TWI406385B - Electrostatic discharge protection device - Google Patents

Abstract

An electrostatic discharge (ESD) protection device including a first discharge unit, a second discharge unit, a first trigger unit, and a second trigger unit is disclosed. The first discharge unit is serially connected to the second discharge unit between a first pad and a second pad to release ESD current. When an ESD event occurs, the first trigger unit triggers the first discharge unit. When the first discharge unit is triggered, the second trigger unit triggers the second discharge unit.

Description

Electrostatic discharge protection device

The present invention relates to an electrostatic discharge (ESD) protection device, and more particularly to a high voltage electrostatic discharge protection device having a high efficiency trigger circuit.

Component damage caused by Electrostatic Discharge (ESD) has become one of the most important reliability issues for integrated circuit products. In particular, as the size is continuously reduced to a depth of a micron, the gate oxide layer of the MOS semiconductor is also thinner and thinner, and the integrated circuit is more susceptible to damage due to the electrostatic discharge phenomenon. In order to avoid the ESD phenomenon from destroying the integrated circuit, a general solution is to provide an ESD protection device in the integrated circuit.

Figure 1 shows a conventional ESD protection device. As shown, the ESD protection device 100 has a detection circuit 110 and a protection circuit 130. When an ESD event occurs at the contact pad 121 and the contact pad 122 is at a ground potential, the detection circuit 110 triggers the protection circuit 130 to release the ESD current. However, since the detecting circuit 110 has the capacitance C and the resistance R, the space occupied by the ESD protection device 100 is large.

Figure 2 is a cross-sectional view of another conventional ESD protection device. The ESD protection device 200 is a low voltage Zener triggered voltage controlled rectifier. However, the ESD protection device 200 cannot be applied to high voltage components such as LEDs, LCD driver integrated circuits, or power management integrated circuits.

The present invention provides an electrostatic discharge protection device including a first discharge unit, a second discharge unit, a first trigger unit, and a second trigger unit. The first and second discharge units are connected in series between a first contact pad and a second contact pad for discharging an electrostatic discharge current. The first trigger unit includes a first transistor and at least one first diode. The first transistor and the first diode are connected in series between the first contact pad and the first discharge unit. When an electrostatic discharge event occurs, the first trigger unit triggers the first discharge unit. The second trigger unit includes a second transistor and is coupled between the first contact pad and the second discharge unit. The second transistor triggers the second discharge unit when the first discharge unit is triggered.

The present invention provides another electrostatic discharge protection device including a first discharge unit, a second discharge unit, a first trigger unit and a second trigger unit. The first and second discharge cells are connected in series between a first contact pad and a second contact pad. The first trigger unit is coupled between the first contact pad and the first discharge unit. The second trigger unit is coupled between the first contact pad and the second discharge unit. When the first trigger unit triggers the first discharge unit, the second trigger unit triggers the second discharge unit.

In order to make the features and advantages of the present invention more comprehensible, the preferred embodiments are described below, and are described in detail with reference to the accompanying drawings.

The ESD protection device proposed by the present invention is a high voltage (HV) device and has a high efficiency trigger circuit. Figure 3 is a schematic view of the ESD protection device of the present invention. As shown, the ESD protection device 300 is coupled between the contact pads 351 and 353. When an ESD event occurs at the contact pad 353 and the contact pad 351 is a grounding potential, the ESD protection device 300 can release the ESD current to ground.

As shown, the ESD protection device 300 includes discharge cells 311, 313 and triggering units 331, 333. The discharge cells 311 and 313 are connected in series between the contact pads 351 and 353. The present invention does not limit the kinds of discharge cells 311 and 313, and possible embodiments of the discharge cells 311 and 313 will be described later.

In this embodiment, the trigger unit 331 is coupled between the contact pad 353 and the discharge unit 311. When the ESD event occurs at the contact pad 353 and the contact pad 351 is at the ground potential, the trigger unit 331 triggers the discharge unit 311. Therefore, a current path is formed between the contact pad 353, the trigger unit 331, the discharge unit 311, and the contact pad 351.

