Study of in Situ Silver Migration in Amorphous Boron Nitride CBRAM Device

Abstract

We report the dependence of the thickness of amorphous boron nitride (a-BN) on the characteristics of conductive bridge random access memory (CBRAM) structured with the Ag/a-BN/Pt stacking sequence. The a-BN thin film layers of three different thicknesses of 5.5, 11, and 21.5 nm were prepared by the sputtering deposition. Depending on the thickness of the a-BN layer, the devices are found to be in either low-resistance state (LRS) or high-resistance state (HRS) prior to any consecutive switching cycle. All devices with 5.5 nm thick a-BN switching layer are in LRS as the pristine state, while devices with 21.5 nm thick a-BN layer are found to be in HRS as the pristine state. To attain reliable switching cycles, initial RESET and electroforming process are necessarily required for the devices with 5.5 and 21.5 nm thick a-BN layer, respectively. However, the devices with the a-BN layer of thickness between 5.5 and 21.5 nm in pristine states are in either HRS or LRS. This dependence of the a-BN thickness on different resistance states in the pristine state can be explained by in situ Ag diffusion during its sputter deposition to form a top electrode on the a-BN layer. Our finding shows a detailed investigation and a deep understanding of the switching mechanism of Ag/a-BN/Pt CBRAM devices with respect to different a-BN thicknesses for the future computing system.

Emulation of Biological Synapse Characteristics from Cu/AlN/TiN Conductive Bridge Random Access Memory

“…The most deposition techniques were prepared by DC reactive sputtering or RF sputtering for good resistive switching. Ag electrode tends to smaller operation voltage compared to the Cu electrode due to high diffusivity [ 21 , 26 , 43 , 44 , 45 ]. The selector and synaptic device applications are demonstrated even though the resistive switching performances of Cu/AlN/TiN in this work are not overwhelming compared to the previous works.…”

Synaptic Characteristics of an Ultrathin Hexagonal Boron Nitride (h‐BN) Diffusive Memristor

“…The in situ Ag + ions migration during the Ag thin‐film deposition leading to the Ag filament formation in amorphous BN (a‐BN) thin film was confirmed in a previous study. [ 35 ] Moreover, a number of studies have been conducted which confirmed the formation of conducting filaments as well as electrochemically active metal ions migration in various switching materials including h ‐BN. [ 6,13,27,36 ]…”

Building Functional Memories and Logic Circuits with 2D Boron Nitride

“…[ 42,43 ] There have been noteworthy endeavors toward understanding the operating mechanism of resistive switching (RS) of the vertical stacked memristors. [ 44–52 ] Boron ionic migration and conductive filament formation have been used to control spatially electrical conductivity in BN memristors, studied by a bunch of characteristic methods, such as transmission electron microscope (TEM), [ 53–55 ] conductive atomic force microscope (CAFM), [ 56,57 ] electron energy loss spectroscopy (EELS), [ 54,57 ] and I – V electrical measurement. [ 33,34,53,54,56–58 ] Interestingly, it is reported that nonvolatile and volatile resistive switching transition can be modulated in BN by altering test parameters (SET and RESET voltage ranges, compliance currents, etc.…”