| abstract |
A semiconductor device structure is provided. The semiconductor device structure includes a semiconductor substrate and a gate stack over the semiconductor substrate. The semiconductor device structure also includes a sealing structure over a sidewall of the gate stack , and a width ratio of the sealing structure to the gate stack is in a range from about 0.05 to about 0.7. The semiconductor device structure further includes an etch stop layer over the semiconductor substrate, the gate stack, and the sealing structure . The etch stop layer is in contact with the sealing structure. |