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Al 2 O 3 /HfO 2 Multilayer High‐k Dielectric Stacks for Charge Trapping Flash Memories
Author(s) -
Spassov Dencho,
Paskaleva Albena,
Krajewski Tomasz A.,
Guziewicz Elzbieta,
Luka Grzegorz,
Ivanov Tzvetan
Publication year - 2018
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201700854
Subject(s) - trapping , annealing (glass) , materials science , dielectric , flash memory , electric field , high κ dielectric , electron , optoelectronics , analytical chemistry (journal) , chemistry , composite material , ecology , physics , chromatography , quantum mechanics , computer science , biology , operating system
Dielectric and electrical properties of Al 2 O 3 /HfO 2 multilayer stacks deposited by atomic layer deposition (ALD) in dependence on the thickness of Al 2 О 3 and HfO 2 layers and the post‐deposition annealing (PDA) in different ambient (O 2 , N 2 , air) are investigated in terms of their application as trapping layers in emerging charge‐trapping non‐volatile flash memories. Differentiation is made between different processes giving rise to hysteresis effects: trapping of electrons and holes under positive and negative gate bias, respectively (as useful processes which define the memory window), and the generation of positive charge under high electric field stress (which degrades the stacks and results in permanent damage and ultimately in breakdown). Dependence of these processes on HfO 2 and Al 2 O 3 thickness as well as annealing ambient is analyzed. It is established that electrically active defects and trapping phenomena are most strongly affected by the annealing ambient. Oxygen annealing is favorable in terms of charge storage ability as it increases electron trapping and improves the electric field stress stability of Al 2 О 3 /HfO 2 multilayer stacks.