Niu Gang, Calka Pauline, Auf der Maur Matthias, Santoni Francesco, Guha Subhajit, Fraschke Mirko, Hamoumou Philippe, Gautier Brice, Perez Eduardo, Walczyk Christian, Wenger Christian, Di Carlo Aldo, Alff Lambert, Schroeder Thomas
IHP GmbH - Leibniz institute for innovative microelectronics, Im Technologiepark 25, 15236 Frankfurt (Oder), Germany.
Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education &International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, China.
Sci Rep. 2016 May 16;6:25757. doi: 10.1038/srep25757.
Filament-type HfO2-based RRAM has been considered as one of the most promising candidates for future non-volatile memories. Further improvement of the stability, particularly at the "OFF" state, of such devices is mainly hindered by resistance variation induced by the uncontrolled oxygen vacancies distribution and filament growth in HfO2 films. We report highly stable endurance of TiN/Ti/HfO2/Si-tip RRAM devices using a CMOS compatible nanotip method. Simulations indicate that the nanotip bottom electrode provides a local confinement for the electrical field and ionic current density; thus a nano-confinement for the oxygen vacancy distribution and nano-filament location is created by this approach. Conductive atomic force microscopy measurements confirm that the filaments form only on the nanotip region. Resistance switching by using pulses shows highly stable endurance for both ON and OFF modes, thanks to the geometric confinement of the conductive path and filament only above the nanotip. This nano-engineering approach opens a new pathway to realize forming-free RRAM devices with improved stability and reliability.
丝状氧化铪基电阻式随机存取存储器（RRAM）被认为是未来非易失性存储器最有前景的候选者之一。此类器件稳定性的进一步提升，尤其是在“关”态下的稳定性，主要受到氧化铪薄膜中氧空位分布不受控制以及丝状生长所导致的电阻变化的阻碍。我们报道了采用互补金属氧化物半导体（CMOS）兼容纳米尖端方法的氮化钛/钛/氧化铪/硅尖RRAM器件具有高度稳定的耐久性。模拟表明，纳米尖端底部电极对电场和离子电流密度提供了局部限制；因此，通过这种方法可实现对氧空位分布和纳米丝状位置的纳米限制。导电原子力显微镜测量证实，丝状结构仅在纳米尖端区域形成。由于导电路径和丝状结构仅在纳米尖端上方的几何限制，使用脉冲进行的电阻切换在开态和关态模式下均显示出高度稳定的耐久性。这种纳米工程方法为实现具有更高稳定性和可靠性的免形成RRAM器件开辟了一条新途径。
