Li Yujia, Tang Jianshi, Gao Bin, Sun Wen, Hua Qilin, Zhang Wenbin, Li Xinyi, Zhang Wanrong, Qian He, Wu Huaqiang
Institute of Microelectronics Beijing Innovation Center for Future Chips (ICFC) Tsinghua University Beijing 100084 China.
Faculty of Information Technology Beijing University of Technology Beijing 100124 China.
Adv Sci (Weinh). 2020 Oct 8;7(22):2002251. doi: 10.1002/advs.202002251. eCollection 2020 Nov.
High-performance selector devices are essential for emerging nonvolatile memories to implement high-density memory storage and large-scale neuromorphic computing. Device uniformity is one of the key challenges which limit the practical applications of threshold switching selectors. Here, high-uniformity threshold switching HfO-based selectors are fabricated by using e-beam lithography to pattern controllable Ag nanodots (NDs) with high order and uniform size in the cross-point region. The selectors exhibit excellent bidirectional threshold switching performance, including low leakage current (<1 pA), high on/off ratio (>10), high endurance (>10 cycles), and fast switching speed (≈75 ns). The patterned Ag NDs in the selector help control the number of Ag atoms diffusing into HfO and confine the positions to form reproducible filaments. According to the statistical analysis, the Ag NDs selectors show much smaller cycle-to-cycle and device-to-device variations ( < 10%) compared to control samples with nonpatterned Ag thin film. Furthermore, when integrating the Ag NDs selector with resistive switching memory in one-selector-one-resistor (1S1R) structure, the reduced selector variation helps significantly reduce the bit error rate in 1S1R crossbar array. The high-uniformity Ag NDs selectors offer great potential in the fabrication of large-scale 1S1R crossbar arrays for future memory and neuromorphic computing applications.
高性能选择器器件对于新兴的非易失性存储器实现高密度存储和大规模神经形态计算至关重要。器件均匀性是限制阈值开关选择器实际应用的关键挑战之一。在此，通过电子束光刻在交叉点区域制备具有高阶且尺寸均匀的可控银纳米点（NDs），制造出高均匀性阈值开关的基于HfO的选择器。这些选择器表现出优异的双向阈值开关性能，包括低漏电流（<1 pA）、高开关比（>10）、高耐久性（>10次循环）和快速开关速度（≈75 ns）。选择器中图案化的银纳米点有助于控制扩散到HfO中的银原子数量，并限制其位置以形成可重复的细丝。根据统计分析，与具有非图案化银薄膜的对照样品相比，银纳米点选择器的循环间和器件间变化要小得多（<10%）。此外，当将银纳米点选择器与电阻式开关存储器集成在单选择器单电阻（1S1R）结构中时，选择器变化的减小有助于显著降低1S1R交叉阵列中的误码率。高均匀性银纳米点选择器在制造用于未来存储器和神经形态计算应用的大规模1S1R交叉阵列方面具有巨大潜力。
