Insulators for high density circuits

1. A method of forming an insulator comprising:

forming a material layer having a material layer thickness on a substrate at provides a base for fabricating one or more integrated circuits;

foaming the material layer to form a foamed material layer having a surface and a foamed thickness, the foamed thickness being greater than the material layer thickness;

treating the surface to make the surface hydrophobic; and

forming an interconnection conductive structure for the one or more integrated circuits in the foamed material layer.

2. The method of claim 1 , wherein forming a material layer having a thickness on a substrate comprises:

forming a polymer layer on the substrate.

3. The method of claim 1 , wherein forming a material layer having a thickness on a substrate comprises:

applying an aerogel to the substrate;

spinning the substrate; and

curing the aerogel such that, after curing, the thickness is between about 0.6 microns and about 0.8 microns.

4. A method of forming an insulator comprising:

forming a polymer layer on a substrate that provides a base for fabricating one or more integrated circuits;

foaming the polymer layer to form a foamed polymer layer having a surface and a foamed polymer dielectric constant between about 0.8 and about 1.0;

treating the surface to make the surface hydrophobic; and

forming an interconnection conductive structure for the one or more integrated circuits in the foamed polymer layer.

5. The method of claim 4 , wherein forming a polymer layer on substrate comprises:

depositing polyimide containing silane on the substrate.

6. The method of claim 4 , wherein foaming the polymer layer to form a foamed polymer layer having a surface and a foamed polymer dielectric constant between about 0.8 and 1.0 comprises:

forming a foamed polymer layer having a depth of between about 1.8 and 2.0 microns.

7. The method of claim 4 , wherein treating the surface to make the surface hydrophobic comprises:

flowing methane radicals over the surface.

8. A method of forming an insulator comprising:

forming a polymer layer on a substrate that provides a base for fabricating one or more integrated circuits;

foaming the polymer layer with a supercritical fluid to form a foamed polymer layer having a surface and a foamed polymer dielectric constant between about 0.8 and 1.0;

treating the surface to make the surface hydrophobic; and

forming an interconnection conductive structure for the one or more integrated circuits in the foamed polymer layer.

9. The method of claim 8 , wherein forming a polymer layer on a substrate comprises:

forming a polyimide layer on the substrate.

10. The method of claim 8 , wherein foaming the polymer layer with a supercritical fluid includes exposing the polymer layer to a CO 2 supercritical fluid.

11. The method of claim 8 , wherein foaming the polymer layer with a supercritical fluid includes exposing the polymer layer to a supercritical fluid with a critical pressure below about 100 atmospheres and a critical temperature of about room temperature.

12. The method of claim 8 , wherein foaming the polymer layer with a supercritical fluid includes exposing the polymer layer to a supercritical fluid that is nontoxic and nonflammable.

13. The method of claim 8 , wherein foaming the polymer layer with a supercritical fluid includes exposing the polymer layer to a supercritical fluid selected from a group comprising NH 3 , NR 3 , ROH, H 2 O, CO 2 , N 2 O, He, Ne, Ar, HF, HCl, HBr, BCl 3 , Cl 2 , F 2 , O 2 , N 2 , CH 4 , C 2 H 6 , C 3 H 8 , C 2 H 4 , CO(OCH 3 ) 2 , CF 4 , C 2 F 4 , CH 3 F, and C 5 H 2 F 6 O 2 .

14. The method of claim 8 , wherein the method further includes depressurizing after exposing the polymer layer to the supercritical fluid at a rate such that the polymer layer converts to the foamed polymer layer before substantial diffusion of the supercritical fluid out of the polymer layer occurs.

15. A method of forming an insulator comprising:

forming a polymer layer having a thickness on a substrate from a polymer having a silane additive, the substrate providing a base for fabricating one or more integrated circuits;

foaming the polymer layer to form a foamed polymer layer having a surface and a foamed polymer layer thickness, the foamed polymer layer thickness is greater an the polymer layer thickness by a factor of about between about 2.8 and 3.2;

treating the surface to make the surface hydrophobic; and

forming an interconnection conductive structure for the one or more integrated circuits in the foamed polymer layer.

16. The method of claim 15 , wherein forming a polymer layer includes forming a layer of parylene containing silane followed by a low temperature bake.

17. The method of claim 15 , wherein the method further includes curing the polymer layer before foaming the polymer layer.

18. A method of forming an insulator comprising:

forming a polymer layer having a thickness on a substrate from a polymer having a silane additive, the substrate providing a base for fabricating one or more integrated circuits;

foaming the polymer layer to form a foamed polymer layer having a surface and a foamed polymer layer thickness, the foamed polymer layer thickness is greater than the polymer layer thickness;

exposing the surface to a gas to make the surface hydrophobic; and

forming an interconnection conductive structure for the one or more in grated circuits in the foamed polymer layer.

