Sanyo Electric Co., Ltd.

Sanyo Semiconductor Co., Ltd.

Mitsuru Soma

Hirotsugu Hata

Yoshimasa Amatatsu

Minoru Akaishi

Reiki Fujimori

In a conventional semiconductor device, part of a dielectric film of a capacitive element is removed when photoresist is peeled off, and this causes problems of variation in capacitance value of the capacitive element and deterioration of breakdown voltage characteristics. In a semiconductor device according to the present invention, a silicon nitride film serving as a dielectric film is formed on the top face of a lower electrode of a capacitive element, and an upper electrode is formed on the top face of the silicon nitride film. The upper electrode is formed of a laminated structure having a silicon film and a polysilicon film protecting the silicon nitride film. This structure prevents part of the silicon nitride film from being removed when, for example, photoresist is peeled off, thereby preventing variation in capacitance value of the capacitive element and deterioration of the breakdown voltage characteristics.

Semiconductor device with silicon capacitor

In the substrate and the epitaxial layer, isolation regions are formed to divide the substrate and the epitaxial layer into a plurality of element formation regions. Each of the isolation regions is formed by connecting first and second P type buried diffusion layers with a P type diffusion layer. By disposing the second P type buried diffusion layer between the first P type buried diffusion layer and the P type diffusion layer, a lateral diffusion width of the first P type buried diffusion layer is reduced. This structure allows a formation region of the isolation region to be reduced in size.

Semiconductor device and method of manufacturing the same

In a semiconductor device according to the present invention, two epitaxial layers are formed on a P type substrate. In the substrate and the epitaxial layers, isolation regions are formed to divide the substrate and the epitaxial layers into a plurality of islands. Each of the isolation regions is formed by connecting first and second P type buried layers with a P type diffusion layer. By disposing the second P type buried layer between the first P type buried layer and the P type diffusion layer, a lateral diffusion width of the first P type buried layer is reduced. By use of this structure, a formation region of the isolation region is reduced in size.

In a semiconductor device of the present invention, an epitaxial layer is formed on a P type single crystal silicon substrate. Isolation regions are formed in the epitaxial layer, and are divided into a plurality of element formation regions. An NPN transistor is formed in one of the element formation regions. An N type diffusion layer is formed between a P type isolation region and a P type diffusion layer which is used as a base region of the NPN transistor. This structure makes the base region and the isolation region tend not to be short-circuited. Hence, the breakdown voltage characteristics of the NPN transistor can be improved.

In a semiconductor device of the present invention, two epitaxial layers are formed on a P type single crystal silicon substrate. One of the epitaxial layers has an impurity concentration higher than that of the other epitaxial layer. The epitaxial layers are divided into a plurality of element formation regions by isolation regions. In one of the element formation regions, an NPN transistor is formed. Moreover, between a P type diffusion layer, which is used as a base region of the NPN transistor, and a P type isolation region, an N type diffusion layer is formed. Use of this structure makes it hard for a short-circuit to occur between the base region and the isolation region. Thus, the breakdown voltage characteristics of the NPN transistor can be improved.

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Saitama, Japan

Mitsuru Soma