Fan-out PoP structure with inconsecutive polymer layer

1. A method comprising:

forming a polymer layer over a carrier;

patterning the polymer layer to form a first opening;

forming a through-via over the patterned polymer layer;

placing a device die, with at least a portion of a die attach film attached to the device die being in the first opening;

molding the device die and the through-via in a molding compound;

forming redistribution lines electrically coupled to the device die and the through-via;

removing the carrier from the polymer layer; and

forming a second opening in the polymer layer to expose the through-via.

2. The method of claim 1 further comprising:

forming a solder region in the second opening of the polymer layer.

3. The method of claim 2 further comprising dispensing an underfill to contact the die attach film.

4. The method of claim 1 , wherein the polymer layer is formed on an adhesive layer, and the device die is attached to the adhesive layer through the die attach film.

5. The method of claim 1 , wherein the forming the second opening in the polymer layer comprises laser drill.

6. The method of claim 1 , wherein the forming the through-via comprises:

after the patterning the polymer layer to form the first opening, forming a conductive seed layer over the polymer layer and extending into the first opening; and

after the through-via is formed, removing portions of the conductive seed layer not covered by the through-via, with an adhesive layer underlying the polymer layer being revealed.

7. A method comprising:

forming a dielectric layer over a base layer;

removing a part of the dielectric layer to form a first opening, with a portion of the base layer exposed through the first opening;

attaching a device die to the base layer through the first opening;

encapsulating the device die in an encapsulating material;

planarizing the encapsulating material and the device die, with metal features in the device die exposed;

forming redistribution lines electrically coupling to the metal features in the device die;

removing the base layer from the dielectric layer;

forming a second opening in the dielectric layer; and

forming a conductive feature extending into the second opening.

8. The method of claim 7 further comprising:

forming a metal post over the dielectric layer, wherein the metal post is encapsulated by the encapsulating material, and the conductive feature is joined to the metal post.

9. The method of claim 8 , wherein the forming the metal post comprises:

depositing a seed layer, wherein the seed layer comprises a first portion over the dielectric layer, and a second portion extending into the first opening;

plating to form an upper portion of the metal post; and

removing portions of the seed layer not covered by the upper portion of the metal post, wherein the second portion of the seed layer is removed.

10. The method of claim 9 , wherein the conductive feature is in contact with the seed layer.

11. The method of claim 7 , wherein after the device die is attached to the base layer, the device die is spaced apart from a portion of the dielectric layer by a space in the first opening, and the encapsulating material is filled into the space.

12. The method of claim 7 , wherein the conductive feature comprises a solder region, and the method further comprises bonding a package component to the solder region.

13. The method of claim 12 further comprising filling an underfill between the dielectric layer and the package component.

14. The method of claim 13 , wherein the device die is attached to the base layer through a die attach film, and the underfill further contacts the die attach film.

15. A method comprising:

forming a polymer layer having a first opening therein;

depositing a seed layer comprising:

a first portion over the polymer layer; and

a second portion in the first opening;

applying and patterning a photo resist to form a second opening in the photo resist, with a portion of the seed layer exposed through the second opening;

plating a metallic material into the second opening to form a metal post;

removing the photo resist;

removing portions of the seed layer not covered by the metallic material, wherein the second portion of the seed layer is removed;

attaching a device die to a layer underlying the polymer layer through a die attach film, wherein the die attach film has at least a portion in the first opening; and

dispensing a molding compound, with the device die molded in the molding compound, wherein the polymer layer contacts the molding compound.

16. The method of claim 15 , wherein an entirety of the die attach film is in the first opening.

17. The method of claim 15 , wherein the molding compound comprises a portion having a first edge contacting an edge of the polymer layer, and a second edge contacting an edge of the die attach film and an edge of the device die.

18. The method of claim 15 , wherein the device die comprises metal pillars at a front side, and wherein the method further comprises performing a planarization on the molding compound to make a surface of the molding compound to be coplanar with surfaces of the metal pillars.

19. The method of claim 15 further comprising:

forming a third opening in the polymer layer; and

filling a solder region into the third opening.

20. The method of claim 19 further comprises dispensing an underfill to contact the solder region, the polymer layer, and the molding compound.