A semiconductor integrated circuit device which has a plurality of very fine storing elements and especially can suppress the kink current of a MOS transistor without lowering the junction characteristic of its diffusion layer. In the device, the angle between the underside of the end part of a field oxide film (2) formed in a peripheral element region, and the principal surface of a semiconductor substrate (1) is smaller than the corresponding angle relative to a storing element region. Also, the extension of the end part of the field oxide film (2) in the peripheral element region in the principal surface direction of the semiconductor substrate (1) is larger than the corresponding extension relative to a circuit element region. <IMAGE>
