Methods of forming self-aligned vias and air gaps

Patent metadata

Field	Value
Publication number	US-10403542-B2
Application number	US-201816003827-A
Country	US
Kind code	B2
Filing date	Jun 8, 2018
Priority date	Jun 10, 2017
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A first metallization layer comprises a set of first conductive lines that extend along a first direction on a first dielectric layer on a substrate. Pillars are formed on recessed first dielectric layers and a second dielectric layer covers the pillars. A dual damascene etch provides a contact hole through the second dielectric layer and an etch removes the pillars to form air gaps.

First claim

What is claimed is:

1. A method to provide self-aligned air gaps, the method comprising:
recessing first conductive lines on a first dielectric layer on a substrate, the first conducting lines extending along a first direction on the first dielectric layer;
forming pillars on the recessed first conductive lines;
depositing a second dielectric layer between the pillars;
etching the second dielectric layer to form a contact hole in the second dielectric layer between adjacent pillars;
depositing a metal film in the contact hole;
removing the second dielectric layer to expose the pillars;
removing the pillars to form air gaps; and
depositing a cap layer to enclose the air gaps.

2. The method of claim 1 , further comprising selectively growing a seed layer on the recessed first conductive lines, the pillars being formed from the seed layer.

3. The method of claim 2 , wherein the pillars are formed by oxidizing the seed layer.

4. The method of claim 3 , wherein the seed layer comprises tungsten and the pillars comprise tungsten oxide.

5. The method of claim 3 , further comprising forming a conformal liner on the recessed first conductive lines and the first dielectric layer, the seed layer formed on the conformal liner.

6. The method of claim 1 , further comprising forming a hard mask layer on the second dielectric layer after depositing the metal film and before removing the second dielectric layer to expose the pillars.

7. The method of claim 1 , further comprising forming a conformal liner on the second dielectric after forming the opening in the second dielectric layer.

8. The method of claim 1 , wherein removing the pillars comprises selectively etching the pillars using a metal halide etchant.

9. The method of claim 8 , wherein the pillars comprise tungsten oxide and the metal halide etchant comprises a tungsten halide.

10. The method of claim 1 , wherein the second dielectric layer is a flowable film.

11. The method of claim 1 , wherein depositing the metal in the contact hole comprises depositing a metal overburden and removing the overburden to form a metal film that is level with a top of the second dielectric layer.

12. A method to provide self-aligned air gaps, the method comprising:
recessing first conductive lines on a first dielectric layer on a substrate, the first conducting lines extending along a first direction on the first dielectric layer;
forming a conformal liner on the first conductive lines and the first dielectric layer;
selectively depositing a metal in the recessed first conductive lines;
oxidizing the metal to form pillars on the recessed first conductive lines;
depositing a second dielectric layer between the pillars;
etching the second dielectric layer with a dual damascene etch to form a contact hole in the second dielectric layer between adjacent pillars;
forming a conformal liner in the contact hole;
depositing a metal film in the contact hole on the conformal liner;
masking and removing the second dielectric layer to expose the pillars;
masking and removing the pillars to form air gaps; and
depositing a cap layer to enclose the air gaps.

13. The method of claim 12 , further comprising selectively growing a seed layer on the recessed first conductive lines, the pillars being formed from the seed layer.

14. The method of claim 13 , wherein the pillars are formed by oxidizing the seed layer.

15. The method of claim 14 , wherein the seed layer comprises tungsten and the pillars comprise tungsten oxide.

16. The method of claim 12 , wherein removing the pillars comprises selectively etching the pillars using a metal halide etchant.

17. The method of claim 16 , wherein the pillars comprise tungsten oxide and the metal halide etchant comprises a tungsten halide.

18. The method of claim 12 , wherein the second dielectric layer is a flowable film.

19. The method of claim 12 , wherein depositing the metal in the contact hole comprises depositing a metal overburden and removing the overburden to form a metal film that is level with a top of the second dielectric layer.

Assignees

• Applied Materials Inc

Inventors

• Roy Susmit Singha
• Duan Ziqing
• Mallick Abhijit Basu
• Gopalraja Praburam

Classifications

• H10W20/0693

  by forming self-aligned vias · CPC title

• H01J37/32165

  Plural frequencies · CPC title

• H01J37/32091

  the radio frequency energy being capacitively coupled to the plasma · CPC title

• H10P50/285

  of materials not containing Si, e.g. PZT or Al2O3 · CPC title

• H10W20/425

  Barrier, adhesion or liner layers · CPC title