Matsushita Electric Industrial Co., Ltd.

Hirotsugu Honda

Hiroyuki Doi

Takuo Akashi

Katsujirou Arai

Naritsugu Yoshii

Masafumi Doi

A semiconductor device includes a heavily doped layerof p-type formed in the surface of an n-type wellan intermediately doped layerof p-type formed to adjoin and surround the heavily p-doped layerand an isolation regionformed to surround the heavily p-doped layerand the intermediately p-doped layerThe heavily p-doped layerhas a higher dopant concentration than the wellThe intermediately p-doped layerhas a higher dopant concentration than the welland a lower dopant concentration than the heavily p-doped layer

Semiconductor device comprising voltage regulator element

A field oxide surrounding an active region, an N-type doped layer formed in the active region, and an electrode formed on the field oxide in the vicinity of the active region are provided on a P-type semiconductor substrate. During the operation as a constant voltage device, a desired voltage is applied to the electrode. Then, trapping of carriers in the interface between the field oxide and the semiconductor region can be suppressed, although such trapping is ordinarily caused by a reverse breakdown phenomenon at the pn junction between the doped layer and the P-type semiconductor substrate. Accordingly, the variation in strength of the electric field between the doped layer and the semiconductor substrate can be suppressed. As a result, it is possible to suppress a variation in reverse withstand voltage, which is usually caused by a reverse breakdown voltage at a pn junction, for a semiconductor device functioning as a constant voltage device.

Semiconductor device and method for driving the same

A semiconductor device providing an improved effect of suppressing variation with time of reverse breakdown voltage applied to PN junction, particularly, a voltage-regulator device, is provided. The semiconductor device includes an impurity diffusion layer formed on a surface of a certain-conductivity-type semiconductor substrate or well, the impurity diffusion layer having a conductivity opposite to that of the semiconductor substrate or well, and a device separating insulation film formed at a distance from the impurity diffusion layer, and a distance between an end of the impurity diffusion layer and an end of the device separating insulation film is defined to be not less than 1.2 &mgr;m.

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Kyoto, Japan

Hirotsugu Honda