Date: March 2020
NAND, one type of flash memories is an non-volatile memory storage that can be electrically erased and reprogrammed. Wide applications have been found including memory cards, USB flash drives, and solidstate drives (SSD). In order to have a higher bit density, starting from last few years, 3D architecture, so-called vertical NAND (V-NAND) or 3D NAND, was introducted.
With the help of its material analysis capability, MSS firstly unveils detailed information about one of the latest V-NAND products (Samsung 970 EVO Plus) in the market.
# What MSS can do for you?
1.lamella preparation depth over 10um, stable quality ensure your "only one" sample safe
2.Reducing massive curtain effects
3. Fisrtly provide "Roundness evaluation", let you check sample etching quality from top to buttom
MSS material analysis niches
1. Super thin lamella preparation to reduce ghost imaging
2. Reducing massive curtain effects
3. Roundness evaluation
Samsung 970 EVO Plus
▲Figure 1: a) Samsung V-NAND SSD 970 EVO Plus with a capacity of 2 TB, purchased from the market.
b) OM image of the Samsung’s 1TB 92-layer V-NAND.
c) SEM cross-section view of the 92-layer V-NAND dies, stacked in vertical direction. Each package includes 16 V-NAND dies (#1 to #16).
Cross-section view of the 92-layer V-NAND
▲Figure 2: Cross-section view prepared by focused ion beam (FIB), in two perpendicular direction (X and Y), of the 92-layer V-NAND cell array by scanning electron microscopy (SEM). Massive curtain effects normally observed for big area FIB cuts are not found in these images. The red scale bar is 2 ㎛.
Zoom-in SEM images of the cell array
▲Figure 3: Zoom-in SEM images of Fig. 2. The imaging areas are marked by the green dotted rectangles and numbers. From 1-5 images, highmagnification SEM images of structures of interest can be clearly obtained. Curtain effects can only be barely seen. The red scale bar is 2 ㎛.
Transmission Electron microscopy (TEM) analysis on the 3D floating gate structure
▲Figure 4: a) Cross-section TEM (XTEM) image of the floating gate structure.
b)-d) Zoom-in XTEM images of a) taken at upper b), middle c), and bottom d) locations.
Plan-view TEM analysis along the cell array structure
▲Figure 5: Plan-view TEM images taken at upper a), middle b), and bottom
▲Figure 6: Roundness analysis (MSS algorithm) on the doughnut-like structure taken at upper, middle, and bottom locations. It clearly shows the diameter of the doughnut-like structure decreases with the depth, as well as the roundness.
Energy dispersive X-ray spectrometer (EDS )analysis
▲Figure 7: Clear elemental distribution of the cell array can be obtained by TEM/EDS analysis.