High density and program-erasable metal-insulator-silicon capacitor with a dielectric structure of SiO2∕HfO2–Al2O3nanolaminate∕Al2O3

We demonstrate a program-erasable metal-insulator-silicon capacitor with a dielectric structure of SiO2∕HfO2–Al2O3 nanolaminate (HAN)∕Al2O3. The memory capacitor exhibits a high capacitance density of 4.5fF∕μm2, a large memory window of 1.45 V in the case of +12Vprogram∕−12Verase for 5 ms, nearly symmetrical positive and negative flatband voltages under the program/erase operations with the same magnitudes of voltage and time, and no erase saturation. This is attributed to the fact that the introduction of atomic-layer-deposited high-dielectric-constant HAN∕Al2O3 layers increases the electric field across the tunnel oxide and reduces that across the blocking layer, hence, preventing effectively Fowler-Nordheim tunneling current through the blocking layer. Additionally, we find that the HAN is a promising charge storage layer with sufficient trapping centers for electrons and holes.