Multilayered tantalum-aluminum oxide films grown by atomic layer deposition

Dielectric films, laminated by thin layers of tantalum oxide and aluminum o xide alternatively, have been grown from metallic chlorides and H2O by usin g atomic layer deposition (ALD) at 310 degrees C. The thickness of each lay er is controlled by altering the number of cycles of the ALD process. The m ultilayered structure is confirmed by using Auger electron spectrometry dep th-profiling analysis for Ta and Al atoms. The as-deposited films are found to have a very flat surface morphology and to remain amorphous after annea ling at 500 degrees C for 6 hr. The electrical properties, such as the brea kdown field strength, the leakage current, and the relative dielectric cons tant, have been characterized to evaluate the multilayered dielectrics from the viewpoint of their application as insulating materials for thin-film e lectroluminescent devices. The leaky characteristics of pure tantalum oxide is significantly improved by the insertion of aluminum oxide as interlayer s. The dielectric permittivity is gradually decreased from 28 to 8.1 with i ncreasing aluminum oxide content. The Al2O3-Ta2O5 nanolaminates possess hig h charge-storage factors up to 3.6 mu C/cm(2). This value is much larger th an those of aluminum oxide and tantalum oxide.