Method to improve mechanical strength of low-K dielectric film using modulated UV exposure

• US 7,611,757 B1
• Filed: 06/28/2007
• Issued: 11/03/2009
• Est. Priority Date: 04/16/2004
• Status: Active Grant

• Current Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Original Assignee: Novellus Systems Incorporated (Lam Research Corporation)
• Inventors: Cho, Seon-Mee, Srinivasan, Easwar, Fu, Haiying, Bandyopadhyay, Ananda K., Mordo, David
• Primary Examiner(s): Cleveland; Michael
• Assistant Examiner(s): WIECZOREK, MICHAEL P
• Application Number:
  US11/824,049
• Time in Patent Office: 859 Days
• Field of Search: 427/558
• US Class Current: 427/558
• 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 21/02216 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 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/02348 treatment by exposure to UV light
• CPC Class Codes: H01L 21/3105 After-treatment
• CPC Class Codes: H01L 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC
• CPC Class Codes: H01L 21/31695 Deposition of porous oxides or porous glassy oxides or oxide based porous glass

Abstract

Methods and apparatus for improving mechanical properties of a dielectric film on a substrate are provided. In some embodiments, the dielectric film is a carbon-doped oxide (CDO). The methods involve the use of modulated ultraviolet radiation to increase the mechanical strength while limiting shrinkage and limiting any increases in the dielectric constant of the film. Methods improve film hardness, modulus and cohesive strength, which provide better integration capability and improved performance in the subsequent device fabrication procedures such as chemical mechanical polishing (CMP) and packaging.

Claims

1. A method of processing a substrate, comprising

(a) introducing a processing gas comprising an organosilicon compound into a processing chamber;

(b) reacting the processing gas to deposit a first dielectric layer, wherein the first dielectric layer comprises silicon, carbon, and dopant; and

(c) curing the first dielectric layer with modulated ultraviolet curing radiation;

wherein one or more mechanical properties of the dielectric layer is improved; and

wherein the modulated ultraviolet curing radiation modulates one or more of wavelength, substrate temperature, and spectral distribution with a period of between about 1 millisecond and 30 seconds.

2. The method of claim 1, wherein the modulated ultraviolet curing radiation further modulates duration of exposure.

3. The method of claim 1, wherein the one or more mechanical properties are hardness and modulus.

4. The method of claim 1, wherein the dielectric layer shrinks by less than 25%.

5. The method of claim 1, wherein a dielectric constant of the dielectric layer changes by less than 8%.

6. The method of claim 1, wherein the organosilicon compound is an alkylsilane, an alkoxysilane, a linear siloxane, a cyclic siloxane, a silylalkene, or a silylalkyne.

7. The method of claim 1, wherein the organosilicon compound is trimethylsilane, di-tert-butylsilane, tetramethylsilane, tetraethoxysilane (TEOS), methyltriethoxysilane (MTEOS), methyltrimethoxysilane (MTMOS), diethoxymethylsilane (DEMS), methyldimethoxysilane (MDMOS), trimethylmethoxysilane (TMMOS), dimethyldimethoxysilane (DMDMOS), octamethylcyclotetrasiloxane (OMCTS), tetramethylcyclotetrasiloxane (TMCTS)), vinyltrimethylsilane (VTMS), trimethylsilylacetylene (TMSA), or bis-trimethylsilylacetylene (BTMSA).

8. The method of claim 1, wherein the dopant is oxygen.

9. The method of claim 1, wherein the dopant is nitrogen.

10. The method of claim 1, wherein the dielectric film is incorporated in a manufactured device.

11. A method of processing a substrate, comprising

(a) introducing a processing gas comprising an organosilicon compound into a processing chamber;

(b) reacting the processing gas to deposit a first dielectric layer, wherein the first dielectric layer comprises silicon, carbon, and oxygen; and

(c) curing the first dielectric layer with modulated ultraviolet curing radiation;

wherein one or more mechanical properties of the dielectric layer is improved; and

wherein the modulated ultraviolet curing radiation comprises at least three cycles of ultraviolet curing radiation and wherein modulation characteristics vary from cycle to cycle.

12. The method of claim 11, wherein the modulation characteristics comprise intensity, wavelength, spectral distribution, and duration of exposure.

13. The method of claim 11, wherein the dielectric film is incorporated in a manufactured device.

14. The method of claim 11, wherein the dielectric layer shrinks by less than 25%, and a dielectric constant of the dielectric layer changes by less than 8%.

15. The method of claim 11, wherein the organosilicon compound is an alkylsilane, an alkoxysilane, a linear siloxane, a cyclic siloxane, a silylalkene, or a silylalkyne.

16. A method of processing a substrate, comprising

(a) introducing a processing gas comprising an organosilicon compound into a processing chamber;

(b) reacting the processing gas to deposit a first dielectric layer, wherein the first dielectric layer comprises silicon, carbon, and nitrogen; and

(c) curing the first dielectric layer with modulated ultraviolet curing radiation;

wherein one or more mechanical properties of the dielectric layer is improved; and

wherein the modulated ultraviolet curing radiation comprises at least three cycles of ultraviolet curing radiation and wherein modulation characteristics vary from cycle to cycle.

17. The method of claim 16, wherein the modulation characteristics comprise intensity, wavelength, spectral distribution, and duration of exposure.

18. The method of claim 16, wherein the dielectric film is incorporated in a manufactured device.

19. The method of claim 16, wherein the dielectric layer shrinks by less than 25%, and a dielectric constant of the dielectric layer changes by less than 8%.

20. The method of claim 16, wherein the organosilicon compound is an alkylsilane, an alkoxysilane, a linear siloxane, a cyclic siloxane, a silylalkene, or a silylalkyne.