Method for removing a pore-generating material from an uncured low-k dielectric film

• US 7,977,256 B2
• Filed: 03/06/2008
• Issued: 07/12/2011
• Est. Priority Date: 03/06/2008
• Status: Expired due to Fees

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Liu, Junjun, Toma, Dorel I., Lee, Eric M.
• Primary Examiner(s): Nguyen; Khiem D
• Application Number:
  US12/043,814
• Publication Number:
  US 20090227118A1
• Time in Patent Office: 1,223 Days
• Field of Search: 438/308, 438/378, 438/502, 438/795, 438/778, 257/E21.211, 257/E21.324, 257/E21.328, 257/E21.471, 257/E21.476, 257/E21.347, 257/E21.475
• US Class Current: 438/778
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02203 the layer being porous
• CPC Class Codes: H01L 21/02216 the compound being a molecule comprising at least one silicon-oxygen bond and the compound having hydrogen or an organic group attached to the silicon or oxygen, e.g. a siloxane
• CPC Class Codes: H01L 21/02271 deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition H01L21/02266 takes precedence
• CPC Class Codes: H01L 21/02345 treatment by exposure to radiation, e.g. visible light
• CPC Class Codes: H01L 21/02348 treatment by exposure to UV light
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/31695 Deposition of porous oxides or porous glassy oxides or oxide based porous glass

Abstract

A method of forming a porous low dielectric constant (low-k) dielectric film on a substrate is described, wherein the dielectric constant of the low-k dielectric film is less than a value of approximately 4. The method comprises exposing the low-k dielectric film to infrared (IR) radiation and adjusting a residual amount of cross-linking inhibitor, such as pore-generating material, within the low-k dielectric film.

Claims

1. A method of preparing a porous low dielectric constant (low-k) film on a substrate, comprising:

forming a low-k dielectric film on a substrate, wherein said low-k dielectric film as-formed on said substrate comprises a structure-forming material and a cross-linking inhibitor;

exposing said low-k dielectric film to infrared (IR) radiation to remove at least part of said cross-linking inhibitor, wherein said exposing to said IR radiation occurs prior to any exposure of said low-k dielectric film to ultraviolet (UV) radiation, and said IR radiation contains substantially monochromatic electromagnetic (EM) radiation having a narrow band of wavelengths;

selecting one or more IR properties of said exposing said low-k dielectric film to infrared (IR) radiation to adjust a residual amount of said cross-linking inhibitor remaining in said low-k dielectric film in order to tune a mechanical property of said low-k dielectric film, an electrical property of said low-k dielectric film, an optical property of said low-k dielectric film, a pore size of said low-k dielectric film, or a porosity of said low-k dielectric film, or a combination of two or more thereof;

exposing said low-k dielectric film to ultraviolet (UV) radiation following said exposing said low-k dielectric film to infrared (IR) radiation; and

exposing said low-k dielectric film to second IR radiation during said exposing said low-k dielectric film to ultraviolet (UV) radiation.

2. The method of claim 1, wherein said cross-linking inhibitor comprises moisture, water, solvent, contaminants, pore-generating material, residual pore-generating material, a weakly bonded side group to the structure-forming material, pore-generating molecules, or fragments of pore-generating molecules, or any combination of two or more thereof.

3. The method of claim 1, wherein said cross-linking inhibitor comprises a pore-generating material, and wherein said forming said low-k dielectric film having said structure-forming material and said cross-linking inhibitor comprises co-polymerizing a structure-forming molecule and a pore-generating molecule on a surface of said substrate.

4. The method of claim 1, wherein said cross-linking inhibitor comprises a pore-generating material, and wherein said forming said low-k dielectric film having said structure-forming material and said cross-linking inhibitor comprises depositing a structure-forming molecule having a pore-generating molecular side group weakly bonded to said structure-forming molecule on a surface of said substrate.

5. The method of claim 1, wherein said adjusting said residual amount of said cross-linking inhibitor comprises substantially removing said cross-linking inhibitor from said low-k dielectric film during said exposing said low-k dielectric film to infrared (IR) radiation.

6. The method of claim 1, wherein said one or more IR properties comprises a time duration for said exposing said low-k dielectric film to infrared (IR) radiation, an IR intensity for said exposing said low-k dielectric film to infrared (IR) radiation, or an IR dose for said exposing said low-k dielectric film to infrared (IR) radiation, or a combination of two or more thereof.

7. The method of claim 1, wherein said mechanical property comprises an elastic modulus (E), or a hardness (H), or both.

8. The method of claim 1, wherein said electrical property comprises a dielectric constant (k).

9. The method of claim 1, wherein said optical property comprises a refractive index (n).

10. The method of claim 1, further comprising:

exposing said low-k dielectric film to additional IR radiation, wherein said additional IR radiation comprises polychromatic IR radiation, monochromatic IR radiation, pulsed IR radiation, or continuous wave IR radiation, or a combination of two or more thereof.

