TWI435433B - Esd protection device - Google Patents

Description

Electrostatic discharge protection element

The present disclosure relates to an electronic device, and more particularly to an electrostatic discharge protection device.

In general, various electronic devices are provided with an Electrostatic Discharge (ESD) protection mechanism to avoid the moment when the electronic device touches the electronic device when the human body is exposed to excessive static electricity. The current causes damage, or the electronic device is prevented from being affected by static electricity from the environment or the transport tool, resulting in a malfunction.

In the electrostatic discharge device, a Silicon Controlled Rectifier (SCR) can be generally provided as an electrostatic discharge protection component, and has a lower holding voltage after the sudden collapse, thereby protecting the integrated circuit from being protected. The damage of the electrostatic discharge is widely used in general electrostatic discharge devices because the controlled rectifier has a better electrostatic discharge capability and a smaller area occupied by the integrated circuit.

However, in the case where the sustain voltage is too low and is less than the normal operating voltage of the integrated circuit, if the component is disturbed by external noise under normal operating conditions, a latch up effect will be caused, thereby causing the integrated circuit. Malfunction or damage.

Embodiments of the present invention provide an electrostatic discharge protection circuit for performing electrostatic discharge protection.

One aspect of the present disclosure relates to an electrostatic discharge protection component that includes a controlled rectifier equivalent circuit, a switch, and a control circuit. The 整流 control rectifier equivalent circuit includes a first equivalent transistor and a second equivalent transistor. The switch is electrically coupled between the equivalent circuit of the step-controlled rectifier and the pad, wherein when the switch is turned on, the electrostatic discharge current is discharged from the pad via the switch, the first equivalent transistor, and the second equivalent transistor. The control circuit is configured to generate a control voltage according to an electrostatic discharge current flowing through the switch, the first equivalent transistor and the second equivalent transistor to control the switch to be closed, wherein when the switch is turned off, the electrostatic discharge current is self-welded from the pad via the second The effect transistor is discharged.

Another aspect of the present disclosure is directed to an electrostatic discharge protection component that includes a controlled rectifier equivalent circuit, a switch, and a control circuit. The equivalent circuit of the controlled rectifier includes an equivalent PNP type double carrier junction transistor and an equivalent NPN type double carrier junction transistor. The first end of the switch is electrically coupled to the base of the pad and the equivalent PNP type bipolar junction transistor, and the second end of the switch is electrically coupled to the emitter of the equivalent PNP type bipolar junction transistor . The first end of the control circuit is electrically coupled to the emitter of the equivalent NPN transistor and the control terminal of the switch, and the second end of the control circuit is electrically coupled to the low level voltage.

According to the technical content of the present disclosure, the application of the aforementioned electrostatic discharge protection element can prevent the occurrence of a latch-up effect when the electrostatic discharge protection mechanism is activated.

This summary is intended to provide a simplified summary of the disclosure This Summary is not an extensive overview of the disclosure, and is intended to be illustrative of the embodiments of the invention.

The embodiments are described in detail below with reference to the accompanying drawings, but the embodiments are not intended to limit the scope of the invention, and the description of the structure operation is not intended to limit the order of execution, any component recombination The structure, which produces equal devices, is within the scope of the present invention. In addition, the drawings are for illustrative purposes only and are not drawn to the original dimensions.

As used herein, "about", "about" or "substantially" generally means that the error or range of the index value is within 20%, preferably within 10%, and more preferably It is within 5 percent. In the text, unless otherwise stated, the numerical values referred to are regarded as approximations, that is, the errors or ranges indicated by "about", "about" or "roughly".

In addition, as used herein, "coupled" or "connected" may mean that two or more elements are in direct physical or electrical contact with each other, or indirectly in physical or electrical contact with each other, and "coupled" It can also mean that two or more elements operate or act on each other.

