Porous low E (<2.0) thin films by transport co-polymerization
Methods and products of Transport co-polymerization (“TCP”) that are useful for preparations of low Dielectric Constant (“ε”) thin films are disclosed. Transport co-polymerization (“TCP”) of reactive intermediates that are generated from a first precursor with a general structural formula (Z) m —Ar—(CX′X″Y) n (VI) with a second reactive intermediate that is generated from a cage compound (e.g. Fullerenes, Methylsilsesquioxane, Hydrosilsesquioxane, and Adamantanyl) or a cyclic-compounds (e.g. Cyclo-Siloxanes and 2,2-Paracyclophanes) results in co-polymer films that are useful for making porous low ε (≦2.0) thin films. The porous thin films of this invention consist of nano-pores with uniform pore distribution thus retain high rigidity thus are suitable for manufacturing of future ICs using copper as conductor. Preparation methods and stabilization processes for low k co-polymers that consist of sp 2 C—Z and HC-sp 3 C α —X bonds are also revealed. A preparation method is achieved by controlling the substrate temperature and feed rate of the major precursors. One stabilization process includes a post annealing of as-deposited co-polymer films under the presence of hydrogen under high temperatures. The reductive annealing of these films is conducted at temperatures from −20° C. to −50° C. to +20° C. to +50° C. of their Reversible Crystal Transformation (“CRT”) temperatures, then quenching the resulting films to −20° C. to −50° C. below their “CRT” temperatures. The reductive annealing is conducted before the as-deposited film was removed from a deposition system and still under the vacuum. “Re-stabilization” processes of co-polymer surfaces that are exposed to reactive plasma etching are also disclosed; thus, further coating by barrier metal, cap layer or etch-stop layer can be safely applied.
1. A co-polymer dielectric thin film prepared on a substrate by transport co-polymerization (“TCP”) of a first reactive intermediate with a second reactive intermediate, wherein the first reactive intermediate is formed from a first co-precursor, and wherein the second reactive intermediate is formed from a second co-precursor, the co-polymer dielectric thin film comprising:
a co-Poly(Para-Xylylene) (“Co-PPX”) having repeating-units selected from the group consisting of ((—CH 2 —C 6 H 4 —H 2 C—) a (—CF 2 —C 6 H 4 —F 2 C—) b ) n oo , ((—CF 2 —C 6 F 4 —F 2 C—) a (—CH 2 C 6 F 4 —H 2 C—) b ) n oo , and ((—CF 2 —C 6 H 2 F 2 F 2 —C—) a (—CF 2 —C 6 F 4 —H 2 C—) b ) n oo , wherein, “a” is an integer that ranges from 3 to 10; “b” is an integer that ranges from 20 to 100; and n oo is an integer of at least 10;
wherein the TCP is performed under a vacuum with a low system-leakage-rate, an inert atmosphere, or both; and
wherein the film is at least semicrystalline.
2. The co-polymer dielectric thin film of claim 1 , wherein a major composition of the co-PPX is a PPX-F, having a major repeating unit comprising (—CF 2 —C 6 H 4 —F 2 C—).
3. The co-polymer dielectric thin film of claim 2 , wherein the PPX-F content is within the range of 65 to 95 molar %.
4. The co-polymer dielectric thin film of claim 2 , wherein the PPX-F content is within the range of 75 to 90 molar %.
5. The co-polymer dielectric thin film of claim 1 , wherein a minor composition of the co-PPX is a PPX-N and its derivatives, having a minor repeating unit comprising (—CH 2 —C 6 H 4 —H 2 C—).
6. The co-polymer dielectric thin film of claim 1 , wherein the film is transparent.
7. A dielectric film prepared on a substrate by transport polymerization of at least two reactive intermediates, wherein the dielectric film comprises a copolymer having at least two repeating units, wherein a first repeating unit is a partially-fluorinated poly(paraxylylene), and wherein a second repeating unit has a general formula of {Z′} m —Ar—(CX′X″} n ,
wherein n is an integer equal to or greater than 2, and wherein in m+n is no greater than a number of sp 2 substitution sites on Ar,
wherein each of X′ and X″ is a hydrogen, a fluorine, an alkyl group, a fluorinated alkyl group, a phenyl group, or a fluorinated phenyl group,
wherein each Z′ is a hydrogen or a fluorine,
wherein Ar is an aromatic moiety; and
wherein the film is porous.
8. The dielectric film of claim film of claim 7 , wherein the second repeating unit is an unfluorinated, partially fluorinated, or fully fluorinated paraxylylene moiety.
9. The dielectric film of claim 7 , wherein the film is a copolymer of —CF 2 C 6 H 4 CF 2 — and —CH 2 C 6 H 4 CH 2 —monomers.
10. The dielectric film of claim 9 , wherein a molar percentage of PPX-F in the copolymer is equal to or greater than 50%.
11. A dielectric film prepared on a substrate by transport polymerization of at least two reactive intermediates, wherein the dielectric film comprises a copolymer having at least two repeating units, wherein a first repeating unit is a partially-fluorinated poly(paraxylylene), and wherein a second repeating unit has a general formula of Ar—(CX′X″} n ,
wherein n is equal to or greater than 2,
wherein each of X′ and X″ is a hydrogen, a fluorine, an alkyl group, a fluorinated alkyl group, a phenyl group, or a fluorinated phenyl group,
wherein Ar is an aromatic moiety or a fluorine-substituted aromatic moiety, and
wherein the dielectric film is porous.