A semiconductor device and a method of manufacturing the same. The semiconductor device includes a channel, a gate, and a memory layer is interposed between the channel and the gate. The memory layer includes a tunnel insulating layer adjacent to the channel, a charge blocking layer adjacent to the gate, and a charge storing layer interposed between the tunnel insulating layer and the charge blocking layer. The tunnel insulating layer includes a first insulating layer adjacent to the channel and an air layer interposed between the first insulating layer and the charge storing layer.