Strained isolation regions
An isolation trench having localized stressors is provided. In accordance with embodiments of the present invention, a trench is formed in a substrate and partially filled with a dielectric material. In an embodiment, the trench is filled with a dielectric layer and a planarization step is performed to planarize the surface with the surface of the substrate. The dielectric material is then recessed below the surface of the substrate. In the recessed portion of the trench, the dielectric material may remain along the sidewalls or the dielectric material may be removed along the sidewalls. A stress film, either tensile or compressive, may then be formed over the dielectric material within the recessed portion. The stress film may also extend over a transistor or other semiconductor structure.
1. A semiconductor structure comprising:
a substrate;
an isolation trench formed in the substrate, the isolation trench being at least partially filled with a dielectric material, an entire top surface of the dielectric material in the isolation trench being recessed lower than a top surface of the substrate, the entire top surface of the dielectric material extending between sidewalls of the isolation trench having a planar surface;
a transistor gate over the substrate; and
a contact etch stop layer over the substrate and the dielectric material within the isolation trench in a direction orthogonal to a plane of the top surface of the substrate immediately below the transistor gate, the contact etch stop layer being in direct contact with the substrate along sidewalls of the isolation trench.
2. The semiconductor structure of claim 1 , wherein the contact etch stop layer comprises a tensile stress film.
3. The semiconductor structure of claim 1 , wherein the contact etch stop layer comprises a compressive stress film.
4. The semiconductor structure of claim 1 , wherein the contact etch stop layer covers the transistor gate.
5. The semiconductor structure of claim 1 , wherein at least a portion of the dielectric material is recessed from about 200 Å to about 500 Å.
6. A semiconductor structure comprising:
a substrate;
a shallow trench isolation formed in the substrate, the shallow trench isolation comprising a trench at least partially filled with a dielectric material;
a recess in the shallow trench isolation exposing the substrate along a sidewall of the shallow trench isolation, an entire upper surface of the dielectric material being a planar top surface, the planar top surface extending between sidewalls of the shallow trench isolation; and
a contact etch stop layer in the recess and on the substrate, the contact etch stop layer being in direct contact with the substrate along the sidewall and being directly over the dielectric material.
7. The semiconductor structure of claim 6 , wherein all of the dielectric material within the shallow trench isolation is recessed below a top surface of the substrate.
8. The semiconductor structure of claim 6 , wherein the contact etch stop layer comprises a tensile stress film or a compressive stress film.
9. The semiconductor structure of claim 6 , further comprising a transistor on the substrate.
10. The semiconductor structure of claim 9 , wherein the contact etch stop layer covers the transistor.
11. The semiconductor structure of claim 6 , wherein the recess has a depth of about 200 Å to about 500 Å.
12. A semiconductor structure comprising:
a substrate having a first top side and an opposing first bottom side, the substrate having an isolation trench formed therein on the first top side, the isolation trench being at least partially filled with a dielectric material, an entire upper surface of the dielectric material having a planar top surface lower than an upper corner of the isolation trench;
a transistor gate over the substrate; and
a stress layer over the dielectric material, the transistor gate, and the substrate, the stress layer directly contacting the substrate within the isolation trench, the stress layer comprising a plurality of individual stress layers.
13. The semiconductor structure of claim 12 , wherein the stress layer directly contacts an upper portion of the isolation trench.
14. The semiconductor structure of claim 12 , wherein the stress layer comprises a tensile stress film or a compressive stress film.
15. The semiconductor structure of claim 12 , wherein at least a portion of the top surface of the dielectric material is recessed about 200 Å to about 500 Å below a first surface of the substrate.
16. The semiconductor structure of claim 12 , wherein the stress layer covers the transistor gate.