Method for manufacturing semiconductor device

A method for manufacturing a semiconductor device, comprising:

• forming at least one epitaxial layer over a substrate;
• patterning the epitaxial layer into a semiconductor fin;
• forming an isolation structure around the semiconductor fin;
• depositing a semiconductor capping layer over the semiconductor fin and the isolation structure, wherein the semiconductor capping layer has a first portion that is amorphous on a top surface of the isolation structure and adjacent to the semiconductor fin;
• performing a thermal treatment such that the first portion of the semiconductor capping layer is converted from amorphous into crystalline;
• and
• forming a dummy gate structure over the semiconductor fin.

A method for manufacturing a semiconductor device, comprising:

• forming an epitaxial stack over a substrate;
• patterning the epitaxial stack into a semiconductor fin, wherein the semiconductor fin comprises a plurality of first semiconductor layers and a plurality of second semiconductor layers alternatively arranged;
• depositing a semiconductor capping layer on a sidewall of the semiconductor fin;
• annealing the semiconductor capping layer to induce crystallization in the semiconductor capping layer;
• removing the first semiconductor layers from the semiconductor fin;
• and
• forming a metal gate structure surrounding the second semiconductor layers.