Influence of Y2O3 Doped HfO2 High-k Films on Electrical Properties of MOS and MIM Devices

Abstract

Y2O3 doped HfO2 high-k films were successfully fabricated on P-type and N-type doped Si substrates by liquid phase deposition (LPD) for metal-oxide-semiconductor (MOS) and metal-insulator-metal (MIM) capacitors. The effects of doping different molar concentrations of Y2O3 and nitrogen annealing on the electrical properties of HfO2 thin films were investigated, too. According to the experimental results, the HfO2 film doped with Y2O3 (5 mol%) had a high capacitance density and low leakage current. The improvement of defects at low-temperature deposited films was achieved by using nitrogen annealing at 600°C. The oxide capacitance of the MOS capacitor is 127 pF, approaching the ideal flat-band voltage of -0.53 V, small hysteresis flat band voltage of 0.093 V, and low leakage current density of 3.78 × 10^-5 A/cm² at +5 V. The capacitance density of MIM capacitors at 1 MHz is 2.98 fF/µm², small relatively quadratic voltage coefficient of capacitance (VCC) of -517.96 ppm/V², and leakage current density 1.12 × 10^-2 A/cm² at +3 V. Therefore, Y2O3 doped HfO2 films can be applied in MOSFET, radio frequency, and mixed-signal integrated circuits as a promising candidate to replace SiO2.