Self-aligned dielectric isolation for FinFET devices

1. A method comprising:

forming a set of device features on top of a substrate, said set of device features including at least a first group of device features and a second group of device features;

forming a first dielectric layer directly on top of said set of device features and on top of said substrate, thereby creating a height profile of said first dielectric layer measured from a top surface of said substrate, said height profile being associated with and creating a pattern of an insulating structure that fully surrounds said set of device features, said pattern of said insulating structure separating said first group of device features from said second group of device features in two enclosures; and

forming a second dielectric layer in areas that are defined by said pattern to create said insulating structure,

wherein forming said first dielectric layer comprises depositing a conformal dielectric layer on top of said first group and said second group of device features, said conformal dielectric layer having a thickness that is sufficiently thick to fill up any gap between any two neighboring said device features either within said first group or within said second group.

2. The method of claim 1 , further comprising, before forming said second dielectric layer, removing a portion of said first dielectric layer to form sidewall spacers next to sidewalls of at least some of said set of device features and to expose portions of said substrate that are defined by said pattern of said insulating structure.

3. The method of claim 1 , wherein forming said first dielectric layer comprises depositing a conformal dielectric layer as said first dielectric layer, whose thickness is less than half of a shortest distance between said first and said second groups of device features, creating said height profile that complements a height profile of said insulating structure.

4. The method of claim 1 , further comprising, before forming said second dielectric layer, directionally etching said first dielectric layer to remove portions of said first dielectric layer that surround said first and second groups of device features to expose said substrate underneath thereof, said directional etching substantially maintains said pattern of said insulating structure.

5. The method of claim 4 , further comprising, after forming said second dielectric layer in areas defined by said pattern directly on top of said exposed substrate, removing portions of said second dielectric layer that are deposited on top of said first dielectric layer and on top of said first and second groups of device features.

6. The method of claim 1 , wherein said set of device features is a set of fins of a set of fin-type field-effect-transistors (FinFETs), further comprising forming a set of gates for said set of FinFETs substantially perpendicular to and across said set of fins, said set of gates having their respective two ends directly on top of said insulating structure.

7. The method of claim 6 , further comprising epitaxially forming source and drain of said set of FinFETs from portions of said substrate adjacent to said set of fins.

8. A method comprising:

forming a set of fin structures on top of a substrate, said set of fin structures being part of one or more fin-type field-effect-transistors (FinFETs);

forming a first dielectric layer directly on top of said set of fin structures and on top of said substrate, said first dielectric layer having a height profile that is complement to a pattern of an insulating structure fully surrounding said set of fin structures;

forming a second dielectric layer in areas defined by said pattern to create said insulating structure;

forming a set of gates of said one or more FinFETs perpendicularly across said set of fin structures, having two ends of said set of gates landing directly on top of said insulating structure; and

epitaxially forming source and drain of said one or more FinFETs from portions of said substrate adjacent to said set of fin structures.

9. The method of claim 8 , wherein said set of fin structures includes at least a first group of fin structures and a second group of fin structures, and wherein forming said first dielectric layer comprises causing said first dielectric layer to create said pattern of said insulating structure by said height profile, said pattern of said insulating structure separating said first group of fin structures from said second groups of fin structures.

10. The method of claim 9 , wherein forming said first dielectric layer comprises depositing a conformal dielectric layer to have a thickness, said thickness being more than half of a greatest distance between any two neighboring said fin structures either within said first group or within said second group and being less than half of a shortest distance between said first group of fin structures and said second group of fin structures, creating said height profile that complements a height profile of said insulating structure.

11. The method of claim 9 , further comprising, before forming said second dielectric layer, directionally etching said first dielectric layer to remove portions of said first dielectric layer that surround said first and second groups of fin structures to expose said substrate underneath thereof, said directional etching substantially maintaining said pattern of said insulating structure.

12. The method of claim 11 , further comprising, after forming said second dielectric layer in areas of said pattern directly on top of said exposed substrate, removing portions of said second dielectric layer that are deposited on top of said first dielectric layer and on top of said first and second groups of fin structures.

13. A method comprising:

forming a set of device features on top of a substrate, said set of device features including at least a first group of device features and a second group of device features;

forming a first dielectric layer directly on top of said set of device features and on top of said substrate, thereby creating a height profile of said first dielectric layer measured from a top surface of said substrate, said height profile being associated with and creating a pattern of an insulating structure that fully surrounds said set of device features, said pattern of said insulating structure separating said first group of device features from said second group of device features in two enclosures; and

forming a second dielectric layer in areas that are defined by said pattern to create said insulating structure,

wherein forming said first dielectric layer comprises depositing a conformal dielectric layer as said first dielectric layer, whose thickness is less than half of a shortest distance between said first and said second groups of device features, creating said height profile that complements a height profile of said insulating structure.

14. The method of claim 13 , further comprising, before forming said second dielectric layer, removing a portion of said first dielectric layer to form sidewall spacers next to sidewalls of at least some of said set of device features and to expose portions of said substrate that are defined by said pattern of said insulating structure.

15. The method of claim 13 , further comprising, before forming said second dielectric layer, directionally etching said first dielectric layer to remove portions of said first dielectric layer that surround said first and second groups of device features to expose said substrate underneath thereof, said directional etching substantially maintains said pattern of said insulating structure.

16. The method of claim 15 , further comprising, after forming said second dielectric layer in areas defined by said pattern directly on top of said exposed substrate, removing portions of said second dielectric layer that are deposited on top of said first dielectric layer and on top of said first and second groups of device features.