Display device

A display device comprises a base substrate, a lower interlayer dielectric layer, an oxide semiconductor layer including a first channel region, a first drain region disposed on one side of the first channel region, and a first source region, a first gate insulating layer, a first upper gate electrode, an upper interlayer dielectric layer, and a first source electrode and a first drain electrode, wherein the lower interlayer dielectric layer includes a first lower interlayer dielectric layer disposed on the base substrate, and a second lower interlayer dielectric layer disposed on the first lower interlayer dielectric layer, wherein the first lower interlayer dielectric layer includes silicon nitride and the second lower interlayer dielectric layer comprises silicon oxide, and wherein a composition ratio of nitrogen to silicon in the first lower interlayer dielectric layer ranges from 0.8 to 0.89.