Semiconductor device and method for fabricating the same
A method for fabricating semiconductor device includes the steps of: providing a substrate having a memory region and a periphery region; forming a first trench and a second trench in substrate on the memory region, wherein a width of the second trench is greater than a width of the first trench; forming a first liner in the first trench and the second trench; forming a second liner on the first liner, wherein the second liner completely fills the first trench and partly fills the second trench; and planarizing the second liner and the first liner to form a first isolation structure and a second isolation structure.
1. A semiconductor device, comprising:
a substrate having a memory region and a periphery region;
a first isolation structure in the substrate on the memory region, wherein the first isolation comprises:
a first liner in the substrate; and
a second liner on the first liner;
a second isolation structure adjacent to the first isolation structure, wherein a width of the second isolation structure is greater than a width of the first isolation structure, the second isolation structure comprises:
the first liner in the substrate;
the second liner on the first liner; and
a third liner on the second liner of the second isolation structure and not on the second liner of the first isolation structure.
2. The semiconductor device of claim 1 , further comprising a third isolation structure and a fourth isolation structure in the substrate on the periphery region, wherein a width of the third isolation structure is greater than a width of the second isolation structure and a width of the fourth isolation structure is greater than a width of the third isolation structure.
3. The semiconductor device of claim 2 , wherein each of the third isolation structure and the fourth isolation structure comprises:
the first liner in the substrate;
the second liner on the first liner; and
the third liner on the second liner.
4. The semiconductor device of claim 3 , further comprising a fourth liner on the third liner.
5. The semiconductor device of claim 4 , wherein the third liner and the fourth liner comprise different materials.
6. The semiconductor device of claim 4 , wherein the third liner comprises silicon nitride and the fourth liner comprises silicon oxide.
7. The semiconductor device of claim 1 , wherein the first liner and the second liner comprise same material.
8. The semiconductor device of claim 7 , wherein the first liner and the second liner comprise silicon oxide.
9. The semiconductor device of claim 1 , wherein each of the first liner, the second liner, and the third liner is U-shaped.