Sloped finFET with methods of forming same

• US 10,312,347 B2
• Filed: 01/11/2018
• Issued: 06/04/2019
• Est. Priority Date: 02/06/2015
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Anderson, Brent A., Nowak, Edward J.
• Primary Examiner(s): Nguyen, Cuong Q
• Assistant Examiner(s): Kim, Tong-Ho
• Application Number:
  US15/868,274
• Publication Number:
  US 20180158924A1
• Time in Patent Office: 509 Days
• Field of Search: 257347, 438586
• 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
• CPC Class Codes: H01L 29/6656 using multiple spacer layers, e.g. multiple sidewall spacers
• CPC Class Codes: H01L 29/66795 with a horizontal current flow in a vertical sidewall of a semiconductor body, e.g. FinFET, MuGFET
• CPC Class Codes: H01L 29/66818 the channel being thinned after patterning, e.g. sacrificial oxidation on fin
• CPC Class Codes: H01L 29/7853 the body having a non-rectangular crossection

Abstract

Embodiments of the present disclosure provide an integrated circuit (IC) structure, which can include: a semiconductor fin; a gate dielectric positioned above a first region of the semiconductor fin; a spacer positioned above a second region of the semiconductor fin and adjacent to the gate dielectric; and a source/drain region contacting a third region of the semiconductor fin; wherein the first region of the semiconductor fin includes substantially vertical sidewalls, and the third region of the semiconductor fin includes sloped sidewalls.

Claims

1. A method of forming an integrated circuit (IC) structure, the method comprising:

forming a sacrificial gate on a semiconductor fin;

forming a first spacer on the semiconductor fin, the first spacer positioned circumferentially about the sacrificial gate;

forming a second spacer on the semiconductor fin, the second spacer positioned circumferentially about the first spacer; and

tapering an exposed portion of the semiconductor fin to form sloped sidewalls thereon, the exposed portion of the semiconductor fin positioned adjacent the sacrificial gate, the first spacer, and the second spacer.

2. The method of claim 1, further comprising forming one of a source contact and a drain contact on the sloped sidewalls of the semiconductor fin after the forming of the second spacer.

3. The method of claim 1, further comprising:

forming a dielectric layer on the sacrificial gate, the first spacer, and the second spacer; and

removing a portion of the dielectric layer to expose the sacrificial gate.

4. The method of claim 3, further comprising:

selectively removing the sacrificial gate from the semiconductor fin; and

forming a gate dielectric on an exposed first region of the semiconductor fin after the removing of the sacrificial gate.

5. The method of claim 4, further comprising reducing a width of the exposed first region of the semiconductor fin before the forming of the gate dielectric.

6. The method of claim 1, wherein the sloped sidewalls are oriented at an angle of between approximately seventy degrees and approximately eighty-seven degrees relative to an insulator layer positioned beneath the IC structure.

7. The method of claim 1, wherein the tapering of the exposed portion of the semiconductor fin occurs before the forming of the first spacer and the second spacer.

8. The method of claim 1, wherein the sacrificial gate comprises a polycrystalline silicon material.

9. The method of claim 1, wherein the semiconductor fin comprises at least one of a plurality of semiconductor fins positioned on an insulator layer.

10. A method of forming an integrated circuit (IC) structure, the method comprising:

forming a sacrificial gate on a semiconductor fin;

forming a first spacer on the semiconductor fin, the first spacer positioned circumferentially about the sacrificial gate;

forming a second spacer on the semiconductor fin, the second spacer positioned circumferentially about the first spacer;

tapering an exposed portion of the semiconductor fin to form sloped sidewalls thereon, the exposed portion of the semiconductor fin positioned adjacent the sacrificial gate, the first spacer, and the second spacer;

and

forming one of a source contact and a drain contact on the sloped sidewalls of the semiconductor fin.

11. The method of claim 10, further comprising:

forming a dielectric layer on the sacrificial gate, the first spacer, and the second spacer; and

removing a portion of the dielectric layer to expose the sacrificial gate.

12. The method of claim 11, further comprising:

selectively removing the sacrificial gate from the semiconductor fin; and

forming a gate dielectric on an exposed first region of the semiconductor fin after the removing of the sacrificial gate.

13. The method of claim 12, further comprising reducing a width of the exposed first region of the semiconductor fin before the forming of the gate dielectric.

14. The method of claim 10, wherein the sloped sidewalls are oriented at an angle of between approximately seventy degrees and approximately eighty-seven degrees relative to an insulator layer positioned beneath the IC structure.

15. The method of claim 10, wherein the tapering of the exposed portion of the semiconductor fin occurs before the forming of the first spacer and the second spacer.

16. The method of claim 10, wherein the sacrificial gate comprises a polycrystalline silicon material.

17. The method of claim 10, wherein the semiconductor fin comprises at least one of a plurality of semiconductor fins positioned on an insulator layer.

18. The method of claim 10, wherein forming the first spacer includes:

covering a portion of a region of the semiconductor fin, the region of the semiconductor fin including an initial geometry of the semiconductor fin.

19. The method of claim 18, wherein forming the second spacer includes:

covering a remaining portion of the region of the semiconductor fin.

20. The method of claim 10, wherein forming one of the source contact and the drain contact on the sloped sidewalls of the semiconductor fin further includes:

forming the source contact on the sloped sidewalls of the semiconductor fin, the source contact formed outside of the first spacer and the second spacer; and

forming the drain contact on the sloped sidewalls of the semiconductor fin, opposite the source contact, the drain contact formed outside of the first spacer and the second spacer.