Electrical and dielectric properties of thin film BaTiO3 capacitors deposited by radio frequency magnetron sputtering

Abstract

Thin film BaTiO3 capacitors were deposited by rf magnetron sputtering. The dielectric constant, dielectric loss, conductivity, and breakdown strength of the capacitor were investigated as a function of the sputtering condition and the capacitor design. Films deposited at low substrate temperature were amorphous whereas those deposited at a high substrate temperature were polycrystal. Amorphous films had a low conductivity (7.7 × 10−11/Ω cm), a high breakdown voltage up to 2.5 × 106 V/cm, and a small dielectric constant of around 16. Polycrystal films yielded a high dielectric constant up to 330. However, they also lead to large conductivity. With double layer or graded design, i.e., amorphous layer on the top of polycrystal layer or graded layer, the conductivity could been reduced to the same order as in the amorphous films. The dielectric constant and breakdown voltage of the capacitor with double layer structure were found to be as high as 210 and 1.2 × 106 V/cm, respectively. The dielectric properties of the capacitors were measured over a wide range of frequency (12 Hz–100 kHz). The frequency dependence of the dielectric constant and dielectric loss were explained by polarity, leakage, and interface dissipation mechanism, respectively.