Preventing bridge formation between replacement gate and source/drain region through STI structure

1. A method, comprising:

forming at least one fin above a semiconductor substrate;

forming an isolation structure adjacent said fin;

forming a liner layer above said at least one fin and said isolation structure;

forming a dielectric layer above said liner layer;

recessing said dielectric layer to expose portions of said liner layer disposed on sidewalls of said at least one fin;

removing said exposed portions of said liner layer disposed on said sidewalls of said at least one fin;

removing remaining portions of said dielectric layer after removing said exposed portions of said liner layer, wherein a portion of said liner layer remains on an upper surface of said isolation structure adjacent an interface where said fin contacts said isolation structure after forming said isolation structure, said liner layer comprising a material different than said isolation structure;

forming a sacrificial gate structure including a sacrificial gate insulation layer and a sacrificial gate structure above a portion of said fin;

removing said sacrificial gate structure;

removing said sacrificial gate insulation layer selectively to said liner layer; and

forming a replacement gate structure in a cavity defined by removing said sacrificial gate structure.

2. The method of claim 1 , wherein said isolation structure comprises silicon dioxide and said liner layer comprises silicon nitride.

3. The method of claim 1 , further comprising forming a spacer adjacent said sacrificial gate structure, wherein said liner layer protects said isolation structure from an etchant used to remove said sacrificial gate insulation layer.

4. The method of claim 1 , further comprising:

forming an epitaxial region in said fin after forming said sacrificial gate structure; and

forming a contact etch stop layer above said epitaxial region.

5. The method of claim 1 , wherein forming said at least one fin comprises forming at least a first fin and a second fin, and the method further comprises:

forming a merged epitaxial region between said first and second fins after forming said sacrificial gate structure; and

forming a contact etch stop layer above said merged epitaxial region.

6. The method of claim 5 , wherein a portion of said liner layer is disposed above said isolation structure beneath said merged epitaxial region.

7. The method of claim 6 , further comprising forming a spacer adjacent said sacrificial gate structure, wherein a portion of said liner layer disposed above said isolation structure beneath said merged epitaxial region protects said isolation structure from an etchant used to remove said sacrificial gate insulation layer.

8. A method, comprising:

forming a plurality of fins above a semiconductor substrate;

forming an isolation structure between said plurality of fins;

forming a liner layer above said plurality of fins and said isolation structure;

forming a dielectric layer above said liner layer;

recessing said dielectric layer to expose portions of said liner layer disposed on sidewalls of said plurality of fins;

removing said exposed portions of said liner layer disposed on said sidewalls of said plurality of fins;

removing remaining portions of said dielectric layer after removing said exposed portions of said liner layer, wherein a portion of said liner layer remains on an upper surface of said isolation structure adjacent interfaces where said plurality of fins contact said isolation structure after forming said isolation structure, said liner layer comprising a material different than said isolation structure;

forming a sacrificial gate structure including a sacrificial gate insulation layer and a sacrificial gate structure above portions of said plurality of fins;

forming epitaxial regions in said plurality of fins, wherein said epitaxial regions include a merged region disposed between at least two of said plurality of fins, wherein a portion of said liner layer is disposed above said isolation structure beneath said merged region;

forming a contact etch stop layer above said isolation structure and said epitaxial regions;

removing said sacrificial gate structure;

removing said sacrificial gate insulation layer selectively to said liner layer; and

forming a replacement gate structure in a cavity defined by removing said sacrificial gate structure.

9. The method of claim 8 , wherein said isolation structure comprises silicon dioxide and said liner layer comprises silicon nitride.

10. The method of claim 8 , further comprising forming a spacer adjacent said sacrificial gate structure, wherein said portion of said liner layer disposed beneath said merged region protects said isolation structure from an etchant used to remove said sacrificial gate insulation layer.