. As shown, the electrostatic discharge structure 100 includes a region 110, and ring structures 120, 130, and 140. The ring structure 120 surrounds the region 110. The present invention does not limit the shape of the region 110 and the ring structure 120. In this embodiment, the region 110 is circular, and the ring structure 120 is square. In other embodiments, the shape of the region 110 is the same as the shape of the ring structure 120. For example, the shapes of both the region 110 and the ring structure 120 are rectangular or both are circular (e.g., ...). Figure 2A (As shown).

[0029] This invention does not limit the distance between the outer side of region 110 and the inner side of annular structure 120. In this embodiment, the distance between the center point 110C of region 110 and a first inner point of annular structure 120 is not equal to the distance between the center point 110C and a second inner point of annular structure 120. Furthermore, the distance between the center point 110C and a first inner point of annular structure 120 may be equal to or not equal to the distance between the center point 110C and a third inner point of annular structure 120.

[0030] For example, suppose the center point 110C extends in directions D1 to D3 and intersects the inner side of the annular structure 120 at inner points 120A, 120B, and 120C. In this example, the distance between the center point 110C and the inner point 120A is different from the distance between the center point 110C and the inner point 120B. Furthermore, the distance between the center point 110C and the inner point 120A may be the same or different from the distance between the center point 110C and the inner point 120C. In some embodiments, when the annular structure 120 is circular, the distance between the center point 110C and each inner point of the annular structure 120 is the same.

[0031] The ring structure 130 surrounds the ring structure 120. In this embodiment, the distance between a first outer point of the ring structure 120 and a first inner point of the ring structure 130 is different from the distance between a second outer point of the ring structure 120 and a second inner point of the ring structure 130. In this example, the distance between the first outer point of the ring structure 120 and the first inner point of the ring structure 130 may be the same as or different from the distance between a third outer point of the ring structure 120 and a third inner point of the ring structure 130.

[0032] For example, in direction D1, center point 110C intersects the outer side of ring structure 120 at an outer point 120D and the inner side of ring structure 130 at an inner point 130A. Additionally, in direction D2, center point 110C intersects the outer side of ring structure 120 at an outer point 120E and the inner side of ring structure 130 at an inner point 130B. In this example, the distance between outer point 120D and inner point 130A is different from the distance between outer point 120E and inner point 130B.

[0033] In another possible embodiment, in direction D3, the center point 110C intersects the outer side of the ring structure 120 at an outer point 120F and the inner side of the ring structure 130 at an inner point 130C. In this example, the distance between the outer point 120F and the inner point 130C may be the same as or different from the distance between the outer point 120D and the inner point 130A.

[0034] The present invention does not limit the shape of the annular structure 130. In this embodiment, the annular structure 130 is circular. In other embodiments, the annular structures 120 and 130 may be of other shapes as long as the distance between an outer point of the annular structure 120 and an inner point of the annular structure 130 is different from the distance between another outer point of the annular structure 120 and another inner point of the annular structure 130.

[0035] The annular structure 140 surrounds the annular structure 130. In this embodiment, the shape of the annular structure 140 is the same as that of the annular structure 130, but this is not intended to limit the invention. In other embodiments, the shape of the annular structure 140 differs from that of the annular structure 130.

[0036] In one possible embodiment, the distance between the outer side of the annular structure 130 and the inner side of the annular structure 140 remains constant. For example, in direction D1, the center point 110C intersects the outer side of the annular structure 130 at an outer point 130D and the inner side of the annular structure 140 at an inner point 140A. In direction D2, the center point 110C intersects the outer side of the annular structure 130 at an outer point 130E and the inner side of the annular structure 140 at an inner point 140B. In this example, the distance between the outer point 130D and the inner point 140A is equal to the distance between the outer point 130E and the inner point 140B. Furthermore, in direction D3, the center point 110C intersects the outer side of the annular structure 130 at an outer point 130F and the inner side of the annular structure 140 at an inner point 140C. In this example, the distance between the outer point 130F and the inner point 140C is equal to the distance between the outer point 130D and the inner point 140A, and equal to the distance between the outer point 130E and the inner point 140B.

[0037] In other embodiments, the distance between an outer point of the ring structure 130 and an inner point of the ring structure 140 may differ from the distance between another outer point of the ring structure 130 and another inner point of the ring structure 140. Furthermore, the present invention does not limit the angles between directions D1 and D3. In one possible embodiment, the angle between direction D1 and direction D2 is 45 degrees, and the angle between direction D2 and direction D3 is 45 degrees.