The trigger unit 333 is coupled between the contact pad 353 and the discharge unit 313. When the trigger unit 331 triggers the discharge unit 311, the trigger unit 333 triggers the discharge unit 313. That is, after the current path is formed, the trigger unit 333 can trigger the discharge unit 313 so that the ESD current is started by the contact pad 353, and is discharged to the ground via the discharge cells 313, 311 and the contact pad 351.

Figure 4A is a possible embodiment of the ESD protection device of the present invention. As shown, the trigger unit 331 includes a transistor M _P1 and a diode module 431. The trigger unit 333 includes a transistor M _P2 . In this embodiment, the trigger units 331 and 333 can form a current mirror circuit.

In the present embodiment, the transistors M _P1 and M _P2 are both P-type transistors, but are not intended to limit the present invention. The gate of the transistor M _P1 is coupled to the drain, the source is coupled to the contact pad 353, and the drain is coupled to the cathode of the diode module 431. The gate of the transistor M _P2 is coupled to the gate of the transistor M _P1 , the source of which is coupled to the contact pad 353 , and the drain of the transistor is coupled to the discharge unit 313 .

As shown, the diode module 431 has diodes D ₁ -D _n . The arrangement of the diodes D ₁ to D _n is as shown in FIG. 4A, which is connected in series between the transistor M _P1 and the discharge cell 311. In this embodiment, the cathode of the diode D ₁ is used as the cathode of the diode module 431 and coupled to the drain of the transistor M _P1 .

The present invention does not limit the number of diodes in the diode module 431. In a possible embodiment, there may be only a single diode. In this example, the anode of the diode is coupled to the discharge unit 311, and the cathode thereof is coupled to the drain of the transistor M _P1 .

By controlling the number of diodes (i.e., controlling the breakdown voltage of the diode module 431), the ESD protection device 300 can be disabled in the normal mode of operation. For example, in the normal operation mode (the ESD event does not occur), when the operating voltage is less than the breakdown voltage of the diode module 431, the trigger unit 331 does not provide the trigger current to the discharge unit 311. Since the current path cannot be formed between the contact pad 353, the trigger unit 331, and the discharge unit 311 and the contact pad 351, the ESD protection device 300 does not operate.

However, in the ESD protection mode (the ESD event occurs), since the ESD voltage is much larger than the breakdown voltage of the diode module 431, the trigger unit 331 provides a trigger current to the discharge unit 311 for triggering the discharge unit 311. Therefore, a current path is formed between the contact pad 353, the trigger unit 331, the discharge unit 311, and the contact pad 351.

After the discharge unit 311 is triggered, the trigger unit 333 will provide a trigger current to the discharge unit 313 for triggering the discharge unit 313. When both of the discharge cells 313 and 311 are triggered, the ESD current can be started by the contact pad 353 and discharged to the ground via the discharge cells 313, 311.

In addition, in the present embodiment, the discharge cells 311 and 313 are respectively silicon controlled rectifiers (SCR) 411 and 413, but are not intended to limit the present invention. In other embodiments, those skilled in the art may utilize other components having discharge conduction functions as the discharge cells 311 and 313. In addition, since the structure of the 矽-controlled rectifier is well known to those skilled in the art, it will not be described again.

In this embodiment, the step-controlled rectifier 411 has an anode, a cathode, and a trigger end. As shown in the figure, the anode of the rectifier rectifier 411 is coupled to the discharge unit 313, and the cathode is coupled to the contact pad 351, and the trigger end is coupled to the anode of the diode module 431. In the present embodiment, the trigger terminal of the pilot rectifier 411 has a P-type dopant.

Similarly, the controlled rectifier 413 also has an anode, a cathode, and a trigger end. The anode of the step-up rectifier 413 is coupled to the contact pad 353, the cathode of which is coupled to the anode of the step-controlled rectifier 411, and the trigger end thereof is coupled to the drain of the transistor M _P2 . In this embodiment, the trigger terminal of the pilot rectifier 413 also has a P-type dopant.

When an ESD event occurs at the contact pad 353 and the contact pad 351 is at ground potential, the ESD voltage can conduct the crystal M _P1 . When the gate voltage of the transistor M _P1 is greater than the breakdown voltage of the diode module 431, a trigger current will flow into the trigger terminal of the step-controlled rectifier 411.

