| 摘要 |
A measurement instrument which detects the thickness of the outer layer of a wafer 24, includes a filtered white light source forming an aperture image. The white light source includes a halogen lamp 10, a condensing lens 12, a circular aperture 14, a collimator lens 16, a narrow band filter wheel 18, and a second collimator lens 20. A monochromatic beam generated by this filtered white light source illuminates the entire surface of the wafer 24 with collimated light that has passed through a third collimator lens 22. The light reflected off the wafer 24 returns through the third collimator lens 22 and forms an aperture image upon an optical device which redirects this image to a charge coupled device (CCD) camera 30. The image is converted to a map of measured reflectance data by a digitizing circuit 34 and a computer 36. This map of measured reflectance data is then self-normalized and compared to reference reflectance data to generate a map of the outer layer thickness profile of the wafer 24.
|
