Stacked gate MOS structure for multiple voltage power supply applications

摘要

A capacitor structure is formed on a semiconductor substrate to provide split voltages for semiconductor circuits. An active area is formed in the substrate serving as a lower capacitor plate for a bottom capacitor. A thin dielectric layer and field oxide regions are formed on the substrate, and the dielectric layer is covered with a capacitor plate over the active area to complete the bottom capacitor. A thick dielectric layer is formed over the device and a via is formed through the thick dielectric layer to the upper capacitor plate. A second lower plate is formed for a top capacitor. An inter-layer dielectric layer is formed over the second lower plate. An upper capacitor layer is formed over the inter-layer dielectric layer to form a top capacitor with a different capacitance value from the bottom capacitor. The value of the capacitance can be varied by selection of the permittivity and/or thickness of the dielectric layer and by variation of the effective plate area of the top and bottom capacitors.