The leakage current in the cross array is the main obstacle of the high density integration of memory. In the 1 Transmitting / 1 Receiving (1T1R) structure, transistor is used as a gating tube to isolate the bypass leakage, but the transistor is not suitable for three-dimensional stacking. Therefore, the development of three-dimensional stacking gating device with high uniformity, high selection ratio and high current density is the key to achieve three-dimensional Resistive Random Access Memory (RRAM) integration. It is difficult for the existing gating device to meet the above requirements at the same time.

Aiming to solve this problem, research group at Institute of Microelectronics of the Chinese Academy of Sciences (IMECAS) led by academician LIU Ming put forward the idea of using the trapezoidal band structure to construct the gating tube device and develop a high performance gating device, TaOx-based selector with trapezoidal band structure. It is formed by rapid thermal annealing in O₂ plasma. It is fully compatible with the Complementary Metal Oxide Semiconductor (CMOS) process and has high uniformity. With the salient features such as high current density (1MA/cm²), high selectivity (5×104), low off-state current (~10 pA), robust endurance (>1010), self- compliance and excellent uniformity, it can provide a good solution to high density 3D Integration of resistance type memory with two ends structure.

The results were published in Nanoscale entitled" Super non-linear RRAM with ultra-low power for 3D vertical nano-crossbar arrays". The paper based on this research, Fully BEOL Compatible TaOx-based Selector with High Uniformity and Robust Performance, was received in 62nd International Electron Devices Meeting (IEDM) of Institute of Electrical and Electronics Engineers (IEEE) (December 3-7, 2016. San Francisco). First author o LUO Qing made a report at the meeting.