SEMICONDUCTOR DEVICE

PURPOSE:To increase the degree of stability as well as to make the area of chip smaller by a method wherein the current supply terminal of a buried Zener diode and a voltage output terminal are provided within the island whereon an isolation region is formed. CONSTITUTION:A buried Zener diode 10, which generates a junction breakdown on the A part, is formed on a P isolation region 4 and an N buried layer 1, and when a current supply terminal 8 and a voltage output terminal 9 are provided in the island surrounded by a P isolation region 3, and a Zener current is controlled by the resistance Rz 11 of the N-epitaxial layer 2 located between the current supply terminal 8 and the N buried layer 1. The Zener current is restricted by the resistance Rz 11 of the N-epitaxial layer 2 located between the current supply terminal 8 and the N buried layer 1. Voltage drop can be disregarded when the parasitic resistance Ro 12 generated on the side of the voltage output terminal 9 is received at high impedance. As a result, the state of low drift and low noise is obtained because a breakdown is generated on the buried part, and as a Zener current controlling resistor is provided in the same island as the Zener diode, the chip area can be made smaller.