Patent Number: 
Section: claims

1. An electron beam measurement apparatus, which measures, based on information on an image, a pattern formed on a sample, comprising an electron optical system that has a lens and a deflector and scans a predetermined observation region on the sample with an electron beam emitted from an electron source, a detector for detecting a charged particle secondarily generated from the sample by irradiation with the electron beam, and means for forming an image based on the detected charged particle, the patterns being delineated in a single layer present on a substrate by a multi-exposure method, the electron beam measurement apparatus including:means for classifying patterns, which are included in an image acquired by the irradiation with the electron beam on the patterns on the sample, into groups according to an exposure history record, the exposure history record being acquired based on brightness of the patterns included in the image and a difference between shapes of white bands of the patterns. 2. The electron beam measurement apparatus according to claim 1, whereinthe patterns are classified into the groups based on an image formed based on a secondary electron of the charged particle and an image formed based on a reflective electron of the charged particle. 3. The electron beam measurement apparatus according to claim 1, whereinthe patterns are classified into the groups according to the exposure history record by comparing the acquired image with a design database. 4. The electron beam measurement apparatus according to claim 1, whereinthe patterns are classified into the groups such that a pattern having portion arranged alternately is included in one of the groups that is different from the other group including the other pattern. 5. The electron beam measurement apparatus according to claim 1, whereinan image processing parameter or an waveform processing parameter is used for each of the classified groups to obtain the size of a portion of the pattern included in the group or the position of the contour of the portion of the pattern, the used parameter varying depending on the group. 6. The electron beam measurement apparatus according to claim 1, whereina reference image or a reference waveform is used for each of the classified groups to obtain the size of a portion of the pattern included in the group or the position of the contour of the portion of the pattern, the used reference image or the used reference waveform varying depending on the group. 7. The electron beam measurement apparatus according to claim 1, whereininformation on a relative positional relationship between the classified groups is obtained. 8. An electron beam measurement apparatus, which measures, based on information on an image, a pattern formed on a sample, comprising an electron optical system that has a lens and a deflector and scans a predetermined observation region on a sample with an electron beam emitted from an electron source, a detector for detecting a charged particle secondarily generated from the sample by irradiation with the electron beam, and means for forming an image based on the detected charged particle, the patterns being delineated in a single layer present on a substrate by a multi-exposure method, the electron beam measurement apparatus including:means for classifying the patterns in the plurality of images into a plurality of groups according to an exposure history record by irradiating patterns with the electron beam to acquire a plurality of images respectively indicating regions that mostly overlap each other under respective image acquisition conditions different from each other, whereinany of the images that is acquired under any of the image acquisition conditions is used for any of the groups to obtain the size of a portion of the pattern included in the group or the position of the contour of the portion of the pattern, the image acquisition condition varying depending on the group. 9. The electron beam measurement apparatus according to claim 1, whereinthe patterns are delineated on the sample by a double patterning technique. 10. The electron beam measurement apparatus according to claim 1, whereinthe image formed based on the detected charged particle is a scanning electron microscope image. 11. The electron beam measurement apparatus according to claim 8, whereinthe patterns are delineated on the sample by a double patterning technique. 12. The electron beam measurement apparatus according to claim 8, whereinthe image formed based on the detected charged particle is a scanning electron microscope image.