Method for fabricating semiconductor device

A method for fabricating semiconductor device, comprising:

• providing a substrate having a first region and a second region;
• forming a first gate structure on the first region and a second gate structure on the second region;
• forming an interlayer dielectric (ILD) layer around the first gate structure and the second gate structure;
• removing the first gate structure and the second gate structure to expose the substrate on the first region and the second region;
• removing part of the substrate on the second region to form a first recess exposing the substrate;
• removing part of the substrate on the first region to form a second recess exposing the substrate, wherein the depths of the first recess and the second recess are different and the substrate exposed by the first recess and the substrate exposed by the second recess comprise same material;
• and
• forming a first metal gate on the first region and a second metal gate on the second region.