Embodiments relate to a flash memory device and a method of manufacturing a flash memory device, which may increase a coupling coefficient between a control gate and a floating gate by increasing a surface area of floating gate. In embodiments, a flash memory device may be formed by forming a photoresist pattern for forming a floating gate on a semiconductor substrate including an oxide film, a floating gate poly film, and a BARC (Bottom AntiReflect Coating), performing a first etching process using the photoresist pattern as a mask, to etch the floating gate poly film to a predetermined depth, depositing and forming a polymer to cover the photoresist pattern, forming spacers of the polymer at both sidewalls of the photoresist pattern, forming a second etching process using the spacers as a mask, to expose the oxide film, and removing the BARC, the photoresist pattern and the spacers by ashing and stripping.