[0038] Figure 2A This is a schematic diagram of the electrostatic discharge structure of the present invention. As shown in the figure, the electrostatic discharge structure 200 includes region 210, and ring structures 220, 230 and 240. Figure 2A resemblance Figure 1 The difference is that, Figure 2A Region 210 and ring structure 220 are both circular in shape, and ring structures 230 and 240 are both square in shape.

[0039] In this embodiment, when the center point 210C of region 210 extends in directions D1 to D8, the center point 210C intersects the inner side of the ring structure 220 at inner points 220A to 220H. In this example, the distances between the center point 210C and the inner points 220A to 220H of the ring structure 220 are all the same. Furthermore, in directions D1 to D8, the center point 210C intersects the outer side of the ring structure 220 at outer points 220I to 220P and intersects the inner side of the ring structure 230 at inner points 230A to 230H. In this example, the distance between outer point 220I and inner point 230A is different from the distance between outer point 220J and inner point 230B.

[0040] In some embodiments, the distance between outer point 220I and inner point 230A is the same as the distance between outer point 220K and inner point 230C, the distance between outer point 220M and inner point 230E, and the distance between outer point 220O and inner point 230G. Additionally, the distance between outer point 220J and inner point 230B may be the same as the distance between outer point 220L and inner point 230D, the distance between outer point 220N and inner point 230F, and the distance between outer point 220P and inner point 230H.

[0041] The center point 210C extends in directions D1 to D8, intersecting the outer side of the ring structure 230 at outer points 230I to 230P, and intersecting the inner side of the ring structure 240 at inner points 240A to 240H. In this embodiment, the distance between the outer point 230I and the inner point 240A is the same as the distance between the outer point 230J and the inner point 240B, the distance between the outer point 230K and the inner point 240C, the distance between the outer point 230L and the inner point 240D, the distance between the outer point 230M and the inner point 240E, the distance between the outer point 230N and the inner point 240F, the distance between the outer point 230O and the inner point 240G, and the distance between the outer point 230P and the inner point 240H.

[0042] Figure 2B This is a schematic diagram of the region allocation of the electrostatic discharge structure of the present invention. In this embodiment, the ring structure 220 has regions 221 and 222. The conductivity type of region 221 may be the same as or different from that of region 222. The present invention does not limit the number of regions. The ring structure 220 includes more regions, such as 223 to 228, but this is not intended to limit the present invention. In other embodiments, the ring structure 220 has other numbers of regions.

[0043] Regions 221 to 228 are arranged sequentially to form a ring structure 220. In this example, each of regions 221 to 228 is adjacent to and contacts the other two regions. For example, region 222 is located between regions 221 and 223 and contacts regions 221 and 223. In one possible embodiment, regions 221, 223, 225, and 227 have the same conductivity type, and regions 222, 224, 226, and 228 have the same conductivity type.

[0044] Additionally, the annular structure 230 has regions 231 and 232. The conductivity type of region 231 may be the same as or different from that of region 232. Furthermore, the conductivity type of region 231 may be the same as or different from that of region 221, and the conductivity type of region 232 may be the same as or different from that of region 222. In some embodiments, the annular structure 230 may have more regions, such as 233 to 238, but this is not intended to limit the invention.

[0045] Regions 231 to 238 are arranged sequentially to form a ring structure 230. In this example, each of regions 231 to 238 is adjacent to and contacts two regions. For example, region 232 is located between regions 231 and 233 and contacts regions 231 and 233. Furthermore, regions 231 to 238 correspond to regions 221 to 228, respectively. In one possible embodiment, regions 231, 233, 235, and 237 have the same conductivity type, and regions 232, 234, 236, and 238 have the same conductivity type.

[0046] In some embodiments, regions 210, 221, and 231 constitute a first electrostatic discharge element, and regions 210, 222, and 232 constitute a second electrostatic discharge element. The first electrostatic discharge element may be the same as or different from the second electrostatic discharge element. In one possible embodiment, at least one of the first and second electrostatic discharge elements is a PNP bipolar transistor, an NPN bipolar transistor, or a silicon controlled rectifier (SCR).

