Input/output pad circuit having electrostatic discharge tolerance and comprising encircling well

Abstract

The invention relates to an input / output pad circuit having electrostatic discharge tolerance and comprising an encircling well, which comprises a semiconductor main body and an encircling well, wherein the semiconductor main body is provided with a first conduction type and a contact pad, and the encircling well is provided with a second conduction type and is laid out to be a circle of area as an electrostatic discharge circuit encircling in the semiconductor main body. The encircling well is relatively deep, and the encircling well also provides a first end point of a diode formed in the semiconductor main body besides the defined area as the electrostatic discharge circuit. In the area encircled by the encircling well, a diode is coupled with the contact pad, a transistor is coupled with a reference voltage device, and the diode and the transistor are connected in series and form a parasitic device in the semiconductor main body.

Description

technical field [0001] The present invention relates to an electrostatic discharge protection circuit in an integrated circuit, and more particularly to an input / output pad circuit including a surrounding well with electrostatic discharge tolerance. Background technique [0002] Integrated circuits often include an ESD protection circuit coupled to the I / O pads. A representative ESD protection circuit can be found in US Patent No. 6,858,902 to Salling et al., entitled "EFFICIENT ESD PROTECTION WITH APPLICATION FOR LOW CAPACITANCE I / O PADS." [0003] As in the US patent specification of Salling et al. Figure 4 As shown in , a prior art ESD protection circuit includes a diode between the contact pad and the supply potential VDD, which leaks to limit high voltage operation during an ESD event with a high positive voltage to VDD. The ESD protection circuit also includes a field effect transistor located between the contact pad and ground, with a parasitic bipolar transistor or...

AI Technical Summary

Problems solved by technology

[0005] It can be seen that the above-mentioned existing electrostatic discharge protection circuit and the circuit structure coupled with the input / output pad obviously still have inconvenience and defects in use, and need to be further improved urgently.

In order to solve the above-mentioned problems, the relevant manufacturers have tried their best to find a solution, but for a long time no suitable design has been developed, and the general product has no suitable structure to solve the above-mentioned problems. This is obviously the relevant industry. Urgent problem

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