Charged particle beam apparatus
View Patent ↗With a multi-beam type charged particle beam apparatus, and a projection charged particle beam apparatus, in the case of off-axial aberration corrector, there is the need for preparing a multitude of multipoles, and power supply sources in numbers corresponding to the number of the multipoles need be prepared. In order to solve this problem as described, a charged particle beam apparatus is provided with at least one aberration corrector wherein the number of the multipoles required in the past is decreased by about a half by disposing an electrostatic mirror in an electron optical system.
1. A charged particle beam apparatus comprising:
a charged particle source;
a stage for supporting a specimen;
a beam separator;
an electrostatic mirror disposed in a path of charged particles emitted from the charged particle source, between the charged particle source and the stage; and
an aberration corrector disposed between the beam separator and the electrostatic mirror, in a section of the path of the charged particles between the charged particle source and the electrostatic mirror, and a section of the path of the charged particles between the electrostatic mirror and the stage, for use in common with both of those sections of the path;
wherein a field where the aberration corrector is formed is made up of magnetic quadrupole fields in combination with electrostatic octupole fields for correction of off-axial aberration, and
wherein the magnetic quadrupole fields are symmetric with respect to a symmetry plane and the electrostatic octupole fields are antisymmetric with respect to the symmetry plane.
2. The charged particle beam apparatus according to claim 1 ,
wherein the beam separator is disposed in a section of the path of the charged particles between the charged particle source and the aberration corrector, and a section of the path of the charged particles between the aberration corrector and the stage, for use in common with both of those sections of the path.
3. The charged particle beam apparatus according to claim 1 , wherein the aberration corrector includes an electron lens.
4. The charged particle beam apparatus according to claim 1 , further comprising:
a multi-beams forming unit for turning the charged particles into a plurality of charged particle beams, disposed between the charged particle source, and the aberration corrector, and
a detector for detecting secondary charged particles generated from the specimen due to application of the plurality of charged particle beams to the specimen.
5. The charged particle beam apparatus according to claim 1 , wherein the electrostatic mirror is comprised of a plurality of electrodes divided in a circumferential direction of the electrostatic mirror.
6. The charged particle beam apparatus according to claim 1 , wherein the electrostatic mirror is comprised of a plurality of electrodes divided in the shape of concentric circles.
7. The charged particle beam apparatus according to claim 1 , wherein the charged particles pass through the aberration corrector twice due to respective tracks of the charged particles, being reflected by the electrostatic mirror.
8. The charged particle beam apparatus according to claim 1 , wherein the aberration corrector includes a twelve pole, for correction of off-axial aberration.
9. A charged particle beam apparatus comprising:
a charged particle source;
a stage for supporting a specimen;
an electrostatic mirror disposed in a path of charged particles emitted from the charged particle source, between the charged particle source and the stage;
an aberration corrector disposed in a section of the path of the charged particles between the charged particle source and the electrostatic mirror, and a section of the path of the charged particles between the electrostatic mirror and the stage, for use in common with both of those sections of the path;
a second electrostatic mirror disposed in a section of the path of the charged particles between the aberration corrector and the stage, and
a second aberration corrector disposed in a section of the path of the charged particles between the aberration corrector, and the second electrostatic mirror, and a section of the path of the charged particles, between the second electrostatic mirror and the stage, for use in common with both of those sections of the path.
10. The charged particle beam apparatus according to claim 9 , further comprising:
a beam separator disposed in a section of the path of the charged particles between the charged particle source and the aberration corrector, a section of the path of the charged particles between the aberration corrector and the second aberration corrector, and a section of the path of the charged particles between the second aberration corrector and the stage, for use in common with those three sections of the path.