Patent ID: 7569819

Claim:
An electron beam system having a function of obtaining a backscattered electron image by directing a sharply focused electron beam at a surface of a specimen and detecting backscattered electrons emanating from the specimen, said electron beam system comprising: accelerating voltage-setting means for setting an accelerating voltage of the electron beam; emission current-measuring means for measuring an emission current of the electron beam; signal intensity-measuring means for measuring intensity of an output signal from an amplifier that amplifies an output signal from a backscattered electron detector; amplification factor-adjusting means for adjusting an amplification factor of the amplifier such that contrast of the backscattered electron image is varied by increasing or reducing intensity of the output signal from the amplifier; offset-adjusting means for adjusting an offset of the amplifier such that brightness of the backscattered electron image is varied by increasing or reducing a DC component of the output signal from the amplifier; storage means for storing the intensity of the output signal from the amplifier, amplification factor, and offset when the intensity of a backscattered electron signal was measured under conditions including at least one of a reference accelerating voltage and a reference emission current and using a reference specimen having a known average atomic number; and calculational means for finding an amplification factor and an offset of the amplifier to make a correction such that the amplifier produces a signal intensity equal to the intensity of the backscattered electron signal produced under conditions including at least one of the reference accelerating voltage and the reference emission current when at least one of accelerating voltage and emission current that has been set is varied from the reference accelerating voltage and/or the reference emission current, wherein when the backscattered electron image is obtained under conditions including at least one of an arbitrary accelerating voltage and an arbitrary emission current, the calculational means finds an amplification factor and an offset of the amplifier at which the amplifier produces an intensity equal to the intensity of the backscattered electron signal obtained under the conditions including at least one of the reference accelerating voltage and the reference emission current, based on the intensity of the output signal from the amplifier, amplification factor, and offset obtained when the intensity of the backscattered electron signal was measured under the conditions including at least one of the reference accelerating voltage and the reference emission current stored in the storage means, and wherein the amplification factor-adjusting means and the offset-adjusting means adjust the amplification factor and the offset of the amplifier, respectively, such that the found amplification factor and offset are achieved.