Example embodiments relate to a non-volatile semiconductor memory device and a method of manufacturing the same. A semiconductor device includes an isolation layer protruding from a substrate, a spacer, a tunnel insulation layer, a floating gate, a dielectric layer pattern and a control gate. The spacer may be formed on a sidewall of a protruding portion of the isolation layer. The tunnel insulation layer may be formed on the substrate between adjacent isolation layers. The floating gate may be formed on the tunnel insulation layer. The floating gate contacts the spacer and has a width that gradually increases from a lower portion toward an upper portion. The dielectric layer pattern and the control gate may be sequentially formed on the floating gate.