Sung Hyun Jo

3D-stackable crossbar resistive memory based on Field Assisted Superlinear Threshold (FAST) selector

We report the integration of 3D-stackable 1S1R passive crossbar RRAM arrays utilizing a Field Assisted Superlinear Threshold (FAST) selector. The sneak path issue in crossbar memory integration has been solved using the highest reported selectivity of 1010. Excellent selector performance is presented such as extremely sharp switching slope of <; 5mV/dec., selectivity of 1010, sub-50ns operations, > 100M endurance and processing temperature less than 300°C. Measurements on the 4Mb 1S1R crossbar array show that the sneak current is suppressed below 0.1nA, while maintaining 102 memory on/off ratio and > 106 selectivity during cycling, enabling high density memory applications.

Cross-Point Resistive RAM Based on Field-Assisted Superlinear Threshold Selector

We report a 3-D-stackable 1S1R passive cross-point resistive random access memory (RRAM). The sneak (leakage) current challenge in the cross-point RRAM integration has been overcome utilizing a field-assisted superlinear threshold selector. The selector offers high selectivity of >107, sharp switching slope of <;5 mV/decade, ability to tune the threshold voltage, stable operation at 125°C, and endurance of >1011. Furthermore, we demonstrate 1S1R integration in which the selector-subthreshold current is <;10 pA while offering >102 memory ON/OFF ratio and >106 selectivity during cycling. Combined with self-current-controlled RRAM, the 1S1R enables high-density and high-performance memory applications.

Self-limited RRAM with ON/OFF resistance ratio amplification

We demonstrate sub-5nm filament based electrochemical metallization RRAM with self-limited program in a reliable and controllable manner. This RRAM removes the necessity for any external current compliance in a 1TnR (1S1R) architecture. Furthermore, we report a novel technique to amplify RRAMs intrinsic ON/OFF resistance ratio by a factor of >104, which offers significant cell-, circuit- and system-level benefits such as reduced power, reduced BER and increased read bandwidth in high density RRAM.

3D ReRAM with Field Assisted Super-Linear Threshold (FAST TM ) Selector technology for super-dense, low power, low latency data storage systems

3D Resistive Ram (ReRAM) technology exhibits the best attributes to suit present and emerging non-volatile memory storage applications. However, the major challenge to make ReRAM work in a 3D crossbar array is the integration of a selector device with a ReRAM device. The selector device will need to solve the so called “sneak path” barrier and enable large density memory arrays with low power consumption. Here, we report a Field Assisted Superlinear Threshold (FASTTM) Selector technology that overcomes the sneak path barrier with a selectivity ratio of 10E10. The switching and recover speed, on/off ratio, switching slope, program, erase, and read endurance, and variability of the FASTTM selector will be discussed. Prototype 1S1R devices with the FASTTM selector integrated with a low current ReRAM cell have been demonstrated and characterized. Figure 1 shows the representative I-V characteristics of a ReRAM cell with integrated FASTTM selector.

Resistive random access memory with high selectivity and ON/OFF ratio amplification sensing

The suppression of sneak paths in a cross-point RRAM array, one of the most challenging tasks in high density RRAM integration, has been successfully demonstrated by utilizing a Field Assisted Superlinear Threshold (FAST) selector (1, 2). The FAST selector provides a volatile switching behavior at the critical electric field. Excellent selector performance is presented, including high selectivity of > 107, sharp switching slope of <;5mV/dec, and large endurance of > 1011. Furthermore, the volatile switch based selector offers various benefits such as small operation voltage overhead in the 1S1R (1 selector 1 resistor) integration, large sensing margin and increased memory ON/OFF ratio.