Porogens, Porogenated Precursors and Methods for Using the Same to Provide Porous Organosilica Glass Films with Low Dielectric Constants
A chemical vapor deposition method for producing a porous organosilica glass film comprising: introducing into a vacuum chamber gaseous reagents including at least one precursor selected from the group consisting of an organosilane and an organosiloxane, and a porogen that is distinct from the precursor, wherein the porogen is a C 4 to C 14 cyclic hydrocarbon compound having a non-branching structure and a degree of unsaturation equal to or less than 2; applying energy to the gaseous reagents in the vacuum 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 labile organic material to provide the porous film with pores and a dielectric constant less than 2.6.
1 . A chemical vapor deposition method for producing a porous organosilica glass film 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 %, said method comprising:
providing a substrate within a vacuum chamber;
introducing into the vacuum chamber gaseous reagents including at least one precursor selected from the group consisting of an organosilane and an organosiloxane, and a porogen that is distinct from the precursor, wherein the porogen is a C 4 to C 14 cyclic hydrocarbon compound having a non-branching structure and a degree of unsaturation equal to or less than 2;
applying energy to the gaseous reagents in the vacuum 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 labile organic material to provide the porous film with pores and a dielectric constant less than 2.6.
2 . The method of claim 1 wherein the dielectric constant is less than 2.2.
3 . The method of claim 1 wherein v is from 20 to 30 atomic %, w is from 20 to 45 atomic %, x is from 5 to 20 atomic %, y is from 15 to 40 atomic % and z is 0.
4 . The method of claim 1 wherein the energy is plasma energy and the porogen is removed by exposure to ultraviolet radiation.
5 . The method of claim 1 wherein most of the hydrogen in the porous film is bonded to carbon.
6 . The method of claim 1 wherein the porous film has a density less than 1.5 g/ml.
7 . The method of claim 1 wherein the pores have an equivalent spherical diameter less than or equal to 5 nm.
8 . 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 porogen precursor.
9 . 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 .
10 . 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.
11 . The method of claim 1 wherein the porogen is a C 7 to C 10 cyclic hydrocarbon compound.
12 . The method of claim 11 wherein the porogen is selected from the group consisting of: cyclooctane, cycloheptane, cyclooctene, cyclooctadiene, cycloheptene, and mixtures thereof.
13 . The method of claim 11 wherein the porogen is a C 8 cyclic hydrocarbon compound.
14 . The method of claim 13 wherein the porogen is selected from the group consisting of: cyclooctane, cyclooctene, and mixtures thereof.
15 . The method of claim 14 wherein the porogen is cyclooctane.
16 . The method of claim 1 , wherein the organosiloxane is diethoxymethylsilane (DEMS).
17 . The method of claim 13 , wherein the at least one precursor is represented by:
(a) the formula R 1 n (OR 2 ) p (O(O)CR 3 ) 4−(n+p) Si where R 1 is independently H or C 1 to C 4 linear or branched, saturated, singly or multiply unsaturated, cyclic, partially or fully fluorinated hydrocarbon; R 2 is independently C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, R 3 is independently H, C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, n is 1 to 3 and p is 0 to 3;
(b) the formula R 1 n (OR 2 ) p (O(O)CR 4 ) 3−n−p Si—O—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 and R 6 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;
(c) the formula R 1 n (OR 2 ) p (O(O)CR 4 ) 3−n−p Si—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 and R 6 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;
(d) 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;
(e) the formula (R 1 n (OR 2 ) p (O(O)CR 3 ) 4−(n+p) Si) t CH 4−t where R 1 is independently H or C 1 to C 4 linear or branched, saturated, singly or multiply unsaturated, cyclic, partially or fully fluorinated hydrocarbon; R 2 is independently C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, R 3 is independently H, C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, n is 1 to 3, p is 0 to 3, and t is 2 to 4, provided that n+p≦4;
(f) the formula (R 1 n (OR 2 ) p (O(O)CR 3 ) 4−(n+p) Si) t NH 3−t where R 1 is independently H or C 1 to C 4 linear or branched, saturated, singly or multiply unsaturated, cyclic, partially or fully fluorinated hydrocarbon; R 2 is independently C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, R 3 is independently H, C 1 to C 6 linear or branched, saturated, singly or multiply unsaturated, cyclic, aromatic, partially or fully fluorinated hydrocarbon, n is 1 to 3, p is 0 to 3 and t is 1 to 3, provided that n+p≦4; or
(g) cyclic carbosilanes of the formula (CR 1 R 3 SiR 1 R 3 ) x , where R 1 and R 3 are independently H, C 1 to C 4 , linear or branched, saturated, singly or multiply unsaturated, cyclic, partially or fully fluorinated, and x is an integer from 2 to 8.
18 . The method of claim 14 , wherein the at least one precursor is a member selected from the group consisting of diethoxymethylsilane, dimethoxymethylsilane, di-isopropoxymethylsilane, di-t-butoxymethylsilane, methyltriethoxysilane, methyltrimethoxysilane, methyltri-isopropoxysilane, methyltri-t-butoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-isopropoxysilane, dimethyldi-t-butoxysilane, and tetraethoxysilane.
19 . The method of claim 1 , wherein said at least one precursor is a mixture of a first organosilicon precursor with two or fewer Si—O bonds with a second organosilicon precursor with three or more Si—O bonds, and the mixture is provided to tailor a chemical composition of the porous film.
20 . The method of claim 1 wherein the gaseous reagents include a mixture of diethoxymethylsilane and tetraethoxysilane.
21 . A composition comprising:
(a)(i) at least one precursor selected from the group consisting of diethoxymethylsilane, dimethoxymethylsilane, di-isopropoxymethylsilane, di-t-butoxymethylsilane, methyltriethoxysilane, methyltrimethoxysilane, methyltri-isopropoxysilane, methyltri-t-butoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldi-isopropoxysilane, dimethyldi-t-butoxysilane, and tetraethoxysilane, trimethylsilane, tetramethylsilane, diethoxymethylsilane, dimethoxymethylsilane, ditertiarybutoxymethylsilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltriacetoxysilane, methyldiacetoxysilane, methylethoxydisiloxane, dimethyldiacetoxysilane, bis(trimethoxysilyl)methane, bis(dimethoxysilyl)methane, tetraethoxysilane, triethoxysilane, and mixtures thereof; and
(ii) a porogen distinct from the at least one precursor, said porogen being a member selected from the group consisting of cyclooctene, cycloheptene, cyclooctane, cyclooctadiene, cycloheptane, cycloheptadiene, cycloheptatriene, and mixtures thereof.
22 . The composition of claim 21 provided in a kit, wherein the porogen and the precursor are maintained in separate vessels.
23 . The composition of claim 22 wherein at least one of the vessels is a pressurizable stainless steel vessel.
24 . The composition of claim 21 wherein the porogen and the precursor are maintained in a single vessel having a separation means for maintaining the porogens and the precursor separate.