Structures for providing electrical isolation in semiconductor devices

1. A semiconductor package structure comprising:

a printed circuit board (PCB) or package substrate;

an interposer bonded to the PCB or package substrate through first solder bumps disposed on a first side of the interposer, the first solder bumps having a first pitch; and

a plurality of semiconductor chips, each of the semiconductor chips (i) being bonded to a second side of the interposer through second solder bumps having a second pitch that is less than the first pitch, and (ii) comprising a substrate with one or more transistors or integrated circuits formed thereon;

wherein the first solder bumps have diameters of 10 μm or less, and the second solder bumps have diameters of 100 to 300 μm.

2. The semiconductor package structure of claim 1 , wherein adjacent semiconductor chips bonded to the interposer are separated by air gaps or insulating passivation material, the air gaps or insulating passivation material providing electrical isolation between the adjacent chips.

3. The semiconductor package structure of claim 1 , wherein the semiconductor chips are bonded to the second side of the interposer in an arrangement that minimizes distances between adjacent semiconductor chips bonded to the interposer.

4. The semiconductor package structure of claim 1 , wherein diameters of the first solder bumps are greater than diameters of the second solder bumps.

5. The semiconductor package structure of claim 1 , wherein the interposer comprises silicon material and conductive lines and conductive vias formed in the silicon material, the conductive lines and conductive vias being configured to route signals (i) between chips of the plurality of semiconductor chips, and (ii) between the semiconductor chips and the PCB or package substrate.

6. The semiconductor package structure of claim 1 , wherein the one or more transistors or integrated circuits include a first layer of III-V semiconductor material.

7. The semiconductor package structure of claim 6 ,

wherein the first layer of III-V semiconductor material comprises gallium nitride (GaN),

wherein the one or more transistors or integrated circuits include a second layer of III-V semiconductor material comprising aluminum gallium nitride (AlGaN), and

wherein the one or more transistors or integrated circuits comprise a high electron mobility transistor (HEMT) that includes the first layer of III-V semiconductor material and the second layer of III-V semiconductor material.

8. A semiconductor structure comprising:

a plurality of semiconductor chips, wherein each of the semiconductor chips comprises a substrate with one or more transistors or integrated circuits formed thereon;

first solder bumps on a top surface of each of the plurality of semiconductor chips;

an interposer having a first side bonded to the plurality of semiconductor chips through the first solder bumps in an arrangement that includes air gaps separating adjacent semiconductor chips, wherein the air gaps abut respective side surfaces of the adjacent semiconductor chips; and

a printed circuit board (PCB) or package substrate bonded to the interposer through second solder bumps disposed on a second side of the interposer;

wherein the first solder bumps have diameters of 10 μm or less, and the second solder bumps have diameters of 100 to 300 μm.

9. The semiconductor structure of claim 8 , wherein the first solder bumps are separated by a first bump-to-bump pitch and the second solder bumps are separated by a second bump to bump pitch that is greater than the first bump-to-bump pitch.

10. The semiconductor structure of claim 8 , wherein the plurality of semiconductor chips is bonded to the first side of the interposer in an arrangement that minimizes distances between adjacent semiconductor chips bonded to the interposer.

11. The semiconductor structure of claim 8 , wherein the one or more transistors or integrated circuits include a first layer of III-V semiconductor material.

12. The semiconductor structure of claim 11 , wherein the first layer of III-V semiconductor material comprises gallium nitride (GaN).

13. The semiconductor structure of claim 11 , further comprising a second layer of III-V semiconductor material on the first layer of III-V semiconductor material, the second layer of III-V semiconductor material comprising aluminum gallium nitride (AlGaN).

14. The semiconductor structure of claim 13 , wherein the one or more transistors or integrated circuits comprise a high electron mobility transistor (HEMT) that includes the first layer of III-V semiconductor material and the second layer of III-V semiconductor material.

15. The semiconductor structure comprising:

a plurality of semiconductor chips, wherein each of the semiconductor chips comprises a substrate with one or more transistors or integrated circuits formed thereon;

first solder bumps having a first pitch on a top surface of each of the plurality of semiconductor chips;

an interposer having a first side bonded to the plurality of semiconductor chips through the first solder bumps in an arrangement that includes air gaps separating adjacent semiconductor chips, wherein the air gaps abut respective side surfaces of the adjacent semiconductor chips;

a package substrate having a top surface bonded to the interposer through second solder bumps disposed on a second side of the interposer, wherein the second solder bumps have a second pitch that is greater than the first pitch; and

third solder bumps directly on a bottom surface of the package substrate;

wherein the first solder bumps have diameters of 10 μm or less, and the second solder bumps have diameters of 100 to 300 μm.

16. The semiconductor structure of claim 15 , wherein the adjacent semiconductor chips are electrically isolated.

17. The semiconductor structure of claim 15 , the plurality of semiconductor chips are bonded to the first side of the interposer in an arrangement that minimizes distances between adjacent semiconductor chips bonded to the interposer.

18. The semiconductor structure of claim 15 , wherein diameters of the second solder bumps are greater than diameters of the first solder bumps.

19. The semiconductor structure of claim 15 , wherein the one or more transistors or integrated circuits include a first layer of III-V semiconductor material and a second layer of III-V semiconductor material on the first layer of III-V semiconductor material; wherein the first layer of III-V semiconductor material comprises gallium nitride (GaN); and wherein the second layer of III-V semiconductor material comprising aluminum gallium nitride (AlGaN).

20. The semiconductor structure of claim 8 , wherein the plurality of semiconductor chips are bonded to the interposer via flip-chip bonding.