A device includes a semiconductor region surrounded with the isolation region and includes a first active region, a channel region and a second active region arranged in that order in a first direction. A first side portion of the first active region and a second side portion of the second active region faces each other across a top surface of the channel region in the first direction. A gate electrode covers the top surface and the first and second side portions and extends in a second direction that intersects the first direction. A first diffusion layer is formed in the first active region. A second diffusion layer is formed in the second active region. An embedded contact plug is formed in the first active region and extends downwardly from the upper surface of the semiconductor region and contacts with the first diffusion layer.