It is well known in the art that the step-controlled rectifier has an npn transistor and a pnp transistor. After the trigger current (P+ doping region) of the pilot rectifier 411 receives the trigger current, the npn transistor in the rectifier rectifier 411 is triggered. After the npn transistor is triggered, another trigger current can be supplied to the base of the pnp transistor in the sense rectifier 411, thereby triggering the pnp transistor in the pilot rectifier 411.

After both the npn transistor and the pnp transistor in the pilot rectifier 411 are triggered, a current path is formed between the contact pad 353, the trigger unit 331, the discharge unit 311, and the contact pad 351. By virtue of the characteristics of the current mirror, the trigger unit 333 can trigger the discharge element 313 such that the ESD current is initiated by the contact pad 353, via the discharge elements 313, 311 and the contact pads 351, to the ground.

Figure 4B is another possible embodiment of the ESD protection device of the present invention. As shown, the trigger unit 331 includes a transistor M _N2 . The trigger unit 333 includes a transistor M _N1 , a diode module 431 , and a resistor 450 . In this embodiment, the transistors M _N1 and M _N2 are all N-type transistors.

The gate of the transistor M _N1 is coupled to the drain thereof, the source of which is coupled to the contact pad 351 and the drain of which is coupled to the anode of the diode module 431. The resistor 450 is coupled between the gate and the source of the transistor M _N1 . The gate of the transistor M _N2 is coupled to the gate of the transistor M _N1 , the drain of which is coupled to the discharge unit 313 , and the source thereof is coupled to the contact pad 351 .

In the present embodiment, the discharge cells 311 and 313 are the controlled rectifiers 415 and 417, respectively. As shown, the controlled rectifier 417 has an anode, a cathode, and a trigger end. The anode of the voltage control rectifier 417 is coupled to the contact pad 353, and the cathode is coupled to the discharge unit 311, and the trigger end is coupled to the cathode of the diode module 431. In the present embodiment, the trigger terminal of the pilot rectifier 417 has an N-type dopant.

The voltage controlled rectifier 415 also has an anode, a cathode, and a trigger end. The anode of the rectifier rectifier 415 is coupled to the cathode of the rectifier rectifier 417, the cathode of which is coupled to the contact pad 351, and the trigger end thereof is coupled to the drain of the transistor M _N2 . In the present embodiment, the trigger terminal of the pilot rectifier 415 has an N-type dopant.

In this embodiment, when an ESD event occurs on the contact pad 353, and the contact pad 351 is at the ground potential, the transient voltage generated by the ESD event is greater than the breakdown voltage of the diode module 431, so that the conductive crystal can be turned on. M _N1 and M _N2 . Therefore, the ESD current can be started by the contact pad 353, discharged to the ground via the discharge cells 313, 311 and the ground pad 351.

Figure 5 is another schematic view of the ESD protection device of the present invention. Fig. 5 is similar to Fig. 3 except that the triggering unit 531 and the discharging unit 511 are added to Fig. 5. In a possible embodiment, when a current path is formed between the contact pad 353, the trigger unit 331, the discharge unit 311, and the contact pad 351, the trigger unit 333 triggers the discharge unit 313, and the trigger unit 531 triggers the discharge unit 511. Since the internal circuit structure of the trigger unit 531 is the same as that of the trigger unit 333, and the discharge units 511 and 313 are the same, they will not be described again.

Figure 6 is another schematic view of the ESD protection device of the present invention. As shown, the ESD protection device 600 is coupled between the contact pads 651 and 653. When an ESD event occurs at the contact pad 653 and the contact pad 651 is at ground potential, the ESD protection device 600 can release the ESD current from the contact pad 653 to the contact pad 651.

In the present embodiment, the ESD protection device 600 includes discharge cells 611, 613 and trigger units 631, 633, 635, 637. The discharge cells 611 and 613 are connected in series between the contact pads 651 and 653. The trigger unit 631 is coupled between the contact pad 653 and the discharge unit 611. The trigger unit 633 is coupled between the contact pad 653 and the discharge unit 613. The trigger unit 635 is coupled between the contact pad 651 and the discharge unit 611. The trigger unit 637 is coupled between the contact pad 651 and the discharge unit 613.

