A semiconductor device includes a first capacitor structure, a second capacitor structure, and an insulation pattern. The first capacitor structure includes a first lower electrode, a first dielectric layer and a first upper electrode sequentially stacked on a substrate. The second capacitor structure includes a second lower electrode, a second dielectric layer and a second upper electrode sequentially stacked on the substrate, and is adjacent to the first capacitor structure. The insulation pattern partially fills a space between the first and second capacitor structures, and an air gap is formed between the first and second capacitor structures on the insulation pattern.