11. The method of claim 1, wherein said narrow band of wavelengths is within the range extending from approximately 8 microns to approximately 12 microns.

12. The method of claim 1, further comprising:

exposing said low-k dielectric film to ultraviolet (UV) radiation to cause bond dissociation and generation of cross-link initiators, and to cause partial cross-linking within said low-k dielectric film.

13. The method of claim 12, wherein said exposing said low-k dielectric film to UV radiation comprises exposing said low-k dielectric film to polychromatic UV radiation, monochromatic UV radiation, pulsed UV radiation, or continuous wave UV radiation, or a combination of two or more thereof.

14. The method of claim 12, wherein said exposing said low-k dielectric film to UV radiation comprises exposing said low-k dielectric film to UV radiation with a wavelength ranging from approximately 200 nanometers to approximately 400 nanometers.

15. The method of claim 12, wherein said exposing said low-k dielectric film to UV radiation comprises exposing said low-k dielectric film to UV radiation with a wavelength ranging from approximately 300 nanometers to approximately 450 nanometers.

16. The method of claim 15, wherein said exposing said low-k dielectric film to UV radiation comprises adjusting a time duration for said exposing said low-k dielectric film to ultraviolet (UV) radiation during said exposing said low-k dielectric film to second IR radiation, a UV intensity for said exposing said low-k dielectric film to ultraviolet (UV) radiation, or a UV dose for said exposing said low-k dielectric film to ultraviolet (UV) radiation, or a combination of two or more thereof.

17. The method of claim 1, further comprising:

exposing said low-k dielectric film to third IR radiation following said exposing said low-k dielectric film to ultraviolet (UV) radiation.

18. The method of claim 1, further comprising:

exposing said low-k dielectric film to first ultraviolet (UV) radiation following said exposing said low-k dielectric film to infrared (IR) radiation; and

exposing said low-k dielectric film to second UV radiation during said exposing said low-k dielectric film to second infrared (IR) radiation, wherein said second UV radiation is different than said first UV radiation.

19. The method of claim 18, wherein said adjusting said residual amount of said cross-linking inhibitor comprises adjusting a time duration for said second UV radiation during said exposing said low-k dielectric film to second infrared (IR) radiation, a UV intensity for said second UV radiation, or a UV dose for said second UV radiation, or a combination of two or more thereof.

20. The method of claim 18, wherein said second UV radiation comprises exposing said low-k dielectric film to UV radiation with a wavelength ranging from approximately 300 nanometers to approximately 450 nanometers.

21. The method of claim 1, further comprising:

heating said substrate by elevating the temperature of a substrate holder in contact with said substrate before said exposing said low-k dielectric film to infrared (IR) radiation, during said exposing said low-k dielectric film to infrared (IR) radiation, or after said exposing said low-k dielectric film to infrared (IR) radiation, or any combination of two or more thereof.

22. The method of claim 1, wherein said structure-forming material comprises diethoxymethylsilane (DEMS).

23. A method of preparing a porous low dielectric constant (low-k) film on a substrate, comprising:

forming a low-k dielectric film on a substrate, wherein said low-k dielectric film comprises a structure-forming material and a cross-linking inhibitor;

exposing said low-k dielectric film to infrared (IR) radiation;

substantially removing all of said cross-linking inhibitor from said low-k dielectric film during said exposing said low-k dielectric film to infrared (IR) radiation prior to any exposure of said low-k dielectric film to ultraviolet (UV) radiation;

exposing said low-k dielectric film to ultraviolet (UV) radiation following said exposing said low-k dielectric film to infrared (IR) radiation; and

exposing said low-k dielectric film to second IR radiation during said UV exposure.

24. A method of preparing a porous low dielectric constant (low-k) film on a substrate, comprising:

forming a low-k dielectric film on a substrate, wherein said low-k dielectric film as-formed on said substrate comprises a structure-forming material and a pore-generating material;

exposing said low-k dielectric film to infrared (IR) radiation to remove at least part of said pore-generating material and form a porous low-k dielectric film, wherein said exposing to said IR radiation occurs prior to any exposure of said low-k dielectric film to ultraviolet (UV) radiation, and said IR radiation contains substantially monochromatic electromagnetic (EM) radiation having a narrow band of wavelengths;

selecting one or more IR properties of said exposing said low-k dielectric film to said infrared (IR) radiation to adjust a residual amount of said pore-generating material remaining in said porous low-k dielectric film in order to tune a mechanical property of said porous low-k dielectric film, an electrical property of said porous low-k dielectric film, an optical property of said porous low-k dielectric film, a pore size of said porous low-k dielectric film, or a porosity of said porous low-k dielectric film, or a combination of two or more thereof;

exposing said low-k dielectric film to ultraviolet (UV) radiation following said exposing said low-k dielectric film to infrared (IR) radiation; and

exposing said low-k dielectric film to second IR radiation during said exposing said low-k dielectric film to ultraviolet (UV) radiation.