19. The method of claim 18 , wherein exposing the surface to a as comprises:

exposing the surface to methane.

20. The method of claim 18 , wherein exposing the surface to a gas comprises:

passing a methane gas through a plasma to form a plurality of methane radicals; and

exposing the surface to at least some of the plurality of methane radicals.

21. A method of forming an insulator comprising:

forming a polymer layer having a thickness on a substrate from a polymer having a silane additive, the substrate providing a base for fabricating one or more integrated circuits;

foaming the polymer layer to form a foamed polymer layer having a surface, a cell size, and a foamed polymer layer thickness, the foamed polymer layer thickness is greater than the polymer layer thickness, and the cell size is less than about one-tenth of a micron;

exposing the surface to a gas to make the surface hydrophobic; and

forming an interconnection conductive structure for the one or more integrated circuits in the foamed polymer layer.

22. The method of claim 21 , wherein exposing the surface to a gas includes exposing the surface to methane.

23. The method of claim 21 , wherein exposing the surface to a gas includes:

passing a methane gas through a plasma to form a plurality of methane radicals; and

exposing the surface to at least some of the plurality of methane radicals.

24. A method of forming an insulator comprising:

forming an aerogel layer on a substrate that provides a base for fabricating one or more integrated circuits,

foaming the aerogel layer to form a foamed aerogel layer having a surface;

treating the surface to make the surface hydrophobic; and

forming an interconnection conductive structure for the one or more integrated circuits in the foamed aerogel layer.

25. The method of claim 24 , wherein forming an aerogel layer having a surface on a substrate comprises:

forming an aerogel layer having a cell size of less than one micron.

26. The method of claim 24 , wherein forming an aerogel layer having a surface on a substrate comprises:

forming an aerogel layer having a cell size of less than one-tenth micron.

27. The method of claim 24 , wherein treating the surface to make the surface hydrophobic comprises:

exposing the surface to methane radicals.

28. The method of claim 24 , wherein treating the surface to make the surface hydrophobic comprises:

forming a plurality of methane radicals using a high frequency electric field; and

exposing the surface to at least some of the plurality of methane radicals.

29. A method of forming a conductive structure comprising:

forming a material layer having a material layer thickness on a substrate;

foaming the material layer to form a foamed material layer having a surface and a foamed thickness, the foamed thickness being greater than the material layer thickness;

treating the surface to make the surface hydrophobic;

forming channels in the foamed material layer; and

filling the channels with a metal.

30. The method of claim 29 , wherein filling the channels with a metal includes filling the channels with a metal selected from a group consisting of silver, aluminum, gold, copper, tungsten, and alloys of silver, aluminum, gold, copper, and tungsten.

31. The method of claim 29 , wherein forming channels in the foamed material layer includes:

applying a photoresist to the surface of the foamed material layer;

forming patterns for the channels in the photoresist; and

etching the photoresist.

32. A method of forming a conductive structure comprising:

forming a polymer layer having a thickness on a substrate that provides a base for fabricating one or more integrated circuits, the polymer layer having a silane additive;

foaming the polymer layer to form a foamed polymer layer having a surface and a foamed polymer layer thickness, the foamed polymer layer thickness greater than the polymer layer thickness;

exposing the surface to a gas to make the surface hydrophobic;

forming channels in the foamed material layer; and

filling the channels with a metal.

33. The method of claim 32 , wherein foaming the polymer layer includes forming a foamed polymer layer having a thickness of between about 1.8 and 2.0 microns.

34. The method of claim 32 , wherein foaming the polymer layer includes forming a foamed polymer layer of polyimide containing silane.

35. The method of claim 34 , wherein the method further include curing a layer of polyimide containing silane before foaming the layer of polyimide containing lane.

36. A method of forming a conductive structure comprising:

forming a foamed aerogel layer on a substrate that provides a base for fabricating one or more integrated circuits, the aerogel layer having a surface;

treating the surface to make the surface hydrophobic;

forming channels in the foamed aerogel layer; and

filling the channels with a metal.

37. The method of claim 36 , wherein forming a foamed aerogel layer includes

applying an aerogel to the substrate;

spinning the substrate; and

curing the aerogel.

38. The method of claim 36 , wherein filling the channels with metal includes filling the channels with a metal selected from a group consisting of silver, aluminum, gold, copper, tungsten, and alloys of silver, aluminum, gold, copper, and tungsten.

39. The method of claim 36 , wherein forming channels in the foamed aerogel layer includes:

applying a photoresist to the surface of the foamed material layer;

forming patterns for the channels in the photoresist; and

etching the photoresist.