A method for fabricating a semiconductor device by using a plasma-enhanced atomic layer deposition apparatus. A substrate comprising a silicon substrate and a first oxide layer is provided. A plurality of stacked structures are deposited on the substrate, which comprises a dielectric layer and a conductive layer. The stacked structures are etched to form trenches. A second oxide layer is deposited by using a plasma-enhanced atomic layer deposition apparatus that includes a chamber, an upper electrode, a lower electrode, and a three-dimensional rotation device. The upper electrode is connected to a first radio-frequency power device. The upper electrode is configured to generate a plasma. The lower electrode is connected to a second radio-frequency power device. The three-dimensional rotation device drives the substrate to rotate. A high resistance layer is deposited on the second oxide layer. A low resistance layer is deposited on the high resistance layer.