Method for evaluating a region of an object

1. A method for evaluating an object with a tool having a charged particle imager and a charged particle miller, the method comprising:

applying an iterative imaging and milling process to a region of the object having a plurality of vertically stacked layers formed thereon, the iterative imaging and milling process comprising:

(a) acquiring, by the charged particle imager, a charged particle image of a first sub-region of the region;

(b) milling, by the charged particle miller and along a milling plane oriented non-parallel to the plurality of vertically stacked formed on the object, the sub-region to expose another sub-region of the region directly below the milled first sub-region; and

(c) repeating the acquiring and milling steps for each of a plurality of sub-regions below the first sub-region of the region until a penultimate sub-region of the region;

acquiring, by the charged particle imager, a charged particle image of a last sub-region of the region directly below the penultimate sub-region; and

generating three-dimensional information about a content of the region based on charge particle images of the first sub-region through the last sub-region of the region.

2. The method according to claim 1 wherein each sub-region in the first through last sub-regions comprises a layer from the plurality of vertically stacked layers of the object.

3. The method according to claim 1 wherein the sub-regions are oriented in relation to the plurality of vertically stacked layers of the object.

4. The method according to claim 1 wherein the acquiring of the charged particle image of each sub-region of the region comprising illuminating the sub-region with a charged particle beam that has an interaction depth that exceeds a depth of the sub-region.

5. The method according to claim 1 wherein the acquiring of the charged particle image of each sub-region of the region is preceded by performing a registration between the sub-region and a previously milled sub-region.

6. The method according to claim 1 wherein the acquiring of the charged particle image of each sub-region out of the first sub-region until the penultimate sub-region is followed by moving the object between a first location in which the object is accessible to the charged particle imager and out of a field of view of the charge particle miller to a second location in which the object is accessible to the charged particle miller and is out a field of view of the charged particle imager.

7. The method according to claim 1 further comprising:

repeating, for each sub-region out of a first sub-region of an additional region until a penultimate sub-region of the additional region, the steps of: (a) acquiring, by a charged particle imager, a charged particle image of the sub-region; and (b) milling, by a charged particle miller, the sub-region to expose another sub-region of region;

acquiring, by the charged particle imager, a charged particle image of a last sub-region of the additional region; and

generating three-dimensional information about a content of the additional region based on charge particle images of the first sub-region till last sub-region of the additional region.

8. The method according to claim 7 wherein the region and the additional region differ from each other by depth.

9. The method according to claim 7 wherein the region and the additional region differ from each other by a number of layers.

10. The method according to claim 1 wherein the charged particle imager is parallel to the charged particle miller.

11. The method according to claim 1 wherein the charged particle imager is oriented in relation to the charged particle miller.

12. The method according to claim 1 wherein the charged particle imager is a scanning electron microscope.

13. The method according to claim 1 wherein the charged particle image of each sub-region is a backscattered electron image of the sub-region.

14. The method according to claim 1 wherein the charged particle image of each sub-region is a secondary electron image of the sub-region.

15. The method according to claim 1 wherein the charged particle image of each sub-region is a combination of a secondary electron image of the sub-region and of a backscattered electron image of the sub-region.

16. A computer-readable memory product that stores instructions that, once executed by a computerized tool that includes a mechanical stage, a charged particle imager and a charged particle miller, cause the computerized tool to evaluate a region of an object having a plurality of vertically stacked layer formed thereon and positioned on the mechanical stage by performing the steps of:

(a) acquiring, by the charged particle imager, a charged particle image of a first sub-region of the region;

(b) milling, by the charged particle miller and along a milling plane oriented non-parallel to the plurality of vertically stacked formed on the object, the sub-region to expose another sub-region of the region directly below the milled first sub-region; and

(c) repeating the acquiring and milling steps for each of a plurality of sub-regions below the first sub-region of the region until a penultimate sub-region of the region;

acquiring, by the charged particle imager, a charged particle image of a last sub-region of the region directly below the penultimate sub-region; and

generating three-dimensional information about a content of the region based on charge particle images of the first sub-region till last sub-region of the region.

17. The method according to claim 1 wherein the charged particle imager is a scanning electron microscope and the charged particle miller is a focused ion beam device.

18. The method according to claim 17 wherein each sub-region in the first through last sub-regions comprises a layer from the plurality of vertically stacked layers of the object.

19. The method according to claim 17 wherein the object is positioned on a mechanical stage and disposed in a vacuum chamber and wherein the charged particle imager and the charged particle miller direct beams of electrons and ions, respectively, into the chamber towards the region of the object having a plurality of vertically stacked layers formed thereon.

20. The method according to claim 1 wherein milling by the charged particle miller is an angle diagonal to an upper surface of the object.