Thyristor for electrostatic discharge

Abstract

The invention relates to a thyristor for electrostatic discharge. The thyristor comprises a parasitic PNP tube, a parasitic NPN tube and a short-channel N-channel metal oxide semiconductor (NMOS) tube, wherein the emitter of the parasitic PNP tube is connected with an anode binding post, the base of the parasitic PNP tube is connected with the anode binding post through an N-trap parasitic resistor, and the collector of the parasitic PNP tube is connected with the base of the parasitic NPN tube and is connected with a cathode binding post through a P-trap parasitic resistor; the emitter of the parasitic NPN tube is connected with the cathode binding post, and the collector of the parasitic NPN tube is connected with the anode binding post through the N-trap parasitic resistor; and the drain of the short-channel NMOS tube is connected with the anode binding post through the N-trap parasitic resistor, the source of the short-channel NMOS tube is connected with the cathode binding post, and the grid length of the short-channel NMOS tube is less than 0.35 micron. The actual grid length of the short-channel NMOS tube is changed in a certain range, so that low and adjustable thyristor trigger voltage can be acquired.

Description

technical field [0001] The invention relates to the field of protection circuit design of semiconductor integrated circuits, in particular to a thyristor used for electrostatic discharge. Background technique [0002] During the manufacture, packaging and use of integrated circuit chips, ESD (Electro Static Discharge, electrostatic discharge) phenomenon will occur. ESD is manifested as an instantaneous high-voltage pulse, and the large amount of charge released in this instant is very likely to destroy the functional devices inside the integrated circuit. Therefore, a thyristor for electrostatic discharge is usually provided between the internal circuit and the external signal source or power supply. [0003] At present, the structure of a typical discharge unit thyristor in a commonly used electrostatic protection circuit is as follows: figure 1 shown, where the left P + , N well, right P well, N + constitutes a thyristor, the N on the left + and P + common connection...

AI Technical Summary

Problems solved by technology

[0005] However, the trigger voltage (conduction voltage) of the protection device composed of thyristors depends on the voltage applied to the anode when the reverse p-n junction formed by N well and P well breaks down. Generally, the conduction voltage of the protection device is higher than that of the internal The breakdown voltage of the gate oxide layer of the circuit. When the gate oxide layer is broken down, the protection device is not turned on, and it cannot really protect the internal circuit.

Images