Nonvolatile Memory-Operation Mechanism for Ag-Doped PEO-Based Cbram-Cells
As shown in Fig. 1, CBRAM cell was fabricated on SiO2 grown on a Si wafer. Arrays of Pt electrode (width and length, 1,000 and 10 um) were patterned on the 100 nm-thick Pt electrode. Then, Ag-doped PEO was spin-coated on the array of Pt electrode. Note that, the Ag-doped PEO is made by mixing the AgNO3 and PEO with a co-solvent of acetonitrile and ethanol at 30 oC for 3 hrs. AgNO3 is separated into Ag+ and NO3- ions in solvent. Ag+ion locate negative defect site. Ag+ ions move cathode and are reduced to Ag atoms when the positive bias was applied to anode and the negative bias was applied to cathode.
The reduced Ag atoms at the cathode lead to a growth of the Ag filament, which finally reaches the anode. The shape of Ag filament is changed by the compliance current. We investigated relationship between their nonvolatile memory characteristics and the shape of Ag filament.
Fig. 2 shows various CBRAM characteristics depending on compliance current. It was observed that reset voltage increased from -0.1 to -0.6 V when compliance current increase from 10-6 to 10-3A. But set voltage and high resistance state (HRS) were not changed.
Fig. 3 shows SEM images for Ag filament depending on compliance current. It indicates that Ag filament is reduced when compliance current decreased from 10-3 to 10-6A. The reset voltage of CBRAM cells increased with compliance current. It implied that higher compliance current led to forming the thicker filament. This result was corresponds with SEM image.
We present NVM operation mechanism of Ag-doped PEO-based CBRAM by revealing of relationship between Ag filament and memory characteristics.
* This work was financially supported by the Industrial Strategic Technology Development Program (10039191, The Next Generation MLC PRAM, 3D ReRAM, Device, Materials and Micro Fabrication Technology Development) funded by the Ministry of Trade, Industry and Energy (MOTIE), Republic of Korea and the Brain Korea 21 Plus, Republic of Korea..
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