Focal mechanism and method for controlling focal point position, and apparatus and method for inspecting semiconductor wafer
US6541747B1 · kind B1 · utility
Assignees
Inventors
Key dates
| Filing date | Sep 14, 2000 |
| Grant date | Apr 1, 2003 |
| Priority date | — |
| Expiry date | Sep 14, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B7/36
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
For effecting auto-focussing of an objective lens used for observing a semiconductor wafer, a semiconductor microscopic device includes an inspection stage for supporting a semiconductor wafer and an objective lens for observing the semiconductor wafer. For automatic focussing of the objective lens, a defocussing magnitude of a light spot is detected using a knife edge. A collimator lens is oscillated by a voice coil motor to oscillate the light spot on the wafer. A peak value of the defocussing quantity detected at this time is peak-held to generate a position detection signal. The inspection stage is vertically moved so that this position detection signal will be equal to a pre-set target value.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.