As shown in Fig1, the only visible layer is the Top metal layer. The lower metal layers become invisible because of the Chemical-Mechanical Process (CMP). Sometimes the desired FIB locations are on the lower metal layers, as shown on Fig2.

As shown on Fig2, the Blue metal layer is the Top metal layer and the Red metal layer is the underneath metal layer. Both Fig1 and Fig2 show the same area of the layout. Clearly, the Blue metal layer is visible from Fig1 but Red metal layer drops off from Fig1 because of the CMP process. Assume we need to make a connection between the two points indicated in Fig2, this would be very difficult, if not impossible, without the help of the Navigation software to pin-point the locations on the Red metal layer that is invisible under either the Microscope of SEM/FIB machine.

The Knight’s Navigation software will allow us to overlap these two different images together, as shown on Fig3. Since we can easily find the locations in the layout, we can use the layout locations to guide us to the locations on the real silicon. With the help of the Navigation software, we can “see” the layers that are otherwise invisible with either the Microscope of SEM/FIB machines.

We take GDS2 files in various medias. If the metal operations are desired, then only the metal layers are required in GDS2 format.