Method and system of using a scanning electron microscope in semiconductor wafer inspection with Z-stage focus
US6791095B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 21, 2002 |
| Grant date | Sep 14, 2004 |
| Priority date | — |
| Expiry date | Mar 21, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J2237/20292
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A method for inspecting a semiconductor wafer using an SEM having a nominal focal plane and operable for guiding a beam. The SEM having a stage movable in each of an X-, Y-, and Z-direction, including moving the SEM stage in the XY-direction to a first location for inspection, optically sensing the location of the top surface of an area in relation to the focal plane of the stage, adjusting the position of the stage in the Z-direction so that the top surface of the area is substantially at the focal plane, inspecting the areas, and moving the stage in the XY-direction to the next location such that the next area is under the SEM beam for inspection. The Z-stage using a non-contact optical sensor to provide feedback to drive a plurality of piezoelectric actuator to move the wafer to the focal plane.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.