Abstract
Increasing demands for mass storage and new paradigm computing ask for non-volatile memories that can meet reliability requirements. Hf <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Zr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> -based (HZO) memory has attracted growing attention due to its excellent CMOS compatibility. This letter investigated the time dependent dielectric breakdown (TDDB) of HZO ferroelectric under both forward and reverse stress conditions, which is relevant to the memory's practical operation. The key similarities and the differences for both breakdown conditions have been identified and the underlying mechanism is explored. It is found that the pre-existing oxygen vacancies near the bottom electrode play the key role and all the observed phenomenon can be explained. Therefore, the precise control of these pre-existing oxygen vacancies can be critical for future TDDB improvement.
Highlights
HfO2-based ferroelectric (FE) materials have attracted much attention due to their potential adoption in future memory, logic and neuromorphic applications
A 12 nm Hf0.5Zr0.5O2 (HZO) FE layer was deposited on the bottom electrode using ALD under 250oC
For forward stress, +3.5V was applied and the breakdown can occur in all the devices before the constant voltage stress (CVS) measurement completes
Summary
HfO2-based ferroelectric (FE) materials have attracted much attention due to their potential adoption in future memory, logic and neuromorphic applications. The ferroelectricity of HfO2 originate from its orthorhombic phase, which can be stabilized by doping, introducing defects, and rapid thermal annealing [1]. Comparing with the traditional perovskite ferroelectrics, HfO2based ferroelectric has better CMOS compatibility and scalability. Their reliability issues remain a big concern. On the other hand, during device operation, the time dependent dielectric breakdown can occur, leading to leakage issues and even the loss of ferroelectric property. As one important reliability issue, TDDB in FE materials needs to be addressed properly [3]. The rearrangement of oxygen vacancies through cycling or the use of NH3 plasma treatment and microwave annealing (MWA)
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