Read Disturbance in Cross-Point Phase-Change Memory Arrays-Part II: Array Simulations Considering External Currents

• Published in: IEEE transactions on electron devices Vol. 70; no. 2; pp. 521 - 526
• Main Authors: Kim, Donguk, Jang, Jun Tae, Kim, Changwook, Kim, Hyun Wook, Hong, Eunryeong, Ban, Sanghyun, Shin, Minchul, Lee, Hanwool, Lee, Hyung Dong, Mo, Hyun-Sun, Woo, Jiyong, Kim, Dae Hwan
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2023; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Arrays; Current sources; Delays; Disturbances; Inrush current; Integrated circuit modeling; Melting; Phase change materials; Phase-change memory (PCM); Phased arrays; read disturbance; Resistance; selector; storage class memory (SCM); Transistors
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2022.3231807

In Part I of this study, we demonstrated that when a high-read current from phase-change memory (PCM) programmed at a high-SET current (<inline-formula> <tex-math notation="LaTeX">{I}_{\text {SET}}{)} </tex-math></inline-formula> is achieved, melting dynamics in the chalcogenide layer are promoted, thus leading to read disturbances. Therefore, we analyzed additional external current sources that worsened the read disturbances by considering the PCM cell and additional selector and core circuits used in practical applications. By means of HSPICE simulations, the impact of two noticeable external overshoot and inrush currents generated during respective SET and read operations in one-selector and one-PCM (1S-1R) array was investigated. Our findings show that resistance-related components mainly affect the magnitude of the inflowing external current to the 1S-1R cell. The PCM can thus be easily heated up by the current, making the memory state vulnerable to the melting process. For these reasons, we showed that the disturbance primarily observed in the high <inline-formula> <tex-math notation="LaTeX">{I}_{\text {SET}} </tex-math></inline-formula> operated PCM can also occur even at low-<inline-formula> <tex-math notation="LaTeX">{I}_{\text {SET}} </tex-math></inline-formula> settings, given the actual cross-point array environment. Finally, we explored the maximum achievable array size that ensures disturbance-free read endurance by quantifying the read current to examine the location wherein the melting occurs.