Reduced Threshold Current in NbO2 Selector by Engineering Device Structure

The leakage current scaling issues for NbO2 selector devices are investigated. By introducing a rough Pt bottom electrode (BE) (RMS roughness ~2.5 nm) and inserting a 20-nm-thick dielectric layer (Nb2O5 and HfO2) between the BE and NbO2 layer, we show that the threshold current for the insulator-metal-transition in microscale devices (~150 μm) can be reduced to ~20 μA, close to that realized in nanoscale (~10 nm) 3-D vertical ReRAM. This could be attributed to a thermal confinement effect caused by the presence of a permanent conductive filament in dielectric layer. The experimental results are supported by finite element simulation.

[1]  L. Goux,et al.  Evidences of oxygen-mediated resistive-switching mechanism in TiN\HfO2\Pt cells , 2010 .

[2]  Hyunsang Hwang,et al.  Optimized Lightning-Rod Effect to Overcome Trade-Off Between Switching Uniformity and On/Off Ratio in ReRAM , 2014, IEEE Electron Device Letters.

[3]  Hyunsang Hwang,et al.  Diode-less bilayer oxide (WOx–NbOx) device for cross-point resistive memory applications , 2011, Nanotechnology.

[4]  Seung Chul Chae,et al.  Oxide Double‐Layer Nanocrossbar for Ultrahigh‐Density Bipolar Resistive Memory , 2011, Advanced materials.

[5]  H. C. Jung,et al.  NbO2-based low power and cost effective 1S1R switching for high density cross point ReRAM Application , 2014, Symposium on VLSI Technology.

[6]  Tae Geun Kim,et al.  Effect of nanopyramid bottom electrodes on bipolar resistive switching phenomena in nickel nitride films-based crossbar arrays , 2014, Nanotechnology.

[7]  Hyunsang Hwang,et al.  Co-Occurrence of Threshold Switching and Memory Switching in $\hbox{Pt}/\hbox{NbO}_{x}/\hbox{Pt}$ Cells for Crosspoint Memory Applications , 2012, IEEE Electron Device Letters.

[8]  Chang Jung Kim,et al.  Physical electro-thermal model of resistive switching in bi-layered resistance-change memory , 2013, Scientific Reports.

[9]  R. Elliman,et al.  Determination of thickness and composition of high-k dielectrics using high-energy electrons , 2013 .

[10]  H. Hwang,et al.  Highly uniform and reliable resistance switching properties in bilayer WOx/NbOx RRAM devices , 2012 .

[11]  S. Menzel,et al.  Analysis of Transient Currents During Ultrafast Switching of $\hbox{TiO}_{2}$ Nanocrossbar Devices , 2011, IEEE Electron Device Letters.

[12]  H. Hwang,et al.  Nanoscale (∼10nm) 3D vertical ReRAM and NbO2 threshold selector with TiN electrode , 2013, 2013 IEEE International Electron Devices Meeting.

[13]  R. Elliman,et al.  The use of electron Rutherford backscattering to characterize novel electronic materials as illustrated by a case study of sputter-deposited NbO x films , 2014 .

[14]  W. Tsai,et al.  High-Performance Programmable Metallization Cell Memory With the Pyramid-Structured Electrode , 2013, IEEE Electron Device Letters.

[15]  R Stanley Williams,et al.  Sub-100 fJ and sub-nanosecond thermally driven threshold switching in niobium oxide crosspoint nanodevices , 2012, Nanotechnology.