Semiconductor structure and manufacturing method thereof

A method for manufacturing a semiconductor structure, comprising:

• providing a substrate;
• forming a plurality of stack structures on the substrate, wherein the plurality of stack structures are separated from each other, and the plurality of stack structures comprise a bit line stack structure and a conductive line stack structure;
• forming a plurality of first spacers on sidewalls of the plurality of stack structures, wherein each of the plurality of first spacers comprises a first oxide layer and a first nitride layer;
• forming a contact on the substrate between the two adjacent first spacers, wherein the first nitride layer is located between the first oxide layer and the contact, a top surface of the first oxide layer and a top surface of the first nitride layer are higher than a top surface of the contact;
• performing an oxidation process to oxidize a portion of the first nitride layer into a second oxide layer;
• removing the second oxide layer and the portion of the first oxide layer;
• and
• forming a plurality of second spacers on the plurality of first spacers.