Joint structure for metal pillars
A female structure embedding a first metal pillar and a male structure embedding a second metal pillar. The female structure and the male structure can be locked in with each other, the embedded first metal pillar electrically coupled to the second metal pillar through a metal block. The metal block is electrically coupled to a bottom surface of the first metal pillar, and the metal block wraps peripheral surface of a top end of the second metal pillar. A first embodiment shows the metal block is formed by electroless deposition after matching the female structure to the male structure. A second embodiment shows the metal block is a solder joint.
1. A joint structure for metal pillars comprises:
a plurality of female structures configured on a bottom side of a first electronic component, each female structure comprising
a first metal pillar configured on a bottom side of the first electronic component;
a first dielectric material embedding the first metal pillar; and
a blind hole configured on a bottom side of the first dielectric material;
a plurality of male structures configured on a top side of a second electronic component, each male structure comprising
a second metal pillar configured on a top side of the second electronic component; and
a second dielectric material embedding the second metal pillar; a protrusion of the second metal pillar configured above the top surface of the second dielectric material,
wherein each female structure is electrically coupled to a corresponding male structure; each protrusion of the second metal pillar of a male structure is inserted into a corresponding blind hole of the first female structure, so that the first metal pillar contacts a corresponding second metal pillar; and
a metal block contacts the bottom surface of a corresponding first metal pillar and wraps around a side surface of the protrusion of a corresponding second metal pillar.
2. A joint structure for metal pillars as claimed in claim 1 , wherein
a diameter of the first metal pillar of the female structure is greater than a diameter of the second metal pillar of the male structure.
3. A joint structure for metal pillars as claimed in claim 2 , wherein
a diameter of the blind hole is the same as a diameter of the first metal pillar of the female structure.
4. A joint structure for metal pillars as claimed in claim 3 , wherein
a circular gap configured between the first dielectric material and a corresponding second metal pillar within the blind hole.
5. A joint structure for metal pillars as claimed in claim 4 , wherein
the metal block filling in the circular gap; and
the metal block contacts the bottom surface of a corresponding first metal pillar of the female structure.
6. A joint structure for metal pillars as claimed in claim 5 , wherein
the metal block wrapping around the side surface of the protrusion of a corresponding second metal pillar of the male structure.
7. A joint structure for metal pillars as claimed in claim 6 , wherein
a depth of the blind hole is smaller than a height of the protrusion of the second metal pillar, so that a gap configured between a bottom surface of the first dielectric material of the female structure and a top surface of the second dielectric material of the male structure.
8. A joint structure for metal pillars as claimed in claim 7 , wherein
the metal block wraps around side surface of the protrusion of a corresponding second metal pillar in the gap between the first dielectric material and the second dielectric material.
9. A joint structure for metal pillars as claimed in claim 8 , wherein
a side surface of the metal block exposes in the gap between the bottom surface of the first dielectric material of the female structure and the top surface of the second dielectric material of the male structure.
10. A joint structure for metal pillars as claimed in claim 1 , wherein the metal block is a solder filling in the blind hole.
11. A process for fabricating a plurality of metal pillars embedded in a dielectric layer, comprises:
(1) preparing a first electronic component with a plurality of first metal pads on bottom;
(2) forming photoresist layer on bottom side of the plurality of first metal pads;
(3) forming a plurality of holes, each hole exposes a bottom surface of a corresponding first metal pad;
(4) forming seed layer on a surface of the plurality of holes;
(5) plating to form a plurality of first metal pillars;
(6) flattening the plurality of first metal pillars from bottom, so that each bottom surface of a corresponding metal pillar among the plurality of metal pillars is coplanar with a bottom surface of the photoresist layer;
(7) etching the plurality of first metal pillars from bottom to form a plurality of female structures; wherein a height of each first metal pillar is smaller than a height of the first dielectric layer formed by the photoresist layer, and a blind hole configured under a bottom side of a corresponding first metal pillar;
(8) providing a plurality of male structures formed on a second electronic component with a plurality of second metal pillars embedded in a second dielectric layer, wherein the second dielectric layer is etched from bottom to expose the plurality of second metal pillars, so that each second metal pillar is protruded above a top surface of the second dielectric material to form a protrusion;
(9) matching the plurality of female structures to the plurality of male structures, wherein each protrusion inserts into a corresponding blind hole; and
(10) forming a plurality metal block, each metal block contacts a bottom surface of a corresponding first metal pillar, and each metal block wraps side surface of a protrusion of a corresponding second metal pillar.
12. A process as claimed in claim 11 , wherein
a diameter of the blind hole is the same as a diameter of the first metal pillar of the female structure.
13. A process as claimed in claim 11 , wherein the metal block is formed by electroless deposition.
14. A process as claimed in claim 11 , wherein the metal block is a reflowed solder.