Semiconductor isolation structures comprising shallow trench and deep trench isolation
The present disclosure relates to isolation structures for semiconductor devices and, more particularly, to dual trench isolation structures having a deep trench and a shallow trench for electrically isolating integrated circuit (IC) components formed on a semiconductor substrate. The semiconductor isolation structure of the present disclosure includes a semiconductor substrate, a shallow trench isolation (STI) disposed over the semiconductor substrate, a deep trench isolation (DTI) with sidewalls extending from a bottom surface of the STI and terminating in the semiconductor substrate, a multilayer dielectric lining disposed on the sidewalls of the DTI, the multilayer dielectric lining including an etch stop layer positioned between inner and outer dielectric liners, and a filler material disposed within the DTI.
1. A semiconductor isolation structure comprising:
a semiconductor substrate;
a shallow trench isolation (STI) disposed over the semiconductor substrate;
a doped subcollector disposed over the semiconductor substrate;
a deep trench isolation (DTI) with sidewalls extending from a bottom surface of the STI, through the doped subcollector, and terminating in the semiconductor substrate, wherein the DTI has a bowed section formed in the doped subcollector layer below the STI;
a multilayer dielectric lining disposed on the sidewalls of the DTI, wherein the multilayer dielectric lining comprises an etch stop layer positioned between inner and outer dielectric liners; and
a filler material disposed within the DTI.
2. The isolation structure of claim 1 , wherein the filler material has a top surface that is substantially level with the bottom surface of the STI.
3. The isolation structure of claim 2 , wherein the etch stop layer and the inner dielectric liner have top edge portions that are recessed below the top surface of the filler material.
4. The isolation structure of claim 1 , wherein the outer dielectric liner is formed on the sidewalls of the DTI and has a top edge portion that contacts the bottom surface of the STI.
5. The isolation structure of claim 2 , wherein the outer dielectric liner has a top edge portion that is recessed below the top surface of the filler material.
6. The isolation structure of claim 1 , wherein the doped subcollector layer comprises regions with different dopant concentrations.
7. The isolation structure of claim 6 , wherein the region with a highest dopant concentration is aligned with the bowed section of the DTI having a maximum width.
8. The isolation structure of claim 1 , wherein the STI includes an oxide layer surrounding a capping layer that is disposed on the top surface of the filler material and covers the multilayer dielectric lining.
9. The isolation structure of claim 8 , wherein the DTI includes a bottom section having the oxide layer disposed on top of the outer dielectric liner and beneath the filler material.
10. The isolation structure of claim 1 , wherein the DTI has a depth that is greater than a pre-determined depth for the STI.
11. The isolation structure of claim 1 , wherein a top surface of the filler material is below the bottom surface of the STI.
12. The isolation structure of claim 11 , wherein the top surface of the filler material is located within the bowed section.
13. The isolation structure of claim 12 , wherein the top surface of the filler material is above a maximum width of the bowed section.
14. The isolation structure of claim 1 , wherein the multilayer dielectric lining conforms to the bowed sidewalls of the DTI.
15. The isolation structure of claim 14 , wherein the filler material has bowed sidewalls that are within the bowed section of the DTI.
16. The isolation structure of claim 15 , wherein the bowed sidewalls of the filler material corresponds to the concavity of the bowed sidewalls of the DTI.
17. The isolation structure of claim 15 , wherein the STI includes a capping layer that is disposed on a top surface of the filler material.
18. The isolation structure of claim 17 , wherein the capping layer extends below the top surface of filler material to surround a portion of the bowed sidewalls of the filler material.