Memory structure and manufacturing method thereof

A method of manufacturing a memory structure, comprising:

• forming a first gate structure on a substrate, wherein the first gate structure comprises:
• a first gate disposed on the substrate;
• and
• a charge storage layer disposed between the first gate and the substrate;
• forming a second gate structure on the substrate at one side of the first gate structure, wherein the second gate structure comprises a second gate, and a height of the first gate is higher than a height of the second gate;
• forming a first spacer and a second spacer respectively on one sidewall and the other sidewall of the first gate structure, wherein the first spacer is located between the first gate structure and the second gate structure;
• and
• forming a third spacer on a sidewall of the first spacer, wherein the third spacer covers a portion of a top surface of the second gate, a top surface of the charge storage layer is lower than the entire top surface of the second gate, and the first spacer covers a sidewall of the charge storage layer.