Effects of post-metal annealing on the electrical characteristics of HfO_x-based resistive switching memory devices

Abstract

Post-metal annealing (PMA) has been adopted to reduce the operation voltages of HfOx-based resistive random access memory (RRAM) devices, especially the forming voltage (VForming). TiN/Ti/HfOx/TiN stack structures were fabricated and annealed via rapid thermal annealing (RTA) and furnace annealing (FA) to investigate the annealing effects. The result of X-ray photoelectron spectroscopy (XPS) analysis indicates that the distribution of oxygen towards the interposing Ti layer increases after the annealing process, which facilitates the formation of conductive filaments in the dielectric layer. As a result, VForming can be decreased from 4.60 to 3.24 and 3.36 V via RTA for 30 s at 400 °C and via FA for 60 min at 300 °C, respectively, as compared with that without PMA. However, the VForming of the device annealed via FA for 60 min at 400 °C was higher than that at 300 °C. This turn-around phenomenon of the forming voltages of RRAM devices annealed via FA was found. It was attributed to the conversion of the interposing Ti layer into a highly resistive TiO2 film.

Analysis of the Thermal Degradation Effect on a HfO2-Based Memristor Synapse Caused by Oxygen Affinity of a Top Electrode Metal and on a Neuromorphic System

“…An aluminum capping layer was deposited on Ti and Ta with a thickness of 50 nm to prevent unnecessary reactions between the TE metal and oxygen under ambient conditions. Each memristor with different TE metals was subjected to PMA in a furnace for 1 h at 300, 400, and 500 °C. − Henceforth, for simplicity, an RRAM-based memristor is referred to as a “memristor.”…”

Oxygen annealing effect on resistive switching characteristics of multilayer CeO2/Al/CeO2 resistive random-access memory

“…For both controlled and annealed devices, coefficients of variance (σ/μ) for RESET and SET phenomena are 3.1%, 5.2%, and 3.5%, 2.1%, respectively. We can see that SET voltages of annealed devices are lower than those of controlled device, which can be explained by decreased formation energy of oxygen vacancies in the vicinity of Al atoms [29]. Here, we have shown that good uniformity can be achieved using figure 3(a), which may be due to unstable defects formed by inserting the Al layer in between the two CeO 2 layers.…”

Models Comparison And Validation With the Experimental Nano- Scale Silicon Substrate Based Annealed Pt/HfO2/Pt Resistive Random Access Memory Cell

“…The proposed nonlinear equation is 5) The switching between ON and OFF state is very quick in RRAM models. Here, the switching speed is depending on the exponent term q.…”

“…Post-metal annealing (PMA) is an effective fabrication process to mitigate the voltage reduction problem. [5]. Developing a unique model for a nanoscale metal oxide RRAM device is an important necessity to check its behaviour in a device, circuit-level, and for system implementation.…”