Patterned Wafer Scanner
Original Publication Date: 1985-Mar-01
Included in the Prior Art Database: 2005-Feb-18
This optical scanner and associated electronics detect particulates on a patterned wafer by analyzing the intensity, polarization and azimuthal distribution of light scattered from a scanned spot. It provides a non-destructive on-line inspection of patterned silicon wafers. This scanner avoids mechanical contact with the wafer, using a normally incident, flying-spot excitation light source. Small scanner spot size reduces grating-like effects and increases detection of small particles. This scanner distinguishes light scattering off of particulates from light scattering off of deliberate structures by looking for a signature. After performing as much optical processing as possible, chip-to-chip periodicity on the wafer eliminates false counts.