Detection system for nanometer scale topographic measurements of reflective surfaces
US8384903B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 3, 2008 |
| Grant date | Feb 26, 2013 |
| Priority date | — |
| Expiry date | Aug 19, 2028 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/9501
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A linear position array detector system is provided which imparts light energy to a surface of a specimen, such as a semiconductor wafer, receives light energy from the specimen surface and monitors deviation of the retro or reflected beam from that expected to map the contours on the specimen surface. The retro beam will, with ideal optical alignment, return along the same path as the incident beam if and only if the surface is normal to the beam. The system has a measurement device or sensor within the path of the retro or reflected beam to measure deviation of the retro beam from expected. The sensor is preferably a multiple element array of detector-diodes aligned in a linear fashion. A unique weighting and summing scheme is provided which increases the mechanical dynamic range while preserving sensitivity. The system further includes a bright field Nomarski Differential Interference Contrast sensor used to split the beam into two beams and for scanning in an orientation orthogonal to the orientation of the optical lever created by the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.