Design of CMOS Compatible, High‐Speed, Highly‐Stable Complementary Switching with Multilevel Operation in 3D Vertically Stacked Novel HfO₂/Al₂O₃/TiO_x (HAT) RRAM

Abstract

most importantly cost effectiveness. To some extent RRAM with 3D vertical (3D-VRRAM) design is gearing-up to serve the need of high-density storage and neuromorphic applications. [4][5][6][7] However, sneak leakage paths are one of the major hindrances toward the successful implementation of such 3D-VRRAM array. [8][9][10] Nonlinear current is an effective solution to this problem, which can be added explicitly (adding external device) or implicitly (design built-in nonlinearity) to the 3D-VRRAM devices. [11] In another approach, complementary resistive switching (CRS) can reduce the sneak leakage paths through a large array. The conceptual design, as proposed by Linn et al., [12] is based on three metal lines, i.e., back-to-back connection of two adjacent RRAM cells. [13][14][15][16][17][18] Therefore, if two cells maintain low resistance state (LRS) then the total resistance of the devices is in LRS, but if one of them is in high resistance state (HRS) then the total resistance is HRS. Based on the LRS/HRS configuration the device changes its states either 1 or 0. Both of the electrochemical metallization type [19,20] and valance change memory type [21,22] CRS devices have been reported with different designs by the single layer, [23][24][25][26][27][28] bilayer, [29][30][31][32][33] trilayer, [34][35][36] and also for the carbon-based [37] structures. The conventional CRS with additional metal lines increases the fabrication cost, moreover, it is difficult to accommodate such complicated design in the 3D-VRRAM array. Therefore, the need of time demands an effective design utilizing the 3D approach of the RRAM devices at the same time enhancing the high-speed electrical performances.In our last work, [4] we have reported the design of 3D-VRRAM based on Al 2 O 3 /TiO x (AT) resistive switching (RS) stack. The device was capable to show nonlinear RS switching, in addition CRS was achieved only after the transition failure from LRS to HRS, which automatically restricted the yield of the CRS operation in AT structure. Here we show the design of an additional middle electrode-less 3D-VRRAM CRS device based on the novel HfO 2 /Al 2 O 3 /TiO x (HAT) structure. The natural origin of CRS automatically enhance the yield of the HAT trilayer structure as compare to the AT bilayer. The CRS mechanism is mainly based on the oxygen vacancy (V o ) Complementary resistive switching (CRS) is a suitable approach to minimize the sneak leakage paths through a large resistive random access memory (RRAM) array. Here, an effective CRS design with a HfO 2 /Al 2 O 3 / TiO x (HAT) trilayer structure integrated in a 3D vertically stacked RRAM array is reported. The design shows voltage-controlled resistive switching and CRS performance with multilevel operations. High-speed switching is observed with the HAT design. The device shows SET and the RESET transitions with speeds of −3.5 V@30 ns and +3.8 V@150 ns, respectively. As well as with the DC measurements, the CRS switching is achieved under AC switching dynamics measurement. Maintaining...

Transformation of threshold volatile switching to quantum point contact originated nonvolatile switching in graphene interface controlled memory devices

“…23 Previously, graphene as a barrier layer has been successfully used to reduce the power for anionic CF based devices. 24,25 But it is more challenging to change the entire switching nature from a highly nonlinear volatile TS to a low power operated nonvolatile MS, in the same HfO x based RRAM structure. Here, Ag/HfO x /Pt based standard devices have been used to achieve a lower operating voltage controlled (AE0.3 V) volatile TS with a highly stable nonlinearity of >10 8 .…”

Resistive switching of the HfOx/HfO2 bilayer heterostructure and its transmission characteristics as a synapse

“…Nanoscale transition metal oxide-based resistive switching random access memory (RRAM) devices, due to their various virtues, including high operating speed, low power consumption and excellent scalability, have attracted a great deal of attention. [1][2][3][4] In recent years, a lot of effort has been focused on RRAM based on a bilayer heterostructure consisting of two different oxides or the same oxide with different oxygen contents in virtue of its peculiar performance, such as multilevel resistive switching, [5][6][7] self-rectication functionalities, [8][9][10][11] and synaptic emulation. 12 RRAM has been proposed to emulate the synapse owing to their similarity with nonlinear transmission characteristics.…”

Memristors with organic‐inorganic halide perovskites

“…Recently, multilevel storage in a single memristor has attracted great interests to enhance the storage density without affecting scalability. [155][156][157] A thin fast ionic conductors 158 AgInSbTe (AIST) layer was introduced into an Ag/MAPbI 3 / FTO structure as an Ag reservoir and protecting layer ( Figure 24A). 97 The memristor showed tristate RS in the RESET process, providing multilevel memory capability ( Figure 24B).…”