Patent ID: 7205551
Filing Date: 2007-04-17
Classification: H01J

Abstract:
1. A method of correcting chromatic aberrations in a charged-particle beam comprising the steps of: scanning the charged-particle beam as a probe over a surface of the specimen to obtain scanned images: extracting probe profiles from the scanned images: calculating chromatic aberrations in the beam from the extracted probe profiles: and correcting the chromatic aberrations in the beam based on the calculated chromatic aberrations, wherein the scanned images from which the probe profiles are extracted during said step of extracting the probe profiles consist of first through fifth scanned images, the first scanned image being obtained when the charged-particle beam is just in focus on the specimen surface, the second scanned image being obtained when the beam has been underfocused on the specimen surface under conditions where the energy of the charged particles has been varied by +E, the third scanned image being obtained when the beam has been overfocused under conditions where the energy of the charged particles has been varied by +E, the fourth scanned image being obtained when the beam has been underfocused on the specimen surface under conditions where the energy of the charged particles has been varied by −E, and the fifth scanned image being obtained when the beam has been overfocused on the specimen surface under conditions where the energy of the charged particles has been varied by −E, and wherein chromatic aberrations in the beam are calculated during said step of calculating the chromatic aberrations based on the line profiles found based on the probe profiles.