Patent ID: 6784425
Filing Date: 2004-08-31
Classification: H01J

Abstract:
A method for inspecting a specimen by detecting electrons that scatter from the specimen comprising:scanning and directing an electron beam to irradiate a spot on the specimen, the electron beam causing the electrons to scatter from the irradiated spot on the specimen; setting a high pass filter at a first voltage level, the first voltage level being predetermined; detecting the scattered electrons with the high pass filter that is set at the first voltage level, the high pass filter detecting a first electron intensity level of the scattered electrons; setting the high pass filter at a second voltage level, the second voltage level being predetermined; detecting the scattered electrons with the high pass filter that is set at the second voltage level, the high pass filter detecting a second electron intensity level of the scattered electrons; determining a differential electron intensity level, which is the difference between the first electron intensity level and the second electron intensity level, whereby the differential electron intensity level is the electron intensity level in an energy window between the first and second voltage level; and repeating each of the setting, detecting and determining operations to obtain additional differential electron intensity levels for successively irradiated spots along the scanned specimen, whereby the plurality of determined differential electron intensity levels provide inspection information about the specimen.