In this embodiment, one of the triggering units 631 and 633 first triggers the corresponding discharge unit, and then the other triggers the corresponding discharge unit. For example, in a possible embodiment, after the trigger unit 631 first triggers the discharge unit 611, the trigger unit 633 triggers the discharge unit 613. In another possible embodiment, after the trigger unit 633 triggers the discharge unit 613, the trigger unit 631 triggers the discharge unit 611.

Similarly, in a possible embodiment, when the trigger unit 635 first triggers the discharge unit 611, the trigger unit 637 triggers the discharge unit 613. In another possible embodiment, after the trigger unit 637 triggers the discharge unit 613, the trigger unit 635 triggers the discharge unit 611.

Since the discharge cells 611 and 613 can be triggered by the two trigger units, the trigger voltages of the discharge cells 611 and 613 are smaller than the trigger voltages of the discharge cells 311 and 313 of FIG.

Figure 7A is another possible embodiment of the ESD protection device of the present invention. In the embodiment, when a first current path is formed between the contact pad 653, the trigger unit 631 and the discharge unit 611, the trigger unit 633 triggers the discharge unit 613. Similarly, when a second current path is formed between the contact pad 651, the trigger unit 637, and the discharge unit 613, the trigger unit 635 triggers the discharge unit 611.

In the present embodiment, the trigger units 631 and 633 have a current mirror circuit, and the trigger units 635 and 637 have another current mirror circuit. In addition, the number of diodes of the trigger unit 631 is equal to the number of diodes of the trigger unit 637.

In a possible embodiment, the circuit structure of the trigger unit 631 shown in FIG. 7A is equal to the circuit architecture of the trigger unit 633. In this embodiment, the circuit architecture of the trigger unit 633 is equal to the circuit architecture of the trigger unit 631. Since the operation principle between the trigger units 631, 633 and the discharge units 611 and 613 is the same as that of the circuit structure and FIG. 4A, it will not be described again.

Similarly, the circuit architecture of the trigger unit 635 shown in FIG. 7A may be equal to the circuit architecture of the trigger unit 637. In this embodiment, the circuit architecture of the trigger unit 637 is equal to the circuit architecture of the trigger unit 635. Since the operation principle and circuit architecture between the trigger units 635 and 637 and the discharge units 611 and 613 are the same as those in FIG. 4B, they will not be described again.

In this embodiment, the discharge unit 611 has a first trigger end and a second trigger end, wherein the first trigger end has a P-type dopant and the second trigger end has an N-type dopant. The first trigger terminal of the discharge unit 611 receives a trigger signal from the trigger unit 631. The second trigger terminal of the discharge unit 611 receives the trigger signal from the trigger unit 635.

In addition, the discharge unit 613 also has a first trigger end and a second trigger end, wherein the first trigger end also has a P-type dopant, and the second trigger end has an N-type dopant. The first trigger terminal of the discharge unit 613 receives the trigger signal from the trigger unit 633. The second trigger terminal of the discharge unit 613 receives the trigger signal from the trigger unit 637.

Figure 7B is another possible embodiment of the ESD protection device of the present invention. The invention does not limit the number of discharge cells and trigger cells. In the present embodiment, the ESD protection device 701 has discharge cells DU ₁ to DU _K , trigger units TP ₁ to TP _{K ,} and TN ₁ to TN _K . Taking the discharge unit DU ₁ as an example, the discharge unit DU ₁ receives trigger signals from the trigger units TP ₁ and TN _K .

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

110. . . Detection circuit

130. . . protect the circuit

C. . . capacitance

R, 450. . . resistance

431. . . Diode module

D ₁ ~D _n . . . Dipole

411, 413. . . Voltage controlled rectifier

M _P1 ~M _PK , M _N1 ~M _NK . . . Transistor

121, 122, 351, 353, 651, 653. . . Contact pad

311, 313, 611, 613, DU ₁ ~ DU _K . . . Discharge unit

331, 333, 631, 633, 635, 637. . . Trigger unit

100, 200, 300, 500, 600, 701. . . ESD protection device

Figure 1 shows a conventional ESD protection device.

