CN106298745A - Connecting pad electrostatic protection element of integrated circuit - Google Patents

Abstract

A connection pad electrostatic protection component of an integrated circuit. The integrated circuit includes a substrate and a connection pad formed above the substrate. The electrostatic protection component includes an electrostatic discharge structure and a plurality of conductive layers spaced up and down. The electrostatic discharge structure forms Inside the substrate and below the connection pad, the plurality of conductive layers are formed above the substrate and between the electrostatic discharge structure and the connection pad. The plurality of conductive layers electrically connect the electrostatic discharge structure and the connection pad. Connection pad; when static electricity is generated in the connection pad, the electrostatic energy enters the electrostatic discharge structure through the conductive layer, and the electrostatic discharge structure guides the static electricity to the ground, achieving the effect of electrostatic protection.

Description

Integrated circuit connection pad electrostatic protection components

technical field

The invention relates to an electrostatic protection element, in particular to an electrostatic protection element for a connection pad of an integrated circuit.

Background technique

The integrated circuit mainly includes a core circuit (core), which is located under the connection pad (bondpad), and the connection pad is electrically connected to the core circuit (core), and the connection pad can be used as a signal input/output (I/O) terminal or a power supply (power) terminal use. With the advancement of semiconductor technology, the size of integrated circuits has become smaller and smaller, and the layout of its internal core circuits has become more and more precise. However, when the connection pads generate static electricity, the static electricity will enter the core circuit through the connection pads, which may cause the core circuit to be damaged by static electricity.

Contents of the invention

Therefore, the main purpose of the present invention is to provide an electrostatic protection component for the connection pad of an integrated circuit, so that the integrated circuit can be prevented from being harmed by static electricity.

In the connection pad electrostatic protection component of the integrated circuit of the present invention, the integrated circuit includes a substrate and the connection pad formed on the substrate, and the static protection component includes:

An electrostatic discharge structure formed on the substrate and located below the connection pad, the electrostatic discharge structure includes a central electrode area and a plurality of peripheral electrode areas, and the plurality of peripheral electrode areas surround the central electrode successively from inside to outside the periphery of the district; and

A plurality of conductive layers spaced up and down are formed above the substrate and located between the electrostatic discharge structure and the connection pad, and the plurality of conductive layers are electrically connected to the electrostatic discharge structure and the connection pad.

According to the structure of the present invention, when static electricity is generated on the connection pad, the electrostatic energy enters the electrostatic discharge structure through the conductive layer, and the electrostatic discharge structure can guide the static electricity to the ground, so that the static electricity will not enter the integrated circuit The core circuit achieves the effect of electrostatic protection. In addition, since the ESD structure is directly formed on the substrate and located under the connection pads, in other words, the ESD structure only occupies the layout area of the connection pads, so that the present invention achieves an efficient space configuration, Minimize the layout area of the ESD structure.

The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but not as a limitation of the present invention.

Description of drawings

Fig. 1: the schematic top view of the first preferred embodiment of the electrostatic protection element of the present invention;

Figure 2: a schematic cross-sectional view of Figure 1 (1);

Fig. 3: the schematic sectional view of Fig. 1 (two);

Fig. 4: the schematic diagram of this electrostatic discharge structure in the first preferred embodiment of the present invention;

Fig. 5: the schematic diagram of the first conductive layer in the first preferred embodiment of the present invention;

Fig. 6: the schematic diagram of the second conductive layer in the first preferred embodiment of the present invention;

Fig. 7: the equivalent circuit diagram of the electrostatic discharge structure of the present invention;

Figure 8: A schematic diagram of further forming an N-type well area in the first preferred embodiment of the present invention;

Fig. 9: the schematic diagram of this electrostatic discharge structure in the second preferred embodiment of the present invention;

Fig. 10: A schematic diagram of the conductive layer and the electrostatic discharge structure in the second preferred embodiment of the present invention.

