Wafer inspection apparatus with unique illumination methodology and method of operation
US6768543B1 · kind B1 · utility
Inventor
Key dates
| Filing date | Oct 30, 2002 |
| Grant date | Jul 27, 2004 |
| Priority date | — |
| Expiry date | Oct 30, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/956
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A wafer inspection apparatus 10 having a stage with a support surface 42 on which a wafer substrate may rest. The wafer stage is capable of moving the wafer in (x, y) or (r, &thgr;) mode to achieve complete wafer scan. Polarized light from a monochromatic source 12 is directed towards the wafer surface 22. The state of polarization of the beam entering PBS 51 is either s- or p- or circular depending on the exemplary embodiment of the invention. Alternatively, both s- and p-polarization components are simultaneously present with the optical frequency of one of them shifted by &Dgr;f with respect to the other. The reflected light is sensed by detector(s) 16 or 160 and 161. A processor in communication with the detector(s) can generate image of the wafer surface based on reflectance data from a plurality of points generated via wafer (r, &thgr;) scan. The polarizing beam splitters (PBS) 51 and 52 along with the turning mirrors 71 through 76 are configured such that every ray from the source that is directed toward PBS 51 is propagated in two orthogonal planes of incidence. In another exemplary embodiments, two images of the wafer surface taken simultaneously with two counter propagati…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.