Superior Retention of Low-Resistance State in Conductive Bridge Random Access Memory With Single Filament Formation

Abstract

Data retention is one crucial reliability aspect of resistive random access memory (RRAM). The retention failure mechanism of the low-resistance state (LRS) for conductive bridge RAM is generally originated from the lateral diffusion of metal ions/atoms from the filament to its surrounding medium. In this letter, we proposed an effective method to improve the LRS retention by controlling the formation of the single filament. For a certain LRS, the effective surface area for metal ions/atoms diffusion in single filament is less than that of multi-filament. Thus, better LRS retention characteristics can be achieved by reducing the metal species diffusion. The validity of this method is verified by the superior retention characteristics of the LRS programmed by current mode, in comparison with voltage programming mode. The former tends to generate a single filament, while the later grows multi-filament. This letter provides a possible way to enhance the retention characteristics of RRAM.Index Terms-Resistive random access memory (RRAM), single filament, multi-filament, data retention.

Confining Cation Injection to Enhance CBRAM Performance by Nanopore Graphene Layer

“…The spontaneous switching from HRS to LRS can be attributed to the thermally accelerated diffusion of atoms into HfO 2 RS layer from the CFs, leading to the breakdown of the CFs eventually . Diffusion quantity per unit time of atoms from the CFs that bridge both AE and IE is closely related to the total surface area (TSA) of the CFs according to Fick's first law . Limited by the nanohole of the graphene, single or a few robust CFs form in the NG‐based device with smaller TSA and better thermal stability than that of multiple CFs in the control device under the same I CC condition, resulting in the improvement of retention of LRS.…”

Resistive Switching Performance Improvement via Modulating Nanoscale Conductive Filament, Involving the Application of Two‐Dimensional Layered Materials

“…Induced by the diffusion of materials under an electric field, CF would penetrate into the cathode, causing “overgrowth” phenomenon, which will also result in RS failure and strongly reduce device reliability . Moreover, diffusion of single CF is less than that of multi CFs because of the smaller specific surface area, so fewer CFs in LRS often correspond with more superior retention characteristic in LRS . The HRS degradation also depends on resistance in LRS, because lower R on relates to stronger residual CF in HRS, and diffusion of CF's tip will be more serious with larger active area …”

“…In the SET process, the voltage will not drop down after RS occurs in VSM, which still provides opportunities for other CFs, resulting in multi‐CF phenomenon. However, single‐CF formation can be achieved in CSM . Once the formation of single CF has been completed, voltage decreases spontaneously, so CF growing from another areas will be suppressed, and it is more likely to create one robust CF with good retention behavior.…”

Breaking the Current‐Retention Dilemma in Cation‐Based Resistive Switching Devices Utilizing Graphene with Controlled Defects

“…The replacement of Cu active electrode with Ag gives rise to unstable CF and better TS behavior of the SiO 2 ‐based selector, which can be ascribed to the relative higher Ag solubility and weaker chemical interaction in/with SiO 2 . After tuning to lower compliance current ( I CC ) to form more fragile and tiny CF, TS behavior is easier to be observed as reported in various AE/RS/IE structures . And, the LRS retention of cation‐based RS device can be improved by avoiding water to weaken the nanobattery effect .…”

“…In consideration of requirement in a large memory array, low power dissipation and high CF stability are required for RS memory device, while high volatile ON‐state current and poor CF stability are required for TS selector . The CF stability generally correlates to the following factors, namely (i) RS dielectric materials, which wrap the CFs and provide different diffusion barriers; (ii) CF components, which have different solubilities, diffusion coefficients, or chemical interactions in/with a certain RS dielectric; (iii) CF morphologies including size and quantity, which correspond to different effective diffusion areas; (iv) electrochemical environment around the CFs (e.g., moisture), which may take the CF components into galvanic cell reaction owing to the nonequilibrium chemical potential . Considering these important factors, great efforts have been paid to modulate the CF stability.…”