SOI SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

PROBLEM TO BE SOLVED: To reduce crosstalk noise generated in a silicon on insulator(SOI) semiconductor circuit by fixing the potential of a silicon active layer made of silicon having a higher impurity content than a silicon substrate. SOLUTION: For example, a plurality of transistors 130 constituting part of a digital circuit and a plurality of transistors 140 constituting part of an analog circuit are formed on a buried insulating film 102. A silicon active layer 105, which has a predetermined conductive type and which is doped with an impurity at a higher concentration than a silicon substrate 101, is arranged between the transistors 130 and 140. The layer 105 is connected to, e.g. a grounding line to have its electrical potential fixed at 0 V. Therefore, a depletion layer is formed at a portion of the film 102 which is directly under the layer 105. As a result of the formation of the depletion layer, crosstalk noise intruding into the transistor 140 is suppressed, and thus crosstalk noise generated in the SOI semiconductor integrated circuit is reduced.