Resistance switching of copper-doped tantalum oxide prepared by oxidation of copper-doped tantalum nitride

A thin copper-doped tantalum oxide (Cu–TaOx) film was prepared by plasma oxidation of a copper-doped tantalum nitride (Cu–TaN) and its resistance switching behavior was studied. A Cu–TaN film was firstly deposited by co-sputtering of copper and tantalum in a gas mixture of argon and nitrogen as the bottom electrode for a resistance switching device. Subsequently, the Cu–TaN film was oxidized in an oxygen-containing plasma to form an insulating layer. Then a TaN film was deposited on top of the insulating layer as the top electrode to form a MIM structure. The TaN/Cu–TaOx/Cu–TaN (MIM) device exhibited bipolar resistance switching when DC voltages were swept. The MIM device was switched from a high resistive state (HRS) to a low resistive state (LRS) at a SET voltage between + 0.65 and + 0.85 V, and were switched from LRS to HRS at a RESET voltage between − 0.4 and − 0.5 V when a compliant current of 3.5 μA was utilized. The SET voltage was between + 0.7 and + 1.15 V and the RESET voltage was around − 0.6 V when a compliant current was set to 13 μA. The resistance ratios of RHRS/RLRS measured at + 0.3 V were above 10 and 100 when compliant currents of 3.5 and 13 μA were utilized, respectively. The resistance switch was possibly attributed to the reaction in composite filamentary paths which were formed inside the Cu–TaOx layer.

► Cu-doped TaOx as resistor layer for resistance memory.
► Plasma oxidation of Cu-doped TaN.
► Bipolar resistance switching for TaN/Cu–TaOx/Cu–TaN cell.
► Resistance ratio of OFF/ON increases with compliant current.