Non-thermal process for forming porous low dielectric constant films
View Patent ↗Low dielectric materials and films comprising same have been identified for improved performance when used as interlevel dielectrics in integrated circuits as well as methods for making same. In certain embodiments of the invention, there is provided a low-temperature process to remove at least a portion of at least one pore-forming phase within a multiphasic film thereby forming a porous film. The pore-forming phase may be removed via exposure to at least one energy source, preferably an ultraviolet light source, in a non-oxidizing atmosphere.
1. A chemical vapor deposition method for producing a porous film represented by the formula Si v O w C x H y F z , where v+w+x+y+z=100 atomic %, v is from 10 to 35 atomic %, w is from 10 to 65 atomic %, x is from 5 to 30 atomic %, y is from 10 to 50 atomic %, and z is from 0 to 15 atomic %, the method comprising:
providing a substrate within a vacuum chamber;
introducing into the vacuum chamber gaseous reagents comprising at least one structure-former reagent and at least one pore-former reagent that is distinct from the at least one structure-former reagent, wherein the at least one pore-former reagent is a hydrocarbon having from 1 to 13 carbon atoms;
applying energy to the gaseous reagents in the vacuum chamber to induce reaction of the gaseous reagents to deposit a multiphasic film on the substrate, wherein the multiphasic film comprises at least one structure-forming phase and at least one pore-forming phase, and the preliminary film is deposited without added oxidants; and
exposing the multiphasic film to an ultraviolet light source within a non-oxidizing atmosphere for a time sufficient to substantially remove the at least one pore-forming phase contained therein and provide the porous film comprising a plurality of pores and a dielectric constant of 2.7 or less,
wherein the at least one structure-former reagent comprises at least one linear organosilane or organosiloxane selected from the group consisting of: diethoxymethylsilane, tetraethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, dimethylethoxysilane, methyldiethoxysilane, triethoxysilane, trimethylphenoxysilane, phenoxysilane, hexamethyldisiloxane, 1,1,2,2-tetramethyldisiloxane, and octamethyltrisiloxane.
2. The method of claim 1 , wherein the pore-former reagent is at least one member selected form the group consisting of: alphaterpinene, limonene, cyclohexane, 1,2,4-trimethylcyclohexane, 1,5-dimethyl-1,5-cyclooctadiene, camphene, adamantane, 1,3-butadiene, and decahydronaphthelene.
3. The method of claim 1 further comprising treating the porous film with a second energy source.
4. The method of claim 1 wherein the structure-former reagent comprises dimethylethoxysilane.
5. The method of claim 1 wherein the structure-former reagent comprises dimethyldiethoxysilane.
6. The method of claim 1 wherein the structure-former reagent comprises dimethyldimethoxysilane.
7. The method of claim 1 wherein the structure-former reagent comprises thiethoxysilane.
8. The method of claim 1 wherein the structure-former reagent comprises 1,1,2,2-tetramethyldisiloxane.
9. The method of claim 3 wherein the second energy source comprises photons, α-particles, β- particles, γ-rays, x-rays, electron beam, microwave, radio-frequency wavelengths, plasma, or mixtures thereof.
10. The method of claim 3 , wherein the second energy source comprises an ultraviolet light source.
11. The process of claim 10 wherein the ultraviolet light source is comprised of at least one selected from the group consisting of: dispersive, focused, continuous wave, pulsed, shuttered, or mixtures thereof.
12. The method of claim 10 wherein the ultraviolet light source has one or more wavelengths of about 340 nm or below.
13. The process of claim 10 wherein the ultraviolet light source has one or more wavelengths of about 280 nm or below.
14. The process of claim 10 wherein the ultraviolet light source has one or more wavelengths of about 200 nm or below.
15. The process of claim 10 wherein the ultraviolet light source is at least one selected from the group consisting of: an excimer laser, a barrier discharge lamp, a mercury lamp, a microwave-generated UV lamp, a picosecond or sub-picosecond laser, a frequency doubled laser in the IR or visible region, a frequency tripled laser in the IR or visible region, a two-photon absorption from a laser in the visible region, or combinations thereof.
16. The process of claim 1 wherein the exposing step is conducted using a quartz vessel, a deposition chamber, a conveyor belt process system, a hot plate, a vacuum chamber, a cluster tool, a single wafer instrument, a batch processing instrument, a rotating turnstile, or combinations thereof.
17. The process of claim 1 wherein the applying step involves one or more processes selected from the group consisting of: thermal chemical vapor deposition, plasma enhanced chemical vapor deposition, cryogenic chemical vapor deposition, chemical assisted vapor deposition, hot-filament chemical vapor deposition, or combinations thereof.
18. The process for claim 1 wherein the porous film comprises a plurality of pores having an average size of about 100 nanometers or less.
19. The process of claim 18 wherein the porous film comprises a plurality of pores having an average size of about 10 nanometers or less.
20. The process of claim 19 wherein the porous film comprises a plurality of pores having an average size of about 2 nanometers or less.
21. The process of claim 1 wherein the non-oxidizing atmosphere contains at least one gas selected from the group consisting of: nitrogen, carbon dioxide, a reducing gas selected from the group consisting of hydrogen, carbon monoxide, or mixtures thereof, an inert gas, or mixtures thereof.
22. The process of claim 1 wherein the non-oxidizing atmosphere in the exposing step comprises a vacuum.
23. The process of claim 1 wherein the dielectric constant of the porous film after the exposing step is 2.4 or less.
24. The process of claim 23 wherein the dielectric constant of the porous film after the exposing step is 2.2 or less.
25. The process of claim 1 wherein the density of the porous film is at least 25 percent less than the density of the multiphasic film.
26. The process of claim 1 wherein the density of the porous film is at least 50 percent less than the density of the multiphasic film.
27. The method of claim 1 wherein the ultraviolet light source is comprised of at least one selected form the group consisting of: dispersive, focused, continuous wave, pulsed, shuttered, or mixtures thereof.
28. The method of claim 1 wherein the ultraviolet light source has one or more wavelengths of about 340 nm or below.
29. The method of claim 1 wherein the ultraviolet light source has one or more wavelengths of about 280 nm or below.
30. The method of claim 1 wherein the ultraviolet light source has one or more wavelengths of about 200 or below.
31. The method of claim 1 wherein the ultraviolet light source is at least one selected from the group consisting of: an excimer laser, a barrier discharge lamp, a mercury lamp, a microwave-generated UV lamp, a picosecond or sub-picosecond laser, a frequency doubled laser in the IR or visible region, a frequency tripled laser in the IR or visible region, a two-photon absorption from a laser in the visible region, or combinations thereof.
32. The method of claim 1 wherein the structure-former reagent comprises diethoxymethylsilane.
33. The method of claim 32 wherein the pore-former reagent is at least one member form the group consisting of: alpha-terpinene, limonene, cyclohexane, 1,2,4-trimethylcyclohexane, 1,5-dimethyl-1,5-cyclooctadiene, camphene, adamantane, 1,3-butadiene, and decahydronaphthelene.