Other

Sanyo Electric Co., Ltd.

On Semiconductor Trading, Ltd.

Kentaro Ooka

Keiji Mita

Yasuhiro Tamada

In a semiconductor device including a protection diode for preventing electrostatic breakdown employing a low capacitance protection diode, an occupation area of a Zener diode as a voltage limiting element is not needed on a front surface of a semiconductor substrate. A P+ type embedded diffusion layer is formed in a P+ type semiconductor substrate. This is then covered by a non-doped first epitaxial layer. A high resistivity N type second epitaxial layer is then formed on the first epitaxial layer. The second epitaxial layer is divided by a P+ isolation layer into a first protection diode forming region and a second protection diode forming region. An N+ type embedded layer extending from the front surface of the first epitaxial layer of the first protection diode forming region to the first epitaxial layer and the second epitaxial layer, and so on are then formed. A Zener diode is formed by a P+ type upward diffusion layer extending from the P+ type embedded diffusion layer and the N+ type embedded layer.

Semiconductor device and method of manufacturing the same

A conventional semiconductor device, for example, a lateral PNP transistor has a problem that it is difficult to obtain a desired current-amplification factor while maintaining a breakdown voltage characteristic without increasing the device size. In a semiconductor device, that is a lateral PNP transistor, according to the present invention, an N type epitaxial layer is formed on a P type single crystal silicon substrate. The epitaxial layer is used as a base region. Moreover, molybdenum (Mo) is diffused in the substrate and the epitaxial layer. With this structure, the base current is adjusted, and thereby a desired current-amplification factor (hFE) of the lateral PNP transistor is achieved.

In a semiconductor device of the present invention, an N type epitaxial layer is formed on a P type single crystal silicon substrate. In the substrate and the epitaxial layer, an N type buried diffusion layer is formed on a P type buried diffusion layer. With this structure, an upward expansion of the P type buried diffusion layer is checked and a thickness of the epitaxial layer can be made small while maintaining the breakdown voltage characteristics of a power semiconductor element. Accordingly, a device size of a control semiconductor element can be reduced.

Growing community of inventors

Gunma, Japan

Kentaro Ooka