Sacrificial self aligned spacer layer ion implant mask method for forming a split gate field effect transistor (FET) device

A method for fabricating a pair of split gate field effect transistors comprising:

• providing a semiconductor substrate having formed thereupon a gate dielectric layer in turn having formed thereupon a pair of floating gate electrodes which in turn defines a pair of locations of a pair of floating gate electrode channels within the semiconductor substrate;
• forming adjacent a pair of opposite edges of the pair of floating gate electrodes a pair of self aligned spacer layers which defines a pair of locations of a pair of control gate electrode channels within the semiconductor substrate and forming interposed between the pair of floating gate electrodes a single contiguous third self aligned spacer layer which covers the semiconductor substrate interposed between the pair of floating gate electrodes;
• forming within the semiconductor substrate at least in part while employing at least the pair of self aligned spacer layers, the third self aligned spacer layer and the pair of floating gate electrodes as a mask a pair of first source/drain regions adjoining the pair of control gate electrode channels, but not interposed between the pair of floating gate electrodes;
• stripping from adjacent and interposed between the pair of floating gate electrodes the pair of self aligned spacer layers and the third self aligned spacer layer;
• forming upon the pair of floating gate electrodes an inter-gate electrode dielectric layer;
• forming upon the inter-gate electrode dielectric layer, while fully covering the pair of control gate electrode channels and partially covering the pair of floating gate electrodes, a pair of control gate electrodes;
• and
• forming into the semiconductor substrate at least in part while employing at least the pair of control gate electrodes and the pair of floating gate electrodes as a mask a second source/drain region interposed between the pair of floating gate electrodes.