[caf]

In some places, you've shown the same part of the circuit both with and without the metal layers. How did you find the same location on the die after taking the die out of the microscope, removing the additional layers and putting it back?

[kens]

I figured that I would want to study the standard-cell circuits, so I made a detailed panorama of one column of standard-cell circuits with the metal. Then after removing the metal, I made a second panorama of the same column. This made it easy to flip back and forth. (Of course, it would be nice to have a detailed panorama of the entire chip, but it would take way too long.)