Characterization of tantalum pentoxide dielectric films grown by low-pressure and plasma-enhanced chemical vapor deposition

The material properties as well as the electrical behavior of tantalum pentoxide (Ta₂O₅) thin films prepared by low-pressure chemical vapor deposition (LPCVD) and plasma-enhanced chemical vapor deposition (PECVD), in the same reactor, were studied. Ta₂O₅ films were grown on Si and Pt substrates by reacting pentaethoxy tantalum [Ta(OC₂H₅)₅] with oxygen and were annealed in an oxygen furnace at 700°C or oxygen plasma at 350°C. Scanning electron microscopy (SEM), secondary ion mass spectroscopy (SIMS), Auger electron spectroscopy (AES), capacitance-voltage (C-V) and current-voltage (I-V) measurements were employed to characterize the Ta₂O₅ films before and after annealing. Compared to the LPCVD Ta₂O₅ film, the PECVD Ta₂O₅ film deposited at an rf power of 80 W exhibited a denser structure and better dielectric characteristics. Oxygen plasma annealing further d ensified the Ta₂O₅ films and improved their electrical performance on either Si or Pt substrate, without deteriorating the substrate materials.