US Patent 10020317 Memory device with multi-layer channel and charge trapping layer

A 3-D/vertical non-volatile (NV) memory device such as 3-D NAND flash memory and fabrication method thereof, the NV memory device includes vertical openings disposed in a stack of alternating stack layers of first stack layers and second stack layers over a wafer, a multi-layer dielectric disposed over an inner sidewall of each opening, a first channel layer disposed over the multi-layer dielectric, and a second channel layer disposed over the first channel layer, in which at least one of the first or second channel layers includes polycrystalline germanium or silicon-germanium.