[0047] In other embodiments, regions 210, 223, and 233 constitute a third electrostatic discharge element; regions 210, 224, and 234 constitute a fourth electrostatic discharge element; regions 210, 225, and 235 constitute a fifth electrostatic discharge element; regions 210, 226, and 236 constitute a sixth electrostatic discharge element; regions 210, 227, and 237 constitute a seventh electrostatic discharge element; and regions 210, 228, and 238 constitute an eighth electrostatic discharge element. One of the first to eighth electrostatic discharge elements may be the same as or different from another of the first to eighth electrostatic discharge elements. In one possible embodiment, the first, third, fifth, and seventh electrostatic discharge elements are of the same type, and the second, fourth, sixth, and eighth electrostatic discharge elements are of the same type. In this example, the type of the first electrostatic discharge element may be different from the type of the second electrostatic discharge element.

[0048] Figure 2C This is a schematic diagram of the electrical contacts of the electrostatic discharge structure 200 of the present invention. As shown, the electrostatic discharge structure 200 further includes a plurality of electrical contacts 250 and a plurality of electrical contacts 260. The electrical contacts 250 are uniformly disposed within the annular structure 220. The annular structure 220 is electrically connected to a first input / output pin (not shown) through the electrical contacts 250. The electrical contacts 260 are uniformly disposed within the annular structure 230. The annular structure 230 is electrically connected to a second input / output pin (not shown) through the electrical contacts 260. In some embodiments, the first input / output pin may be electrically connected to the second input / output pin.

[0049] In other embodiments, region 210 has multiple electrical contacts (not shown), and ring structure 240 also has multiple electrical contacts (not shown). In this example, region 210 is electrically connected to a third input / output pin via electrical contacts, and ring structure 240 is electrically connected to a fourth input / output pin via electrical contacts. When no electrostatic discharge event occurs, the first and second input / output pins receive a first operating voltage, the third input / output pin receives a second operating voltage, and the fourth input / output pin receives a third operating voltage. In some embodiments, the first operating voltage is less than the second operating voltage, and the third operating voltage may be equal to or less than the first operating voltage.

[0050] Figure 3A for Figure 2B The electrostatic discharge structure is shown in cross-sectional view along the dashed line AA'. Region 210 includes doped regions 211 and 212. The conductivity of doped region 211 may be the same as or different from that of doped region 212. When the conductivity of doped region 211 is the same as that of doped region 212, doped regions 211 and 212 may be integrated into a single doped region. When the conductivity of doped region 211 is different from that of doped region 212, doped region 211 may contact doped region 212. In another possible embodiment, when the conductivity of doped region 211 is different from that of doped region 212, an isolation structure (not shown) is provided between doped regions 211 and 212 to separate them. In some embodiments, doped region 212 is a ring structure (not shown) surrounding doped region 211.

[0051] In other embodiments, doped regions 211 and 212 are disposed within a well W1. The well W1 has a first conductivity type. In this example, when the conductivity type of doped region 211 or 212 is the same as the conductivity type of the well W1, the doping concentration of doped region 211 or 212 is higher than the doping concentration of the well W1. In some embodiments, doped regions 211 and 212 are electrically connected to the input / output pin IO_3 via at least one electrical contact (not shown).

[0052] The conductivity type of region 221 may be the same as or different from that of region 231. In this embodiment, an isolation structure 322A is provided between regions 221 and 231. The isolation structure 322A has a width DS1 and separates regions 221 and 231. In one possible embodiment, regions 221 and 231 are disposed in well W2. Well W2 has a second conductivity type. The second conductivity type is different from the first conductivity type. For example, the second conductivity type is P-type and the first conductivity type is N-type. In another possible embodiment, the second conductivity type is N-type and the first conductivity type is P-type. In some embodiments, when the conductivity type of region 221 or 231 is the same as the conductivity type of well W2, the doping concentration of region 221 or 231 is higher than the doping concentration of well W2.

[0053] In other embodiments, region 221 is electrically connected to input / output pin IO_1 via at least one electrical contact (not shown), and region 231 is electrically connected to input / output pin IO_2 via at least one electrical contact (not shown). In one possible embodiment, input / output pin IO_1 is electrically connected to input / output pin IO_2.

