Packages with through-vias having tapered ends
A package includes a device die, a molding material molding the device die therein, a through-via substantially penetrating through the molding material, wherein the through-via has an end. The end of the through-via is tapered and has rounded sidewall surfaces. The package further includes a redistribution line electrically coupled to the through-via.
1. A method comprising:
forming a conductive post over a carrier;
placing a device die over the carrier;
encapsulating the device die and the conductive post in an encapsulant;
planarizing the encapsulant to expose the conductive post;
after the encapsulant is planarized, etching the conductive post so that the conductive post is recessed into the encapsulant, wherein after the etching, a first top surface of the conductive post is rounded; and
forming a conductive feature over and contacting the conductive post.
2. The method of claim 1 , wherein the device die comprises metal pillars at a second top surface of the device die, and wherein after the etching, the metal pillars of the device die have top surfaces higher than a top surface of the conductive post.
3. The method of claim 1 , wherein the device die comprises metal pillars at a second top surface of the device die, and wherein during the etching, the metal pillars of the device die are not etched.
4. The method of claim 1 further comprising:
forming a dielectric layer over the encapsulant, wherein the dielectric layer comprises a portion extending into a recess formed by the etching the conductive post.
5. The method of claim 4 further comprising:
forming a conductive via extending into the dielectric layer, wherein the via further extends into the recess to contact the conductive post.
6. The method of claim 5 , wherein the etching the conductive post comprises a wet etching process.
7. The method of claim 1 , wherein the forming the conductive post comprises plating the conductive post over the carrier.
8. A method comprising:
forming a patterned photo resist;
plating a conductive post in the patterned photo resist;
removing the patterned photo resist;
encapsulating the conductive post in an encapsulating material;
performing a planarization on the encapsulating material to reveal the conductive post;
etching the conductive post so that the conductive post has a tapered top end; and
forming a redistribution line over and in contact with the conductive post.
9. The method of claim 8 , wherein after the planarization and before the etching, the conductive post has a planar top surface.
10. The method of claim 8 , wherein the etching the conductive post comprises a wet etching process.
11. The method of claim 8 , wherein the redistribution line comprises a via extending into a recess formed in the encapsulant, wherein the recess is formed by the etching the conductive post.
12. The method of claim 8 further comprising forming a dielectric layer over and contacting the encapsulating material, wherein the dielectric layer comprises a lower portion extending into the encapsulating material, and the via extends into the lower portion of the dielectric layer.
13. The method of claim 8 , wherein after the etching the conductive post, the tapered top end of the conductive post is lower than a flat top surface of the encapsulant.
14. The method of claim 8 further comprises encapsulating a device die in the encapsulant, wherein the device die comprises a metal pillar, with the metal pillar exposed after the planarization, and wherein in the etching, the metal pillar is un-etched.
15. A method comprising:
forming a conductive post over a carrier;
placing a device die over the carrier, wherein the device die comprises a metal pillar as a top feature of the device die;
encapsulating the conductive post and the device die in an encapsulating material, wherein the conductive post is in the encapsulating material;
after the encapsulating, performing an etching process, and wherein after the etching process, the conductive post is exposed through the encapsulating material and has a first top surface lower than a second top surface of the metal pillar; and
forming a redistribution line over and in contact with the conductive post.
16. The method of claim 15 , wherein after the etching process, the second top surface of the metal pillar is coplanar with a third top surface of the encapsulant.
17. The method of claim 15 , wherein the etching process comprises etching the conductive post.
18. The method of claim 15 , wherein the etching process comprises etching the encapsulating material.
19. The method of claim 15 , wherein a lower portion of the conductive post has straight edges.
20. The method of claim 1 , wherein after the etching, the rounded top surface of the conductive post is connected to straight sidewalls of the conductive post.