A semiconductor device includes a semiconductor substrate, an active region formed in the semiconductor substrate and extending in a first direction, the active region including a transistor sub-region and a capacitor sub-region, a first trench extending around the transistor sub-region, an isolation layer disposed in the first trench, a second trench extending around the capacitor sub-region, a first transistor including a first insulating layer disposed on the transistor sub-region, the first transistor including a first conductive layer disposed on the first insulating layer, and a first capacitor including a second insulating layer extending over the capacitor sub-region and a sidewall of the second trench, the first capacitor including a second conductive layer disposed on the second insulating layer, the active region having an end portion in the first direction opposite to the transistor sub-region and extending across the first capacitor.