| 摘要 |
PURPOSE:To freely select the substrate potentials of both FET's by isolating each other MOSFET forming region of each conductivity type of a CMOS IC. CONSTITUTION:A p type buried layer 16 is formed in the n<-> type substrate 1, and an n<-> type epitaxial layer 1a is grown on the substrate 1. P type isolation regions are diffusion-formed so as to reach the buried layer 16 from the surface of the layer 1a, and the n<-> type epitaxial layer 1b is isolated from the substrate by means of the buried layer 16 and the isolation regions 17. A p type MOSFET is formed in the n<-> type epitaxial layer 1b, a p type island region is formed in the n<-> type epitaxial layer 1a, and an n type MOSFET is formed in the island region. Since the connection of the p type regions 16 and 17 to the minimum potential point in a circuit enables to connect the n<-> type epitaxial layer 1b to an arbitrary potential point in the circuit, substrate effect can be eliminated. |