[0054] Region 241 is part of the ring structure 240 and has a second conductivity type. The doping concentration of region 241 is higher than that of well W2. In one possible embodiment, region 241 is disposed within substrate 310 as an electrical contact point of substrate 310. In this embodiment, substrate 310 has a second conductivity type. The doping concentration of substrate 310 is lower than that of well W2. In some embodiments, wells W1 and W2 are disposed within substrate 310.

[0055] In other embodiments, the electrostatic discharge structure 200 further includes isolation structures 321 and 323A. Isolation structure 321 separates the doped region 212 from the region 221. Isolation structure 323A separates the regions 231 and 241. In this embodiment, the doped region 211, the doped region 212, and the regions 221 and 231 constitute a first electrostatic discharge element. Figure 4A for Figure 3A A schematic diagram of the types of the first electrostatic discharge element.

[0056] In one possible embodiment, the conductivity of doped regions 211 and 212 is N-type. In this example, when the conductivity of region 221 is different from that of region 231, doped regions 211, 212, 221, and 231 constitute an NPN bipolar transistor. For example, when the conductivity of region 221 is N-type and the conductivity of region 231 is P-type, doped regions 211, 212, 221, and 231 constitute a bipolar transistor NPN1. In this case, doped regions 211 and 212, along with well W1, serve as the collector of bipolar transistor NPN1. Well W2 and region 231 serve as the base of bipolar transistor NPN1. Region 221 serves as the emitter of bipolar transistor NPN1. When the conductivity of region 221 is P-type and the conductivity of region 231 is N-type, doped regions 211, 212, 221, and 231 constitute a bipolar transistor NPN2. At this point, doped regions 211 and 212, along with well W1, serve as the collector of the bipolar transistor NPN2. Well W2 and region 221 serve as the base of the bipolar transistor NPN2. Region 231 serves as the emitter of the bipolar transistor NPN2.

[0057] In another possible embodiment, regions 221 and 231 are both P-type. In this example, when the conductivity of doped region 211 is different from that of doped region 212, doped region 211, doped region 212, regions 221, and 231 constitute a PNP type bipolar transistor. For example, when the conductivity of doped region 211 is N-type and the conductivity of doped region 212 is P-type, doped region 211, doped region 212, regions 221, and 231 constitute a bipolar transistor PNP1. In this case, doped region 212 serves as the emitter of bipolar transistor PNP1. Doped region 211 and well W1 serve as the base of bipolar transistor PNP1. Region 221, region 231, and well W2 serve as the collector of bipolar transistor PNP1. However, when the conductivity of doped region 211 is P-type and the conductivity of doped region 212 is N-type, doped regions 211, 212, regions 221, and 231 constitute a bipolar transistor PNP2. In this example, doped region 212 and well W1 serve as the base of bipolar transistor PNP2. Doped region 211 serves as the emitter of bipolar transistor PNP2. Regions 221, 231, and well W2 serve as the collector of bipolar transistor PNP2.

[0058] In other embodiments, when the conductivity type of doped region 211 is different from that of doped region 212, and the conductivity type of region 221 is different from that of region 231, doped region 211, doped region 212, region 221, and region 231 constitute a silicon controlled rectifier (SCR1). For example, the conductivity types of doped region 211 and region 221 are N-type, and the conductivity types of doped region 212 and region 231 are P-type. In this example, since doped region 212, doped region 211, well W1, well W2, region 231, and region 221 constitute a PNPN structure, doped region 212, doped region 211, region 231, and region 221 constitute a SCR1.

[0059] When the conductivity of doped region 211 and region 231 is N-type and the conductivity of doped region 212 and region 221 is P-type, since doped region 212, doped region 211, well W1, well W2, region 221, and region 231 form a PNPN structure, doped region 212, doped region 211, region 221, and region 231 constitute a silicon controlled rectifier (SCR2).

[0060] When the conductivity of doped region 211 and region 231 is P-type and the conductivity of doped region 212 and region 221 is N-type, since doped region 211, doped region 212, well W1, well W2, region 231, and region 221 form a PNPN structure, doped region 211, doped region 212, region 231, and region 221 constitute a silicon controlled rectifier (SCR3).

[0061] When the conductivity of doped region 211 and region 221 is P-type and the conductivity of doped region 212 and region 231 is N-type, since doped region 211, doped region 212, well W1, well W2, region 221, and region 231 form a PNPN structure, doped region 211, doped region 212, region 221, and region 231 constitute a silicon controlled rectifier (SCR4).

