Method for forming semiconductor structure

A method for forming a semiconductor structure, comprising:

• forming gate structures over a fin structure;
• forming spacers over opposite sides of the gate structure;
• recessing the fin structure to form a source/drain recess;
• forming a native oxide layer over the source/drain recess;
• enlarging a width of the source/drain recess by sequentially performing a first wet cleaning, plasma treating, and second wet cleaning the source/drain recess;
• and
• partially removing the spacers.

A method for forming a semiconductor structure, comprising:

• forming a gate structure over a fin structure;
• forming spacers beside the gate structure;
• forming a source/drain recess in the fin structure;
• first wet cleaning the source/drain recess;
• hydrogen radical treating the source/drain recess;
• second wet cleaning the source/drain recess and the spacers;
• and
• forming a source/drain epitaxial structure in the source/drain recess.