Among them, reference signs

100 electrostatic discharge structure 10P type well area

11 connection pad 121 first N-type electrode area

122 Second N-type electrode area 123 Third N-type electrode area

124 P-type doped region 125P-type electrode region

13 field oxide layer 211 central conductor

212 conductive section 213 first conductive ring body

214 Second conductive grounding ring body 215 Connecting part

31, 32, 33, 34 guide holes 411 central conductor

412 conductive grounding ring body 413 extension

51, 52, 53, 54 guide hole 60 sheath

61 Connection pad window opening 71 First N-type well area

72 Second N-type well area 811 Central conductor

812 arc section 813 bridging part

M1 first conductive layer M2 second conductive layer

M3 third conductive layer B substrate

R1 first resistor R2 second resistor

ZD zener diode FOD field oxidation element

detailed description

Below in conjunction with accompanying drawing, structural principle and working principle of the present invention are specifically described:

An integrated circuit mainly includes a substrate and a conductive layer and a bondpad located above the substrate. The substrate forms various circuit elements (such as resistors, capacitors, transistors, etc.) by means of doping, diffusion, or ion implantation. These circuit elements are electrically connected to each other through the conductive layer to form a core circuit (core), and the connection pads are electrically connected to the conductive layer and can be used as signal input/output (I/O) terminals or power terminals.

Taking any connection pad as an example, the electrostatic protection device of the present invention includes an electrostatic discharge structure and a plurality of conductive layers arranged at intervals up and down. The electrostatic discharge structure is formed inside the substrate and includes a central electrode area and a plurality of peripheral electrode areas. , the plurality of peripheral electrode regions surround the periphery of the central electrode region sequentially from inside to outside. 1-3, the electrostatic discharge structure 100 is formed in the P-well region (P-well) 10 of the substrate B of the integrated circuit, the electrostatic discharge structure 100 is located under the connection pad 11, and the The ESD structure 100 covers the connection pad 11 . 2-4, the ESD structure 100 includes a first N-type electrode region 121, a second N-type electrode region 122, a third N-type electrode region 123, a P-type doped region 124 and a P-type electrode region 125, the aforementioned central electrode region is the first N-type electrode region 121, and the peripheral electrode region includes the two N-type electrode regions 122, the third N-type electrode region 123 and the P-type electrode region 125. These electrode regions 121, 122, 123, 125 are formed on the surface of the substrate B, the P-type doped region 124 is located below the first N-type electrode region 121, and the doping concentration of the P-type doped region 124 is higher than the doping concentration of the P-type well region 10 . Please refer to FIG. 4 , the second N-type electrode region 122 , the third N-type electrode region 123 and the P-type electrode region 125 are centered on the first N-type electrode region 121 and surround the first N-type electrode region 121 from inside to outside. The periphery of the first N-type electrode region 121, please refer to FIG. 2 and FIG. The regions 121, 122, 123, 125 are separated from each other to avoid short circuits.

In the first preferred embodiment shown in FIG. 4, the distribution area of the first N-type electrode region 121 is rectangular, and the second N-type electrode region 122 and the P-type electrode region 125 are annular closed rectangles, each having Four segments. The third N-type electrode region 123 is four independent and unconnected segments located between the second N-type electrode region 122 and the four segments of the P-type electrode region 125 .

Please refer to FIG. 2 and FIG. 3 , the conductive layer successively includes a first conductive layer M1 , a second conductive layer M2 and a third conductive layer M3 from bottom to top. Please refer to FIG. 5 , the first conductive layer M1 includes a central conductor 211 , four independent conductive segments 212 , a first conductive ring 213 and a second conductive ground ring 214 . The central conductor 211 is located directly above the first N-type electrode region 121 , and its bottom surface is electrically connected to the first N-type electrode region 121 through a contact 31 . The four conductive segments 212 are respectively located above the four segments of the second N-type electrode region 122 , and the bottom surfaces thereof are respectively electrically connected to the second N-type electrode region 122 through the via holes 32 . The first conductive ring body 213 is in the form of a ring-shaped closed rectangle, located above the four third N-type electrode regions 123 and covering the third N-type electrode regions 123, the first conductive ring body 213 is connected through the connecting portion 215 The central conductor 211 is electrically connected, and the bottom surface of the first conductive ring 213 is electrically connected to the third N-type electrode region 123 through the via hole 33 . The second conductive grounding ring body 214 is also in the form of a ring-shaped closed rectangle, which is located above the P-type electrode area 125 and covers the P-type electrode area 125. The bottom surface of the second conductive grounding ring body 214 is electrically connected through the guide hole 34 The P-type electrode region 125 is connected.

