Static protection circuit

Abstract

The invention discloses an electrostatic protection circuit. The electrostatic protection circuit includes a P-type LDMOS device, and the P-type LDMOS device includes: an N-type lightly doped body region, a P-type lightly doped drift region, a gate dielectric layer, and a polysilicon gate; In the body region, a source region composed of a P+ region and a body lead-out region composed of an N+ region are formed; in the drift region, a drain P+ diffusion region composed of a P+ region and a drain N+ diffusion region composed of an N+ region are formed. region; the source region and the body region lead-out region are connected to the electrostatic entry end, and the polysilicon gate, the drain P+ diffusion region and the drain N+ diffusion region are all grounded. By adding an N+ region to the drift region of the P-type LDMOS device, the present invention can form a positive feedback structure composed of parasitic PNP and NPN transistors in the electrostatic discharge process, thereby improving the discharge capacity, reducing the snapback voltage and realizing The snapback voltage can be flexibly adjusted and the trigger voltage can be kept constant.

Description

technical field [0001] The invention relates to a semiconductor integrated circuit, in particular to an electrostatic protection circuit. Background technique [0002] Such as figure 1 Shown is the application circuit diagram of the electrostatic protection circuit; the electrostatic protection circuit 102 is arranged between the input and output pads 101 and the ground, and when static electricity appears in the input and output pads 101, the electrostatic protection circuit 102 is triggered and discharges the static electricity. Thus, the protection of the internal circuit 103 is realized. [0003] Such as figure 2 Shown is a schematic diagram of the cross-sectional structure of the existing electrostatic protection circuit; figure 2 The circuit shown adopts a high-voltage PLDMOS structure, and an N-type buried layer 202 is formed on a P-type semiconductor substrate such as a silicon substrate 201, and a body region 203 composed of a high-voltage N well and a high-vol...

AI Technical Summary

Problems solved by technology

The triode is a lateral triode composed of the source region 208, the body region 203 and the drift region 204. The snapback voltage of this lateral triode is very high and the leakage capacity is low.

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