A semiconductor device can include a first gate electrode including a gate insulating pattern, a gate conductive pattern and a capping pattern that are sequentially stacked on a semiconductor substrate, and a first spacer of a low dielectric constant disposed on a lower sidewall of the first gate electrode. A second spacer of a high dielectric constant, that is greater than the low dielectric constant, is disposed on an upper sidewall of the first gate electrode above the first spacer.