Electrical characteristics of multilayered HfO2-Al2O3 charge trapping stacks deposited by ALD

INERA Conference: Vapor Phase Technologies for Metal Oxide and Carbon Nanostructures

物理学;材料科学

Spassov, D.^1 ; Paskaleva, A.^1 ; Guziewicz, E.^2 ; Luka, G.^2 ; Akrajewski, T.^2 ; Kopalko, K.^2 ; Wierzbicka, A.^2 ; Blagoev, B.^1

Institute of Solid State Physics, Bulgarian Academy of Sciences, Tzarigradsko Chaussee 72, Sofia

1734, Bulgaria^1

Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, Warsaw

02-668, Poland^2

关键词: Atomic layer deposited;    Charge trapping properties;    Conduction Mechanism;    Electrical characteristic;    Hopping conduction;    Non-volatile memory;    Poole-Frenkel effect;    Post deposition annealing;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/764/1/012016/pdf
DOI  :  10.1088/1742-6596/764/1/012016

学科分类：材料科学（综合）

来源: IOP

【 摘 要 】

Electrical and charge trapping properties of atomic layer deposited HfO2-Al2O3multilayer stacks with two different Al2O3sublayer thicknesses were investigated regarding their implementation in charge trapping non-volatile memories. The effect of post deposition annealing in oxygen at 600°C is also studied. The decreasing Al2O3thickness increases the stack's dielectric constant and the density of the initial positive oxide charge. The initial oxide charge increases after annealing to ∼61012cm-2and changes its sign to negative for the stacks with thicker Al2O3. The annealing enhances the dielectric constant of the stacks and reduces their thickness preserving the amorphous status. Nevertheless the annealing is not beneficial for the stacks with thicker Al2O3as it considerably increases leakage currents. Conduction mechanisms in stacks were considered in terms of hopping conduction at low electric fields, and Fowler- Nordheim tunnelling, Schottky emission and Poole-Frenkel effect at higher ones. Maximum memory windows of about 12 and 16V were obtained for the as-grown structures with higher and lower Al2O3content, respectively. In latter case additional improvement (the memory window increase up to 23V) is achieved by the annealing.