[0062] Figure 3B for Figure 2B A cross-sectional view of the electrostatic discharge structure along the dashed line BB'. Figure 3B resemblance Figure 3A The difference lies in the fact that the width DS2 of the isolation structure 322B between regions 222 and 232 is greater than that of the isolation structure 322B. Figure 3A The width DS1 of the isolation structure 322A between regions 221 and 231. In one possible embodiment, the area of ​​the isolation structure 322B mapped to the substrate 310 is larger than the area of ​​the isolation structure 322A mapped to the substrate 310.

[0063] An isolation structure 322B is disposed within the well W2, separating regions 222 and 223. In other embodiments, region 222 is electrically connected to input / output pin IO_1 via at least one electrical contact (not shown), and region 232 is electrically connected to input / output pin IO_2 via at least one electrical contact (not shown). The conductivity type of region 222 may be the same as or different from that of region 232. Taking region 222 as an example, when the conductivity type of region 222 is the same as that of well W2, the doping concentration of region 222 is higher than that of well W2. When the conductivity type of region 222 is the same as that of well W1, the doping concentration of region 222 is higher than that of well W1. Furthermore, Figure 3B Region 242 is part of the ring structure 240. Because the characteristics of region 242 are similar to... Figure 3A The region 241 is not discussed further.

[0064] In this embodiment, doped region 211, doped region 212, region 222 and 232 constitute a second electrostatic discharge element. Figure 4B for Figure 3BA schematic diagram of the types of the second electrostatic discharge element. In one possible embodiment, the conductivity of doped regions 211 and 212 is N-type. In this example, if the conductivity of region 222 is N-type and the conductivity of region 232 is P-type, then doped regions 211, 212, 222, and 232 constitute an NPN bipolar transistor. In this example, doped regions 211 and 212, along with well W1, serve as the collector of a bipolar transistor NPN3. Well W2 and region 232 serve as the base of the bipolar transistor NPN3. Region 222 serves as the emitter of the bipolar transistor NPN3. However, if the conductivity of region 222 is P-type and the conductivity of region 232 is N-type, then doped regions 211, 212, 222, and 232 constitute an NPN bipolar transistor. In this case, doped regions 211 and 212, along with well W1, serve as the collector of a bipolar transistor NPN4. Well W2 and region 222 serve as the base of the bipolar transistor NPN4. Region 232 serves as the emitter of the bipolar transistor NPN4.

[0065] In another possible embodiment, regions 222 and 232 are both P-type, and the conductivity of doped region 211 is different from that of doped region 212. In this example, if the conductivity of doped region 211 is N-type and the conductivity of doped region 212 is P-type, then doped region 211, doped region 212, regions 222, and 232 constitute a PNP bipolar transistor. In this case, doped region 211 and well W1 serve as the base of a bipolar transistor PNP3. Doped region 212 serves as the emitter of bipolar transistor PNP3. Regions 222, 232, and well W2 serve as the collector of bipolar transistor PNP3. If the conductivity of doped region 211 is P-type and the conductivity of doped region 212 is N-type, then doped region 211, doped region 212, regions 222, and 232 constitute a PNP bipolar transistor. In this case, doped region 211 serves as the emitter of bipolar transistor PNP4. Doped region 212 and well W1 serve as the base of bipolar transistor PNP4. Regions 222, 232, and well W2 serve as the collector of bipolar transistor PNP4.

[0066] In other embodiments, when the conductivity type of doped region 211 is different from that of doped region 212, and the conductivity type of region 222 is different from that of region 232, doped region 211, doped region 212, region 222, and region 232 constitute a silicon controlled rectifier (SCR5). For example, the conductivity types of doped region 211 and region 222 are N-type, and the conductivity types of doped region 212 and region 232 are P-type. In this example, since doped region 212, doped region 211, wells W1 and W2, region 232, and region 222 constitute a PNPN structure, doped region 212, doped region 211, region 232, and region 222 constitute a SCR5.

[0067] When the conductivity of doped region 211 and region 232 is N-type and the conductivity of doped region 212 and region 222 is P-type, since doped region 212, doped region 211, well W1, well W2, region 222, and region 232 form a PNPN structure, doped region 212, doped region 211, region 222, and region 232 constitute a silicon controlled rectifier (SCR6).

