HIGH-VOLTAGE DEVICE ISOLATION STRUCTURE OF HIGH-VOLTAGE BCD PROCESS AND MANUFACTURING METHOD THEREOF

摘要

A high-voltage device isolation structure of a high-voltage BCD process and a manufacturing method thereof. The isolation structure comprises: a semiconductor substrate (10) having a first doping type; epitaxial layers (13, 15) having a second doping type, the first doping type being opposite to the second doping type; an isolation region having the first doping type, penetrating the epitaxial layers and extending to the inside of the semiconductor substrate, doping concentration of the isolation region and doping concentration of the epitaxial layers being in a same order of magnitudes; and a field oxidization layer (18), located above the isolation region. The structure can enable an epitaxial island where the BCD high-voltage device is located to be isolated effectively, increase breakdown voltage of the high-voltage device in the BCD process, and can enable parasitic threshold voltage of the aluminum wire and silicon surface of the high-voltage device to reach over 1200 V when thickness of the field oxidization layer is of a minimum value, thereby improving flatness of steps of the oxidization layer on the silicon surface in the entire BCD process and improving reliability of the high-voltage device.