A flash memory device and its manufacturing method are presented. The flash memory device includes a substrate; a memory unit on the substrate, comprising a channel structure, wherein the channel structure comprises, sequentially from inner to outer of the channel structure, a channel layer comprising a first component substantially perpendicular to an upper surface of the substrate and a second component on the first component, a tunnel insulation layer wrapped around the channel layer, a charge capture layer wrapped around the tunnel insulation layer, and a blocking layer wrapped around the charge capture layer; a plurality of gate structures wrapped around the channel structure and arranged along a symmetry axis of the channel structure with a topmost gate structure wrapped around the second component; and a channel contact component connecting to, and forming a Schottky contact with, the second component of the channel layer. This device reduces the leakage current.