Semiconductor device and method for fabricating the same
A method for fabricating a semiconductor device includes the steps of providing a substrate having a low-voltage (LV) region and a medium-voltage (MV) region, forming a first metal gate on the LV region and a second metal gate on the MV region, forming a first patterned mask on the second metal gate, removing part of the first metal gate, forming a second patterned mask on the first metal gate, removing part of the second metal gate, and then forming a first hard mask on the first metal gate and a second hard mask on the second metal gate.
1 . A semiconductor device, comprising:
a substrate having a medium-voltage (MV) region and a low-voltage (LV) region;
a first gate structure on the LV region and a second gate structure on the MV region, wherein a bottom surface of the first gate structure is even with a bottom surface of the second gate structure; and
a first hard mask on the first gate structure and a second hard mask on the second gate structure, wherein the first hard mask and the second hard mask comprise different thicknesses.
2 . The semiconductor device of claim 1 , wherein a surface of the substrate on the LV region is even with a surface of the substrate on the MV region.
3 . The semiconductor device of claim 2 , wherein a bottom surface of the first gate structure is even with a bottom surface of the second gate structure.
4 . The semiconductor device of claim 2 , wherein a thickness of the second hard mask is less than a thickness of the first hard mask.
5 . The semiconductor device of claim 1 , wherein a surface of the substrate on the LV region is higher than a surface of the substrate on the MV region.
6 . The semiconductor device of claim 5 , wherein a bottom surface of the first gate structure is higher than a bottom surface of the second gate structure.
7 . The semiconductor device of claim 5 , wherein a thickness of the first hard mask is less than a thickness of the second hard mask.
8 . The semiconductor device of claim 1 , wherein top surfaces of the first hard mask and the second hard mask are coplanar.