Sanyo Electric Co., Ltd.

Ryo Kanda

Shuichi Kikuchi

Seiji Otake

Shigeaki Okawa

Kazuhiro Yoshitake

Iwao Takahashi

Yoshinori Sato

Hirotsugu Hata

A semiconductor integrated circuit device according to the present invention includes an N-type embedded diffusion region between a substrate and an epitaxial layer in first and second island regions serving as small signal section. The N-type embedded diffusion region connects to N-type diffusion regions having supply potential. The substrate and the epitaxial layer are thus partitioned by the N-type embedded diffusion region having supply potential in the island regions serving as small signal section. This structure prevents the inflow of free carriers (electrons) generated from a power NPN transistor due to the back electromotive force of the motor into the small signal section, thus preventing the malfunction of the small signal section.

Semiconductor integrated circuit device

A conventional semiconductor device, for example, a MOS transistor including an offset gate structure has a problem that it is difficult to reduce the device size. In a semiconductor device according to the present invention, for example, in a P-channel MOS transistor including an offset gate structure, a LOCOS oxide film is formed between a source region and a drain region in an N type epitaxial layer. A gate electrode is formed to be positioned on the LOCOS oxide layer. In addition, a P type diffusion layer as the drain region and a P type diffusion layer as the source region are formed with a high positional accuracy with respect to the gate electrode. This structure makes it possible to reduce the device size of the MOS transistor.

Semiconductor device and method of manufacturing the same

A conventional semiconductor device has a problem that it is difficult to obtain a desired breakdown voltage characteristic due to a reduction in a punch-through breakdown voltage between drain and source regions. In a semiconductor device according to the present invention, a P type diffusion layer is formed in an N type epitaxial layer. An N type diffusion layer as a back gate region is formed in the P type diffusion layer. The N type diffusion layer is formed by self-alignment using a drain electrode. This structure makes it possible to increase an impurity concentration of the N type diffusion layer in a vicinity of a P type diffusion layer as a source region. As a result, it is possible to improve a punch-through breakdown voltage between the drain and the source regions, and to achieve a desired breakdown voltage characteristic of the MOS transistor.

In a semiconductor device of the present invention, an N type epitaxial layer is formed on a P type single crystal silicon substrate. The substrate and the epitaxial layer are partitioned into a plurality of element formation regions by isolation regions. Each of the isolation regions is formed of a P type buried diffusion layer and a P type diffusion layer coupled thereto. The P type buried diffusion layer is joined to N type buried diffusion layers on both sides thereof to form PN junction regions. On the other hand, the P type diffusion layer is joined to N type diffusion layers on both sides thereof to form PN junction regions. This structure suppresses extension of widthwise diffusion of the P type buried diffusion layer and the P type diffusion layer, thus making it possible to reduce the device size.

Isolation structure for semiconductor device including double diffusion isolation region forming PN junction with neighboring wells and isolation region beneath

In a conventional semiconductor device, for example, a MOS transistor, there is a problem that a parasitic transistor is prone to be operated due to an impurity concentration in a back gate region and a shape of diffusion thereof. In a semiconductor device of the present invention, for example, a MOS transistor, a P type diffusion layeras the back gate region, and an N type diffusion layeras a drain region, are formed in an N type epitaxial layer. In the P type diffusion layer, an N type diffusion layeras a source region and a P type diffusion layerare formed. The P type diffusion layeris formed by performing ion implantation twice so as to correspond to a shape of a contact hole. Moreover, impurity concentrations in surface and deep portions of the P type diffusion layerare controlled. By use of this structure, a device size is reduced, and an operation of a parasitic NPN transistor is suppressed.

Semiconductor device and manufacturing method thereof

A semiconductor integrated circuit device according to the present invention includes a diode in a second island region. The anode region of the diode and the dividing region in a first island region having a horizontal PNP transistor are electrically connected to each other; the cathode region of the diode and the collector region of a power NPN transistor are electrically connected to each other. Accordingly, the dividing region in the first island region having a horizontal PNP transistor becomes lower in potential than the dividing regions in the other island regions, so that the inflow of free carriers (electrons) to the horizontal PNP transistor can be prevented.

In a conventional semiconductor device, there is a problem that an N-type diffusion region provided for protecting an element from an overvoltage is narrow and a breakdown current is concentrated so that a PN junction region for protection is broken. In a semiconductor device of the present invention, an N-type buried diffusion layer is formed across a substrate and an epitaxial layer. A P-type buried diffusion layer is formed across a wider region on an upper surface of the N-type buried diffusion layer so that a PN junction region for overvoltage protection is formed. A P-type diffusion layer is formed so as to be connected to the P-type diffusion layer. A breakdown voltage of the PN junction region is lower than a breakdown voltage between a source and a drain. With this structure, the concentration of the breakdown current is prevented so that the semiconductor device can be protected from the overvoltage.

Semiconductor device

According to a semiconductor device of an embodiment of the present invention, a P-type buried diffusion layer is formed across a substrate and an epitaxial layer. An N-type buried diffusion layer is formed in the P-type buried diffusion layer. An overvoltage protective PN junction region is formed below an element formation region. A breakdown voltage of the PN junction region is lower than a source-drain breakdown voltage. This structure prevents a breakdown current from concentratedly flowing into the PN junction region and protects the semiconductor device from overvoltage.

In a semiconductor device of the present invention, an N-type buried diffusion layer is formed across a substrate and an epitaxial layer. A P-type buried diffusion layer is formed across an upper surface of the N-type buried diffusion layer over a wide range to form a PN junction region for an overvoltage protection. A P-type diffusion region is formed so as to be connected to the P-type buried diffusion layer. A breakdown voltage of the PN junction region is lower than a breakdown voltage between a source and a drain. This structure makes it possible to prevent a concentration of a breakdown current and protect the semiconductor device from an overvoltage.

Semiconductor device for overvoltage protection

A semiconductor integrated circuit device according to the invention includes an N-type embedded diffusion region between a substrate and a first epitaxial layer in island regions serving as small signal section. The substrate and the first epitaxial layer are thus partitioned by the N-type embedded diffusion region having supply potential in the island regions serving as small signal section. This structure prevents the inflow of free carriers (electrons) generated from a power NPN transistor due to the back electromotive force of the motor into the small signal section, thus preventing the malfunction of the small signal section.

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Gunma, Japan

Ryo Kanda