Study of electrical properties of hafnium oxide thin film based metal–insulator–metal capacitors: pre and post metallic annealing

Abstract

Metal–insulator–metal (MIM) capacitors having hafnium oxide (HfO₂) high-κ dielectric thin film were fabricated and subsequently studied for their electrical and micro-structural properties. The MIM capacitors were found to possess low leakage current density of about 2.7 × 10⁻⁹ A/cm² at −1 V, high capacitance density of about 18.1 fF/μm² at 0 V, 1 MHz and improved quadratic voltage coefficient of capacitance (VCC) of about 120 ppm/V² at 1 MHz. The electrical properties of MIM capacitors are found to be governed by Frenkel–Poole mechanism at low and intermediate fields (<1500 kV/cm) and by Schottky emission at high fields (>1500 kV/cm). The dielectric thin films have amorphous structure which has been correlated with the electrical properties of MIM capacitors. The HfO₂ thin film possess good micro-structural properties in term of low roughness, which is in agreement with the obtained electrical properties of thin film based MIM capacitors. Further, post metallic annealing of MIM capacitors results in decrease in leakage current density to ~5.1 × 10⁻¹⁰ A/cm² at −1 V, increase in capacitance density to ~23.1 fF/μm² at 0 V, 1 MHz and improvement in quadratic VCC to reach a value of ~95 ppm/V² at 1 MHz. The electrical characteristics of as-fabricated and annealed MIM capacitors are in accordance with the International Technology Roadmap for Semiconductor 2013 guidelines. The obtained electrical properties suggest the possible use of MIM capacitors in analog/mixed-signal applications.