The effect of reactive ion etch (RIE) process conditions on ReRAM device performance

Abstract

The recent surge of research on resistive random access memory (ReRAM) devices has resulted in a wealth of different materials and fabrication approaches. In this work, we describe the performance implications of utilizing a reactive ion etch (RIE) based process to fabricate HfO 2 based ReRAM devices, versus a more unconventional shadow mask fabrication approach. The work is the result of an effort to increase device yield and reduce individual device size. Our results show that choice of RIE etch gas (SF 6 versus CF 4 ) is critical for defining the post-etch device profile (cross-section), and for tuning the removal of metal layers used as bottom electrodes in the ReRAM device stack. We have shown that etch conditions leading to a tapered profile for the device stack cause poor electrical performance, likely due to metal re-deposition during etching, and damage to the switching layer. These devices exhibit nonlinear I-V during the low resistive state, but this could be improved to linear behavior once a near-vertical etch profile was achieved. Device stacks with vertical etch profiles also showed an increase in forming voltage, reduced switching variability and increased endurance.

High reliability CoFeB/MgO/CoFeB magnetic tunnel junction fabrication using low-damage ion beam etching

“…The calculation of defect density has been reported in many previous researches. [27][28][29][30] In this work, we assume that some defects that cause dielectric breakdown exist in the pattern edge of the MTJ samples. Then the defect density can be calculated with the following equation…”

Review of Manufacturing Process Defects and Their Effects on Memristive Devices

“…The etching step may lead to material redeposition along the device's sidewalls. This material can form a leakage path next to the VCM-based memristive device reducing the resistance and the forming voltage and increasing the device's variability [1,1]. After manufacturing the TE, the memristor is pacified, which means that the device is isolated from the surroundings and the TE is connected to the metal layers.…”

Mimicking Synaptic Behaviors with Cross-Point Structured TiOx/TiOy-Based Filamentary RRAM for Neuromorphic Applications

“…Various studies for the stable controllability of metal oxide-based RRAM, with TiO 2 [7,9], Ta 2 O 5 [5,10], and HfO 2 [4,11] being the most popular [9], have been conducted. Improvements in resistance variability and controllability have been achieved using pulse modulation [5], structural modification [10,11], fabrication [12], and interfacial analysis, [8,9]. Furthermore, it has been suggested that bi-layered RRAM with a certain combination of metal oxides produces remarkably reliable and gradual multistate resistance change [9,13].…”