Structure of memory device having floating gate with protruding structure

A structure of memory device, comprising:

• a plurality of trench isolation lines in a substrate, extending along a first direction;
• an active region in the substrate between adjacent two of the trench isolation lines;
• a dielectric layer on the active region of the substrate;
• a floating gate, in a top-view perspective over the substrate, disposed on the dielectric layer corresponding to a memory cell between adjacent two of the trench isolation lines, wherein the floating gate comprises a first protruding structure extending along the first direction from a sidewall of the floating gate;
• a first insulating layer, in the top-view perspective, crossing over the floating gate and the trench isolation lines;
• a control gate line, in the top-view perspective, disposed on the first insulating layer over the floating gate, extending along a second direction intersecting with the first direction, wherein the control gate line has a second protruding structure correspondingly stacked over the first protruding structure of the floating gate;
• and
• an erase gate line between adjacent two of the control gate lines, wherein the first protruding structure and the second protruding structure are extending into the erase gate line.