Corner rounding of electrically conductive layers in a replacement electrode integration scheme can be alleviated by employing compositionally modulated sacrificial material layers. An alternating stack of insulating layers and compositionally modulated sacrificial material layers can be formed over a substrate. Each of the compositionally modulated sacrificial material layers has a vertical modulation of material composition such that each compositionally modulated sacrificial material layer provides greater resistance to conversion into a silicon-oxide-containing material at upper and lower portions thereof than at a middle portion thereof during a subsequent oxidation process. Bird's beak features can be formed with lesser dimensions, and electrically conductive layers formed by replacement of remaining portions of the sacrificial material layers with a conductive material can have less corner rounding. Reduction in corner rounding can increase effectiveness of the control gates for a three-dimensional memory device.