1 is a schematic view showing an electrostatic discharge protection element according to a first embodiment of the present invention. As shown in FIG. 1, the electrostatic discharge protection device 100 includes a controlled rectifier equivalent circuit 110, a switch 120, and a control circuit 130, wherein the controlled rectifier is an electronic component having a P/N/P/N semiconductor interface. The controlled rectifier equivalent circuit 110 includes a first equivalent transistor 112 and a second equivalent transistor 114. The switch 120 is electrically coupled between the controlled rectifier equivalent circuit 110 and the pad 105. The control circuit 130 is electrically coupled to the controlled rectifier equivalent circuit 110 and the switch 120, and controls the switch according to the electrostatic discharge (ESD) current flowing from the pad 105 through the controlled rectifier equivalent circuit 110 or a part of the equivalent circuit thereof. 120 is turned on or off.

Operationally, in the case where the switch 120 is turned on, when an electrostatic discharge condition occurs to generate a transient electrostatic discharge current, the electrostatic discharge current from the pad 105 via the switch 120, the first equivalent transistor 112, and the second equivalent transistor 114 And flowing through the control circuit 130 to the low level voltage VSS or the ground voltage GND, thereby discharging; that is, the electrostatic discharge current is discharged from the pad 105 via the controlled rectifier equivalent circuit 110. At this time, the control circuit 130 generates a control voltage VA according to the electrostatic discharge current flowing through the switch 120, the first equivalent transistor 112, and the second equivalent transistor 114, thereby controlling the switch 120 to be turned off.

Then, when the switch 120 is turned off, if an electrostatic discharge current occurs and a transient electrostatic discharge current is generated, the electrostatic discharge current flows from the pad 105 to the low position via the second equivalent transistor 114 through the control circuit 130. The discharge is performed by the quasi-voltage VSS or the ground voltage GND. Specifically, the electrostatic discharge current does not flow through the switch 120 and the first equivalent transistor 112, but is discharged directly from the pad 105 via the second equivalent transistor 114, and the electrostatic discharge current is not controlled by the whole The rectifier equivalent circuit 110 discharges, but only discharges through the second equivalent transistor 114 in the rectifier rectifier equivalent circuit 110.

Secondly, when the electrostatic discharge current flowing to the control circuit 130 via the second equivalent transistor 114 is changed, so that the control voltage VA is changed to a certain voltage, the switch 120 is switched back from the off state to the on state according to the control voltage VA. . For example, as shown in FIG. 1, the switch 120 may include a P-type metal oxide half field effect transistor (MOSFET) MS, and when the electrostatic discharge current is changed, the control voltage VA is lowered to be lower than the P-type metal oxide half field effect transistor. When the threshold voltage of the MS is reached, the P-type MOS field-effect transistor MS is returned from the off state to the on state correspondingly.

Since the ESD protection element 100 releases the ESD current by the Rectifier Rectifier Equivalent Circuit 110, the control circuit 130 controls the switch 120 to be turned off according to the ESD current, so that the Rectifier Rectifier Equivalent Circuit 110 continues. The operation of the electrostatic discharge is switched to a single equivalent transistor for discharging after a certain period of time (that is, the mode of turning off the discharge of the original controlled rectifier), so that the controlled rectifier equivalent circuit 110 can be suddenly collapsed. The holding voltage does not fall to an excessively low level, and the level of the sustain voltage is relatively increased. In this way, after the electrostatic discharge protection element 100 discharges the electrostatic discharge current, the sustain voltage is not too low and is less than the normal operating voltage of the integrated circuit, which can further prevent the component from being disturbed by external noise under normal operating conditions. Latch Up effect.

In this embodiment, the first equivalent transistor 112 can be an equivalent PNP type bipolar junction transistor (BJT) M1, and the second equivalent transistor 114 can be an equivalent NPN type dual carrier junction. Crystal (BJT) M2. The base of the equivalent PNP-type bipolar junction transistor M1 (eg, the n-type heavily doped semiconductor layer 142 can serve as the base of the transistor M1) is electrically coupled to the first end of the pad 105 and the switch 120. The emitter of the equivalent PNP type bipolar junction transistor M1 (eg, the p-type heavily doped semiconductor layer 144 can serve as the emitter of the transistor M1) is electrically coupled to the second end of the switch.

