Abstract: An arithmetic device calculates the surface potential of a silicon layer by performing computation based on a mathematical expression and device parameters stored in a storage device. Likewise, the arithmetic device calculates the surface potential of a bulk layer under a buried oxide film when the silicon layer is in a partially depleted state and when the silicon is in a fully depleted state. The arithmetic device then performs computation based on the calculated surface potential of the silicon layer, the calculated surface potential of the bulk layer, and mathematical expressions stored in the storage device, and obtains the surface potential of the bulk layer by iterative calculation. The arithmetic device performs computation based on the surface potential of the bulk layer obtained by iterative calculation and mathematical expressions stored in the storage device, and calculates the lower surface potential of the silicon layer.

Abstract: An arithmetic device calculates the surface potential of a silicon layer by performing computation based on a mathematical expression and device parameters stored in a storage device. Likewise, the arithmetic device calculates the surface potential of a bulk layer under a buried oxide film when the silicon layer is in a partially depleted state and when the silicon is in a fully depleted state. The arithmetic device then performs computation based on the calculated surface potential of the silicon layer, the calculated surface potential of the bulk layer, and mathematical expressions stored in the storage device, and obtains the surface potential of the bulk layer by, iterative calculation. The arithmetic device performs computation based on the surface potential of the bulk layer obtained by iterative calculation and mathematical expressions stored in the storage device, and calculates the lower surface potential of the silicon layer.

Abstract: For manufacturing an integrated circuit, the production of a design for the circuit that comprises a plurality of MOS transistors is controlled by employment of a circuit simulator. ##EQU1## are calculated in the circuit simulator for the terminal nodes of the MOS transistors upon prescription of the voltages between gate and source V.sub.gs, between drain and source V.sub.ds, and between the substrate and source V.sub.bs in a consistent transistor model wherein drift, diffusion and short-channel effects are taken into consideration.