A method of operating a flash memory structure including a programming step. The method includes providing a flash memory device, the flash memory device comprising a substrate of first conductivity type, a source region of second conductivity type being defined in the substrate and a drain region of second conductivity type defined in the substrate. The flash memory device can be a split gate, a stacked gate, or other type of physical structure. The method includes applying a drain voltage of first polarity type on the drain region and applying a control gate voltage of a first conductivity type on the control gate. The method also includes applying a source voltage of second polarity type ranging from about 0.1 volt to about 0.5 volt on the source region, while maintaining a ground potential on the substrate to inject electrons onto a floating gate to program the floating gate.