Conductive-bridging random access memory: challenges and opportunity for 3D architecture

Abstract

The performances of conductive-bridging random access memory (CBRAM) have been reviewed for different switching materials such as chalcogenides, oxides, and bilayers in different structures. The structure consists of an inert electrode and one oxidized electrode of copper (Cu) or silver (Ag). The switching mechanism is the formation/dissolution of a metallic filament in the switching materials under external bias. However, the growth dynamics of the metallic filament in different switching materials are still debated. All CBRAM devices are switching under an operation current of 0.1 μA to 1 mA, and an operation voltage of ±2 V is also needed. The device can reach a low current of 5 pA; however, current compliance-dependent reliability is a challenging issue. Although a chalcogenide-based material has opportunity to have better endurance as compared to an oxide-based material, data retention and integration with the complementary metal-oxide-semiconductor (CMOS) process are also issues. Devices with bilayer switching materials show better resistive switching characteristics as compared to those with a single switching layer, especially a program/erase endurance of >10 5 cycles with a high speed of few nanoseconds. Multi-level cell operation is possible, but the stability of the high resistance state is also an important reliability concern. These devices show a good data retention of >10 5 s at >85°C. However, more study is needed to achieve a 10-year guarantee of data retention for non-volatile memory application. The crossbar memory is benefited for high density with low power operation. Some CBRAM devices as a chip have been reported for proto-typical production. This review shows that operation current should be optimized for few microamperes with a maintaining speed of few nanoseconds, which will have challenges and also opportunities for three-dimensional (3D) architecture.

Highly Uniform Resistive Switching Performances Using Two-Dimensional Electron Gas at a Thin-Film Heterostructure for Conductive Bridge Random Access Memory

“…Figure 1c displays 100 consecutive I−V curves (voltage sweep without compliance current setting) of the CBRAM cell, which exhibited highly uniform I−V curves compared to previous CBRAM reports using Cu ion drift. 17 To prove that the filament is composed of metallic Cu, we performed the measurement of resistance as a function of temperature for the SET state sample, as shown in Figure 1c (inset). For general dependence of metallic resistance on the temperature 13…”

“…10−16 Unfortunately, previous CBRAM devices revealed a nonuniform resistance switching characteristics in the writing/erasure processes due to the uncontrolled formation and rupture of the filament under repetitive electrical stimuli, which induced reliability issues, although they outperform oxide-based RRAM devices in terms of high endurance and long retention times. 17 Typically, once a large filament is formed by the excessive migration of metal ions, such as Cu, under electrical bias, it is difficult to recover from LRS to the initial HRS state because the filament cannot be sufficiently ruptured, which impedes the practical application of the CBRAM. 18 Still, discussions on the shape of Cu filaments and their growth direction are controversial, which further stalls the development of CBRAM, even in the generally used Cu/Al 2 O 3 active electrode/solid electrolyte system.…”

Memórias Não Voláteis: Uma visão geral sobre as principais tecnologias, suas características e níveis de maturidade

“…Possui como características, tensão de ±3 V [9], velocidade de leitura/escrita entre 5 ns [16] e 20 ns [35], durabilidade entre 10 4 e 10 7 ciclos de escrita [9], e em alguns casos 10 8 ciclos [19], que é relativamente baixo quando comparadas à OxRAM [16] que chegam a 10 12 ciclos [16], além disso já existe um protótipo de 16 Gb [41] numa célula de 6F 2 [35]. A CBRAM sofre principalmente das mesmas limitac ¸ões da OxRAM, que são as características operacionais ideais nunca ocorrerem de forma simultânea [16], por exemplo, a memória de 16 Gb citada tem apenas 10 6 ciclos de escrita de durabilidade [41], além de ter falhado em demonstrar uma alta confiabilidade [9]. Logo, a CBRAM é uma tecnologia interessante, com características de desempenho adequados mas, por enquanto, ainda com uma durabilidade inferior a tecnologias semelhantes como a OxRAM, além de não apresentar vantagens significativas em relac ¸ão a essas.…”

Extending Memory Capacity in Consumer Devices with Emerging Non-Volatile Memory: An Experimental Study

“…In the past several decades, various works have investigated how to employ novel data storage technologies (e.g., phase-change memory, PCM [48-51, 53-55, 57-77]; spin-transfer torque magnetic RAM, STT-MRAM [52,55,[78][79][80][81][82]; metal-oxide resistive RAM, ReRAM [83][84][85][164][165][166][167][168]; conductive bridging RAM, CBRAM [86,[169][170][171]; ferroelectric RAM, FeRAM [87,[172][173][174]) to build fast non-volatile memories. Intel and Micron recently announced the first widely-available commercial NVM device based on the 3D XPoint non-volatile memory technology [175], called Intel Optane [143].…”