[0068] When the conductivity of doped region 211 and region 232 is P-type and the conductivity of doped region 212 and region 222 is N-type, since doped region 211, doped region 212, well W1, well W2, region 232, and region 222 form a PNPN structure, doped region 211, doped region 212, region 232, and region 222 constitute a silicon controlled rectifier (SCR7).

[0069] When the conductivity of doped region 211 and region 222 is P-type and the conductivity of doped region 212 and region 232 is N-type, since doped region 211, doped region 212, well W1, well W2, region 222, and region 232 form a PNPN structure, doped region 211, doped region 212, region 222, and region 232 constitute a silicon controlled rectifier (SCR8).

[0070] Please refer to Figure 2B Assume that regions 210 (including doped regions 211 and 212), 221, and 231 constitute a first electrostatic discharge (ESD) element, and regions 210 (including doped regions 211 and 212), 222, and 232 constitute a second ESD element. In this example, since the width DS1 between regions 221 and 231 is smaller than the width DS2 between regions 222 and 232, the conduction impedance of the first ESD element is smaller than that of the second ESD element. Therefore, when an ESD event occurs in region 210 and the ring structures 220 and 230 are coupled to ground, the second ESD element conducts first, followed by the first ESD element.

[0071] In another possible embodiment, regions 210, 223, and 233 constitute a third electrostatic discharge (ESD) element. In this example, since the width DS3 between regions 223 and 233 is smaller than the width DS2 between regions 222 and 232, the conduction impedance of the third ESD element is smaller than that of the second ESD element. Therefore, when an ESD event occurs in region 210 and the ring structures 220 and 230 are coupled to ground, the second ESD element conducts first, followed by the third ESD element. In some embodiments, when the width DS3 is greater than the width DS1, the third ESD element conducts first, followed by the first ESD element. However, when the width DS3 is less than the width DS1, the first ESD element conducts first, followed by the third ESD element.

[0072] In this embodiment, the distance (i.e., DS1 to DS3) between the outer side of the ring structure 220 and the inner side of the ring structure 230 is related to the conduction impedance of the electrostatic discharge element. The greater the distance between the outer side of the ring structure 220 and the inner side of the ring structure 230, the greater the conduction impedance of the corresponding electrostatic discharge element. Conversely, the smaller the distance between the outer side of the ring structure 220 and the inner side of the ring structure 230, the smaller the conduction impedance of the corresponding electrostatic discharge element. When an electrostatic discharge event occurs, the electrostatic discharge element with a large conduction impedance conducts earlier than the electrostatic discharge element with a small conduction impedance.

[0073] In some embodiments, the first and second electrostatic discharge (ESD) elements may both be bipolar transistors. In this example, since the first and second ESD elements do not experience snapback breakdown, mis-conduction by the first and second ESD elements under normal operation (without an ESD event) can be avoided. In another possible embodiment, the first and second ESD elements may both be silicon controlled rectifiers (SCRs). In this example, because the first and second ESD elements have low on-resistance, they can quickly release the ESD current when an ESD event occurs.

[0074] In other embodiments, one of the first and second electrostatic discharge elements is a bipolar transistor, and the other is a silicon controlled rectifier (SCR). In this example, when an electrostatic discharge event occurs, the electrostatic discharge element with a larger on-resistance (such as the bipolar transistor) turns on first, followed by the electrostatic discharge element with a smaller on-resistance (such as the SCR). By having the SCR turn on later than the bipolar transistor, the holding voltage of the SCR can be increased, preventing the SCR from being falsely triggered under normal operation, and allowing for rapid release of the electrostatic discharge current when an electrostatic discharge event occurs.

[0075] Please refer to Figure 2B By controlling the conductivity of regions 221-228 and 231-238, the electrostatic discharge structure 200 may have eight electrostatic discharge elements. For example, regions 210, 221, and 231 form a first electrostatic discharge element, regions 210, 222, and 232 form a second electrostatic discharge element, and regions 210, 223, and 233 form a third electrostatic discharge element. In other embodiments, the electrostatic discharge structure 200 has other numbers of electrostatic discharge elements when the annular structures 220 and 230 have other numbers of regions. Furthermore, by controlling the conductivity of regions 221-228 of the annular structure 220 and regions 231-238 of the annular structure 230, the electrostatic discharge structure 200 has other types of electrostatic discharge elements.