Figure 2 is a cross-sectional view of another conventional ESD protection device.

Figure 3 is a schematic view of the ESD protection device of the present invention.

Figure 4A is a possible embodiment of the ESD protection device of the present invention.

Figure 4B is another possible embodiment of the ESD protection device of the present invention.

Figure 5 is another schematic view of the ESD protection device of the present invention.

Figure 6 is another schematic view of the ESD protection device of the present invention.

Figure 7A is another possible embodiment of the ESD protection device of the present invention.

Figure 7B is another possible embodiment of the ESD protection device of the present invention.

300. . . ESD protection device

311, 313. . . Discharge unit

331, 333. . . Trigger unit

351, 353. . . Contact pad

Claims (28)

An electrostatic discharge protection device comprising: a first discharge unit; a second discharge unit connected in series with a first contact pad and a second contact pad for releasing an electrostatic discharge current; a first trigger unit includes a first transistor and at least one first diode. The first transistor and the first diode are connected in series between the first contact pad and the first discharge unit. The first trigger unit triggers the first discharge unit when an electrostatic discharge event occurs; and a second trigger unit includes a second transistor coupled between the first contact pad and the second discharge unit The second transistor triggers the second discharge unit when the first discharge unit is triggered. The electrostatic discharge protection device of claim 1, wherein the first electro-crystalline system is a first P-type transistor having a first gate, a first source, and a first drain. The first gate is coupled to the first drain, the first source is coupled to the first contact pad, and the first drain is coupled to the cathode of the first diode. The electrostatic discharge protection device of claim 2, wherein the first discharge unit is a first silicon controlled rectifier (SCR) having a first anode, a first cathode, and a first The first anode is coupled to the second discharge unit, and the first cathode is coupled to the second contact pad. The first trigger end is coupled to the anode of the first diode. The electrostatic discharge protection device of claim 3, wherein the second electro-crystalline system is a second P-type transistor having a second gate, a second source, and a second drain. The first gate is coupled to the first gate, the first source is coupled to the first contact pad, and the first drain is coupled to the second discharge unit. The electrostatic discharge protection device of claim 4, wherein the second discharge unit is a second controlled rectifier having a second anode, a second cathode, and a second trigger end, the second The anode is coupled to the first contact pad, the second cathode is coupled to the first anode, and the second trigger end is coupled to the second drain. The electrostatic discharge protection device of claim 1, further comprising a third discharge unit and a third trigger unit, wherein the third discharge unit and the second and first discharge units are connected in series to the first and the first Between the two contact pads, the third trigger unit has a third transistor coupled between the first contact pad and the third discharge unit. When the first discharge unit is triggered, The third transistor triggers the third discharge unit. The electrostatic discharge protection device of claim 1, wherein the first electro-crystalline system is a first N-type transistor having a first gate, a first source, and a first drain. The first gate is coupled to the first drain, the first source is coupled to the first contact pad, and the first drain is coupled to the anode of the first diode. The electrostatic discharge protection device of claim 7, wherein the first trigger unit further comprises a resistor coupled between the first gate and the first source. The electrostatic discharge protection device of claim 8, wherein the first discharge unit is a first silicon controlled rectifier (SCR) having a first anode, a first cathode, and a first The first anode is coupled to the second contact pad, and the first cathode is coupled to the cathode of the first diode. The electrostatic discharge protection device of claim 9, wherein the second electro-crystalline system is a second N-type transistor having a second gate, a second source, and a second drain. The second gate is coupled to the first gate, the first drain is coupled to the second discharge unit, and the first source is coupled to the first contact pad. The electrostatic discharge protection device of claim 10, wherein the second discharge unit is a second controlled rectifier having a second anode, a second cathode, and a second trigger end, the second The anode is coupled to the first cathode, the second cathode is coupled to the first contact pad, and the second trigger end is coupled to the second drain. The electrostatic discharge protection device of claim 1, further comprising: a third trigger unit, comprising a third transistor and at least one second diode, the third transistor and the second diode The body is connected in series between the