A Comparative Study on the Ferroelectric Performances in Atomic Layer Deposited Hf0.5Zr0.5O2 Thin Films Using Tetrakis(ethylmethylamino) and Tetrakis(dimethylamino) Precursors

Abstract

The chemical, physical, and electrical properties of the atomic layer deposited Hf 0.5 Zr 0.5 O 2 thin films using tetrakis(ethylmethylamino) (TEMA) and tetrakis(dimethylamino) (TDMA) precursors are compared. The ligand of the metal-organic precursors strongly affects the residual C concentration, grain size, and the resulting ferroelectric properties. Depositing Hf 0.5 Zr 0.5 O 2 films with the TDMA precursors results in lower C concentration and slightly larger grain size. These findings are beneficial to grow more ferroelectric-phase-dominant film, which mitigates its wake-up effect. From the wake-up test of the TDMA-Hf 0.5 Zr 0.5 O 2 film with a 2.8 MV/cm cycling field, the adverse wake-up effect was well suppressed up to 10 5 cycles, with a reasonably high double remanent polarization value of 40 μC/cm 2. The film also showed reliable switching up to 10 9 cycles with the 2.5 MV/cm cycling field without involving the wake-up effect but with the typical fatigue behavior.

Impact of Pt grain size on ferroelectric properties of zirconium hafnium oxide by chemical solution deposition

“…With different materials as substrates, the contrast was considerably high because of the large distance between the TECs. In addition, the small HZO grain size also expresses the greater ferroelectric properties as reported elsewhere [ 30 , 31 ]. The grain size change leads to the various TECs and results in the change of the ferroelectric properties.…”

Large Remnant Polarization in a Wake-Up Free Hf0.5Zr0.5O2 Ferroelectric Film through Bulk and Interface Engineering

“…Moreover, ozone pulses during ALD are known to remove carbon, which may be present as a result of the incomplete reaction of the organic precursors and can substantially affect the crystallization characteristics of the samples during thermal post-annealing. Previous researches have shown that incomplete carbon removal under an insufficient oxygen environment stabilizes the t-phase in annealed HfO 2 -based thin films. − The remaining t-phase might then undergo a phase transition to the o-phase during electric field cycling, which results in wake-up behavior . Therefore, an ozone pulse with an adequate length appeared to be promising for achieving a wake-up free HZO ferroelectric thin film …”

“…The sample deposited at the lower ozone dosage shows a higher amount of carbon (Figure c); the XPS measurement revealed approximately 2.1% carbon in the sample that was grown at a 5 s ozone pulse, while the samples deposited at higher O 3 dosages (>15 s) were almost free of carbon . Carbon removal from the HZO film when deposited with a sufficient oxygen supply can facilitate grain growth during the subsequent RTA, preventing the stabilization of the t-phase during the cooling process. − A schematic (Figure d) shows how carbon contaminations (indicated as black circles) can pin the grain boundaries and slow the grain growth rate during the RTA process …”

“…Thus, the pulse length is a crucial parameter for providing enough oxygen for stoichiometric oxide formation and to avoid the generation of oxygen vacancies . In addition, C–O bonds are present as a result of incomplete reactions of the precursors that can prevent the agglomeration of the nanoscale domains, resulting in the stabilization of the tetragonal non-ferroelectric phase. − The t-phase can subsequently transfer to the o-phase under the application of a strong electric field resulting in the wake-up effect. Therefore, the removal of the C–O bonds from the sample by applying ozone pulses with an adequate length can remarkably change the subsequent annealing behavior of the as-grown film. , …”

Unipolar Parity of Ferroelectric-Antiferroelectric Characterized by Junction Current in Crystalline Phase Hf1−xZrxO2 Diodes

“…The fatigue mechanisms of ferroelectric layer are attributed to polarization degradation with domain pinning and/or nucleation inhibition for switch cycling [42]. The oxygen vacancies at the interface between the HZO and the TiN electrode benefit the t-phase stability, i.e., suppress the m-phase formation [33,43]. The excessive oxygen vacancies accumulation would lead to a breakdown via strong interactions between the individual vacancies [44].…”