[0076] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any person skilled in the art can make modifications and refinements without departing from the spirit and scope of the invention. For example, the systems, apparatus, or methods described in the embodiments of the present invention can be implemented in physical embodiments of hardware, software, or a combination of hardware and software. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An electrostatic discharge structure, characterized in that, include: First area; A first ring structure surrounds the first region, and has a second region and a third region; A second ring structure surrounds the first ring structure and has a fourth region and a fifth region; as well as A third ring structure surrounds the second ring structure. The distance between the second and fourth regions is different from the distance between the third and fifth regions.

2. The electrostatic discharge structure as described in claim 1, characterized in that, The shape of the first ring structure is different from that of the second ring structure.

3. The electrostatic discharge structure as described in claim 2, characterized in that, The shape of the second ring structure is the same as that of the third ring structure.

4. The electrostatic discharge structure as described in claim 2, characterized in that, The conductivity type of the second region is different from that of the fourth region; the conductivity type of the first region is N-type.

5. The electrostatic discharge structure as described in claim 4, characterized in that, The first region, the second region, and the fourth region constitute a first transistor.

6. The electrostatic discharge structure as described in claim 2, characterized in that, The first region includes a first doped region and a second doped region. The conductivity of the first doped region is different from that of the second doped region, and the conductivity of the second region is the same as that of the fourth region.

7. The electrostatic discharge structure as described in claim 6, characterized in that, The second doped region surrounds the first doped region.

8. The electrostatic discharge structure as described in claim 6, characterized in that, The first region, the second region, and the fourth region constitute a second transistor.

9. The electrostatic discharge structure as described in claim 8, characterized in that, The conductivity type of the third region is different from that of the fifth region.

10. The electrostatic discharge structure as described in claim 9, characterized in that, The first, third, and fifth regions constitute a silicon controlled rectifier.

11. The electrostatic discharge structure as described in claim 10, characterized in that, Including: A first input / output pin is electrically connected to the first doped region and the second doped region; A second input / output pin, electrically connected to the second ring structure and the third ring structure; and A third input / output pin is electrically connected to the third ring structure.

12. The electrostatic discharge structure as described in claim 11, characterized in that, Including: A first isolation structure separates the second and fourth regions; as well as A second isolation structure separates the third and fifth regions.

13. The electrostatic discharge structure as described in claim 12, characterized in that, When an electrostatic discharge event occurs, the silicon controlled rectifier turns on first, and then the second transistor turns on.

14. The electrostatic discharge structure as described in claim 12, characterized in that, Including: One base; A first well is disposed within the substrate; as well as A second well is disposed within the substrate. The first doped region and the second doped region are disposed in the first well, the first ring structure and the second ring structure are disposed in the second well, and the third ring structure is disposed in the substrate.

15. The electrostatic discharge structure as described in claim 14, characterized in that, The area of ​​the first isolation structure mapped onto the substrate is smaller than the area of ​​the second isolation structure mapped onto the substrate.

16. The electrostatic discharge structure as described in claim 14, characterized in that, The conductivity type of the first well is different from that of the second well, and the conductivity type of the second well is the same as that of the substrate.

17. The electrostatic discharge structure as described in claim 16, characterized in that, Including: A third isolation structure is disposed within the first well and separates the first doped region from the second doped region.

18. The electrostatic discharge structure as described in claim 1, characterized in that: The first ring structure further includes a sixth region and a seventh region. The conductivity type of the sixth region is the same as that of the second region, and the conductivity type of the seventh region is the same as that of the third region. The third region comes into contact with the second and sixth regions; The sixth region comes into contact with the third and seventh regions.

19. The electrostatic discharge structure as described in claim 18, characterized in that: The second ring structure further includes an eighth region and a ninth region. The conductivity type of the eighth region is the same as that of the fourth region, and the conductivity type of the ninth region is the same as that of the fifth region. The fifth region comes into contact with the fourth and eighth regions; The eighth region comes into contact with the fifth and ninth regions.

20. The electrostatic discharge structure as described in claim 19, characterized in that: The first, second, and fourth regions constitute a first electrostatic discharge element; the first, third, and fifth regions constitute a second electrostatic discharge element; the first, sixth, and eighth regions constitute a third electrostatic discharge element; and the first, seventh, and ninth regions constitute a fourth electrostatic discharge element. When the first electrostatic discharge element is turned on, the third electrostatic discharge element is turned on. When the second electrostatic discharge element is turned on, the fourth electrostatic discharge element is turned on.

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