고분자 고체 전해질을 통한 비휘발성 전도성의 브릿지 메모리 셀 특성 구현에 관한 연구

Abstract

Recently, conductive bridge memory (CBM) cells containing solid electrolytes such as a-Si, Cu-doped ZrO2, Cu-doped SiO2, Ag-Ge-Se, Ta2O5 have been reported by several groups. We researched the bipolar resistive switching behavior of conductive bridge memory depends on the solid electrolyte film thickness. To approach the issue, we used the PEO (Polyethylene oxide) of molecular weight 600,000 and fabricated the conductive bridge memory which have structure of Ag reactive electrode, PSE (polymer solid electrolyte) film, and Pt inert electrode. A PEO film was formed by spin-coating process and reactive electrode was deposited by thermal evaporator process on Φ 250 nm hole patterned wafer. Conductive bridge can be formed or ruptured into PEO film when apply the external voltage on Ag electrode. To evaluate the effect of PEO film thickness, we measured the electrical characteristics such as current verse voltage (I-V) Sweep, retention time and endurance cycles with modulating the PEO film thickness. We found that the Vset increased from 0.58 to 1.88 V and the absolute Vreset decreased from 2.56 to 0.16 V when the PEO film thickness was increased from 10.29 to 60.64 nm. In particular, the memory cell showed the electrical characteristics such as memory margin 4.25 × 104, retention time for 105 sec and about 103 endurance cycles of program and erase when PEO film thickness was 10.29 nm as the best. In addition, current conduction mechanism of the conductive bridge memory followed the Poole-Frenkel emission and ohmic conduction model. These results will be a good reference in the near future design of nano-scale conductive bridge memory.