A semiconductor device includes a package and a cooling cover. The package includes a first die having an active surface and a rear surface opposite to the active surface. The rear surface has a cooling region and a peripheral region enclosing the cooling region. The first die includes micro-trenches located in the cooling region of the rear surface. The cooling cover is stacked on the first die. The cooling cover includes a fluid inlet port and a fluid outlet port located over the cooling region and communicated with the micro-trenches.