Dual-side power rail design and method of making same

1. A method comprising:

patterning openings to expose a front-side power delivery network (PDN) and a front-side input/output (I/O) pin of a front-side interconnect structure of a device, wherein the device comprises a device layer including a transistor, and the front-side interconnect structure is on a front side of the device layer;

filling the openings with a conductive material;

removing a back-side interconnect structure on a back side of the device layer to expose the device layer;

attaching a first tester to the device, the first tester electrically connected to the front- side PDN and the front-side I/O pin through the conductive material; and

running the first tester to detect a defect location of the device layer.

2. The method of claim 1 , wherein running the first tester comprises:

shining a laser beam or photon emission from the back side of the device layer to detect the defect location of the device while running the first tester.

3. The method of claim 2 , wherein shining the laser beam or the photo emission comprises:

shining the laser beam using a light visually X (LVx) detector; or

shining the photon emission using an emission microscopy (EMMI) detector.

4. The method of claim 1 , further comprising:

before patterning the openings:

attaching a second tester to the device, the second tester electrically connected to a back-side PDN and a back-side I/O pin of the back-side interconnect structure; and

running the second tester.

5. The method of claim 4 , wherein the first tester is different from the second tester, and wherein running the first tester comprises:

running the first tester to perform a power failure analysis (PFA) test.

6. The method of claim 1 , wherein patterning the openings comprises:

etching a carrier substrate;

etching a bonding layer bonding the carrier substrate to the front-side interconnect structure; and

etching a dielectric layer of the front-side interconnect structure.

7. The method of claim 6 , wherein etching the carrier substrate, etching the bonding layer, and etching the dielectric layer comprise:

dry etching the carrier substrate;

dry etching the bonding layer; and

dry etching the dielectric layer.

8. The method of claim 1 , further comprising:

forming conductive pads on the conductive material, each of the conductive pads being wider than each of the openings; and

electrically connecting the first tester with the conductive pads.

9. The method of claim 8 , further comprising:

before electrically connecting the first tester, depositing a dielectric layer on a carrier substrate and between the conductive pads.

10. The method of claim 1 , wherein the front-side interconnect structure includes a plurality of layers of front-side conductive features, wherein the front-side PDN and the front-side I/O pin are in an topmost layer of the plurality of layers of front-side conductive features, and wherein the topmost layer is thicker than other layers of the plurality of layers of front-side conductive features.

11. The method of claim 10 , wherein the back-side interconnect structure includes a plurality of layers of back-side conductive features, and wherein the plurality of layers of back-side conductive features include a back-side power rail and a back-side I/O pin.

12. A device comprising:

a transistor structure;

a front-side interconnect structure on a front side of the transistor structure, the front-side interconnect structure including a front-side power delivery network (PDN) and a front-side input/output (I/O) pin; and

a back-side interconnect structure on a back side of the transistor structure, the back-side interconnect structure including a back-side PDN in electrical communication with a power supply voltage, wherein the back-side PDN is in contact with a backside of a source/drain region of the transistor structure though a power rail.

13. The device of claim 12 , further comprising:

a carrier substrate; and

a bonding layer bonding the carrier substrate to the front-side interconnect structure.

14. The device of claim 12 , the back-side interconnect structure further including a back-side I/O pin.

15. The device of claim 12 , wherein the front-side interconnect structure includes a plurality of layers of front-side conductive features, wherein the front-side PDN and the front-side I/O pin are in an topmost layer of the plurality of layers of front-side conductive features, and wherein the topmost layer is thicker than other layers of the plurality of layers of front-side conductive features.

16. A method comprising:

forming a transistor structure on a semiconductor substrate;

forming a front-side interconnect structure over a front side of the transistor structure, wherein forming the front-side interconnect structure includes:

forming a front-side power delivery network (PDN) and a front-side input/output (I/O) pin in the front-side interconnect structure;

removing the semiconductor substrate; and

forming a back-side interconnect structure over a back side of the transistor structure, wherein forming the back-side interconnect structure includes:

forming a back-side PDN in the back-side interconnect structure.

17. The method of claim 16 , wherein forming the back-side interconnect structure further comprises:

forming a back-side I/O pin in the back-side interconnect structure.

18. The method of claim 16 , wherein forming the front-side interconnect structure comprises:

forming the front-side PDN and the front-side I/O pin in a top layer of a plurality of layers of front-side conductive features, wherein the top layer is thicker than other layers of the plurality of layers of front-side conductive features.

19. The method of claim 16 , further comprising:

forming a bonding layer bonding a carrier substrate to the front-side interconnect structure.

20. The method of claim 16 , further comprising:

patterning openings to expose the front-side PDN and the front-side I/O pin;

filling the openings with a conductive material;

removing the back-side interconnect structure;

electrically connecting a front-side tester to the front-side PDN and the front-side I/O pin through the conductive material; and

running the front-side tester to detect a defect location of the transistor structure.