second contact pad and the first discharge unit, the third trigger unit triggers the first discharge unit when an electrostatic discharge event occurs, and a fourth trigger unit includes a fourth transistor And being coupled between the second contact pad and the second discharge unit. When the first discharge unit is triggered, the fourth transistor triggers the second discharge unit. The electrostatic discharge protection device of claim 12, wherein the first electro-crystalline system is a first P-type transistor having a first gate, a first source, and a first drain. The first gate is coupled to the first drain, the first source is coupled to the first contact pad, and the first drain is coupled to the cathode of the first diode. The electrostatic discharge protection device of claim 13, wherein the first discharge unit is a first silicon controlled rectifier (SCR) having a first anode, a first cathode, and a first a first anode is coupled to the second discharge unit, the first cathode is coupled to the second contact pad, and the first trigger end is coupled to the anode of the first diode The second trigger end is coupled to the cathode of the second diode. The electrostatic discharge protection device of claim 14, wherein the second electro-crystalline system is a second P-type transistor having a second gate, a second source, and a second drain. The first gate is coupled to the first gate, the first source is coupled to the first contact pad, and the first drain is coupled to the second discharge unit. The electrostatic discharge protection device of claim 15, wherein the second discharge unit is a second controlled rectifier having a second anode, a second cathode, a third trigger end, and a fourth In the triggering end, the second anode is coupled to the first contact pad, the second cathode is coupled to the first anode, and the third triggering end is coupled to the second drain. The electrostatic discharge protection device of claim 16, wherein the third electro-crystalline system is a first N-type transistor having a third gate, a third source, and a third drain. The third gate is coupled to the third drain, the third source is coupled to the second contact pad, and the third drain is coupled to the anode of the second diode. The electrostatic discharge protection device of claim 17, wherein the third trigger unit further comprises a resistor coupled between the third gate and the third source. The electrostatic discharge protection device of claim 18, wherein the fourth electro-crystalline system is a second N-type transistor having a fourth gate, a fourth source, and a fourth drain. The fourth gate is coupled to the third gate, the fourth drain is coupled to the fourth trigger terminal, and the fourth source is coupled to the second contact pad. An electrostatic discharge protection device includes: a first discharge unit; a second discharge unit connected in series with a first contact pad and a second contact pad; a first trigger unit coupled Between the first contact pad and the first discharge unit; and a second trigger unit coupled between the first contact pad and the second discharge unit, when the first trigger unit triggers the first discharge The second trigger unit triggers the second discharge unit. The electrostatic discharge protection device of claim 20, wherein when a current starts from the first contact pad, flows through the first trigger unit, the first discharge unit, and the second contact pad, the first The second trigger unit triggers the second discharge unit. The electrostatic discharge protection device of claim 20, wherein the first and second trigger units have a current mirror circuit. The electrostatic discharge protection device of claim 20, further comprising: a third discharge unit, and the first and second discharge units are connected in series between the first and second contact pads and a third trigger unit And being coupled between the first contact pad and the third discharge unit. When the first trigger unit triggers the first discharge unit, the third trigger unit triggers the third discharge unit. The electrostatic discharge protection device of claim 23, wherein the first, second and third trigger units have a current mirror circuit. The electrostatic discharge protection device of claim 20, further comprising: a third trigger unit coupled between the second contact pad and the first discharge unit; and a fourth trigger unit coupled Between the second contact pad and the second discharge unit, when the third trigger unit triggers the first discharge unit, the fourth trigger unit triggers the second discharge unit. The electrostatic discharge protection device of claim 25, wherein the first and second trigger units have a first current mirror circuit, and the third and fourth trigger units have a second current mirror circuit. The electrostatic discharge protection device of claim 25, wherein the first discharge unit has a first trigger end and a second trigger end, the first trigger end receiving a first from the first trigger unit a trigger signal, the second trigger receiving a second trigger signal from the third trigger unit. The electrostatic discharge protection device of claim 27, wherein the first trigger end has a P-type dopant and the second trigger end has an N-type dopant.