Secondly, the emitter of the equivalent NPN type transistor M2 (for example, the n-type heavily doped semiconductor layer 146 can serve as the emitter of the transistor M2) and the base (for example, the p-type heavily doped semiconductor layer 148 can function as a transistor) The emitter of M2 is electrically coupled to the first end of the control circuit 130. Furthermore, the first end of the control circuit 130 is electrically coupled to the control terminal of the switch 120, and the second end of the control circuit 130 is electrically coupled to the low level voltage VSS or the ground voltage GND.

Operationally, the first end of the control circuit 130 can generate a control voltage according to the electrostatic discharge current flowing through the switch 120, the equivalent PNP type dual carrier junction transistor M1, and the equivalent NPN type dual carrier junction transistor M2. VA, and the switch 120 is turned off according to the control voltage VA. Then, when the electrostatic discharge current flowing to the control circuit 130 via the equivalent NPN-type bipolar junction transistor M2 is changed, so that the control voltage VA is changed to a certain voltage, the switch 120 is restored from the off state according to the control voltage VA. On state.

In practice, the controlled rectifier equivalent circuit 110 can be a low voltage triggered voltage controlled rectifier (LVTSCR), a modified laterally controlled rectifier (MLSCR), or a parasitic controlled rectifier (embedded SCR). The switch 120 may include at least one of a gold oxide half field effect transistor (MOSFET), a bipolar junction transistor (BJT), and a variable resistor; in other words, in the present disclosure, the switch 120 may be powered by a gold oxide half field effect The crystal (which may be P-type or N-type), the bipolar junction transistor (which may be P-type or N-type), a variable resistor or other component that implements a switching function is implemented without the present disclosure. The limit is limited.

2 is a schematic view showing an electrostatic discharge protection element according to a second embodiment of the present invention. As shown in FIG. 2, the ESD protection component 200 includes a 整流 control rectifier equivalent circuit 110, a switch 120, and a control circuit 230, wherein the connection and operation relationship of the 整流 control rectifier equivalent circuit 110, the switch 120, and the control circuit 230 are similar. 1 related embodiment, so it will not be described here.

Secondly, compared with the embodiment shown in FIG. 1, the control circuit 230 in this embodiment further includes an equivalent resistor R1, and the switch 120 includes a transistor (for example, a P-type MOS field-effect transistor MS). The control terminal of the transistor MS is electrically coupled to the first end of the equivalent resistor R1. The first end of the transistor MS is electrically coupled to the pad 105, and the second end of the transistor is electrically coupled to the controlled rectifier. The anode of circuit 110 (e.g., p-type heavily doped semiconductor layer 144 can serve as the emitter of transistor M1 and the anode of gated rectifier equivalent circuit 110). In addition, the first end of the equivalent resistor R1 is more electrically coupled to the base of the equivalent NPN type transistor M2 (eg, the p-type heavily doped semiconductor layer 148 can serve as the emitter of the transistor M2) and the emitter ( For example, the n-type heavily doped semiconductor layer 146 can serve as the emitter of the transistor M2, and the second terminal of the equivalent resistor R1 can be electrically coupled to the low level voltage VSS or the ground voltage GND.

Operationally, in the case where the P-type MOS field-effect transistor MS is turned on, when an electrostatic discharge occurs to generate a transient electrostatic discharge current, the electrostatic discharge current flows from the pad 105 via the P-type MOS field-effect transistor MS, etc. The PNP type bipolar contact junction transistor M1 and the equivalent NPN type bipolar junction junction transistor M2 are discharged through the equivalent resistor R1 to the low level voltage VSS or the ground voltage GND. At this time, one end of the equivalent resistor R1 is based on the static electricity flowing through the P-type MOS field oxide crystal MS, the equivalent PNP type double carrier junction transistor M1, and the equivalent NPN type double carrier junction transistor M2. The discharge current generates a control voltage VA, and when the control voltage VA is gradually increased to the threshold voltage of the P-type MOS field-effect transistor MS, the P-type MOS field-effect transistor MS is turned off.

