Trench capacitor profile to decrease substrate warpage

1. An integrated circuit (IC) comprising:

a substrate comprising sidewalls that define a trench;

a capacitor comprising a plurality of conductive layers and a plurality of dielectric layers that define a trench segment disposed within the trench, wherein a width of the trench segment continuously increases from a front-side surface of the substrate to a first point below the front-side surface, wherein the trench segment comprises inner sidewalls that define a cavity within the trench; and

a capping dielectric layer overlying the capacitor, wherein the capping dielectric layer continuously extends over a top of the cavity.

2. The IC of claim 1 , wherein the trench segment comprises a first sidewall segment defined between the front-side surface and the first point and a second sidewall segment vertically below the first sidewall segment, wherein the first sidewall segment is angled in a first direction that is opposite a second direction of an angle of the second sidewall segment.

3. The IC of claim 1 , wherein a width of the cavity continuously increases from a second point at or below the front-side surface of the substrate to a third point below the second point.

4. The IC of claim 1 , wherein the capping dielectric layer comprises a first material different from a second material of a first dielectric layer in the plurality of dielectric layers.

5. The IC of claim 1 , wherein the plurality of dielectric layers comprises an insulator layer disposed along the front-side surface and the sidewalls of the substrate, wherein the insulator layer directly contacts a first conductive layer in the plurality of conductive layers.

6. The IC of claim 1 , wherein the width of the trench segment at a second point is less than the width of the trench segment at the first point, where the second point is below the first point.

7. The IC of claim 1 , wherein the cavity is sealed at least in part by the capping dielectric layer.

8. The IC of claim 1 , wherein a maximum width of the cavity is less than the width of the trench segment at the front-side surface of the substrate.

9. The IC of claim 1 , wherein the top of the cavity is disposed at or below the front-side surface of the substrate.

10. An integrated circuit (IC) comprising:

a substrate;

a plurality of conductive layers overlying the substrate;

a plurality of dielectric layers overlying the substrate and spaced between the plurality of conductive layers, wherein the plurality of conductive layers and the plurality of dielectric layers define a trench segment extending into the substrate; and

a pillar structure abutting the trench segment, wherein a width of the pillar structure varies from a front-side surface of the substrate in a direction towards a bottom surface of the pillar structure, wherein an outer edge of the pillar structure directly overlies at least a portion of the trench segment.

11. The IC of claim 10 , wherein the pillar structure comprises a first sidewall segment overlying a second sidewall segment, wherein the first sidewall segment and the second sidewall segment are slanted in opposite directions relative to one another.

12. The IC of claim 11 , wherein a height of the first sidewall segment is less than a height of the second sidewall segment.

13. The IC of claim 10 , further comprising:

a capping dielectric layer overlying the substrate, wherein the capping dielectric layer comprises a protrusion extending into the trench segment and a bottom surface disposed below the front-side surface of the substrate.

14. The IC of claim 10 , wherein a first width of the trench segment is aligned with the front-side surface of the substrate and is less than a second width of a bottom surface of the trench segment.

15. The IC of claim 10 , wherein the width of the pillar structure at a first point aligned with the front-side surface of the substrate is greater than the width of the pillar structure at a second point aligned with a bottom of the trench segment.

16. The IC of claim 10 , wherein the trench segment comprises inner sidewalls that define a cavity within the substrate, wherein a maximum width of the pillar structure is greater than a maximum width of the cavity.

17. A method for forming an integrated circuit (IC), the method comprising:

patterning a front-side surface of a substrate to form opposing sidewalls in the substrate that define a trench extending into the front-side surface of the substrate, wherein a distance between the opposing sidewalls of the substrate continuously increases from the front-side surface to a first point below the front-side surface; and

forming a plurality of dielectric layers and a plurality of conductive layers within the trench such that a cavity is sealed within the trench.

18. The method of claim 17 , wherein patterning the front-side surface of the substrate comprises:

performing a first etching process on the substrate to define an upper portion of the trench;

forming a sidewall protection layer along the opposing sidewalls of the substrate; and

performing a second etching process on the substrate to define a lower portion of the trench below the upper portion of the trench, wherein the sidewall protection layer is disposed along the upper portion of the trench during the second etching process.

19. The method of claim 18 , wherein the first etching process includes performing a first dry etch at a first pressure and the second etching process includes performing a second dry etch at a second pressure less than the first pressure.

20. The method of claim 17 , wherein the plurality of conductive layers and the plurality of dielectric layers define a trench segment disposed within the trench, wherein a width of the trench segment continuously increases from the front-side surface of the substrate to the first point.