| 摘要 |
PROBLEM TO BE SOLVED: To measure dimensions highly accurately without depending on a device structure of an LSI, by detecting a first and a second signals as modulation frequency-related components of secondary electrons generated by inadiation with electron beams, and calculating dimensions from phase signal of the first and second signals. SOLUTION: A first detector 26 and a second detector 27 for detecting secondary electrons are arranged to be symmetric to optical axis 15 of an object lens 1 in the vicinity of a pattern 3 to be measured. Filters 30, 31 are set in the back of the detectors 26, 27 respectively to remove noise components from signals detected at the detectors 26, 27 and take out only components of a frequency twice a modulation frequency. A first signal 28 and a second signal 29 are generated through the filters 30, 31, and sent to a phase detector 35. Phase difference of the signals 28 and 29 is detected at the detector 35. A size corresponding to the phase difference is detected at an operating device 36. |