Please refer to FIG. 6, the second conductive layer M2 includes a central conductor 411 and a conductive ground ring 412, the central conductor 411 is located above the central conductor 211 of the first conductive layer M1, the second conductive layer The bottom surface of the central conductor 411 of M2 is electrically connected to the central conductor 211 of the first conductive layer M1 through the via hole 51 . The conductive ground ring body 412 is located above the second conductive ground ring body 214 of the first conductive layer M1 and covers the second conductive ground ring body 214 , and the bottom surface is electrically connected to the second conductive ground ring body through the via hole 52 214, the conductive grounding ring body 412 of the second conductive layer M2 is an annular closed rectangle and has four sections, the central inner side of each section extends toward the central conductor 411 to form an extension part 413, and the four sections Ends of the extension portions 413 respectively cover the four conductive segments 212 of the first conductive layer M1 , and the bottom surface of each extension portion 413 is electrically connected to the corresponding conductive segments 212 through the via holes 53 .

As shown in FIG. 2 and FIG. 3, the third conductive layer M3 includes the connection pad 11, the connection pad 11 is located above the central conductor 411 of the second conductive layer M2, and the passivation 60 is on the second conductive layer M2. A connection pad opening 61 is formed on the top surface of the connection pad 11 of the third conductive layer M3, and the connection pad 11 is exposed in the connection pad opening 61. The bottom surface of the connection pad 11 is electrically connected to the second conductive layer M2 through the via hole 54. Central conductor 411 . For the convenience of illustration, the size of the connection pad 11 and the ESD structure 100 in each figure is only a schematic diagram. For example, the actual size ratio of the connection pad 11 to the ESD structure 100 is about 0.8:1.

According to the aforementioned electrical connection relationship, for the electrostatic discharge structure 100, the first N-type electrode region 121 and the third N-type electrode region 123 are electrically connected to the connection pad 11, and the second N-type electrode region 122 and the third N-type electrode region 123 are electrically connected to the connection pad 11. The P-type electrode region 125 can be connected to ground, so that the electrostatic discharge structure 100 forms an equivalent circuit diagram shown in FIG. 7, which includes a Zener diode ZD, a first resistor R1, and a field-oxide device FOD ) and a second resistor R2.

The Zener diode ZD is composed of the first N-type electrode region 121 and the P-type doped region 124, and the P-N junction between the first N-type electrode region 121 and the P-type doped region 124 forms the P-N junction of the Zener diode ZD. meeting. The field oxide device FOD consists of the second N-type electrode region 122 , the third N-type electrode region 123 and the P-type electrode region 125 to form a transistor. The first resistance R1 is a parasitic resistance generated by the P-type well region 10 , and the second resistance R2 is a parasitic resistance on the third N-type electrode region 123 , which is generated by the layout change of the via 31 .

As shown in FIG. 7, the zener diode ZD is connected in series with the first resistor R1, and is connected between the connection pad 11 and the ground. The field oxide device FOD includes a first terminal, a second terminal and a control terminal. The first terminal and the second terminal are respectively connected to the connection pad 11 and ground, the control terminal is connected to the series connection node of the Zener diode ZD and the first resistor R1, and the second resistor R2 is connected to the field oxidation device FOD in series. The field oxide device FOD can be a field oxide transistor, then the third N-type electrode region 123 is used as the first terminal and is a drain (Drain), and the second N-type electrode region 122 is used as the second terminal and is a source. Pole (Source), the P-type electrode region 125 is used as the control terminal and the gate (Gate); or the field oxide device FOD can be a bipolar junction transistor (BJT), then the third N-type electrode region 123 As the first terminal, it is a collector (Collector), as the second terminal, the second N-type electrode region 122 is an emitter (Emitter), and as the control terminal, the P-type electrode region 125 is a base electrode (Base). ).

When the connection pad 11 generates a surge voltage caused by static electricity, the surge voltage will cause the Zener diode ZD to collapse, and the terminal voltage of the first resistor R1 can conduct the field oxidation element FOD. At this time, the second resistor R2 is to limit the current and buffer the static electricity, so the static electricity is grounded through the field oxidation element FOD after being buffered by the second resistor R2, so as to prevent the field oxidation element FOD from being damaged by static electricity, and more importantly, the static electricity will not reach The core circuit (core) of the integrated circuit achieves the effect of electrostatic protection. On the other hand, with the layout of the second N-type electrode region 122, the third N-type electrode region 123 and the P-type electrode region 125 successively surrounding the periphery of the first N-type electrode region 121, the static electricity can be supplied in all directions. The discharge path makes the electrostatic protection more efficient. In addition, because the four sections of the third N-type electrode region 123 are independent and not connected to each other, when static electricity enters each section of the third N-type electrode region 123, it can avoid the second N-type electrode region 122 Or the case where the P-type electrode region 125 generates a tip discharge.

