Patent ID: 7456403

Claim:
A charged particle beam device, having a source of charged particles for emitting a charged particle beam and a sample stage for placing a sample under the charged particle beam, the charged particle beam device further comprising: an object lens for generating a magnetic field to focus the charged particle beam toward the sample; a transmitted signal conversion member for emitting secondary charged particles by collisions of charged particles transmitted through the sample; and a charged particle detector for detecting the secondary charged particles emitted from the transmitted signal conversion member; wherein the object lens generates the magnetic field under the object lens so that the magnetic field prevents charged particles emitted from the sample surface from reaching the charged particle detector, wherein the transmitted signal conversion member is positioned on the path of the charged particles passing through the sample, and for converting the charged particles passing through the sample into secondary charged particles, and wherein the transmitted signal conversion member has an opening through which the charged particles passing through the sample pass, and the opening has an electrode to which a positive voltage is applied.