Abstract: Semiconductor devices including STI liners are provided. The semiconductor devices may include a STI trench that defines an active region in a substrate, a STI liner that extends conformally along side walls and a bottom surface of the STI trench, a device isolation film that is on the STI liner and fills up at least a part of the STI trench, a first gate structure that is disposed on the active region, and a second gate structure that is spaced apart from the first gate structure. The second gate structure may include a gate insulating film contacting the device isolation film, a gate electrode on the gate insulating film, and spacers on both sides of the gate electrode. Lower surfaces of the spacers may contact an upper surface of the STI liner.