A method for fabricating a semiconductor device includes the steps of forming a magnetic tunneling junction (MTJ) on a substrate, forming a first inter-metal dielectric (IMD) layer on the MTJ, removing part of the first IMD layer to form a damaged layer on the MTJ and a trench exposing the damaged layer, performing a ultraviolet (UV) curing process on the damaged layer, and then conducting a planarizing process to remove the damaged layer and part of the first IMD layer.