Two Series Oxide Resistors Applicable to High Speed and High Density Nonvolatile Memory

Abstract

Nowadays flash memory is one of the most frequently used nonvolatile memories in electronic devices. However, since flash memory is based on Si transistors with floating gates which can store electronic charges, it has basic limitations in its speed and density. It takes longer than 1 lsec for electronic charges to be stored in a floating gate in one cell of flash memory. In addition, we'll reach density limitation in flash memory in the near future by conventional scaling methods, such as decrease in gate length or increase in dielectric constant of the gate oxide, which are commonly applied to Sibased 2-dimensional devices. Thus, in order to overcome the limitations of flash memory, we require a new nonvolatile memory which is not based on Si devices with electronic charge storing phenomena. Here we introduce a next generation nonvolatile memory consisting of two oxide resistors, NiO and VO 2 , where the former is a memory element storing data by utilizing so called bi-stable resistance switching and the latter is a switch element controlling access using the related threshold switching. Since the memory only utilizes resistance switching behaviors of the two oxide resistors, writing and reading times are around several 10s of ns. In addition, it overcomes density limitations by its compatibility with 3-dimensional stack structures due to its low processing temperature lower than 300°C. High performance tests show the feasibility of a universal memory which has advantages of both flash and static random access memories.Si-based flash memory has become the standard for nonvolatile memory which does not lose information in the absence of an external bias. Nonetheless it faces several barriers as cell size is reduced beyond the sub-micrometer region (currently having realized a 40 nm pattern for 32 gigabit NAND flash memory) [1] due to charge leakage across the tunnel oxide. In addition, it needs a little longer time (> 1 ls) to write information by storing charges in a floating gate of flash memory. The efforts of the semiconductor industries have been focused not only on developing scaling methods or modifying device structures for Si-based flash memories [1] but on finding a next generation memory using materials which can circumvent the fundamental limits of Si. The goal of a next generation memory is both to surpass flash memory for nonvolatile memory applications and to realize a universal memory which combines the advantages of nonvolatile slow memory such as flash memory and volatile fast memory such as static random access memory. In order to accomplish this, a class of materials and structures which have easy scalability and rapid programming speed in addition to nonvolatility and low power consumption must be developed. In general, nonvolatile memory consists of a memory element with bi-stable states under zero bias and a switch element with resistance controlled by external bias. The memory element stores the information and the switch element controls access to a specific memory element. Several gro...

Using binary resistors to achieve multilevel resistive switching in multilayer NiO/Pt nanowire arrays

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Synthesis of vanadium dioxide thin films on conducting oxides and metal–insulator transition characteristics

“…To date, VO 2 films have primarily been grown on conducting substrates such as heavily-doped Si or Ge, and Pt [3][4][5]. As far as conducting oxide substrates are concerned; there is a recent report discussing the role of twin boundaries of VO 2 grown on Ga-doped ZnO buffered c-sapphire [6].…”

Atomic layer deposition of vanadium oxide thin films from tetrakis(dimethylamino)vanadium precursor

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