Next, in the case where the P-type MOS field oxide MS is turned off, the potential of the n-type heavily doped semiconductor layer 142 is different from the potential of the p-type heavily doped semiconductor layer 144, and if an electrostatic discharge occurs, When a momentary electrostatic discharge current is generated, the electrostatic discharge current is discharged from the pad 105 via the equivalent NPN-type bipolar junction transistor M2, through the equivalent resistor R1 to the low level voltage VSS or the ground voltage GND. For example, the electrostatic discharge current does not flow through the P-type gold oxide half field effect transistor MS and the equivalent PNP type double carrier junction transistor M1, but directly from the pad 105 via the n-type heavily doped semiconductor layer 142 and equivalent The NPN-type bipolar junction transistor M2 flows to the low level voltage VSS or the ground voltage GND, thereby discharging; in other words, the electrostatic discharge current is not discharged through the overall controlled rectifier equivalent circuit 110, but only The discharge is performed through the NPN-type bipolar junction transistor M2 in the rectifier equivalent circuit 110.

Furthermore, when the electrostatic discharge current flowing to the equivalent resistor R1 via the NPN-type bipolar junction transistor M2 is changed, so that the control voltage VA is changed to a certain voltage, the P-type MOS half-field effect transistor MS is further According to the control voltage VA, the state is restored from the off state to the on state.

In this way, the holding voltage of the step-by-step rectifier circuit 110 can be increased, and after the electrostatic discharge protection device 200 discharges the electrostatic discharge current, the sustain voltage is not too low and is less than The normal operating voltage of the integrated circuit can further avoid the latch up effect that may be caused when the component is disturbed by external noise under normal operating conditions.

In practice, the foregoing control circuit 230 may include an equivalent resistor R1, and may also include a transistor or circuit having the same function as the equivalent resistor R1, and the equivalent resistor R1 may also have a poly resistor and a diffusion. Diffusion resistors, well resistors, etc. or different types of transistors are implemented; in other words, in the present disclosure, the control circuit 230 can be implemented by various types of components or circuits according to actual needs. It is not limited to the disclosure.

The following table (1) is a comparison table of the characteristics of the electrostatic discharge protection element and the general controlled rectifier or protection element in the present disclosure after testing. As shown in Table (1), under the same electrostatic discharge protection capability, the layout area of the electrostatic discharge protection component of the present disclosure only needs 1422 um ² , which is significantly better than that of the NMOS or PMOS protection component. The layout area is even smaller. In addition, the sustain voltage of the electrostatic discharge protection element in the present disclosure is also larger than the sustain voltage of the general controlled rectifier, so that the latch-up effect is less likely to occur.

FIG. 3 is a schematic diagram showing the results of the static discharge protection component and the general controlled rectifier of the present disclosure after Transient Latch-up (TLU) test. As shown in Fig. 3, the sustain voltage of the electrostatic discharge protection device of the present disclosure is about 6.7 V, and the sustain voltage of the conventional controlled rectifier is only 2.1 V. Therefore, in operation, the application of the electrostatic discharge protection element of the present disclosure does avoid the occurrence of a latch-up effect as compared to a conventional controlled rectifier or guard element.

According to the embodiment of the present invention, the electrostatic discharge protection component can be used to switch the path of releasing the electrostatic discharge current during the discharge of the electrostatic discharge current, so that the sustain voltage of the rectifier rectifier equivalent circuit 110 is increased after the collapse. In this way, the sustain voltage is not too low and is less than the normal operating voltage of the integrated circuit, which can further avoid the latch up effect that may be caused when the component is interfered by external noise under normal operating conditions.

The present invention has been disclosed in the above embodiments, but it is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

100, 200. . . Electrostatic discharge protection element

105. . . Solder pad

110. . . Voltage controlled rectifier equivalent circuit

112. . . First equivalent transistor

114. . . Second equivalent transistor

120. . . switch

130, 230. . . Control circuit

142, 146. . . N-type heavily doped semiconductor layer

144, 148. . . P-type heavily doped semiconductor layer

1 is a schematic view showing an electrostatic discharge protection element according to a first embodiment of the present invention.

