5 V. It seems that the resistive switching memory device can be programmed under positive voltage through Cu pillar; however, it is not possible to erase through Cu pillar if it needs lower voltage than that of −1.5 V. Further study is needed to improve Cu pillar robustness under negative voltage on the Cu electrode. Figure 7 Data retention and read endurance characteristics. (a) Typical data retention characteristics

of our Al/Cu/Al2O3/TiN CBRAM device. The thickness of Al2O3 layer is 10 nm. (b) Read endurance characteristics of the Cu pillars in a Al/Cu/Al2O3/TiN structure at high CC of 70 mA. The stronger Cu pillars are obtained when the bias is positive. Conclusions The Cu pillars are formed in Al/Cu/Al2O3/TiN S63845 manufacturer structure under a small voltage of <5 V and a high current of 70 mA. Tight distribution of Selleckchem Dorsomorphin robust Cu pillars for 100 randomly measured devices with an average current of approximately 50 mA at a V read of 1 V is observed.

The Cu pillars have long read pulse endurance of >106 cycles under positive read voltage. Although, the read pulse endurance under negative read voltage is worst due Selleck Doramapimod to Cu dissolution partially. On the other hand, our Al/Cu/Al2O3/TiN memory device shows good bipolar resistive switching behavior at a CC of 500 μA. Good data retention characteristics of >103 s with acceptable resistance ratio of >10 is observed. It is expected that this novel idea to achieve high-density memory through 3D interconnect will have a good alternative of traditional TSV technique owing to a low cost and simple way. Acknowledgments This work was supported by National Science Council (NSC), Taiwan, under contract no. NSC-102-2221-E-182-057-MY2. The authors are grateful to Electronics and Optoelectronics Research Laboratories all (EOL)/Industrial Technology Research Institute (ITRI), Hsinchu, for their support. References 1. Prakash A, Jana D, Maikap S: TaO x based resistive switching

memories: prospective and challenges. Nanoscale Res Lett 2013, 8:418.CrossRef 2. Yang JJ, Strukov DB, Stewart DR: Memristive devices for computing. Nat Nanotechnol 2013, 8:13.CrossRef 3. Torrezan AC, Strachan JP, Medeiros-Ribeiro G, Williams RS: Sub-nanosecond switching of a tantalum oxide memristor. Nanotechnology 2011, 22:485203.CrossRef 4. Lee HY, Chen PS, Wu TY, Chen YS, Wang CC, Tzeng PJ, Lin CH, Chen F, Lien CH, Tsai MJ: Low power and high speed bipolar switching with a thin reactive Ti buffer layer in robust HfO 2 based RRAM. Tech Dig Int Electron Devices Meet 2008, 1–4. 5. Chen YS, Lee HY, Chen PS, Liu WH, Wang SM, Gu PY, Hsu YY, Tsai CH, Chen WS, Chen F, Tsai MJ, Lien C: Robust high-resistance state and improved endurance of HfO x resistive memory by suppression of current overshoot. IEEE Electron Device Lett 2011, 32:1585.CrossRef 6. Tsuji Y, Sakamoto T, Banno N, Hada H, Aono M: Off-state and turn-on characteristics of solid electrolyte switch.