A block copolymer is described, such as one including a first polymer block and a second polymer block that have different structures, wherein the first polymer block includes a first unit derived from an acrylic acid ester, and the second polymer block includes an inorganic material-containing random block, in which a second unit including an inorganic material-containing group and a third unit that is devoid of an inorganic material-containing group are connected to each other to provide a concentration gradient. Also described are methods of manufacturing an integrated circuit device that include forming, on a feature layer, a block copolymer layer including the block copolymer as set forth above; phase-separating the block copolymer layer to form a structure that includes a plurality of first domains that each include the first polymer block, and at least one second domain including the second polymer block; removing the plurality of first domains; and etching the feature layer using the at least one second domain as an etch mask.