Porogens, porogenated precursors and methods for using the same to provide porous organosilica glass films with low dielectric constants
View Patent ↗A porous organosilica glass (OSG) film consists of a single phase of a material represented by the formula Si v O w C x H y F z , where v+w+x+y+z=100%, 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 %, wherein the film has pores and a dielectric constant less than 2.6. The film is provided by a chemical vapor deposition method in which a preliminary film is deposited from organosilane and/or organosiloxane precursors and pore-forming agents (porogens), which can be independent of, or bonded to, the precursors. The porogens are subsequently removed to provide the porous film. Compositions, such as kits, for forming the films include porogens and precursors. Porogenated precursors are also useful for providing the film.
1. A chemical vapor deposition method for producing a porous organosilica glass film, said method comprising:
providing a substrate within a chamber;
introducing into the chamber gaseous reagents comprising:
at least one silicon containing precursor having the formula R 1 n (OR 2 ) p (O(O)CR 4 ) 3−n−p Si—R 7 —SiR 3 m (O(O)CR 5 ) q (OR 6 ) 3−m−q where R 1 and R 3 are independently H or C 1 to C 4 linear or branched, saturated, singly or multiply unsaturated, cyclic, partially or fully fluorinated hydrocarbon; R 2 , R 6 and R 7 are independently C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, R 4 and R 5 are independently H, C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, n is 0 to 3, m is 0 to 3, q is 0 to 3 and p is 0 to 3, provided that n+m≧1, n+p≦3, and m+q≦3 and optionally diethoxymethylsilane; and
at least one porogen selected from the group consisting of:
(i) at least one bicyclic hydrocarbon having a bicyclic structure and the formula C n H 2n−2 , where n is 4 to 14, a number of carbons in the bicyclic structure is from 4 to 12, and the at least one bicyclic hydrocarbon optionally contains a plurality of simple or branched hydrocarbons substituted onto the bicyclic structure; and
(ii) at least one multiply unsaturated bicyclic hydrocarbon having a bicyclic structure and the formula C n H 2n−(2+2x) , where x is a number of unsaturated sites, n is 4 to 14, a number of carbons in the bicyclic structure is from 4 to 12, and the at least one multiply unsaturated bicyclic hydrocarbon optionally contains a plurality of simple or branched hydrocarbons substituents substituted onto the bicyclic structure, and contains endocyclic unsaturation or unsaturation on one of the hydrocarbon substituents;
applying energy to the gaseous reagents in the chamber to induce reaction of the gaseous reagents to deposit a preliminary film on the substrate, wherein the preliminary film contains the porogen; and
removing from the preliminary film substantially all of the porogen to provide the porous film with pores and a dielectric constant less than 2.6.
2. The method of claim 1 , wherein the silicon-containing precursor further comprises diethoxymethylsilane.
3. The method of claim 1 , where in the at least one silicon containing precursor having the formula R 1 n (OR 2 ) p (O(O)CR 4 ) 3−n−p Si—R 7 —SiR 3 m (O(O)CR 5 ) q (OR 6 ) 3−m−q comprises bis(trimethoxysilyl)methane.
4. The method of claim 1 wherein the at least one porogen is selected from the group consisting of: norbornadiene, norbornene, norbornane, decalin, and naphthalene.
5. The method of claim 1 , wherein the dielectric constant is less than 1.9.
6. The method of claim 1 , wherein most of the hydrogen in the porous film is bonded to carbon.
7. The method of claim 1 , wherein the porous film has a density less than 1.5 g/ml.
8. The method of claim 1 , wherein the pores have an equivalent spherical diameter less than or equal to 5 nm.
9. The method of claim 1 , wherein a Fourier transform infrared (FTIR) spectrum of the porous film is substantially identical to a reference FTIR of a reference film prepared by a process substantially identical to the method except for a lack of any porogen.
10. The method of claim 9 , wherein the porous film has a dielectric constant at least 0.3 less than a reference dielectric constant of the reference film.
11. The method of claim 9 , wherein the porous film has a density at least 10% less than a reference density of the reference film.
12. The method of claim 1 , wherein the porous film has an average weight loss of less than 1.0 wt %/hr isothermal at 425° C. under N 2 .
13. The method of claim 1 , wherein the porous film has an average weight loss of less than 1.0 wt %/hr isothermal at 425° C. under air.
14. The method of claim 1 , further comprising treating the preliminary film with at least one post-treating agent selected from the group consisting of thermal energy, plasma energy, photon energy, electron energy, microwave energy and chemicals, wherein the at least one post-treating agent removes from the preliminary film substantially all of the porogen to provide the porous organosilica glass film with pores and a dielectric constant less than 2.6.
15. The method of claim 14 , wherein the at least one post-treating agent improves a property of the resulting porous organosilica glass film before, during and/or after removing substantially all of the porogen from the preliminary film.
16. The method of claim 15 , wherein an additional post-treating agent improves a property of the resulting porous organosilica glass film before, during and/or after the at least one post-treating agent removes substantially all of the porogen from the preliminary film.
17. The method of claim 14 , wherein the at least one post-treating agent is electron energy provided by an electron beam.
18. The method of claim 14 , wherein the at least one post-treating agent is photon energy.
19. The method of claim 14 , wherein the at least one post-treating agent is thermal energy.
20. The method of claim 14 , wherein the at least one post-treating agent is a supercritical fluid.