An integrated circuit semiconductor device includes a substrate including a first surface and a second surface opposite the first surface, a trench in the substrate, the trench extending from the first surface of the substrate toward the second surface of the substrate, a through silicon via (TSV) landing part in the trench, the TSV landing part having a first portion spaced apart from the first surface of the substrate, and a second portion between the first portion and the first surface of the substrate, the first portion being wider than the second portion, a TSV hole in the substrate, the TSV hole extending from the second surface of the substrate and aligned with a bottom surface of the TSV landing part, and a TSV in the TSV hole and in contact with the bottom surface of the TSV landing part.