Layout overlay for FIB operations
US5401972A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 2, 1993 |
| Grant date | Mar 28, 1995 |
| Priority date | — |
| Expiry date | Sep 2, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/31742
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Focused ion bean (FIB) milling through a power plane of a device to expose or cut a hidden, lower-layer conductor requires accurate positioning relative to the hidden conductor of a box defining boundaries of the FIB operation. This can in general be done by aligning surface information (topology or voltage contrast) visible in a FIB or scanning electron microscope (SEM) image with an overlay image generated from stored data describing the device. The location of the hidden conductor relative to the visible surface information is determined from the stored data. Advanced integrated circuits often do not provide enough unique surface information near the FIB operation area to align the images with sufficient accuracy. In accordance with the invention, the imaging area is accurately deflected electronically (without moving the stage or changing the operating conditions of the FIB) to permit alignment over a much larger area, while maintaining pixel resolution and overlay accuracy needed to accurately position the FIB operation box.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.