Tuning the Performance of Pt/HfO₂/Ti/Pt ReRAM Devices Obtained from Plasma-Enhanced Atomic Layer Deposition for HfO₂ Thin Films

Abstract

Ultrathin, dense, high purity, stoichiometric HfO2 films were grown by plasma-enhanced atomic layer deposition from TEMAH and O2 plasma at a substrate temperature of 300°C. Utilizing these high quality HfO2 thin films of precise thickness enabled an accurate study of the effect of the thickness of the oxide, i.e., 5 nm and 8 nm HfO2, and the oxygen exchange layer (OEL), i.e., 5 nm and 10 nm Ti, on the electroforming and resistive switching performance. A thinner oxide layer and a thicker OEL, respectively, resulted in a reduction of the electroforming voltage due to an easier formation of the conductive filament. In addition, differences in the bipolar type resistive switching behavior of various HfO2/Ti cells were observed and a transition into complementary switching was found for the stack built with 8 nm HfO2 and 5 nm Ti.

The Atomic Layer Deposition Technique for the Fabrication of Memristive Devices: Impact of the Precursor on Pre-deposited Stack Materials

“…Structural and electrical characterizations do not show any significant variation with respect to usual HfO 2 -based RS devices reported elsewhere [20,21]. All of them show a forming requirement and are needed to be externally limited to avoid current runaway.…”

Effect of the Threshold Kinetics on the Filament Relaxation Behavior of Ag‐Based Diffusive Memristors

“…The homogeneous 3 and 5 nm thin HfO 2 films with low defect concentration were grown in a plasma-enhanced atomic layer deposition (PE-ALD) process from tetraethyl-methyl-ammonia hafnium (TEMA-Hf) and oxygen plasma at 250 °C. [83,84] Following dielectric deposition, feature size ranging from 2 nm to 10 µm were patterned by photolithography. Final crossbar structures were obtained by sputter deposition of an Ag/Pt (10/20 nm) top electrode accompanied by a lift-off process.…”

Effect of Dielectric Thickness on Resistive Switching Polarity in TiN/Ti/HfO2/Pt Stacks

“…This could prevent the formation of a large enough oxygen vacancy-rich zone at the HfO 2 /Ti interface. This has proven to be the case in a study conducted by Hardtdegen et al in Pt/HfO 2 /Ti/Pt films [42] where, in fact, because of the Ti cap being thinner than the thickness of the HfO 2 layer, a change in the BRS polarity occurred, partially attributed to full Ti cap oxidation. The RS mechanisms proposed could be further favored by a high negative voltage value needed to carry the forming process (although as it was earlier discussed, negative forming resulted in better performance and overall higher number of functional devices but was not mandatory).…”