Low-k dielectric aerogel and preparation method therefor

1. A preparation method for a low-k dielectric organic/inorganic aerogel composite material, comprising:

mixing step:

mixing an alkoxysilane compound or a hydrophobically modified alkoxysilane compound with an organic mixed solvent to form a mixed solution;

hydrolysis step: adding an acid catalyst into the mixed solution in order to perform a hydrolysis reaction;

condensation step: adding a basic catalyst into the mixed solution after the hydrolysis reaction in order to perform a condensation reaction, and also adding a surfactant during the condensation reaction process;

aging step: performing aging of an aerogel board formed via the condensation step in order to promote an aerogel structure to condense further and to achieve a aerogel board structure;

drying step: after gelatinization in the condensation step and stabilization of the aerogel board structure, performing drying under an environment of constant pressure in order to obtain a low-k dielectric silicon-based aerogel board having a uniform structure;

impregnating polymer solution step: impregnating the low-k dielectric silicon-based aerogel board into a dilute polymer solution in order to allow polymer chains to infiltrate into an internal of the low-k dielectric silicon-based aerogel board uniformly, thereby forming a wet polymer/silicon-based composite material, wherein the polymer chains are configured to be covered onto a network skeleton structure of the low-k dielectric silicon-based aerogel board;

phase separation and drying step: placing the wet polymer/silicon-based composite material in order to allow a solvent in the dilute polymer solution to vaporize, thereby performing a liquid-solid phase separation on polymers inside the wet polymer/silicon-based composite material in order to further allow the polymer chains to cover onto the network skeleton structure of the low-k dielectric silicon-based aerogel board and to be dried gradually, and forming a polymer/silicon-based composite material after drying; and

cross-linking and curing step: placing the polymer/silicon-based composite material after drying in order to allow the polymer chains covered onto the network skeleton structure of the low-k dielectric silicon-based aerogel board to perform a cross-linking reaction, and chemical reaction bonding occurred among the polymer chains and occurred between the polymer chains and silicon-based aerogel molecules of the low-k dielectric silicon-based aerogel board during the cross-linking reaction, thereby obtaining a porous and low-k dielectric polymer/silicon-based aerogel composite material after the cross-linking reaction.

2. The preparation method according to claim 1 , wherein the alkoxysilane compound is tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS), and the hydrophobically modified alkoxysilane compound is methyltrimethoxysilane (MTMS) or methyltriethoxysilane (MTES); a mole ratio between the alkoxysilane compound and the hydrophobically modified alkoxysilane compound is between 0:100 and 35:65.

3. The preparation method according to claim 2 , wherein the dilute polymer solution comprises a mixture of a thermal setting polymer, a thermal plastic polymer and a liquid crystal polymer.

4. The preparation method according to claim 3 , wherein the thermal setting polymer is selected from one of the following or a mixture thereof: epoxy, polyimide, phenolic resin, and melamine resin; the thermal plastic polymer is selected from one of the following or a mixture thereof: polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyesteramide and polyethylene terephthalate; the liquid crystal polymer is selected from one of the following or a mixture thereof: poly semi-aromatic liquid crystal polymer and poly aromatic liquid crystal polymer.

5. The preparation method according to claim 1 , wherein the weight ratio between the amount of the surfactant and the amount of the mixture of the alkoxysilane and the hydrophobically modified alkoxysilane compound is between 1:100 and 1:3000.

6. The preparation method according to claim 5 , wherein in the dilute polymer solution comprises a mixture of a thermal setting polymer, a thermal plastic polymer and a liquid crystal polymer.

7. The preparation method according to claim 6 , wherein the thermal setting polymer is selected from one of the following or a mixture thereof: epoxy, polyimide, phenolic resin, and melamine resin; the thermal plastic polymer is selected from one of the following or a mixture thereof: polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyesteramide and polyethylene terephthalate; the liquid crystal polymer is selected from one of the following or a mixture thereof: poly semi-aromatic liquid crystal polymer and poly aromatic liquid crystal polymer.

8. The preparation method according to claim 1 , wherein a polymer concentration of the dilute polymer solution used in the impregnating polymer solution step is between 0.01 wt % and 60 wt %, thereby allowing the polymer chains to uniformly infiltrate into the internal of the low-k dielectric silicon-based aerogel board in order to form the wet polymer/silicon-based composite material.

9. The preparation method according to claim 8 , wherein in the dilute polymer solution comprises a mixture of a thermal setting polymer, a thermal plastic polymer and a liquid crystal polymer.

10. The preparation method according to claim 9 , wherein the thermal setting polymer is selected from one of the following or a mixture thereof: epoxy, polyimide, phenolic resin, and melamine resin; the thermal plastic polymer is selected from one of the following or a mixture thereof: polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyesteramide and polyethylene terephthalate; the liquid crystal polymer is selected from one of the following or a mixture thereof: poly semi-aromatic liquid crystal polymer and poly aromatic liquid crystal polymer.

11. The preparation method according to claim 1 , wherein the dilute polymer solution comprises a mixture of a thermal setting polymer, a thermal plastic polymer and a liquid crystal polymer.

12. The preparation method according to claim 11 , wherein the thermal setting polymer is selected from one of the following or a mixture thereof: epoxy, polyimide, phenolic resin, and melamine resin; the thermal plastic polymer is selected from one of the following or a mixture thereof: polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyamide, polyesteramide and polyethylene terephthalate; the liquid crystal polymer is selected from one of the following or a mixture thereof: poly semi-aromatic liquid crystal polymer and poly aromatic liquid crystal polymer.

13. The preparation method according to claim 1 , wherein a structural uniformity, a contraction ratio and a strength of the polymer/silicon-based aerogel composite material after drying are adjusted and controlled based on the following factors during preparation: a content of the alkoxysilane compound or the hydrophobically modified alkoxysilane compound, a total solvent content, a hydrolysis criterion, a condensation speed, a content of the surfactant, an aging speed, a drying speed, a concentration of the dilute polymer solution, an infiltration uniformity of the polymers and a cross-linking level of the polymer chains.

14. The preparation method according to claim 1 , wherein a porosity of the porous and low-k dielectric polymer/silicon-based aerogel composite material is higher than 60%, a density thereof is between 0.12 and 0.45 g/cm 3 , and a dielectric property thereof decreases along with an increase of the porosity; wherein a dielectric constant thereof is between 1.23 and 1.987, and a dielectric loss thereof is between 0.0052 and 0.023; the porous and low-k dielectric polymer/silicon-based aerogel composite material is used for a dielectric layer in a high- frequency circuit, an insulation layer in a semiconductor device or a microwave circuit in a communication integrated circuit.