Charged particle beam application device
The charged particle beam application device is provided with a charged particle source and an objective lens that converges charged particle beam generated by the charged particle source onto a sample. In this case, the charged particle beam application device is further provided with an aberration generating element installed between the charged particle beam source and the objective lens, a tilt-use deflector installed between the aberration generating element and the objective lens, a deflection aberration control unit for controlling the aberration generating element, a first electromagnetic field superposing multipole installed between the aberration generating element and the objective lens, and an electromagnetic field superposing multipole control unit for controlling the first electromagnetic field superposing multipole. The aberration generating element has such a function that when the charged particle beam is tilted relative to the sample by the tilt-use deflector, a plurality of resulting aberrations are cancelled with one another. Moreover, the first electromagnetic field superposing multipole has a function to change the orbit of a charged particle beam having energy different from that of the main charged particle beam in the charged particle beam.
1. A charged particle beam application device for converging a charged particle beam generated by a charged particle source on a sample by using an objective lens, the device comprising:
an aberration generating element installed between the charged particle beam source and the objective lens;
a tilt-use deflector installed between the aberration generating element and the objective lens;
a deflection aberration control unit for controlling the aberration generating element;
a first electromagnetic field superposing multipole installed between the aberration generating element and the objective lens; and
an electromagnetic field superposing multipole control unit for controlling the first electromagnetic field superposing multipole,
wherein the first electromagnetic field superposing multipole is controlled to deflect respective orbits of a low speed electron beam and a high speed electron beam such that a controlled distance between said orbits within the objective lens is less than an uncontrolled distance between said orbits within the objective lens, thereby controlling a high-order chromatic aberration, and
wherein the first electromagnetic field superposing multipole is controlled to cause no orbit change in a main electron beam, the main electron beam being disposed between the low speed electron beam and the high speed electron, and wherein the first electromagnetic field superposing multipole is controlled to cause the low speed electron beam and the high speed electron beam to maintain a substantially constant distance with respect to each other until reaching the objective lens.
2. The charged particle beam application device according to claim 1 ,
wherein when the charged particle beam is made incident on the objective lens, the deflection aberration control unit controls the aberration generating element so as to cancel a deflection chromatic aberration or a deflection comma aberration that is determined by a position in the objective lens.
3. The charged particle beam application device according to claim 1 ,
wherein the electromagnetic field superposing multipole control unit controls the first electromagnetic field superposing multipole so as to allow the first electromagnetic field superposing multipole to form a first electromagnetic field superposing field for canceling a change in an orbit of a main charged particle beam in the charged particle beam.
4. The charged particle beam application device according to claim 3 ,
wherein the first electromagnetic field superposing field is a bipolar field or a quadrupolar field.
5. The charged particle beam application device according to claim 1 ,
wherein the aberration generating element is further provided with a lens of at least one stage and a deflector of at least one stage, both of which are installed on an optical axis of the charged particle beam.
6. The charged particle beam application device according to claim 1 ,
wherein the tilt-use deflector is further provided with deflectors of at least two stages respectively installed on an optical axis of the charged particle beam.
7. The charged particle beam application device according to claim 1 , further comprising:
a second electromagnetic field superposing multipole that is installed between the aberration generating element and the objective lens, and controlled by the electromagnetic field superposing multipole control unit.
8. The charged particle beam application device according to claim 7 ,
wherein the electromagnetic field superposing multipole control unit controls the first electromagnetic field superposing multipole and the second electromagnetic field superposing multipole so as to allow the first electromagnetic field superposing multipole and the second electromagnetic field superposing multipole to form the first electromagnetic field superposing field and second electromagnetic field superposing field for canceling a change in an orbit of a main charged particle beam in the charged particle beam, and
the electromagnetic field superposing multipole control unit controls the first electromagnetic field superposing multipole and the second electromagnetic field superposing multipole such that a direction in which the first electromagnetic field superposing field is exerted and a direction in which the second electromagnetic field superposing field is exerted are set in a same direction or reversed directions, relative to charged particle beams having energies different from energy of the main charged particle beam.
9. The charged particle beam application device according to claim 8 ,
wherein each of the first electromagnetic field superposing field and the second electromagnetic field superposing field is a bipolar field or a quadrupolar field.