Sacrificial fin for contact self-alignment

Patent metadata

Field	Value
Publication number	US-11646358-B2
Application number	US-202217728437-A
Country	US
Kind code	B2
Filing date	Apr 25, 2022
Priority date	Apr 15, 2020
Publication date	May 9, 2023
Grant date	May 9, 2023

Abstract

A method is presented for forming a self-aligned middle-of-the-line (MOL) contact. The method includes forming a fin structure over a substrate, depositing and etching a first set of dielectric layers over the fin structure, etching the fin structure to form a sacrificial fin and a plurality of active fins, depositing a work function metal layer over the plurality of active fins, depositing an inter-layer dielectric (ILD) and a second set of dielectric layers. The method further includes etching the second set of dielectric layers and the ILD to form a first, via portion and to expose a top surface of the sacrificial fin, removing the sacrificial fin to form a second via portion, and filling the first and second via portions with a conductive material to form the MOL contact in the first via portion and a contact landing in the second via portion.

First claim

The invention claimed is:

1. A method for forming a self-aligned middle-of-the-line (MOL) contact in MOL processing, the method comprising:
etching a fin structure to form a sacrificial fin and a plurality of active fins;
depositing a work function metal (WFM) layer over the plurality of active fins;
forming a first via portion to expose a top surface of the sacrificial fin;
removing the sacrificial fin to form a second via portion; and
filling the first and second via portions with a conductive material to form a self-aligned MOL contact in the first via portion and a contact landing in the second via portion replacing the sacrificial fin such that a top surface of the contact landing directly contacts a bottom surface of the MOL contact to enable self-alignment and maintain a limited critical dimension (CD) defined by a width of the sacrificial fin.

2. The method of claim 1 , wherein a bottom spacer is deposited after deposition of the WFM layer.

3. The method of claim 1 , wherein a bottom epi layer is formed under the sacrificial fin and the plurality of active fins.

4. The method of claim 3 , wherein a top epi layer is formed over the plurality of active fins before depositing a set of dielectric layers.

5. The method of claim 1 , wherein a width of the sacrificial fin is less than a width of each of the plurality of active fins.

6. The method of claim 1 , wherein a critical dimension of the self-aligned MOL contact is defined by a width of the sacrificial fin.

7. The method of claim 1 , wherein the WFM layer directly contacts sidewalls of the plurality of active fins.

8. The method of claim 1 , wherein a bottom epi layer is disposed under and in direct contact with the contact landing.

9. The method of claim 8 , wherein an entirety of a bottom surface of the contact landing engages a top surface of the bottom epi layer.

10. The method of claim 9 , wherein the bottom epi layer extends under the self-aligned MOL contact and under the active fin.

11. A method for forming a self-aligned middle-of-the-line (MOL) contact in MOL processing, the method comprising:
forming a sacrificial fin and a plurality of active fins over a substrate by employing a U-shaped mandrel;
forming a first via portion extending to a top surface of the sacrificial fin;
removing the sacrificial fin to form a second via portion; and
filling the first and second via portions with a conductive material to form the self aligned MOL contact in the first via portion and a contact landing in the second via portion replacing the sacrificial fin such that a top surface of the contact landing directly contacts a bottom surface of the MOL contact to enable self-alignmentand maintain a limited critical dimension (CD) defined by a width of the sacrificial fin.

12. The method of claim 11 , wherein a width of the sacrificial fin is less than a width of each of the plurality of active fins.

13. The method of claim 11 , wherein a critical dimension of the self-aligned MOL contact is defined by a width of the sacrificial fin.

14. The method of claim 11 , wherein a bottom epi layer is formed under the sacrificial fin and the plurality of active fins.

15. The method of claim 14 , wherein a top epi layer is formed over the plurality of active fins before depositing dielectric layers.

16. The method of claim 15 , wherein a WFM layer directly contacts sidewalk of the plurality of active fins.

17. The method of claim 16 , wherein a bottom spacer is deposited after deposition of the WFM layer.

18. The method of claim 11 , wherein a bottom epi layer is disposed under and in direct contact with the contact landing.

19. The method of claim 18 , wherein an entirety of a bottom surface of the contact landing engages a top surface of the bottom epi layer.

20. The method of claim 19 , wherein the bottom epi layer extends under the self-aligned MOL contact and under the active fin.

Assignees

• IBM

Inventors

• Mignot Yann
• Seshadri Indira
• Fan Su Chen
• Waskiewicz Christopher J
• Miller Eric

Classifications

• H10D64/01318

  the conductor comprising a layer of alloy material, compound material or organic material contacting the insulator, e.g. TiN (comprising a layer of alloys of Si, Ge or C H10D64/01314) · CPC title

• H10D64/667

  the conductor comprising a layer of alloy material, compound material or organic material contacting the insulator, e.g. TiN workfunction layers (having lateral variation H10D64/671) · CPC title

• H10D30/6219

  characterised by the source or drain electrodes · CPC title

• H10D30/6211

  having fin-shaped semiconductor bodies integral with the bulk semiconductor substrates · CPC title

• H10D30/0243

  using dummy structures having essentially the same shapes as the semiconductor bodies, e.g. to provide stability · CPC title