The Study of Abnormal Current Degradation Behavior in Ti /HfO2/TiN Resistive Random Access Memory

Kuan-Ju Chou^1*, Ting-Chang Chang¹, Chih-Yang Lin¹, Chun-Kuei Chen¹, Yi-Ting Tseng¹

¹Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan

* Presenter:Kuan-Ju Chou, email:mark3352@g-mail.nsysu.edu.tw

This study investigates the electrical characteristics of Ti/HfO2/TiN resistive random access memory (RRAM). After the forming process, the DC sweeping cycle experiment was conducted, and both on and off state current had obviously declining tendency during cycle experiment. Besides, the reproducibility for this abnormal phenomenon can be found in different via size. Moreover, we use current fitting analysis to investigate the carrier transport mechanisms. The results show that the carrier transport mechanism of the initial on-state current is space-charge-limited current conduction mechanism and changes into hopping carrier transport mechanisms after 100 sweeping cycles. For the initial off-state current, the carrier transport mechanism, Schottky emission, changes into hopping conduction. By comparing the different values of the Schottky distance and Schottky barrier, we propose physical models to explain the behavior of abnormal current degradation. Finally, COMSOL electric field simulation analysis was conducted to realize the electric field distribution around filament, and the conducting behavior model was verified.

Keywords: Titanium, Top electrode, Current degradation, Schottky thermal emission, Hopping conduction