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

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.