Atomic-layer-deposited Al_2O_3-HfO_2-Al_2O_3 dielectrics for metal-insulator-metal capacitor applications

摘要

Atomic-layer-deposited Al_2O_3-HfO_2-Al_2O_3 dielectrics have been investigated to replace conventional silicon oxide and nitride for radio frequency and analog metal-insulator-metal capacitors applications. In the case of 1-nm-Al_2O_3, sufficiently good electrical performances are achieved, including a high dielectric constant of ～17, a small dissipation factor of 0.018 at 100 kHz, an extremely low leakage current of 7.8 X 10~(-9) A/cm~2 at 1 MV/cm and 125℃, perfect voltage coefficients of capacitance (74 ppm/V~2 and 10 ppm/V). The quadratic voltage coefficient of capacitance decreases with the applied frequency due to the change of relaxation time with different carrier mobility in insulator, and correlates with the dielectric composition and thickness, which is of intrinsic property owing to electric field polarization. Furthermore, the conduction mechanism of the AHA dielectrics is also discussed, indicating the Schottky emission dominated at room temperature.