Effect of Nitrogen Plasma Treatment on Electrical Characteristics for Pd Nanocrystals in Nonvolatile Memory

Abstract

Pd nanocrystals (NCs) are successfully embedded in a TaN/SiO 2 /HfAlO/Si structure. The initial memory window increases at a higher rate with increasing fabrication temperature of Pd NCs compared with the linear variation of Pd NC density, which is related to the thermally induced neutral traps in the HfAlO film around Pd NCs. After manufacturing a TaN/SiO 2 /Pd NCs/HfAlO/Si/Al structure, the subsequent N 2 plasma treatment is conducted at 300 C for 3 min. The number of leakage current paths in the SiO 2 blocking layer adjacent to TaN is clearly reduced, but that of leakage current paths in SiO 2 /HfAlO around Pd NCs is slightly increased owing to the thermal stress. The thermally induced neutral traps in the HfAlO film around the Pd NCs can be passivated by nitrogen atoms, which leads to the improvement of the final memory window for the Pd NC samples fabricated at 600-700 C. However, the intrinsic traps in the HfAlO film play an important role in memory characteristic and the final memory window is reduced by thermal densification for the Pd NC samples fabricated at 500 C.

Robust Data Retention and Superior Endurance of Silicon–Oxide–Nitride–Oxide–Silicon-Type Nonvolatile Memory with NH3-Plasma-Treated and Pd-Nanocrystal-Embedded Charge Storage Layer

“…This is ascribed to material mismatching and thermal damage caused by the NC forming process. 6,7) This phenomenon results in a serious Fermi level pinning effect that shifts the effective work function at the interface between the metal NCs and the dielectric. [8][9][10][11] Thus, it is difficult for electron charges to be stored in quantum wells accurately and it is easy for them to be pinned on interface states between the NCs and the dielectric.…”

“…Palladium (Pd) metal was selected as the NC material in this study owing to its high work function of 5.1 eV 13) as well as its good performance in Pd NC NVMs. 7,14) The electrical characteristics, including the program and erase (P/E) speeds, charge retention, and endurance, for the CT-NVM with embedded Pd NCs with and without NH 3 PT are demonstrated. Additionally, the multilevel cell (MLC) retention characteristics of the NH 3 -plasma-treated device were also investigated in this study.…”

Robust Data Retention and Superior Endurance SONOS Nonvolatile Memory with NH₃ Plasma Treated and Pd NCs Embedded Charge Storage Layer

“…Recently, the charge trapping type non-volatile memories (CT-NVMs) with embedded metal nanocrystals (NCs) have been extensively investigated to be the next generation NVM since the benefit of combination of quantum wells and discrete trap sites [1], [2]. As metal NCs embedded in dielectric, the interface between dielectric and NCs always lies in unstable state and shallow defects [3], [4]. The shallow deficiencies around NC can easily lead stored charges out of the quantum well through trap-assisted tunneling mechanism [5], resulting in the serious data retention issue, especially in the environment at high temperature.…”