Patent ID: 7643139

Claim:
A defect detecting method comprising the steps of: projecting a first laser beam having a wavelength in the range of 210 to 390 nm on a surface of a sample from a first direction inclined at an angle between 3° and 30° to the surface of the sample by projection of the first laser beam, the sample being a SOI wafer which has an oxide film layer and a SOI layer; detecting light scattered from the surface of the sample by projection of the first laser beam; projecting a second laser beam having a second wavelength in the range of 210 to 390 mm on the surface of the sample from a second direction inclined to the surface of the sample; detecting light scattered from the surface of the sample by projection of the second laser beam; and detecting defects including sizes below 0.1 μm formed on the surface of the sample by processing detection signals provided upon the detection of scattered light by projection of the first laser beam and the detection scattered light by projection of the second laser beam; wherein in the step of projecting the first laser beam, said first laser beam is S polarized laser beam and a penetration depth of the first laser beam into the SOI layer formed on the surface of the sample is 10 nm or below in a condition when a reflectance of the first laser beam is 70% or above.