Hydrogenation and nitridization processes for reducing oxygen content in a film

• US 10,236,207 B2
• Filed: 02/21/2017
• Issued: 03/19/2019
• Est. Priority Date: 06/20/2016
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Swenberg, Johanes S., Liu, Wei, Graoui, Houda, Sharma, Shashank, Muthukrishnan, Shankar, George, Rene
• Primary Examiner(s): Lee, Kyoung
• Assistant Examiner(s): Sylvia, Christina
• Application Number:
  US15/438,490
• Publication Number:
  US 20170365512A1
• Time in Patent Office: 756 Days
• CPC Class Codes: H01L 21/28518 the conductive layers comprising silicides H01L21/28537 takes precedence
• CPC Class Codes: H01L 21/28556 by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/28568 the conductive layers comprising transition metals H01L21/28518 takes precedence
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/7685 the layer covering a conductive structure H01L21/76849 takes precedence
• CPC Class Codes: H01L 21/76855 After-treatment introducing at least one additional element into the layer
• CPC Class Codes: H01L 21/76856 by treatment in plasmas or gaseous environments, e.g. nitriding a refractory metal liner
• CPC Class Codes: H01L 21/76862 Bombardment with particles, e.g. treatment in noble gas plasmas; UV irradiation
• CPC Class Codes: H01L 21/76889 by forming silicides of refractory metals

Abstract

Embodiments described herein generally relate to a sequential hydrogenation and nitridization process for reducing interfacial and bulk O atoms in a conductive structure in a semiconductor device. A hydrogenation and plasma nitridization process is performed on a metal nitride layer in a conductive structure prior to deposition of a second metal layer, thereby reducing interfacial oxygen atoms formed on a surface of the metal nitride and oxygen atoms present in the bulk metal layers of the conductive structure. As a result, adhesion of the second metal layer to the metal nitride layer is improved and the electrical resistance of the contact structure is reduced.

Claims

1. A method of forming a conductive structure, comprising:

depositing a metal nitride layer on a semiconductor substrate to form a portion of a semiconductor device, wherein the metal nitride layer has an exposed surface, and the process of depositing the metal nitride layer is performed in a first processing environment;

forming a metal silicide in the portion by performing a thermal anneal process on the metal nitride layer in a second processing environment;

exposing the metal nitride layer to plasma-excited hydrogen species in a third processing environment, wherein exposing the metal nitride layer reduces the concentration of oxygen atoms at the exposed surface of the metal nitride layer, and the third processing environment includes a lower concentration of oxygen than the first or second processing environment;

exposing the metal nitride layer to plasma-excited nitrogen species, wherein exposing the metal nitride layer increases the concentration of nitrogen atoms at the exposed surface of the metal nitride layer; and

after exposing the metal nitride layer, depositing a metal layer on the exposed surface of the metal nitride layer, wherein each of the metal nitride layer and the metal layer comprises an electrically conductive material different from one another.

2. The method of claim 1, wherein exposing the metal nitride layer to plasma-excited hydrogen species and plasma-excited nitrogen species are performed prior to forming the metal silicide.

3. The method of claim 2, further comprising, after forming the metal silicide, exposing the metal nitride layer to plasma-excited hydrogen species and plasma-excited nitrogen species a second time.

4. The method of claim 3, further comprising exposing the metal nitride layer to the plasma-excited hydrogen species prior to exposing the metal nitride layer to plasma-excited nitrogen species the second time and after forming the metal silicide.

5. The method of claim 1, wherein exposing the metal nitride layer to plasma-excited nitrogen species is performed in the third processing environment.

6. The method of claim 1, further comprising, prior to depositing the metal nitride layer, performing a surface preparation process on a surface of the semiconductor substrate.

7. The method of claim 6, wherein depositing the metal nitride layer on the semiconductor substrate comprises depositing the metal nitride layer on the surface.

8. The method of claim 1, wherein exposing the metal nitride layer to plasma-excited hydrogen species is performed in the third processing environment, and the plasma-excited hydrogen species are formed by an inductively coupled plasma.

9. The method of claim 1, wherein depositing the metal nitride layer on a semiconductor substrate is performed using an atomic layer deposition (ALD) process, and the metal nitride layer comprises titanium.

10. The method of claim 1, wherein the plasma-excited hydrogen species are formed from a process gas that comprises H₂.

11. The method of claim 10, wherein the plasma-excited hydrogen species are formed by an inductively coupled plasma that is disposed adjacent to a surface of the semiconductor substrate.

12. A method of forming a conductive structure, the method comprising:

depositing a metal nitride layer on a semiconductor substrate to form a portion of a semiconductor device, wherein the metal nitride layer has an exposed surface;

forming vacancies in the metal nitride layer by exposing oxygen atoms included within and at the exposed surface of the metal nitride layer to hydrogen atoms;

filling the vacancies in the metal nitride layer with nitrogen atoms by exposing the metal nitride layer to a nitrogen-containing plasma;

forming a metal silicide in the portion of the semiconductor device by performing a thermal anneal process on the metal nitride layer; and

after filling the vacancies in the metal nitride layer, depositing a metal layer on the exposed surface of the metal nitride layer, wherein each of the metal nitride layer and the metal layer comprises an electrically conductive material different from one another.

13. The method of claim 12, wherein forming the vacancies is performed in a same processing chamber as filling the vacancies.

14. The method of claim 12, wherein exposing the oxygen atoms to hydrogen atoms comprises forming a plasma using a process gas that has reactive species that essentially comprise H₂.

15. The method of claim 12, wherein exposing the oxygen atoms to hydrogen atoms comprises exposing the metal nitride layer to thermally disassociated hydrogen gas.

16. The method of claim 12, wherein forming the metal silicide is performed in a same processing chamber as forming the vacancies.

17. The method of claim 12, wherein forming the vacancies and filling the vacancies are both performed prior to forming the metal silicide.

18. The method of claim 12, wherein forming the vacancies and filling the vacancies are both performed after forming the metal silicide.

19. The method of claim 12, wherein filling the vacancies in the metal nitride layer with nitrogen atoms increases a concentration of nitrogen atoms at the exposed surface of the formed metal nitride layer.

20. A method of forming a conductive structure, comprising:

depositing a metal nitride layer on a semiconductor substrate to form a portion of a semiconductor device, wherein the metal nitride layer has an exposed surface;

removing oxygen atoms from the metal nitride layer to form vacancies therein by exposing oxygen atoms included within and at the exposed surface of the metal nitride layer to hydrogen atoms;

after removing the oxygen atoms, adding nitrogen atoms to fill the vacancies in the metal nitride layer by exposing the metal nitride layer to a nitrogen-containing plasma;

forming a metal silicide in the portion of the semiconductor device by performing a thermal anneal process on the metal nitride layer; and

after adding the nitrogen atoms to the metal nitride layer, depositing a metal layer on the exposed surface of the metal nitride layer, wherein each of the metal nitride layer and the metal layer comprises an electrically conductive material different from one another.