Circuit tracing using a focused ion beam

1. A method for identifying functional componentry associated with a switchable power interface on an integrated circuit, wherein the switchable power interface comprises a source and a drain with a control switch therebetween, said control switch being controllable by a control signal during operation of the integrated circuit, the method comprising:

connecting, with deposited conductive material, the source and the drain;

applying an external voltage bias to a power input of the switchable power interface via one of the source and the drain;

exposing the integrated circuit to a focused ion beam; and

gathering an image of the integrated circuit during exposure to determine areas of high contrast indicating functional componentry in operative connection with the switchable power interface.

2. The method of claim 1 , wherein the switchable power interface is a power switch transistor.

3. The method of claim 1 , wherein the functional componentry comprises one or more functional transistors.

4. The method of claim 1 , wherein the functional componentry comprises at least a portion of a processing core in a multi-core processor.

5. The method of claim 1 , wherein the deposited conductive material is deposited by said focused ion beam.

6. The method of claim 1 , wherein a prior image of the integrated circuit is gathered with a prior external voltage bias applied to the power input prior to the step of connecting the source and the drain, said prior image for comparing to the image in isolating said areas of high contrast.

7. A method for identifying distinctly powered functional blocks on an integrated circuit, each of the functional blocks powered via respective power interfaces of a switchable power interface on the integrated circuit, the method comprising:

applying an external voltage bias to the switchable power interface;

imaging the integrated circuit using a focused ion beam;

identifying imaged components exhibiting high contrast as representative of the respective power interfaces;

conductively closing a selected one of the identified imaged components;

imaging the integrated circuit using said focused ion beam; and

identifying an area of high contrast as representative of a given one of the distinctly powered functional blocks as being operatively powered via said selected one of the respective power interfaces.

8. The method of claim 7 , wherein said imaged components consist of power switch transistors, and wherein said conductively closing comprises shorting a selected one of said power switch transistors.

9. The method of claim 8 , wherein said shorting comprises shorting source and drain nodes of said selected one of said power switch transistors.

10. The method of claim 7 , wherein said area of high contrast is representative of a powering circuit of said given one of the distinctly powered functional blocks.

11. The method of claim 7 , wherein said conductive closing comprises depositing conductive material using said ion beam.

12. A method for identifying distinctly powered functional blocks on an integrated circuit, each of the functional blocks powered via respective power interfaces of a switchable power interface on the integrated circuit, the method comprising:

identifying the respective power interfaces;

conductively closing a selected one of the respective power interfaces;

applying an external voltage bias to the switchable power interface;

imaging the integrated circuit using a focused ion beam; and

identifying an area of high contrast as representative of a given one of the distinctly powered functional blocks as being operatively powered via said selected one of the respective power interfaces.

13. The method of claim 12 , wherein said identifying comprises, prior to said conductively closing:

imaging the integrated circuit using a focused ion beam; and

identifying imaged components exhibiting high contrast as representative of the respective power interfaces.

14. The method of claim 12 , wherein said respective power interfaces consist of power switch transistors, and wherein said conductively closing comprises shorting a selected one of said power switch transistors.

15. The method of claim 14 , wherein said shorting comprises shorting source and drain nodes of said selected one of said power switch transistors.

16. The method of claim 12 , wherein said area of high contrast is representative of a powering circuit of said given one of the distinctly powered functional blocks.

17. The method of claim 12 , wherein said conductive closing comprises depositing conductive material using said ion beam.

18. A method for identifying a switchable power interface on an integrated circuit, wherein the switchable power interface comprises a source and a drain with a control switch therebetween, the control switch being controllable by a control signal during operation of the integrated circuit, the method comprising:

applying an external voltage bias to a power input on the integrated circuit;

gathering an image of the integrated circuit when exposed to an ion beam; and

identifying an endpoint of an area of high contrast indicating conductive connectivity with said power input, said endpoint identifying the switchable power interface having the source and the drain.

19. The method of claim 18 , wherein the method further comprises connecting, with a deposited conductive material, the source and the drain.

20. The method of claim 19 , wherein the method further comprises gathering a second image of the integrated circuit after said connecting, and comparing said second image to identify areas of high contrast shown solely in said second image and thus indicative of functional componentry in operative connection with said switchable power interface.

21. The method of claim 19 , wherein said deposited conductive material is deposited by said ion beam.

22. The method of claim 20 , wherein said functional componentry is at least a portion of a processing core in a multi-core processor.

23. A device for identifying distinctly powered functional blocks on an integrated circuit, each of the functional blocks powered via respective power interfaces of a switchable power interface on the integrated circuit, the device comprising:

a focused ion beam emitter for directing an ion beam at a substrate;

a secondary electron detector for measuring at each of a plurality of locations on the substrate respective intensities of secondary electrons emitted from the substrate when exposed to the ion beam, each said measured intensity for generating image data indicative of features at each said respective location; and

a bias applicator for connecting an external voltage bias to a portion of the integrated circuit conductively associated with said switchable power interface;

wherein differences in regions of high contrast in respective images of said integrated circuit taken before and after shorting said switchable power interface indicate a distinctly powered functional block on said integrated circuit.

24. The device of claim 23 , wherein the focused ion beam emitter is configured to deposit conductive material for shorting said switchable power interface.

25. The device of claim 24 , wherein said switchable power interface is a power switch transistor.