A semiconductor device includes a substrate having a magnetic tunneling junction (MTJ) region and a logic region, an inter-metal dielectric (IMD) layer on the substrate, a MTJ in the IMD layer on the MTJ region, a first metal interconnection in the IMD layer on the logic region, and protrusions adjacent to two sides of the first metal interconnection. Preferably, the MTJ further includes a bottom electrode, a fixed layer, a barrier layer, a free layer, and a top electrode.