A semiconductor device includes a first magnetic tunneling junction (MTJ) and a second MTJ on a substrate, a first top electrode on the first MTJ and a second top electrode on the second MTJ, a passivation layer between the first MTJ and the second MTJ, and an ultra low-k (ULK) dielectric layer on and directly contacting the passivation layer and around the first MTJ and the second MTJ. Preferably, a top surface of the passivation layer includes a V-shape and a valley point of the V-shape is higher than a bottom surface of the first top electrode.