imec presents smallest HfO2 based rram cell

The rram cell – an emerging technology for nonvolatile memory and a candidate to replace NAND Flash technology in sub 10nm memories - was presented at the IEEE International Electron Devices Meeting (IEDM) in Washington. The research was undertaken to address the issue of current charge storage Flash memories which face scaling limitations beyond 18nm. RRAM is based on the electronic switching of a resistor element material between two stable (low/high) resistive states. The major strengths of the technology are its potential density and speed. According to imec, its new rram cell features a novel Hf/HfOx resistive element stack. It couples a cell area of less than 10x10nm² with a reliability endurance of more than 10⁹ cycles. The cell has fast nanosecond range on/off switching times at low voltages and a large resistive window (>50). imec states that it shows no closure of the on/off window after functioning at 200°C for 30h. And, adds the nanoelectronics specialist, the device even remained operating failure free functioning for 30h with a thermal stress of 250°C. The switching energy per bit is below 0.1pJ and ac operating voltages are below 3V, meeting the requirements for device level nonvolatile memory. imec also further clarified the impact of film crystallinity on the operation of rram cells, especially with a view on further scaling. According to imec, it sheds light on the role of the cap layer and on the switching mechanisms. The results were obtained in cooperation with imec's key partners in its core cmos programs, Globalfoundries, Intel, Micron, Panasonic, Samsung, TSMC, Elpida, Hynix, Fujitsu and Sony.