Reliable resistive switching device based on bi-layers of ZrOx/HfOx films

Resistance random access memory (ReRAM) has attracted great attention due to their drastically reduced power consumption, fast switching speed, and nondestructive readouts [1]. However, non-uniformity and reliability issue are still considered as barriers for future high density memory applications. To solve these issues, our group proposed single crystal Schottky diode device [1] in 2005. Recently, new structures were proposed to improve the reliable switching. In case of binary oxide memory, bi layers structures (Ta
2
O
5-δ
/TaO
2-β
, TiO
x
/HfO
x
) show excellent switching properties, which can be explained by redox mechanism at active layer. [2, 3] In this paper, to improve the switching and uniformity properties, we adopted the bi-layers of ZrO
x
/HfO
x
structure. Pt/ZrO
x
/HfO
x
bi-layers structure was fabricated on the TiN/Ti/SiO
2
/Si wafer. The HfO
x
layer was deposited by atomic layer deposition (ALD) system and subsequently, Pt/Zr stack (50 um × 50 um) was patterned by lithography. The formation of bi-layers was confirmed by XPS data. The thickness of ZrO
x
and HfO
x
layer were 5 nm and 3 nm, respectively.