A method of manufacturing an integrated circuit device and an integrated circuit device prepared according to the method, the method including forming a silicon oxycarbonitride (SiOCN) material layer on an active region of a substrate, the forming the SiOCN material layer including using a precursor that has a bond between a silicon (Si) atom and a carbon (C) atom; etching a portion of the active region to form a recess in the active region; baking a surface of the recess at about 700° C. to about 800° C. under a hydrogen (H2) atmosphere, and exposing the SiOCN material layer to the atmosphere of the baking while performing the baking; and growing a semiconductor layer from the surface of the recess baked under the hydrogen atmosphere.