Method of manufacturing integrated circuit device

A method of manufacturing an integrated circuit device includes forming a mold structure, which has a mold layer and a support layer sequentially stacked, on a substrate, forming a vertical hole through the mold structure in a vertical direction and a bowing space extending outward from the vertical hole in a horizontal direction in a first vertical level area, exposing the vertical hole and the bowing space to a preprocessing atmosphere to make the support layer have a first surface state and the mold layer have a second surface state different from the first surface state, forming a bowing complementary pattern filling the bowing space by a selective deposition process using the difference between the first surface state and the second surface state, and forming a lower electrode in the vertical hole and in contact with the mold layer, the support layer, and the bowing complementary pattern.