Method for fabricating a split gate flash memory cell

A method of fabricating a split-gate flash memory cell, comprising the steps of:

• providing a semiconductor substrate;
• defining an active area on the substrate;
• forming a first insulating layer as a first gate insulating layer within the active area;
• forming a first conductive layer on the first gate insulating layer;
• forming a buffer layer on the first conductive layer;
• removing portions of the buffer layer to form a floating gate insulating layer;
• forming a second conductive layer on the surface of the first conductive layer and the floating gate insulating layer;
• removing portions of the first conductive layer and the second conductive layer, such that the second conductive layer remaining on the sidewalls of the floating gate insulating layer forms conductive first spacers having conductive tips situated at the tips, the first conductive layer remaining under the conductive spacers and under the floating gate insulating layer forms a composite conductive layer, the conductive spacers and the composite conductive layer are combined as a floating gate, wherein the conductive tips are suitable for tip discharging, and the floating gate insulating layer, the floating gate and the first gate insulating layer are combined as a floating gate region;
• forming a second insulting layer on the surface of the floating gate region and the substrate;
• forming a third conductive layer on the second insulating layer;
• removing portions of the third conductive layer and the second insulating layer to form a first opening and a second opening, such that the remaining third conductive layer forms the control gate and the remaining second insulating layer forms the second gate insulating layer;
• forming a source region by implanting impurity ions through the first opening into the substrate;
• forming insulating second spacers on the sidewalls of the first opening and the second opening;
• and forming a drain region on the substrate within the second opening.