2 is a schematic view showing an electrostatic discharge protection element according to a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing the results of the static discharge protection component and the general controlled rectifier of the present disclosure after Transient Latch-up (TLU) test.

200. . . Electrostatic discharge protection element

105. . Solder pad

110. . . Voltage controlled rectifier equivalent circuit

112. . . First equivalent transistor

114. . . Second equivalent transistor

120. . . switch

230. . . Control circuit

142, 146. . . N-type heavily doped semiconductor layer

144, 148. . . P-type heavily doped semiconductor layer

Claims (11)

An electrostatic discharge protection component comprising: a controlled rectifier equivalent circuit comprising a first equivalent transistor and a second equivalent transistor; a switch electrically coupled to the gated rectifier equivalent circuit and a Between the pads, wherein when the switch is turned on, an electrostatic discharge current is discharged from the pad via the switch, the first equivalent transistor, and the second equivalent transistor; and a control circuit for depending on the flow And generating, by the switch, the first equivalent transistor and the second equivalent transistor, a control voltage to control the switch to be turned off, wherein when the switch is turned off, the electrostatic discharge current is from the pad via the first The second equivalent transistor is discharged. The electrostatic discharge protection device of claim 1, wherein the switch returns from a closed state to a conductive state when an electrostatic discharge current flowing through the second equivalent transistor is changed such that the control voltage is changed to a certain voltage. . The electrostatic discharge protection device of claim 1, wherein the control circuit comprises an equivalent resistor, and an electrostatic discharge current flows through the equivalent resistor such that one of the equivalent resistors generates the control voltage. The electrostatic discharge protection device of claim 1, wherein the switch comprises a transistor, the control circuit comprises an equivalent resistor, and one of the control terminals is electrically coupled to the first resistor. The first end of the transistor is electrically coupled to the pad, and the second end of the transistor is electrically coupled to an anode of the equivalent circuit of the step-controlled rectifier. The electrostatic discharge protection device of claim 4, wherein the first equivalent electro-crystal system is an equivalent PNP-type transistor, and the second equivalent electro-crystal system is an equivalent NPN-type transistor, the equivalent One of the PNP-type transistors is electrically coupled to the pad, and one of the equivalent PNP-type transistors is electrically coupled to the second end of the transistor, and one of the equivalent NPN-type transistors is The pole and the emitter are electrically coupled to the first end of the equivalent resistor. The electrostatic discharge protection device of claim 1, wherein the switch comprises at least one of a metal oxide half field effect transistor, a double carrier junction transistor, and a variable resistor. An electrostatic discharge protection component comprising: a controlled rectifier equivalent circuit comprising an equivalent PNP type dual carrier junction transistor and an equivalent NPN type dual carrier junction transistor; a switch, one of the switches The first end is electrically coupled to a pad and a base of the equivalent PNP type bipolar junction transistor, and the second end of the switch is electrically coupled to the equivalent PNP type bipolar junction One of the crystals of the crystal; and a control circuit, the first end of the control circuit is electrically coupled to one of the emitters of the equivalent NPN type transistor and one of the control terminals of the switch, and the second end of the control circuit Electrically coupled to a low level voltage. The electrostatic discharge protection device of claim 7, wherein the switch comprises a transistor, the control circuit comprises an equivalent resistor, and the first end of the equivalent resistor is electrically coupled to one of the transistors. The terminal and the base of the equivalent NPN-type transistor and the emitter, the second end of the equivalent resistor is electrically coupled to the low-level voltage. The electrostatic discharge protection device of claim 8, wherein the electro-crystalline system is a gold oxide half field effect transistor or a double carrier junction transistor. The electrostatic discharge protection device of claim 7, wherein the switch comprises at least one of a metal oxide half field effect transistor, a double carrier junction transistor, and a variable resistor. The electrostatic discharge protection device of claim 7, wherein the first end of the control circuit is based on flowing through the switch, the equivalent PNP type dual carrier junction transistor, and the equivalent NPN type dual carrier connection The electrostatic discharge current of the surface transistor generates a control voltage, and the switch is turned off according to the control voltage.