Silicon controlled rectifier structure for ESD (electro-static discharge) protection

Abstract

The invention discloses a silicon controlled rectifier structure for ESD (electro-static discharge) protection. The structure comprises a first well region and a second well region, wherein the first well region and the second well region have opposite conduction types; a first diffusion region with the first conduction type is arranged on the surface of the boundary area of the first well region and the second well region; the doping concentration of the first diffusion area is larger than the doping concentration of a well region which is contacted and has the same conduction type with the first diffusion area; in a well region with the opposite conduction type with the first diffusion region, a third well region which has the same conduction type with the well region and that the doping concentration is higher than that of the region is arranged; and the third well region is arranged below an isolating region adjacent to the first diffusion region. The silicon controlled rectifier structure has a higher clamping voltage under the condition that the breakover ability is not decreased, so that the risk of latch failure is reduced.

Description

technical field [0001] The invention relates to a structure of a silicon controlled rectifier used for electrostatic protection. Background technique [0002] An existing silicon-controlled rectifier (SCR for short) formed by positive-feedback coupling of two triodes can be used as an electrostatic protection device. figure 1 It is a schematic diagram of a cross-sectional structure of a specific existing silicon controlled rectifier 10, which includes two contiguous N-type deep wells 12 and P-type wells 11 on a P-type substrate 1, and the P-type well 11 is located on an N-type deep well. In the well 12, a P-type diffusion region 14 (usually a P+ diffusion region) and an N-type diffusion region 15 (usually an N+ diffusion region) are provided on the surface of the P-type well 11, and a P-type diffusion region is provided on the surface of the N-type deep well. Region 16 (usually P+ diffusion region) and N-type diffusion region 17 (usually N+ diffusion region). The diffusion...

AI Technical Summary

Problems solved by technology

[0004] In the above silicon controlled rectifier structure, the breakdown usually occurs at the boundary between the P-type well 11 and the N-type deep well 12, by adjusting the P-type well boundary and the N-type diffusion region or the P-type diffusion in the N-type deep well The contact area of ​​the region is used to adjust the breakdown voltage and trigger voltage, and the effect is not obvious when the well boundary is far from the diffusion region; when the well boundary is closer to the diffusion region, the adjusted breakdown voltage curve is gentler (belonging to punch-through breakdown mechanism), the stability of the breakdown voltage is difficult to control

Therefore, it is difficult to adjust the structure of the silicon controlled rectifier to be an electrostatic protection device suitable for various voltage ranges.

Images