Please refer to FIG. 8, a first N-type well region 71 and a second N-type well region 72 can be further formed in the P-type well region 10, and the top of the first N-type well region 71 is connected to the first N-type electrode. The region 121 is located below the guide hole 31, and the bottom of the first N-type well region 71 extends to the edge of the P-type well region 10, and the top of the second N-type well region 72 is connected to the third N-type electrode region 123 And located below the guide hole 33 , and the bottom of the second N-type well region 72 also extends to the edge of the P-type well region 10 . The doping concentration of the first N-type well region 71 and the second N-type well region 72 is lower than that of the first N-type electrode region 121 and the third N-type electrode region 123 to provide an electrostatic buffer Function, can also produce the parasitic effect of the second resistor R2.

The aforementioned first preferred embodiment discloses an electrostatic discharge structure 100 with a rectangular layout. Please refer to the second preferred embodiment shown in FIG. The distribution area is circular, and the second N-type electrode region 122, the third N-type electrode region 123, and the P-type electrode region 125 are respectively ring-shaped, and centered on the first N-type electrode region 121. Surrounding the periphery of the first N-type electrode region 121 from inside to outside, because the second preferred embodiment adopts a circular layout, naturally there is no problem of tip discharge.

Same as the first preferred embodiment, the second preferred embodiment also includes a plurality of conductive layers arranged sequentially from bottom to top. Please refer to FIG. 10 , the conductive layer includes a first conductive layer, and the first conductive layer includes a central conductor 811 and an arc segment 812 . The central conductor 811 is located above the first N-type electrode region 121 , and its bottom surface is electrically connected to the first N-type electrode region 121 through via holes. The arc section 812 is located above the second N-type electrode area 122, and the bottom surface is electrically connected to the second N-type electrode area 122 through a guide hole, a channel is formed between the two ends of the arc section 812, and the center A bridge portion 813 extends from the conductor 811, the bridge portion 813 passes through the channel of the arc segment 812, and the end of the bridge portion 813 is located above the third N-type electrode region 123, the bottom surface of the end of the bridge portion 813 It is also electrically connected to the third N-type electrode region 123 through the via hole. By analogy as described in the first preferred embodiment, the second N-type electrode region 122 and the P-type electrode region 125 can be electrically connected to each other through other conductive layers, and the central conductor 811 can be connected to the connection pad through other conductive layers 11 electrical connections.

To sum up, since the electrostatic discharge structure 100 can be distributed in a rectangle or a circle, the user can choose a rectangular or circular electrostatic discharge structure 100 according to the actual layout requirements of the integrated circuit, so that the electrostatic protection device of the present invention can be used more flexible.

Certainly, the present invention also can have other multiple embodiments, without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding Changes and deformations should belong to the scope of protection of the appended claims of the present invention.

Claims (10)

