Radiant energy – Inspection of solids or liquids by charged particles – Electron probe type
Patent
1988-02-09
1988-12-13
Anderson, Bruce C.
Radiant energy
Inspection of solids or liquids by charged particles
Electron probe type
250311, 250306, 250309, 250397, 250307, 250396ML, H01J 37153
Patent
active
047912952
ABSTRACT:
An apparatus using an electron beam for repeatedly scanning a specimen. The apparatus has an xy stigmator equipped with x-axis and y-axis coils to which correcting currents I.sub.x and I.sub.y are respectively fed. The values of these correcting currents are systematically varied for every scan. The signal emanating from the specimen is converted into a signal D indicating the diameter of the beam moving in a direction during each scan. When the signal D indicates that the diameter of the beam assumes its minimum value, the values of the correcting currents fed to the x-axis and y-axis coils are determined about two perpendicular directions of scan. The combinations of these values are referred to as I.sub.xa, I.sub.ya and I.sub.xb, I.sub.yb. Finally, the correcting currents I.sub.x, I.sub.y fed to the coils are set to (I.sub.xa +I.sub.xb)/2 and (I.sub.ya +I.sub.yb)/2, respectively.
REFERENCES:
patent: 4214163 (1980-07-01), Namae et al.
patent: 4392054 (1983-07-01), Sato et al.
patent: 4567369 (1986-01-01), Smith et al.
Anderson Bruce C.
Berman Jack I.
Jeol Ltd.
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