Electrodeposition of Titania Thin Films on Metallic Surface for High‐k Dielectric Applications

Abstract

Current microelectronics devices based on flexible as well as rigid substrates demand high dielectric constant (k) films to be grown on conductive substrate from a low‐cost, low‐temperature deposition technique. In this study, we produced high‐k titania (TiO2) films through an affordable electrodeposition protocol from the electrochemical bath maintained at about 0°C. The deposition occurs through a rapid hydrolysis mechanism of titanium containing ions in the precursor solution aided by electrochemically generated hydroxyl ions formed near the cathode surface (copper (Cu) substrate). Upon attaining a sufficient supersaturation level, such hydrolyzed species precipitate to form a titania thin film on the cathode surface. While depositing from a highly acidic precursor solution, Cu substrate was protected by a cathodic potential (−3 to −5 V against the counter electrode). The resultant titania films show nanoparticulate structures evolved from nucleation and growth events of the in situ precipitated particles. Much higher deposition rate (about 1 μm/min) was observed compared with that of typical chemical bath deposition. The resultant films with a thickness of 1500 nm grown on Cu exhibit very high dielectric properties (e.g., k∼30, capacitance density >110 nF/in.2 at 100 kHz) and moderate breakdown voltage (VB) (∼17.5 V). These properties indicate the potential of electrodeposited titania films to be used as a small‐area thin‐film capacitor for miniaturized electronic devices.