Semiconductor device

A semiconductor device, comprising:

• a semiconductor substrate of a first conductivity type;
• an intermediate region disposed on a top surface of the semiconductor substrate, the intermediate region including at least one stacked structure in which a first semiconductor region of a second conductivity type has stacked thereon a second semiconductor region having a conductivity type differing from that of the first semiconductor region, such that the first semiconductor region is a lowermost layer that forms a Zener diode with the semiconductor substrate, and the first semiconductor region and the second semiconductor region form a PIN diode;
• a third semiconductor region of the second conductivity type embedded in a top part of the second semiconductor region of an uppermost layer of the intermediate region, the third semiconductor region facing the semiconductor substrate through the intermediate region and forming a PIN diode with the second semiconductor region of the uppermost layer;
• and
• a fourth semiconductor region of the first conductivity type embedded in a portion of a top part of the third semiconductor region and forming a Zener diode with the third semiconductor region;
• wherein an impurity concentration of the second semiconductor region is lower than impurity concentrations of the first semiconductor region and the third semiconductor region.