Provided is a semiconductor device. The semiconductor device may include a substrate and a stacked insulation layer on a sidewall of an opening which penetrates the substrate. The stacked insulation layer can include at least one first insulation layer and at least one second insulation layer whose dielectric constant is different than that of the first insulation layer. One insulation layer may be a polymer and one insulation layer may be a silicon based insulation layer. The insulation layers may be uniform in thickness or may vary as a distance from the substrate changes.