Semiconductor device

Abstract

In the semiconductor device including an ESD protection N-type MOS transistor which reduces increase of occupied area and has a sufficient ESD protective function, a drain region of the ESD protection N-type MOS transistor is electrically connected to a drain contact region via a drain extended region. The drain extended region is provided on a side surface and a lower surface of an ESD protection trench isolation region, and is formed of an impurity diffusion region of the same conductivity type as that of the drain region. The drain contact region is formed of an impurity diffusion region of the same conductivity type as that of the drain region.

Description

technical field [0001] The present invention relates to a semiconductor device having an ESD protection element between an external connection terminal and an internal circuit area, and the ESD protection element is formed to protect internal elements formed in the internal circuit area from being destroyed by ESD. Background technique [0002] In a semiconductor device having a MOS transistor, it is known to fix the gate potential of the N-type MOS transistor to ground ( Vss) and set to the off state, so-called cut-off transistors. [0003] In order to prevent ESD destruction of internal circuit components, it is important to introduce as large a proportion of static pulses as possible into the cut-off transistors and not propagate them to internal circuit components, or to change fast and large static pulses into slow and small ones. The signal is then transmitted. [0004] In addition, unlike the MOS type transistors constituting other internal circuits such as logic ci...

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Problems solved by technology

[0005] Therefore, there is a problem that the area occupied by the cut-off transistor is large, especially in a small IC chip, which becomes a cause of an increase in the cost of the entire IC.

[0006] In addition, an off transistor usually adopts a combination of a plurality of drain regions, source regions, and gate electrodes in a comb shape. However, by combining a plurality of transistors, there are cases where it is difficult to make an N-type MOS for ESD protection The transistor operates uniformly as a whole. For example, current concentration occurs in the part close to the external connection terminal, and the original ESD protection function cannot be fully exerted and is destroyed.

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