Preparation and properties of tantalum oxide films by sol‐gel method

The preparation of tantalum oxide thin film by the sol‐gel method is discussed. The conditions of the film growth are investigated carefully to avoid pinholes and cracks. In particular, the effect of hydrochloric acid added to the sol solution is clarified. The spectral and electrical properties of the thin film are investigated. The as‐grown film was amorphous and became crystallized at 720°C. The relative dielectric constant increases with an increase of the heat‐treatment temperature and the breakdown voltage decreased rapidly when the heat‐treatment temperature exceeded 600°. The optimum heat‐treatment temperature to achieve both high relative dielectric constant and high breakdown voltage was 400°C. It was found by TEM observation that the rapid degradation of the breakdown voltage was due to pinholes created during crystallization process.