Process integration techniques using a carbon layer to form self-aligned structures

• US 10,600,687 B2
• Filed: 04/19/2017
• Issued: 03/24/2020
• Est. Priority Date: 04/19/2017
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Mosden, Aelan, Kumar, Kaushik
• Primary Examiner(s): Wilczewski, Mary A
• Application Number:
  US15/491,786
• Publication Number:
  US 20180308753A1
• Time in Patent Office: 1,070 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 self-aligned structures 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 recessed carbon layer portions in the self-aligned structure region, wherein a height of each recessed carbon layer portion is lower than a height of the self-aligned contact regions;

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

removing the patterned structures;

forming the self-aligned structures by replacing each patterned structure with a conductor to provide a self-aligned contact in the self-aligned contact region;

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

removing at least some of the cap layer and the recessed carbon layer portions not protected by the blocking mask;

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

removing the cap layer and the recessed carbon layer portions from the self-aligned structure region.

2. The method of claim 1, further comprising removing the recessed carbon layer portions 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 recessed carbon layer portions from regions outside of the self-aligned structure region.

3. 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.

4. The method of claim 2, further comprising after removing the recessed carbon layer portions 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.

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 4, wherein, in providing the dielectric layer in regions not protected by the blocking mask prior the removing the blocking mask step:

the dielectric layer is provided to surround portions of the blocking mask.

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

9. The method of claim 1, wherein prior to providing the blocking mask, at least a portion of the cap layer is within the self-aligned structure region.

10. The method of claim 9, wherein the filling at least a portion of the self-aligned structure region with the carbon layer includes:

completely filling the self-aligned structure region with the carbon layer.

11. 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 in a portion of the self-aligned contact regions;

forming recessed carbon layer portions in the self-aligned structure region, wherein a height of each recessed carbon layer portion is lower than a height of the self-aligned contact regions;

removing the patterned structures;

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

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

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

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

removing the recessed carbon layer portions from the self-aligned contact regions.

12. The method of claim 11, 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).

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

14. The method of claim 13, wherein the recessed carbon layer portions are removed from the self-aligned contact regions by utilizing an oxygen plasma etch.

15. The method of claim 13, wherein in providing the dielectric in areas not protected by the blocking mask, the dielectric is provided to surround portions of the blocking mask.

16. The method of claim 15, further including providing a cap layer within the self-aligned contact regions and above the recessed carbon layer portions prior to providing the blocking mask, and

wherein the self-aligned contacts include a conductor within the self-aligned contact regions previously filled and covered by the carbon layer, the cap layer, and the blocking mask.

17. The method of claim 11, further comprising forming a cap layer above the recessed carbon layer portions in at least the self-aligned contact regions, and at least part of the cap layer is within the self-aligned contact regions.

18. The method of claim 17, wherein the cap layer protects the recessed carbon layer portions in at least the self-aligned contact region from at least some processing steps performed after formation of the cap layer.

19. The method of claim 17, wherein the gate liner is a silicon nitride and the cap layer is an oxide.

20. The method of claim 11, wherein the providing of the carbon layer includes:

providing the carbon layer to extend over the gate regions, and to fill and extend above the self-aligned contact regions; and

wherein the method further includes forming a cap layer on the recessed carbon layer portions after forming the recessed carbon layer portions, with at least part of the cap layer within the self-aligned contact regions, and

wherein the blocking mask is provided above the cap layer.