Flash memory structure and method of making the same

A flash memory structure, comprising:

• a first gate structure;
• a second gate structure;
• and
• a source and a drain respectively disposed at one side of said first gate structure and at the other side of said second gate structure;
• wherein said first gate structure and said second gate structure are formed on a substrate next to each other, and there is a gap disposed between said first gate structure and said second gate structure;
• said first gate structure and said second gate structure respectively comprise:
• a first insulating layer, a first conductive layer, a second insulating layer, a second conductive layer, a mask layer and a spacer to cover the sidewall of said mask layer,
• wherein said spacer serves as an etching mask and said gap is self-alignment defined by using said spacer;
• wherein said first conductive layer and said second insulating layer of said first gate structure have a trench and said second conductive layer extends to said trench to connect said first conductive layer, and said first gate structure serves as a select gate and said second gate structure serves as a control gate and a floating gate;
• wherein there is no implanted area in said substrate between said first gate structure and said second gate structure.