Methods for pillar connection on frontside and passive device integration on backside of die

1. A transistor device, comprising:

a die comprising a first surface, a second surface, a semiconductor layer structure that is between the first and second surfaces and comprises a plurality of transistor cells, and terminals coupled to the transistor cells;

one or more conductive pillar structures that protrude from the first surface of the die and are electrically connected to one or more of the terminals; and

at least one conductive via that extends into the second surface of the die.

2. The transistor device of claim 1 , wherein the terminals comprise an input terminal, an output terminal, and/or a ground terminal.

3. The transistor device of claim 2 , wherein the one or more conductive pillar structures provide electrical connection to the input terminal and/or the output terminal, and wherein the at least one conductive via provides electrical connection to the ground terminal.

4. The transistor device of claim 1 , wherein the die comprises a substrate between the semiconductor layer structure and the second surface of the die, the at least one conductive via extends through the substrate, and the semiconductor layer structure comprises one or more epitaxial layers on the substrate.

5. The transistor device of claim 1 , wherein the semiconductor layer structure comprises a Group-III nitride material.

6. The transistor device of claim 5 , wherein the die comprises a silicon carbide substrate between the Group-III nitride material and the second surface.

7. The transistor device of claim 1 , further comprising:

a package substrate comprising one or more conductive connections,

wherein the one or more conductive pillar structures attach the die to the package substrate adjacent the first surface of the die, and electrically connect the one or more of the terminals to the one or more conductive connections.

8. The transistor device of claim 1 , further comprising:

a package substrate comprising at least one conductive connection,

wherein the die is attached to the package substrate adjacent the second surface of the die, and the at least one conductive via electrically connects at least one of the terminals to the at least one conductive connection.

9. The transistor device of claim 2 , further comprising:

at least one passive electronic component on the second surface of the die, wherein the at least one passive electronic component is electrically connected to at least one of the terminals by the at least one conductive via.

10. A transistor device, comprising:

a die comprising a first surface, a second surface, a semiconductor layer structure that is between the first and second surfaces and comprises a plurality of transistor cells adjacent the first surface, and terminals coupled to the transistor cells;

at least one passive electronic component on the second surface of the die and electrically connected to at least one of the terminals; and

one or more conductive pillar structures that protrude from the first surface of the die and provide electrical connections to one or more of the terminals.

11. The transistor device of claim 10 , wherein the terminals comprise an input terminal, an output terminal, and/or a ground terminal.

12. The transistor device of claim 11 , wherein the at least one passive electronic component is at least one integrated passive device (IPD) comprising a discrete capacitor, inductor, and/or resistor on the second surface of the die.

13. The transistor device of claim 11 , further comprising:

a metal layer extending on the second surface of the die and electrically connecting the at least one passive electronic component to the at least one of the terminals.

14. The transistor device of claim 13 , wherein the metal layer is a first metal layer, and further comprising:

an insulator layer on the first metal layer opposite the second surface,

wherein the at least one passive electronic component is on the insulator layer opposite the first metal layer, and comprises patterns of a second metal layer defining one or more discrete capacitors, inductors, and/or resistors.

15. The transistor device of claim 13 , further comprising:

at least one conductive via that extends into the second surface of the die and the semiconductor layer structure to electrically connect the metal layer on the second surface of the die to the at least one of the terminals.

16. The transistor device of claim 10 , wherein the semiconductor layer structure comprises a Group-III nitride material.

17. The transistor device of claim 16 , wherein the die comprises a silicon carbide substrate between the Group-III nitride material and the second surface.

18. The transistor device of claim 10 , further comprising:

a package substrate comprising one or more conductive connections,

wherein the one or more conductive pillar structures attach the die to the package substrate adjacent the first surface of the die, and electrically connect the one or more of the terminals to the one or more conductive connections.

19. A method of fabricating a transistor device, the method comprising:

forming a transistor structure comprising a first surface, a second surface, a semiconductor layer structure that is between the first and second surfaces and comprises a plurality of transistor cells, and terminals coupled to the transistor cells;

forming one or more conductive pillar structures that protrude from the first surface to provide electrical connections to one or more of the terminals; and

forming at least one conductive via that extends into the second surface.

20. The method of claim 19 , wherein the transistor structure further comprises a substrate between the semiconductor layer structure and the second surface, wherein forming the at least one conductive via comprises:

attaching the first surface to a wafer carrier;

performing a thinning operation on the second surface to reduce a thickness of the substrate; and

forming the at least one conductive via extending into the second surface to provide electrical connection to at least one of the terminals responsive to the thinning operation and with the first surface attached to the wafer carrier.

21. The method of claim 20 , wherein forming the one or more conductive pillar structures is performed before attaching the first surface to the wafer carrier.

22. The method of claim 20 , wherein the wafer carrier is a first wafer carrier, and wherein forming the one or more conductive pillar structures comprises:

detaching the first surface from the first wafer carrier;

attaching the second surface to a second wafer carrier; and

forming the one or more conductive pillar structures on the first surface with the second surface attached to the second wafer carrier.

23. The method of claim 20 , further comprising:

forming at least one passive electronic component on the second surface with the first surface attached to the wafer carrier,

wherein the at least one passive electronic component is electrically connected to the at least one of the terminals by the at least one conductive via.

24. The method of claim 23 , wherein forming the at least one passive electronic component comprises:

forming a first metal layer on the second surface responsive to the thinning operation;

forming an insulator layer on the first metal layer opposite the second surface; and

forming and patterning a second metal layer on the insulator layer opposite the first metal layer, wherein the at least one passive electronic component comprises patterns of the second metal layer defining one or more discrete capacitors, inductors, and/or resistors.

25. A method of fabricating a transistor device, the method comprising:

forming a transistor structure comprising a first surface, a second surface, a semiconductor layer structure that is between the first and second surfaces and comprises a plurality of transistor cells, a substrate between the semiconductor layer structure and the second surface, and terminals coupled to the transistor cells;

forming one or more conductive pillar structures that protrude from the first surface to provide electrical connections to one or more of the terminals; and

singulating the transistor structure to define a die comprising a portion of the substrate having a thickness of about 50 to about 800 microns.

26. The method of claim 25 , wherein a sidewall of the die extending between the first and second surfaces comprises a first portion adjacent the first surface having a surface characteristic that differs from a second portion adjacent the second surface.

27. The method of claim 26 , further comprising:

forming a trench in the semiconductor layer structure extending from the first surface toward the second surface through the semiconductor layer structure and into the substrate to define the first portion of the sidewall of the die.

28. The method of claim 27 , wherein forming the trench is performed before forming the one or more conductive pillar structures.

29. The method of claim 27 , wherein singulating comprises dicing or sawing through a bottom of the trench in the substrate to define the second portion of the sidewall of the die.

30. The method of claim 25 , wherein the semiconductor layer structure comprises a Group-III nitride, and wherein the substrate comprises silicon carbide.