3D NAND Flash Memory Based on Double-Layer NC-Si Floating Gate with High Density of Multilevel Storage

Abstract

As a strong candidate for computing in memory, 3D NAND flash memory has attracted great attention due to the high computing efficiency, which outperforms the conventional von-Neumann architecture. To ensure 3D NAND flash memory is truly integrated in the computing in a memory chip, a new candidate with high density and a large on/off current ratio is now urgently needed. Here, we first report that 3D NAND flash memory with a high density of multilevel storage can be realized in a double-layered Si quantum dot floating-gate MOS structure. The largest capacitance–voltage (C-V) memory window of 6.6 V is twice as much as that of the device with single-layer nc-Si quantum dots. Furthermore, the stable memory window of 5.5 V can be kept after the retention time of 105 s. The obvious conductance–voltage (G-V) peaks related to the charging process can be observed, which further confirms that the multilevel storage can be realized in double-layer Si quantum dots. Moreover, the on/off ratio of 3D NAND flash memory with a nc-Si floating gate can reach 104, displaying the characteristic of a depletion working mode of an N-type channel. The memory window of 3 V can be maintained after 105 P/E cycles. The programming and erasing speed can arrive at 100 µs under the bias of +7 V and −7 V. Our introduction of double-layer Si quantum dots in 3D NAND float gating memory supplies a new way to the realization of computing in memory.

Fabrication of highly conductive phosphorous-doped nc-SiCx:H thin film on PET

“…With the shrink of size to the scale approximate to the Bohr radius of excitons in Si (∼5 nm), the quantum confinement effect (QCE) enhances significantly, leading to the improved radiative recombination rates of electron-hole pairs and the enlarged optical bandgap energy [1,2]. Comparing to the bulk Si with indirect bandgap and low bandgap energy (∼1.1 eV), Si NCs have prominent advantages in the design of optoelectronic and photovoltaic devices, and Si NC-based thin films have been widely applied in the fields of photodetector, light emitting diodes, data storage and solar cell [3][4][5][6].…”

Self-assembling mechanism of Si-QDs on thermally grown SiO2

“…The serious drawbacks in downsizing traditional metal-insulator-semiconductor devices inspired us to design novel functional devices with well-defined Si nanostructures. In particular, nanometer-scale silicon dots have been widely explored due to their potential advantages for applications of Si-based functional nanodevices, such as thermoelectric generators, [1][2][3] single-electron transistors, [4][5][6][7][8] floating-gate MOS memories, [9][10][11][12][13] electron field emitters, 14,15) and spin-based quantum computation. [16][17][18][19][20] However, to acquire reliable device operation, the dot size, density, uniformity in size, and position must be tuned with great precision and reproducibility because the quantum size effect and discretized energy level in each dot strongly depend on the size and shape.…”

Properties of phosphorus-boron co-doped c-Si quantum dots/SiNx:H thin film prepared by PECVD in-situ deposition

“…Similar as other QD materials, the properties of c-Si QD are determined by QCE [1][2][3] . Accordingly, by simply controlling QD size, the emission/absorption spectra, radiative lifetimes, and the conductivity are able to be effectively modi ed for the intended application [4][5][6][7] . As bene t from the peculiarities, c-Si QD show great potential in manufacturing high-performance optoelectrical devices, in particular for photoluminescence (PL).…”