Effect of Ag source layer thickness on the switching mechanism of TiN/Ag/SiN _x /TiN conductive bridging random access memory observed at sub-µA current

Abstract

Experiments are conducted to compare the resistive switching characteristics for several samples with different amounts of Ag deposition in TiN/Ag/SiN x /TiN conductive bridging random access memory (CBRAM). The compliance current in TiN/Ag/SiN x /TiN CBRAM determines the volatile/non-volatile memory operation as the current level controls the strength of the filament made of Ag. The transient measurement showed that the effective thickness of Ag source layer in the TiN/Ag/SiN x /TiN controls the supply of the Ag atoms into the insulating layer, affecting the strength of the conductive bridge. The mechanism for the switching characteristics and the volatility trend with the amount of Ag deposition is closely investigated using transmission electron microscopy and scanning electron microscopy images. The device shows the conductance potentiation by a voltage pulse train under 1 µA current level, and the higher potentiation rate is observed in the CBRAM with thick Ag source layer.

Electric-Field-Induced Metal Filament Formation in Cobalt-Based CBRAM Observed by TEM

“…Subsequently, the reverse bias induces the rupture and retraction of the filamentary conductive bridge along the sequence shown in Figure f–d (reverse order of Figure d–f). The atomic movement during the convex-shaped pillar development process can be explained using surface diffusion and ionic drift mechanisms at the edge of the metal electrode, as reported in previous CBRAM studies. ,− The morphological changes in the Co pillars and filaments in Figure c–f are reflected in the conductance changes measured by the DC sweep in Figure b. In its pristine state, the device exhibited the lowest conductance, which is consistent with Figure c, where no Co protrusion is observed.…”

“…Because the Co pillars act as virtual electrodes, the reduced effective dielectric layer thickness contributes to an increase in cell conductance during the forming process. The convex-shaped pillar protrusion from the active metal electrode is a feasible step in the Co filament development process because it has also been repeatedly reported in Ag CBRAM studies. − Specifically, Figure S2 shows the convex-shaped Ag pillar observed in an LRS Ag/SiN x /TiN CBRAM cell, where a 10 nm thick SiN x dielectric layer is deposited by PECVD using SiH 4 (800 sccm), N 2 (1000 sccm), and NH 3 (34.5 sccm) gases at 350 °C (Figure S2). The pillar formed by the deformation of the top electrode covers 99.3% of the dielectric layer thickness and results in the conductance increase, which is consistent with the conventional forming process.…”

Conductive Bridge Random Access Memory (CBRAM): Challenges and Opportunities for Memory and Neuromorphic Computing Applications

“…Various switching characteristics are affected by the choice of different AEs. Moreover, the thickness of the AE layer also affects the switching mechanisms in CBRAMs [ 38 ]. Several active metals have been utilized as the AEs in various CBRAM devices.…”

Recent Progress of the Cation Based Conductive Bridge Random Access Memory

“…위칭 메커니즘에 영향을 미친다. [34,35] Ag와 Cu는 전기 화학적으로 활성 금속들 중 고체 전해질층에서의 확산 성이 특히 우수한 편에 속하여 일반적으로 CBRAM에서 가장 많이 사용되는 산화전극이다. [32,35,36] Ag와 Cu 양 이온의 빠른 이온 이동도로 인해 동작 전압이 낮고 이로 인해 전력 소모가 낮아지는 효과를 얻을 수 있으며 동작 속도가 빠르다.…”