1. A connection pad electrostatic protection element of an integrated circuit, the integrated circuit includes a substrate and a connection pad formed on the substrate, it is characterized in that the electrostatic protection element includes: An electrostatic discharge structure formed on the substrate and located below the connection pad, the electrostatic discharge structure includes a central electrode area and a plurality of peripheral electrode areas, and the plurality of peripheral electrode areas surround the central electrode successively from inside to outside the periphery of the district; and A plurality of conductive layers spaced up and down are formed above the substrate and located between the electrostatic discharge structure and the connection pad, and the plurality of conductive layers are electrically connected to the electrostatic discharge structure and the connection pad. 2. The electrostatic protection component for the connection pad of the integrated circuit according to claim 1, wherein the electrostatic discharge structure is formed in a P-type well region of the substrate; The central electrode region is a first N-type electrode region; The plurality of peripheral electrode areas include: a second N-type electrode region surrounding the periphery of the first N-type electrode region; a third N-type electrode region located on the periphery of the second N-type electrode region; and a P-type electrode region surrounding the third N-type electrode region; The electrostatic discharge structure also includes a P-type doped region located below the first N-type electrode region. 3. The electrostatic protection element for the connection pad of an integrated circuit according to claim 2, wherein a first N-type well region and a second N-type well region are formed in the P-type well region, and the first N-type well region The top of the well region is connected to the first N-type electrode region, and the top of the second N-type well region is connected to the third N-type electrode region; The doping concentration of the P-type doped region is higher than that of the P-type well region, and the doping concentration of the first N-type well region and the second N-type well region is lower than that of the first N-type electrode region and the doping concentration of the third N-type electrode region. 4. The electrostatic protection element for connection pads of integrated circuits according to claim 2 or 3, wherein the first N-type electrode region and the P-type doped region form a Zener diode, and the second N-type electrode region . The third N-type electrode region and the P-type electrode region form a field oxidation element, the P-type well region generates a parasitic first resistance, and the third N-type electrode region generates a parasitic second resistance; The zener diode is connected in series with the first resistor and is connected between the connection pad and the ground. The field oxide element includes a first terminal, a second terminal and a control terminal, and the first terminal and the second terminal are respectively connected to The connection pad is connected to the ground, the control terminal is connected to the series connection node of the Zener diode and the first resistor, and the second resistor is connected to the field oxidation element in series. 5. The electrostatic protection element for connection pads of integrated circuits according to claim 4, wherein the field oxide element is a field effect transistor, the third N-type electrode region is used as the first end and is a drain, the The second N-type electrode region is used as the second terminal as the source, and the P-type electrode region as the control terminal is used as the gate. 6. The electrostatic protection device for connection pads of integrated circuits according to claim 4, wherein the field oxide device is a bipolar junction transistor, and the third N-type electrode region is the collector as the first terminal , the second N-type electrode region is used as the second terminal as the emitter, and the P-type electrode region as the control terminal is used as the base. 7. The electrostatic protection component for the connection pad of the integrated circuit according to claim 4, characterized in that, the distribution area of the first N-type electrode region of the electrostatic discharge structure is rectangular; The second N-type electrode region and the P-type electrode region are annular and rectangular, forming four sections respectively; The third N-type electrode region is four independent and unconnected segments, respectively located between the second N-type electrode region and the four segments of the P-type electrode region. 8. The electrostatic protection component for connection pads of integrated circuits according to claim 7, wherein the conductive layer successively includes a first conductive layer, a second conductive layer and a third conductive layer from bottom to top ; The first conductive layer includes a central conductor, four independent conductive segments, a first conductive ring and a second conductive ground ring, the central conductor is located above the first N-type electrode region and is electrically conductive connected to the first N-type electrode region; the four conductive segments are respectively located above the four segments of the second N-type electrode region and electrically connected to the second N-type electrode region; the first conductive ring is a rectangular ring and is located above the four third N-type electrode regions and connected to the central conductor, and the first conductive ring is electrically connected to the third N-type electrode region; the second conductive ground ring is a rectangular ring And located above the P-type electrode area, and electrically connected to the P-type electrode area; The second conductive layer includes a central conductor and a conductive grounding ring, the central conductor is located above the central conductor of the first conductive layer and electrically connected to the central conductor of the first conductive layer; the conductive grounding ring The body is located above the second conductive ground ring body of the first conductive layer and is electrically connected to the second conductive ground ring body. The conductive ground ring body of the second conductive layer is rectangular and has four sections. The four areas The central part of the segment is respectively extended to the central conductor to form four extension parts, the ends of the four extension parts respectively cover the four conductive segments of the first conductive layer, and each extension part is electrically connected to the corresponding conductive segment; The third conductive layer is located above the central conductor of the second conductive layer, and is electrically connected to the central conductor of the second conductive layer and the connection pad. 9. The electrostatic protection component for connection pads of integrated circuits according to claim 4, characterized in that, the distribution area of the first N-type electrode region of the electrostatic discharge structure is circular, and the second N-type electrode region, the first N-type electrode region The three N-type electrode regions and the P-type electrode region are ring-shaped respectively, and take the first N-type electrode region as the center and continuously surround the periphery of the first N-type electrode region from inside to outside. 10. The electrostatic protection component for connection pads of integrated circuits according to claim 9, wherein the conductive layer comprises a first conductive layer comprising a central conductor and an arc segment, the central conductor is located at Above the first N-type electrode area and electrically connected to the first N-type electrode area, the arc-shaped section is located above the second N-type electrode area and electrically connected to the second N-type electrode area, the arc-shaped section A channel is formed between the two ends of the central conductor, and a bridging part extends outward from the central conductor. connected to the third N-type electrode region.