High throughput brightfield/darkfield wafer inspection system using advanced optical techniques
US6816249B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 17, 2001 |
| Grant date | Nov 9, 2004 |
| Priority date | — |
| Expiry date | Jul 17, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/8825
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The broadband brightfield/darkfield wafer inspection system provided receives broadband brightfield illumination information via a defect detector, which signals for initiation of darkfield illumination. The defect detector forms a two dimensional histogram of the defect data and a dual mode defect decision algorithm and post processor assess defects. Darkfield radiation is provided by two adjustable height laser beams which illuminate the surface of the wafer from approximately 6 to 39 degrees. Each laser is oriented at an azimuth angle 45 degrees from the orientation of the manhattan geometry on the wafer, and 90 degrees in azimuth from one another. Vertical angular adjustability is provided by modifying cylindrical lens position to compensate for angular mirror change by translating an adjustable mirror, positioning the illumination spot into the sensor field of view, rotating and subsequently moving the cylindrical lens. A brightfield beamsplitter in the system is removable, and preferably replaced with a blank when performing darkfield illumination. Light level control for the system is provided by a dual polarizer first stage. Light exiting from the second polarizer passes th…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.