US 2011/0079880 A1Published application

Semiconductor device

AssigneesSanyo Electric Co., Ltd., Sanyo Semiconductor Co., Ltd., SANYO Semiconductor Manufacturing Co., Ltd.

InventorsKeiji Mita, Yasuhiro Tamada, Masao Takahashi, Takao Maruyama

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Abstract

A serially-connected diode pair made of diodes having a high withstand voltage and a low on-resistance is formed based on a high withstand voltage vertical PNP bipolar transistor process technology. Two of the diode pairs are connected in parallel to form a bridge so that there is formed a high-efficiency full-wave rectifier circuit that is free from a leakage current due to a parasitic transistor. The serially-connected diode pair is formed by connecting a diode composed of a P type semiconductor substrate, that makes an anode, and an N type buried layer, that makes a cathode, and a diode composed of a P+ type conductive layer, that makes an anode, and an N type epitaxial layer, that makes a cathode, in series with an electrode AC1. An N+ type buried layer and an N+ type conductive layer are foamed to prevent an electric potential at the N+ type buried layer from becoming lower than an electric potential at a P+ type buried layer even when a large positive voltage is applied to the electrode AC1, so as to prevent a parasitic PNP transistor composed of the P+ type buried layer, the N+ type buried layer and the P type semiconductor substrate, that make an emitter, a base and a collector, respectively, from turning on.

Claims8

Dependent claims

A semiconductor device comprising:

a semiconductor substrate of a first general conductivity type;
an epitaxial layer of a second general conductivity type formed on the semiconductor substrate;
a first buried layer of the second general conductivity type buried in the semiconductor substrate;
a second buried layer of the second general conductivity type buried in the first buried layer and having a higher impurity concentration than the first buried layer;
a third buried layer of the first general conductivity type buried in the second buried layer and the epitaxial layer;
a first conductive layer of the first general conductivity type formed in a first portion of the epitaxial layer so as to be on a peripheral portion of the third buried layer;
and
an isolation layer of the first general conductivity type formed in the epitaxial layer so as to isolate the first portion of the epitaxial layer and the third buried layer from other portions of the epitaxial layer,
wherein the semiconductor substrate and the first buried layer are configured to operate as a first diode so that the semiconductor substrate works as an anode and the first buried layer works as a cathode,
the first conductivity layer and the epitaxial layer are configured to operate as a second diode so that the first conductive layer works as an anode and the epitaxial layer works as a cathode, and
the first diode and the second diode are connected serially.

8 more elements

Dependencies are inferred from the claim text.