Patent Number: 
Section: claims

1. An electron-beam metrology system comprising:a specimen stage to mount a specimen on which a device pattern is formed;electron optics to radiate the device pattern with an electron-beam;a secondary electron detector to detect a secondary electron generated by the radiation of the electron-beam; andan information processing system to analyze a signal obtained from the secondary electron detector;wherein a standard reference for metrology is held on the specimen stage; andwherein the standard reference comprises:a first grating unit pattern including an array of gratings having pitch sizes which are verified by an optical method;a second grating unit pattern including an array of gratings having pitch sizes which are smaller than the pitch sizes of the first grating unit pattern; anda positioning mark. 2. An electron-beam metrology system according to claim 1, wherein parallelism of a moving direction of the specimen stage is corrected on the basis of the positioning mark. 3. An electron-beam metrology system according to claim 1, wherein the positioning mark is used to search for the first grating pattern. 4. An electron-beam metrology system according to claim 1, wherein a measurement result of the device pattern is calibrated utilizing information obtained from the standard reference. 5. An electron-beam metrology system according to claim 4, further comprising a display on which the calibrated measurement result is displayed. 6. An electron-beam metrology system according to claim 1, further comprising:storage means which stores a size standard value for metrology;wherein the size standard value is an average value of plural pitch sizes of the second grating unit obtained by plural measurements of the second grating unit. 7. An electron-beam metrology system according to claim 6, wherein the information processing system confirms whether the stored size standard value satisfies a predetermined correctness or not by comparing a measurement result of a pitch size of the first grating unit pattern and the verified pitch size by the optical method. 8. An electron-beam metrology system according to claim 7, wherein a reference value for the confirmation is stored in the storage means. 9. An electron-beam metrology system according to claim 7, further comprising a display which displays an alarm when the size standard value does not satisfy the predetermined correctness. 10. An electron-beam metrology system according to claim 1, wherein the information processing system measures a size of the device pattern using the pitch size of the second grating pattern as the size standard, and verifies the measurement result by comparing a measurement result of a pitch size of the first grating unit pattern and the verified pitch size by the optical method. 11. An electron-beam metrology system according to claim 10, further comprising a display which displays an alarm when the measurement result is not verified. 12. An electron-beam metrology system comprising:a specimen stage to mount a specimen on which a device pattern is formed;electron optics to radiate the device pattern with an electron-beam;a secondary electron detector to detect a secondary electron generated by the radiation of the electron-beam;an information processing system to analyze a signal obtained from the secondary electron detector; andstoring means which stores a size standard value for measuring a size of the deice pattern;wherein the size standard value stored in the storing means is obtained by using a standard reference comprising:a first grating unit pattern including an array of gratings having pitch sizes which are verified by an optical method; anda second grating unit pattern including an array of gratings having pitch sizes which are smaller than the pitch sizes of the first grating unit pattern. 13. An electron-beam metrology system according to claim 12, the size standard is an average value of plural pitch sizes of the second grating unit obtained by a plural measurements of the second grating unit. 14. An electron-beam metrology system according to claim 13, the size standard is verified by comparing a measurement result of a pitch size of the first grating unit pattern and the verified pitch size by the optical method.