Modifying work function of a metal film with a plasma process

Patent metadata

Field	Value
Publication number	US-10347492-B2
Application number	US-201815874132-A
Country	US
Kind code	B2
Filing date	Jan 18, 2018
Priority date	Jan 27, 2017
Publication date	Jul 9, 2019
Grant date	Jul 9, 2019

Abstract

A sequential plasma process is employed to enable the modification of the work function of a p-type metal layer in a metal gate structure. The sequential plasma process includes a plasma hydrogenation and a plasma process that includes electronegative species. The sequential plasma process is performed on a p-type metal layer in a film stack, thereby replacing suboxides and/or other non-stoichiometrically combined electronegative atoms disposed on or within layers of the film stack with stoichiometrically combined electronegative atoms, such as O atoms. As a result, the work function of the p-type metal layer can be modified without changing a thickness of the p-type metal layer.

First claim

The invention claimed is:

1. A method of forming a transistor, the method comprising:
depositing a high-k dielectric layer over a surface of a semiconductor material, wherein the surface of the semiconductor material has a first work function value;
after depositing the high-k dielectric layer, depositing a p-type metal layer over the semiconductor material and the high-k dielectric layer, wherein the p-type metal layer has an exposed surface and a second work function value, and wherein depositing the p-type metal layer comprises:
depositing a first p-type metal layer on the high-k dielectric layer; and
depositing a second p-type metal layer on the first p-type metal layer; and

exposing the exposed surface of the p-type metal layer to plasma-excited electronegative species to change the second work function value to a third work function value, wherein the third work function value is between the first work function value and the second work function value.

2. The method of claim 1 , wherein the first p-type metal layer comprises a metal capping layer that is deposited on the high-k dielectric layer.

3. The method of claim 2 , further comprising, exposing an exposed surface of the metal capping layer to plasma-excited electronegative species prior to depositing the second p-type metal layer.

4. The method of claim 3 , wherein the second p-type metal layer comprises a work function layer that is deposited on the metal capping layer.

5. The method of claim 3 , further comprising, after exposing the exposed surface of the metal capping layer to plasma-excited electronegative species and prior to depositing the second p-type metal layer on the exposed surface, exposing the exposed surface of the metal capping layer to air.

6. The method of claim 1 , wherein exposing the exposed surface of the p-type metal layer to plasma-excited electronegative species comprises stoichiometrically adding atoms from the electronegative species to the p-type metal layer.

7. The method of claim 1 , wherein the plasma-excited electronegative species include atoms having a Paulding electronegativity of at least about 2.5.

8. The method of claim 1 , wherein the plasma-excited electronegative species include at least one of an oxygen-containing species, a nitrogen-containing species, and a fluorine-containing species.

9. The method of claim 1 , wherein the p-type metal layer comprises a metal with a work function value that is equal to or greater than the first work function value.

10. The method of claim 1 , further comprising, prior to exposing the exposed surface of the p-type metal layer to plasma-excited electronegative species, exposing the exposed surface to plasma-excited hydrogen species to remove electronegative atoms from the p-type metal layer.

11. The method of claim 10 , wherein exposing the exposed surface to plasma-excited hydrogen species comprises forming vacancies in the p-type metal layer.

12. The method of claim 11 , wherein exposing the exposed surface of the p-type metal layer to plasma-excited electronegative species comprises filling the formed vacancies in the p-type metal layer with electronegative atoms.

13. The method of claim 10 , wherein the exposed surface is not exposed to air after being exposed to the plasma-excited hydrogen species and before being exposed to the plasma-excited electronegative species.

14. The method of claim 10 , wherein the exposed surface is exposed to the plasma-excited hydrogen species and to the plasma-excited electronegative species in a same processing chamber.

15. The method of claim 1 , wherein the plasma-excited electronegative species are formed by use of an inductively coupled plasma that is disposed adjacent to a surface of the exposed surface of the p-type metal layer.

16. The method of claim 1 , further comprising, prior to exposing the exposed surface of the p-type metal layer to plasma-excited electronegative species, performing a plasma-based conditioning process on a process chamber in which the exposed surface is exposed to the plasma-excited electronegative species.

17. The method of claim 16 , wherein the plasma-based conditioning process is performed on the process chamber when a semiconductor substrate on which the p-type metal layer is deposited is not disposed within the process chamber.

Assignees

• Applied Materials Inc

Inventors

• Hung Steven C H
• Swenberg Johanes S
• Liu Wei
• Graoui Houda

Classifications

• H10P72/0454

  surrounding a central transfer chamber · CPC title

• H10P72/0402

  Apparatus for fluid treatment (H10P72/0441, H10P72/0448 take precedence) · CPC title

• H10P14/418

  the conductive layers comprising transition metals · CPC title

• H10P95/00

  Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass · CPC title

• H10D64/01318 Primary

  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