Electron Charging and Discharging Effects of Tungsten Nanocrystals Embedded in Silicon Dioxide for Low-Voltage Nonvolatile Memory Technology

Abstract

Spherical and well-separated tungsten nanocrystals embedded in the SiO 2 layer are demonstrated for the low-voltage nonvolatile memory device. The tungsten dots are formed, based on the thermal oxidation of the tungsten silicide, with a mean size and aerial density of 4.5 nm and 3.7 ϫ 10 11 /cm 2 , respectively. A pronounced capacitance-voltage hysteresis is observed with a memory window of 0.95 V under the 3 V programming voltage. Also, the endurance of the memory device is not degraded up to 10 6 write/erase cycles.

Metal nanocrystals as charge storage nodes for nonvolatile memory devices

“…The memory effects of the Ag, Au, Pt, W, Co, Ni, NiSi 2 , Ni 1 − x Fe x , TiN and Al metal nanocrystals were investigated [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43]. Devices with Au, Ag and Pt nanocrystals working in the F-N tunneling regime have been investigated and compared with Si nanocrystals memory devices.…”

“…Therefore, metallic materials with high work function, but not the precious metals, are more desirable. There are a number of reports on high work function materials with significant memory effects [30][31][32][33][34][35][36][37][38][39][40][41][42][43]. For example, good memory effects were found for [30,31].…”

Gold nanoparticles via alloy decomposition and their application to nonvolatile memory

“…3-5͒, but only recently have metal nanoparticles been incorporated into metal-oxide-semiconductor ͑MOS͒ capacitor structures. [6][7][8][9] The numerous advantages of metal nanoparticles include a higher density of states around the Fermi level, work function tunability, more uniform charging characteristics, and a greater degree of scalability for the nanocrystal size. 6 Here, we introduce the incorporation of self-assembled Au-rich nanoparticles into MOS capacitors.…”

$\hbox{TiSi}_{2}$ Nanocrystal Metal Oxide Semiconductor Field Effect Transistor Memory

“…[12]- [14], have been proposed to achieve memory devices with longer retention performance. Metal NCs are the perfect material to be used as a floating gate to improve the programming speed [15]- [17]. However, the drawback of using metal NCs is the interdiffusion between NCs and tunnel oxide during device integration, which degrades the tunnel oxide and worsens retention performance [18]- [20].…”