Leakage‐Current Increase in Amorphous Ta₂ O ₅ Films Due to Pinhole Growth during Annealing Below 600°C

Effects of high temperature annealing over the range 400°–1000°C on the leakage current of tantalum pentoxide films deposited by reactive sputtering are investigated. Leakage current of polycrystalline film (annealed above 700°C) is about 10⁷–10⁸ times larger than that of as‐deposited amorphous film. However, it is found that leakage current in film annealed at 600°C increases drastically as well, even though the films have not yet recrystallized. TEM observation reveals that pinholes ranging from 5 nm to 15 nm in diameter are formed near the bottom of the depressions in film annealed even at 600°C. Electrical properties of the films are discussed in terms of crystallographic properties such as pinhole growth and grain boundaries.