High density and program-erasable metal-insulator-silicon capacitor with a dielectric structure of SiO2/HfO2 - Al2 O 3 nanolaminate/Al2 O3

Abstract

We demonstrate a program-erasable metal-insulator-silicon capacitor with a dielectric structure of SiO2 HfO2 - Al2 O3 nanolaminate (HAN) Al2 O3. The memory capacitor exhibits a high capacitance density of 4.5 fFμ m2, a large memory window of 1.45 V in the case of +12 V program-12 V erase 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 Al2 O3 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. © 2006 American Institute of Physics.