Formation of boron-doped titanium metal films with high work function

• US 10,083,836 B2
• Filed: 07/24/2015
• Issued: 09/25/2018
• Est. Priority Date: 07/24/2015
• Status: Active Grant

• Current Assignee: ASM IP Holding B.V. (ASM International NV)
• Original Assignee: ASM IP Holding B.V. (ASM International NV)
• Inventors: Milligan, Robert Brennan
• Primary Examiner(s): Ghyka, Alexander
• Application Number:
  US14/808,979
• Publication Number:
  US 20170025280A1
• Time in Patent Office: 1,159 Days
• Field of Search: None
• CPC Class Codes: H01L 21/28088 the final conductor layer next to the insulator being a composite, e.g. TiN
• CPC Class Codes: H01L 21/28562 Selective deposition
• CPC Class Codes: H01L 21/32051 Deposition of metallic or metal-silicide layers

Abstract

A method for forming a Boron doped metallic film, such as Titanium Boron Nitride, is disclosed. The method allows for creation of the metallic film with a high work function and low resistivity, while limiting the increase in effective oxide thickness. The method comprises a thin metallic layer deposition step as well as a Boron-based gas pulse step. The Boron-based gas pulse deposits Boron and allows for the removal of excess halogens within the metallic film. The steps may be repeated in order to achieve a desired thickness of the metallic film.

Claims

1. A method for forming a Boron-doped metallic film comprising:

depositing a thin metallic layer onto a semiconductor device in a chamber, the depositing step consisting of;

pulsing a metal halogen gas onto the semiconductor device;

purging the semiconductor device and the chamber with an inert gas;

pulsing a nitridizing gas onto the semiconductor device;

purging the semiconductor device and the chamber with the inert gas;

repeating the step of depositing and then;

doping the thin metallic layer with Boron by pulsing a Boron-based gas onto the thin metallic layer to provide Boron in the thin metallic layer to form the Boron-doped metallic film; and

purging the semiconductor device and the chamber with an inert gas;

wherein an electronic work function is modulated by a number of times the depositing step is repeated.

2. The method of claim 1, wherein the depositing step and the pulsing step are repeated until a desired thickness of the Boron-doped metallic film is achieved.

3. The method of claim 2, wherein the desired thickness of the Boron-doped metallic film ranges between 20 and 100 Angstroms.

4. The method of claim 1, wherein the desired thickness of the thin metallic layer is less than or equal to 10 Angstroms.

5. The method of claim 1, wherein the thin metallic layer comprises Titanium Nitride.

6. The method of claim 1, wherein doping the thin metallic layer with Boron further comprises:

pulsing a metal halogen gas onto the thin metallic layer prior to and followed by pulsing the Boron-based gas onto the thin metallic layer.

7. The method of claim 1, wherein the Boron-doped metallic film formed exhibits an electronic work function ranging between 4.95 and 5.10 eV.

8. The method of claim 1, further comprising:

depositing a thin underlayer of undoped Titanium Nitride prior to the depositing step.

9. The method of claim 1, further comprising:

depositing a thin overlayer of undoped Titanium Nitride after the doping the thin metallic layer with Boron.

10. The method of claim 1, wherein the chamber is a single chamber in-situ.

11. The method of claim 1, wherein the steps of purging with an inert gas comprises purging with Argon gas for a duration exceeding 1000 milliseconds.

12. The method of claim 1, wherein the step of pulsing with the metal halogen gas has a duration ranging between 100 and 2000 milliseconds.

13. The method of claim 1, wherein the step of pulsing with the Nitrogen-based gas has a duration ranging between 300 and 5000 milliseconds.

14. The method of claim 1, wherein the step of pulsing with the Boron-based gas has a duration ranging between 100 and 2000 milliseconds.

15. The method of claim 1, wherein the metal halogen gas comprises at least one of:

Titanium Chloride, Zirconium Chloride, Hafnium Chloride, Vanadium Chloride, Niobium Chloride, Tantalum Chloride, Molybdenum Fluoride, or Tungsten Fluoride.

16. The method of claim 1, wherein the Boron-based gas comprises Diborane.

17. The method of claim 1, wherein the nitridizing gas comprises at least one of:

Ammonia, Hydrazine, Methyl Hydrazine, or Dimethyl Hydrazine.

18. The method of claim 1, wherein the inert gas comprises at least one of:

Argon or diatomic Nitrogen.

19. The method of claim 1, wherein the depositing step consists of the steps of pulsing a metal halogen gas, purging the semiconductor device and the chamber with an inert gas, pulsing a nitridizing gas, and purging the semiconductor device and the chamber with the inert gas.

20. The method of claim 1, wherein the metal halogen gas is selected from one or more of the group consisting of Titanium Chloride, Zirconium Chloride, Hafnium Chloride, Vanadium Chloride, Niobium Chloride, Tantalum Chloride, Molybdenum Fluoride, or Tungsten Fluoride and wherein the nitridizing gas is selected from the group consisting of one or more of:

Ammonia, Hydrazine, Methyl Hydrazine, or Dimethyl Hydrazine.