A semiconductor device and a method of fabricating a semiconductor device, the semiconductor device includes an active pattern; a gate structure on the active pattern; a bit-line structure electrically connected to the active pattern; a storage node contact electrically connected to the active pattern; and a landing pad electrically connected to the storage node contact, wherein the landing pad includes a first pad flat sidewall and a second pad flat sidewall that are opposite to each other, a third pad flat sidewall between the first pad flat sidewall and the second pad flat sidewall, a fourth pad flat sidewall between the first pad flat sidewall and the second pad flat sidewall, a first pad curved sidewall between the first pad flat sidewall and the third pad flat sidewall, and a second pad curved sidewall between the first pad flat sidewall and the fourth pad flat sidewall.