Method of preparing mesoporous thin film having low dielectric constant

1 . A method of preparing a mesoporous thin film having a low dielectric constant, comprising:

a first step of mixing at least one cyclic siloxane-based monomer selected from the group consisting of monomers represented by Formula 1, 2 and 3, below, with an organic solvent, an acid catalyst or a base catalyst, and water, to prepare a coating solution; and

a second step of applying the coating solution on a substrate, and heat curing the coating solution applied on the substrate, to obtain a thin film:

wherein R 1 is a hydrogen atom, a C1 to C3 alkyl group, or a C6 to C15 aryl group; R 2 is a hydrogen atom, a C1 to C10 alkyl group, or SiX 1 X 2 X 3 (in which X 1 , X 2 and X 3 are independently each a hydrogen atom, a C1 to C3 alkyl group, a C1 to C10 alkoxy group, or a halogen atom); and p is an integer ranging from 3 to 8;

wherein R 1 is a hydrogen atom, a C1 to C3 alkyl group, or a C6 to C15 aryl group; X 1 , X 2 and X 3 are independently each a hydrogen atom, a C1 to C3 alkyl group, a C1 to C10 alkoxy group, or a halogen atom, at least one of which is a hydrolyzable functional group; and m is an integer ranging from 0 to 10, and p is an integer ranging from 3 to 8; and

wherein R 1 is a hydrogen atom, a C1 to C3 alkyl group, R′CO (in which R′ is a C1 to C3 alkyl group), a halogen atom, or SiX 1 X 2 X 3 (in which X 1 , X 2 and X 3 are independently each a hydrogen atom, a C1 to C3 alkyl group, a C1 to C10 alkoxy group, or a halogen atom, at least one of which is a hydrolysable functional group); and p is an integer ranging from 3 to 8.

2 . The method as set forth in claim 1 , wherein the first step of mixing further comprises adding a porogen.

3 . The method as set forth in claim 1 , wherein the first step of mixing further comprises adding one or a combination of both of a compound represented by Formula 4, below, and a compound represented by Formula 5, below:

X 3 X 2 X 1 Si-M-SiX 1 X 2 X 3   Formula 4

wherein X 1 , X 2 and X 3 are independently each a hydrogen atom, a C1 to C3 alkyl group, a C1 to C10 alkoxy group, or a halogen atom, at least one of which is a hydrolyzable functional group; and M is a single bond, a C1 to C10 alkylene group, or a C6 to C15 arylene group; and

(R 1 ) n Si(OR 2 ) 4-n   Formula 5

wherein R 1 is a hydrogen atom, a C1 to C3 alkyl group, a halogen group, or a C6 to C15 aryl group, and R 2 is a hydrogen atom, a C1 to C3 alkyl group, or a C6 to C15 aryl group, at least one of R 1 and OR 2 is a hydrolyzable functional group; and n is an integer ranging from 0 to 3.

4 . The method as set forth in claim 1, wherein the monomer represented by Formula 1 is at least one selected from the group consisting of compounds represented by Formulas 6 to 11, below,

the monomer represented by Formula 2 is a compound represented by Formula 12, below, and

the monomer represented by Formula 3 is a compound represented by Formula 13, below:

5 . The method as set forth in claim 2 , wherein the monomer represented by Formula 1 is at least one selected from the group consisting of compounds represented by Formulas 6 to 11, below,

the monomer represented by Formula 2 is a compound represented by Formula 12, below, and

the monomer represented by Formula 3 is a compound represented by Formula 13, below:

6 . The method as set forth in claim 3 , wherein the monomer represented by Formula 4 is a compound represented by Formula 14 or 15, below, and

the siloxane monomer represented by Formula 5 includes any one selected from the group consisting of compounds represented by Formulas 16, 17 and 18, below:

7 . The method as set forth in claim 2 , wherein the porogen is selected from the group consisting of polycaprolactone, α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

8 . The method as set forth in claim 2 , wherein the porogen comprises at least one surfactant selected from the group consisting of sulfates, sulfonates, phosphates, carboxylic acids, alkylammonium salts, Gemini surfactants, cetylethylpiperidinium salts, dialkyldimethylammonium, primary amines, poly(oxyethylene)oxide, octaethylene glycol monodecyl ether, octaethylene glycol monohexadecyl ether, and block copolymers.

9 . The method as set forth in claim 1 , wherein the acid catalyst is selected from the group consisting of hydrochloric acid, nitric acid, benzene sulfonic acid, oxalic acid, formic acid, and combinations thereof, and

the base catalyst is selected from the group consisting of potassium hydroxide, sodium hydroxide, triethylamine, sodium bicarbonate, pyridine, and combinations thereof.

10 . The method as set forth in claim 1 , wherein the organic solvent is selected from the group consisting of aliphatic hydrocarbon solvents, including hexane or heptane; aromatic hydrocarbon solvents, including anisole, mesitylene or xylene; ketone-based solvents, including methyl isobutyl ketone, 1-methyl-2-pyrrolidinone, cyclohexanone or acetone; ether-based solvents, including tetrahydrofuran or isopropyl ether; acetate-based solvents, including ethyl acetate, butyl acetate or propylene glycol methyl ether acetate; alcohol-based solvents, including isopropyl alcohol or butyl alcohol; amide-based solvents, including dimethylacetamide or dimethylformamide; silicon-based solvents; and combinations thereof.

11 . The method as set forth in claim 2 , wherein the porogen is used in an amount of 0.01 to 70 wt %, based on the weight of the solid content of the coating solution.

12 . The method as set forth in claim 1 , wherein the coating solution has 5 to 70 wt % solid content, based on the total weight thereof.

13 . A mesoporous dielectric thin film prepared by the method as set forth in claim 1 .

14 . The mesoporous dielectric thin film as set forth in claim 13 , wherein the mesoporous thin film has an X-ray diffraction peak in a range of 2θ=0.3-10°.