Low‐Power High‐Performance Non‐Volatile Memory on a Flexible Substrate with Excellent Endurance

Abstract

Plastic-substrate-based electronic devices are attractive because of their inherit merits of low cost, light weight, environmentally friendly low temperature processing, and the application in fl exible displays and integrated circuits (ICs). Fast progress of logic ICs using thin-fi lm transistors (TFT) on plastic has been demonstrated. However, one fundamental challenge for plastic electronics is the lack of good performance non-volatile memory (NVM) devices. [1][2][3][4][5] This is due to the degraded dielectric quality of charge-based fl ash (CTF) memory from the limited low temperature process. [ 2 ] Alternatively, the resistive random access memory (RRAM) [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] shows promising NVM performance on plastic even when processed at low temperature, but the large set and reset currents are the basic limitation for high-density and low-power operation. In addition, the large switching energies degrade the endurance due to excessive stress.In this paper, record high-performance NVM has been demonstrated on low cost polyimide substrate. A very low set current of 1.6 μ A at 3 V (4.8 μ W) and reset current of −0.5 nA at −2 V (1 nW) were needed to reach the bistable resistance state, which led to a large memory window with a high-to low-resistance state ratio (HRS/LRS) of 9 × 10 2 . Additionally, good retention was obtained with a small HRS/LRS decay from the initial 9 × 10 2 to 7 × 10 2 at 85 ° C for 10 4 s. Furthermore, excellent endurance of 10 5 cycles was measured at a very fast 50 ns switching time. This is the lowest reported switching power NVM on plastic with excellent 10 5 cycling endurance and good retention. The excellent NVM performance on fl exible plastic is due to the using novel ultra-low power hopping conduction mechanism [ 22 ] rather than the conductive fi lament in conventional RRAM. [ 17 , 18 ] This new RRAM device sets a new standard for NVM performance on low-cost fl exible substrates. Figure 1 shows the devices fabricated of Ni/GeO x /HfON/ TaN RRAM on fl exible polyimide substrate. The simple metalinsulator-metal (MIM) structure is useful for embedded and 3D integration.Figure 2 a shows the swept current-voltage ( I-V ) curves of Ni/GeO x /Hf 0.38 O 0.39 N 0.23 /TaN RRAM on fl exible polyimide. The arrows indicate the sweeping direction. The Hf 0.38 O 0.39 N 0.23 (HfON) composition was determined by X-ray photoelectron spectroscopy (XPS), which was controlled by O 2 /N 2 in a sputter system. The HfON has been used as the charge-trapping layer for CTF [ 23 ] NVM due to its high density traps and deep trapping energy. A very low self-compliance set current of 1.6 μ A at 3 V, an even lower reset current of -0.5 nA at -2 V, and a large HRS/LRS memory window of 9 × 10 2 at 0.5 V were all obtained at the same time. These are the lowest set and reset currents of RRAM devices on a plastic fi lm [3][4][5] and are much lower than the conventional RRAM using metallic-fi lament conduction. [ 17 , 18 ] The asymmetric switching I-V curves are ascribed ...

Non-volatile organic memory with sub-millimetre bending radius

“…In particular, high-performance flexible non-volatile memories based on various data storage principles such as resistive type [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] , flash 4,[25][26][27][28][29] and ferroelectric [30][31][32][33][34][35][36][37][38][39][40] hold great promise in a variety of emerging applications ranging from mobile computing to information management and communication. While the recent advances in this area are impressive, novel organic materials and electronic device structures that can be tightly rolled, crumpled, stretched, sharply folded and unfolded repeatedly without any performance degradation still need to be developed.…”

Interface‐engineered resistive memory using plasma‐modified electrode on polyimide substrate

“…dielectric (substrate) ZnO (PES) [22] ~IGZO ~(PES) [23] -GeO x / -HfON (PI) [18] -GeO x /TiO y (PI) -(this work) TaN is much better than that (121%) of control sample, indicating the influence of surface morphology and defect-related surface state on TaN/SiO 2 /PI substrate. In HRS, the CV (only 4%) for the RRAM with N + TaN confirms the effect of interface plasma treatment on TaN.…”

“…To address these concerns, we reported the ultralow power RRAM [15][16][17][18] using covalent-bond GeO x and hopping conduction mechanism. However, the wide switching distributions still need to be improved, especially for flexible electronics applications [18]. For flexible electronics, the device uniformity could be determined by the roughness of gate stacks.…”

“…In recent years, resistive random access memory (RRAM) [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18], as one of the most promising candidates for next-generation NVM, has attracted much attention and has been extensively researched, due to its simple structure, low cost, high performance and embedded memory function. However, the high switching power and poor current distributions are the major drawbacks.…”

Resistive switching of Pt/TiOx/Pt devices fabricated on flexible Parylene-C substrates

“…Recently, the same team has presented 1T1M memory device [15]. Other groups [16][17][18][19][20][21] have used PES, polyethylene terephthalate, polyethylene naphthalate or polyimide based flexible substrates. Aluminium, IZO, TaN and Ni electrodes were utilised with various oxide layers such as Polymer, HfON, Al 2 O 3 or TiO 2 .…”