This review focuses on oxide memristors for resistive random access memory (ReRAM). Possible practical implementations of ReRAM and the problem of leakage through neighboring elements in ReRAM are considered. The main types of resistive switching in memristors are briefly described and the main mechanisms of resistive switching are analyzed. The main characteristics of memristors required for ReRAM are also described. Some memristor structures based on oxides of titanium, silicon, tantalum, and hafnium, as well as multilayer oxide structures are analyzed. The current problems in the creation of ReRAM are highlighted.

Memristive structures are among the most promising options to be components of neuromorphic devices. However, the formation of HfO₂-based devices in crossbar arrays requires considerable time since electroforming is a single stochastic operation. In this study, we investigate how Ar⁺ plasma immersion ion implantation (PI) affects the Pt/HfO₂ (4 nm)/${\mathrm{HfO}}_X{\mathrm{N}}_Y$ (3 nm)/TaN electroforming voltage. The advantage of PI is the simultaneous and uniform processing of the entire wafer. It is thought that Ar⁺ implantation causes defects to the oxide matrix, with the majority of the oxygen anions being shifted in the direction of the TaN electrode. We demonstrate that it is feasible to reduce the electroforming voltages from 7.1 V to values less than 3 V by carefully selecting the implantation energy. A considerable decrease in the electroforming voltage was achievable at an implantation energy that provided the dispersion of recoils over the whole thickness of the oxide without significantly affecting the ${\mathrm{HfO}}_X{\mathrm{N}}_Y$/TaN interface. At the same time, Ar⁺ PI at higher and lower energies did not produce the same significant decrease in the electroforming voltage. It is also possible to obtain self-compliance of current in the structure during electroforming after PI with energy less than 2 keV.

The possibilities of optimization of the two-step atomic layer etching process for HfO2 in conventional plasma etching tools were studied. The surface modification step was realized in Ar/CF4/H2 plasma, and the reaction between the modified layer and the surface was activated by Ar ion bombardment from the plasma in the second step. Investigation of the effects of activation step duration, DC bias during activation, and Ar plasma density was carried out. The mechanism of the etching process has been shown to involve fluorination of oxide during the modification step and subsequent removal of fluorine-containing particles at the activation step. An increase in parasitic sputtering rate and lower process saturation with the growth of DC bias during activation was demonstrated. The advantage of the ALE process in lower surface roughness over the conventional etching process was shown. Similar etching characteristics of HfO2 and ZrO2 suggest a similarity in the etching process for the mixed hafnium-zirconium oxide material.

This review focuses on oxide memristors for resistive random access memory (ReRAM). Possi-ble practical implementations of ReRAM and the problem of leakage through neighboring elements in ReRAM are considered. The main types of resistive switching in memristors are briefly described and the main mechanisms of resistive switching are analyzed. The main characteristics of memristors required for ReRAM are also described. Some memristor structures based on oxides of titanium, silicon, tantalum, and hafnium, as well as multilayer oxide structures are analyzed. The current problems in the creation of ReRAM are highlighted.