Semiconductor devices and methods of forming the same

1. A method comprising:

forming first conductive pillars over and electrically coupled to a first redistribution structure;

attaching a first die to the first redistribution structure, the first die comprising second conductive pillars;

attaching a second die to the first die adjacent the second conductive pillars;

encapsulating the first conductive pillars, the first die, and the second die with an encapsulant;

forming a second redistribution structure over the encapsulant, the first conductive pillars, the first die, and the second die; and

bonding a third die to the first redistribution structure.

2. The method of claim 1 , wherein the first die is attached to the redistribution structure using a first adhesive, and wherein the second die is attached to the first die using a second adhesive.

3. The method of claim 1 , further comprising attaching a dummy die to the first redistribution structure, wherein the attaching the second die to the first die further comprises attaching the second die to the dummy die.

4. The method of claim 1 , further comprising forming the first die, wherein forming the first die comprises:

forming the second conductive pillars over a semiconductor substrate;

attaching the semiconductor substrate and the second conductive pillars to a tape, the tape surrounding the second conductive pillars;

thinning a back-side of the semiconductor substrate opposite the second conductive pillars; and

singulating the first die.

5. The method of claim 1 , further comprising planarizing the encapsulant such that top surfaces of the encapsulant, the first conductive pillars, the second conductive pillars, and the second die are level with one another.

6. The method of claim 1 , wherein the first die, the second die, and the encapsulant are disposed on a first side of the first redistribution structure and the third die is disposed on a second side of the first redistribution structure opposite the first side.

7. A device comprising:

a first device bonded to a first side of a first redistribution structure;

a second device attached to a second side of the first redistribution structure opposite the first side;

a third device attached to the second device;

a molding compound surrounding the second device and the third device; and

a second redistribution structure over the second device, the third device, and the molding compound, wherein the first device and the second device are electrically coupled to the third device using the second redistribution structure.

8. The device of claim 7 , wherein the first device comprises a dynamic random access memory (DRAM) device, wherein the second device comprises a wide input/output (WIO) memory device, and wherein the third device comprises a system-on-chip (SoC).

9. The device of claim 7 , wherein the first device comprises a low-power double data rate synchronous dynamic random access memory (LPDDR) device, wherein the second device comprises a wide input/output (WIO) memory device, and wherein the third device comprises a system-on-chip (SoC).

10. The device of claim 7 , further comprising first conductive pillars extending through the molding compound, the first conductive pillars being electrically coupled to the first redistribution structure and the second redistribution structure, the first device being electrically coupled to the third device through the first conductive pillars.

11. The device of claim 10 , further comprising second conductive pillars extending through the molding compound, the second conductive pillars being electrically coupled to the second device and the second redistribution structure, the second device being electrically coupled to the third device through the second conductive pillars.

12. The device of claim 7 , further comprising a dummy die disposed between the third device and the first redistribution structure, the dummy die comprising silicon.

13. A device comprising:

a first die attached to a first redistribution structure;

a first molding compound over the first redistribution structure and surrounding the first die;

first through vias extending through the first molding compound;

a second redistribution structure over the first die, the first molding compound, and the first through vias;

a second die attached to the second redistribution structure;

a second molding compound over the second redistribution structure and surrounding the second die; and

second through vias and third through vias extending through the second molding compound, the second through vias being electrically coupled to the first through vias, the second through vias comprising vias having circular-shaped cross sections, the third through vias being electrically coupled to the first die, the third through vias comprising vias having oval-shaped cross sections.

14. The device of claim 13 , wherein a distribution of the third through vias per unit area is greater than a distribution of the second through vias per unit area.

15. The device of claim 13 , wherein the second through vias have diameters in a top-down view from 50 μm to 120 μm, wherein the third through vias have widths from 20 μm to 35 μm in the top-down view, and wherein the third through vias have lengths from 35 μm to 50 μm in the top-down view.

16. The device of claim 13 , further comprising a third die bonded to the first redistribution structure opposite the first die, the third die being electrically coupled to the first through vias.

17. The device of claim 16 , further comprising a third redistribution structure over the second through vias, the third through vias, the second die, and the second molding compound, the second through vias and the third through vias being electrically coupled to the second die using the third redistribution structure.

18. The device of claim 17 , wherein the third die comprises a low-power double data rate synchronous dynamic random access memory (LPDDR) die, wherein the first die comprises a wide input/output (WIO) memory die, and wherein the third die comprises a system-on-chip (SoC).

19. The device of claim 16 , wherein the third die is bonded to the first redistribution structure using solder bonds, wherein the first die is attached to the first redistribution structure using a first adhesive, and wherein the second die is attached to the second redistribution structure using a second adhesive.

20. The device of claim 13 , further comprising fourth through vias extending through the first molding compound, wherein the fourth through vias are electrically isolated from the first die and the second die.