Process Integration Techniques Using A Carbon Layer To Form Self-Aligned Structures

• US 20180308753A1
• Filed: 04/19/2017
• Published: 10/25/2018
• Est. Priority Date: 04/19/2017
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Mosden, Aelan, Kumar, Kaushik
• Granted Patent: US 10,600,687 B2
• Time in Patent Office: Days
• CPC Class Codes: H01L 21/0337 characterised by the process involved to create the mask, e.g. lift-off masks, sidewalls, or to modify the mask, e.g. pre-treatment, post-treatment
• CPC Class Codes: H01L 21/76897 Formation of self-aligned vias or contact plugs, i.e. involving a lithographically uncritical step self-aligned silicidation on field effect transistors H01L29/665
• CPC Class Codes: H01L 29/66545 using a dummy, i.e. replacement gate in a process wherein at least a part of the final gate is self aligned to the dummy gate

Abstract

Process integration techniques are disclosed that use a carbon fill layer during formation of self-aligned structures. A carbon layer may be placed over an etch stop layer. A cap layer may be provided over the carbon layer. The carbon layer may fill a high aspect ratio structure formed on the substrate. The carbon layer may be removed from a substrate in a highly selective removal technique in a manner that does not damage underlying layers. The carbon layer may fill a self-aligned contact region that is provided for a self-aligned contact process flow. A tone inversion mask may be used to protect multiple self-aligned contact regions. With the blocking mask in place, the carbon layer may be removed from regions that are not the self-aligned contact region. After removal of the blocking mask, the carbon layer which fills the self-aligned contacts may then be removed.

Claims

1. A method to form self-aligned structures, the method comprising:

providing a substrate with patterned structures, the patterned structures including a self-aligned structure region in which a self-aligned structure will be formed;

forming an etch stop layer in the self-aligned structure region;

filling at least a portion of the self-aligned structure region with a carbon layer;

forming a cap layer over the self-aligned structure region above the carbon layer;

providing a blocking mask over the self-aligned structure region to protect at least a portion of the cap layer and the carbon layer in the self-aligned structure region from at least one processing steps performed after the blocking mask is formed;

removing the blocking mask from the self-aligned structure region;

removing the cap layer and the carbon layer from the self-aligned structure region; and

forming the self-aligned structure in the self-aligned structure region.

2. The method of claim 1, further comprising removing the carbon layer from regions outside of the self-aligned structure region, wherein the blocking mask is utilized to protect the self-aligned structure region during the processing steps which remove the carbon layer from regions outside of the self-aligned structure region.

3. The method of claim 2, further comprising after removing the carbon layer from regions outside of the self-aligned structure region, providing a dielectric layer in regions not protected by the blocking mask prior to the removing the blocking mask step.

4. The method of claim 3, wherein the self-aligned structure is a self-aligned contact.

5. The method of claim 4, wherein the etch stop layer is a gate liner.

6. The method of claim 5, wherein the carbon layer is formed via a spin on process.

7. The method of claim 2, wherein the carbon layer comprises at least one of an atomic layer deposition (ALD) carbon material, spin on carbon (SoC) material, a chemical vapor deposition carbon material, organic planarization layer (OPL) material or a spin on hard mask (SoH) carbon material.

8. The method of claim 1, wherein the carbon layer is formed via a spin on process.

9. A method of utilizing a tone inversion process step to form self-aligned contacts, the method comprising:

providing a substrate having patterned structures which provide gate regions and self-aligned contact regions in which a self-aligned contact will be formed;

forming a gate liner above at least a portion of the gate regions and the self-aligned contact regions;

providing a carbon layer above the gate liner in at least a portion of the gate regions and the self-aligned contact regions;

providing, over the self-aligned contact regions, a blocking mask above the carbon layer in the self-aligned contact regions;

removing at least some of the carbon layer in areas not protected by the blocking mask;

removing the blocking mask from above the self-aligned contact regions;

removing the carbon layer from the self-aligned contact regions; and

forming the self-aligned contacts in the self-aligned contact regions.

10. The method of claim 9, wherein the carbon layer comprises at least one of an atomic layer deposition (ALD) carbon material, spin on carbon (SoC) material, a chemical vapor deposition carbon material, organic planarization layer (OPL) material or a carbon based spin on hard mask (SoH).

11. The method of claim 9, further comprising providing a dielectric in areas not protected by the blocking mask prior to removing the blocking mask.

12. The method of claim 11, wherein the carbon layer is removed from the self-aligned contact regions by utilizing an oxygen plasma etch.

13. The method of claim 9, further comprising forming a cap layer above the carbon layer in at least the self-aligned contact regions.

14. The method of claim 13, further comprising removing a portion of the carbon layer prior to formation of the cap layer, wherein the removing of the portion of the carbon layer removes the carbon layer above the gate regions.

15. The method of claim 13, wherein the cap layer protects the carbon layer in at least the self-aligned contact region from at least some processing steps performed after formation of the cap layer.

16. The method of claim 13, wherein the gate liner is a silicon nitride and the cap layer is an oxide.

17. A method of tone inversion processing for providing self-aligned structures, the method comprising:

providing a patterned substrate comprising a plurality of gate formation structures;

performing an atomic layer deposition, chemical vapor deposition, or spin on process to add carbon material on the patterned substrate, the carbon material filling at least a portion of a self-aligned structure region, the self-aligned structure region being where the self-aligned structures will be subsequently formed;

forming a cap layer above the carbon material;

fabricating a gate conductor by removing layers or features of the gate formation structures as part of a gate conductor fabrication process, removal of the layers or features leaving at least a portion of the cap layer on the patterned substrate;

performing a removal of the cap layer; and

performing a removal of the carbon material in the self-aligned structure region.

18. The method of claim 17, wherein the plurality of gate formation structures include a gate liner layer, the method further comprising adding the carbon material on the patterned substrate above the gate liner layer.

19. The method of claim 17, the gate conductor fabricated by removing at least a portion of the gate formation structures and forming a gate conductor material in a region created by the removal of the portion of the gate formation structures.

20. The method of claim 17, further comprising, after adding the carbon material, removing a portion of the carbon material so that a top of the remaining portion of the carbon material adjacent to the plurality of gate formation structures is recessed when compared to a top of the plurality of gate formation structures.