Growth assessment and scrutinize dielectric reliability of c-axis oriented insulating AlN thin films in MIM structures for microelectronics applications

The present study reports the effect of bottom electrodes (Al, Pt & Ti) on the texture, piezoelectric characteristics, dielectric properties and leakage current behavior of reactive DC magnetron sputtered AlN thin films. X-ray diffraction results revealed that the lattice structure and texture of bottom electrode plays a vital role in c-axis wurtzite phase growth of aluminum nitride (AlN) thin films. A highly (002) oriented c-axis AlN thin films was obtained over Ti as compared to Al and Pt electrodes. The piezoelectric coefficient (d33eff) of these fabricated AlN thin films were measured by piezoresponse force microscopy to evaluate their piezoelectric efficiency in resonators. AlN is a good option for passivation purpose in microelectronic devices because of high chemical stability and excellent dielectric properties. Therefore, the dielectric reliability of AlN thin films is very crucial. Among all structures, AlN/Ti structure exhibits a highest dielectric constant (εr) ∼ 8.63 at 1 MHz. This work also provided a comprehensive study of leakage current conduction mechanism with electric field. The leakage behavior depicts that all AlN film endures a transition from ohmic conduction (E < 70 kV/cm) to SCLC conduction (E > 70 kV/cm). In addition, the breakdown characteristic of these fabricated films was studied for deciding the long-term device reliability and life. This study suggests that the electrode engineering of AlN thin films have a potential in devices for electrical and micro-electro-mechanical system (MEMS) applications.