Multilayer electronic structure with through thickness coaxial structures

1. A multilayer electronic support structure comprising a plurality of dielectric layers of a dielectric material extending in an X-Y plane and comprising at least one coaxial pair of stacked posts extending through at least one layer of the dielectric material in a Z direction that is perpendicular to the X-Y plane, wherein each of said coaxial pair of stacked via posts comprises a cylindrical central post surrounded by a tubular via post separated from the central post by a separating tube of the dielectric material

wherein the cylindrical central post and the tubular via post are cofabricated;

wherein said cylindrical central post is coupled to a voltage source and said tubular via post is coupled to a ground; and

wherein, in the Z direction, both said cylindrical central post and said tubular via post have a plurality of seed layers separated by electroplated layers.

2. The multilayer electronic support structure of claim 1 , wherein the coaxial pair of stacked posts extends through a plurality of layers of the multilayer electronic structure.

3. The multilayer electronic support structure of claim 1 , wherein the central post protrudes over the tubular via post in the Z direction.

4. The multilayer electronic support structure of claim 1 , wherein the coaxial pair of stacked posts extends through all layers of the multilayer electronic structure.

5. The multilayer electronic support structure of claim 1 , wherein the central post has a diameter of at least 30 microns, the tubular via post has an external diameter of at least 150 microns, and the separating tube of the dielectric material has a thickness of at least 30 microns.

6. The multilayer electronic support structure of claim 1 , wherein each post of the stack of posts comprises a seed layer and an electroplated layer.

7. The multilayer electronic support structure of claim 6 , wherein the seed layer comprises one of the following alternatives:

(i) an adhesion layer selected from the list comprising Ti, Cr, Ta, W and combinations thereof;

(ii) an adhesion layer selected from the list comprising Ti, Cr, Ta, W and combinations thereof followed by a copper layer, and (iii) copper.

8. The multilayer composite electronic structure of claim 6 , wherein the electroplated layer comprises copper.

9. The multilayer composite structure of claim 1 , wherein the dielectric material comprises a polymer.

10. The multilayer composite structure of claim 9 , wherein the dielectric material further comprises ceramic or glass reinforcements.

11. The multilayer composite structure of claim 9 , wherein the polymer comprises polyimide, epoxy, Bismaleimide, Triazine and blends thereof.

12. The multilayer composite structure of claim 10 , wherein the reinforcements comprise glass fibers.

13. The multilayer composite structure of claim 10 , wherein the reinforcements comprise particle fillers.

14. An electronic device comprising the multiplayer electronic support structure of claim 1 .

15. A method of fabricating the multilayer composite electronic structure of claim 1 , comprising the steps of:

(a) obtaining a substrate;

(b) covering the substrate with an etch-barrier layer;

(c) applying a seed layer over the etch-barrier layer;

(d) depositing a layer of photoresist over the seed layer;

(e) exposing the photoresist to form a negative pattern comprising at least one coaxial pair of posts;

(f) depositing a metal layer into the negative pattern;

(g) stripping away the photoresist, leaving the at least one coaxial pair of posts upstanding including a cofabricated cylindrical central post and tubular via post extending in a Z direction that is perpendicular to the X-Y plane;

(h) removing the seed layer;

(i) laminating a dielectric material over the at least one coaxial pair of posts in the via layer, wherein said central post is separated from the tubular via post by a separating tube of dielectric material;

(j) thinning away the dielectric material to expose the metal layer;

wherein said cylindrical post is coupled to a voltage source and said tubular via post is coupled to a ground; and

wherein, in the Z direction, both said cylindrical central post and said tubular via post have a plurality of seed layers separated by electroplated layers.

16. The method of claim 15 further comprising depositing additional layers by repeating steps (c) to (h).

17. The method of claim 15 further comprising the step of etching away the substrate.

18. A method of fabricating the multilayer composite electronic structure of claim 1 , comprising the steps of:

(i) obtaining a substrate;

(ii) covering the substrate with an etch-barrier layer;

(iii) applying a seed layer that is typically copper,

(iv) depositing a panel of copper over the seed layer;

(v) applying a layer of photoresist over the panel;

(vi) exposing the photoresist to form a negative pattern of metal posts that comprises at least one separator between a coaxial pair of posts;

(vii) etching away the copper to leave the pattern of metal posts including at least one coaxial pair of posts upstanding including a cofabricated cylindrical central post and

tubular via post extending in a Z direction that is perpendicular to the X-Y plane;

(viii) stripping away the photoresist;

(ix) laminating a dielectric material over the at least one coaxial pair of posts in the via layer, wherein said central post is separated from the tubular via post by a separating tube of dielectric material,

(x) thinning away the dielectric material to expose the metal layer;

wherein said cylindrical post is coupled to a voltage source and said tubular via post is coupled to a ground; and

wherein, in the Z direction, both said cylindrical central post and said tubular via post have a plurality of seed layers separated by electroplated layers.

19. The method of claim 18 further comprising depositing additional layers by repeating steps (iii) to (x).

20. The method of claim 18 further comprising the step of etching away the substrate.