TECHNICAL FIELD

The present disclosure relates generally to electrostatic discharge (ESD) protection devices, and methods of forming the ESD protection devices.

BACKGROUND

ESD protection devices are often used to protect electrical devices from being damaged by ESD events.FIG.1Ashows a simplified cross-sectional view of an exemplary prior art ESD protection device100. As shown inFIG.1A, the prior art ESD protection device100includes a p-type substrate102and a deep n-well104arranged within the p-type substrate102. A collector region106and an emitter/base region108are arranged within the deep n-well104. The collector region106includes a high voltage p-well1061, a p-well1062within the high voltage p-well1061and a p-type contact1063within the p-well1062. The emitter/base region108includes an n-well1081, and a p-type contact1082and an n-type contact1083within the n-well1081. The p-type contact1082and the n-type contact1083are electrically isolated from each other by an isolation structure110therebetween. Further isolation structures112,114are provided at opposite sides of the prior art ESD protection device100. The collector region106is electrically connected to a terminal point116and the emitter/base region108is electrically connected to a terminal point118.

In use, the prior art ESD protection device100is connected to a pair of terminals of an electrical device via the terminal points116,118.FIG.1Bshows an equivalent circuit of the prior art ESD protection device100andFIG.1Cshows a current-voltage plot of the device100in use. As shown inFIGS.1B and1C, the device100operates as a transistor device when the voltage bias between the terminal points116,118is in a positive direction. When this positive voltage bias exceeds a triggering voltage VTof the ESD protection device100(due to an ESD event within the electrical device), the ESD protection device100turns on and conducts current away from the electrical device. This helps to prevent the electrical device from being damaged by the excess current caused by the ESD event. The current conducted through the ESD protection device100may be referred to as the discharge current or the ESD current. The ESD protection device100is usually designed to have a triggering voltage that is slightly lower than a maximum voltage the electrical device can withstand before it is destroyed (or in other words, a breakdown voltage of the electrical device).

On the other hand, as shown inFIGS.1B and1C, when the voltage bias between the terminal points116,118is in a negative direction, the prior art ESD protection device100behaves like a diode. In other words, the device100is a uni-directional device that is unable to support dual polarity bias. To overcome this, a pair of the devices100may be electrically connected in a back-to-back stack configuration as shown inFIG.1D. However, such a structure tends to have a high silicon footprint and a high on-resistance. Further, prior art ESD protection devices, such as the device100, also tend to suffer from problems such as a low failure current and a high on-resistance.

SUMMARY

According to various non-limiting embodiments, there may be provided an ESD protection device including: a substrate including a conductivity region arranged therein; a first terminal region and a second terminal region arranged within the conductivity region; and a field distribution structure including: an intermediate region arranged within the conductivity region between the first terminal region and the second terminal region; an isolation element arranged over the intermediate region; and a first conductive plate and a second conductive plate arranged over the isolation element. The first conductive plate may be electrically connected to the first terminal region and the second conductive plate may be electrically connected to the second terminal region.

According to various non-limiting embodiments, there may be provided a method of forming an ESD protection device. The method may include providing a substrate; forming a conductivity region within the substrate; forming a first terminal region and a second terminal region within the conductivity region; forming a field distribution structure including: an intermediate region within the conductivity region between the first terminal region and the second terminal region; an isolation element over the intermediate region; and a first conductive plate and a second conductive plate over the isolation element. The method may further include forming an electrical connection between the first conductive plate and the first terminal region; and forming an electrical connection between the second conductive plate and the second terminal region.

