Charged particle beam apparatus and sample processing method

1. A charged particle beam apparatus, comprising:

a sample chamber for housing a sample; and

an ion beam column for accelerating an ion beam with an acceleration voltage, and focusing the ion beam on the sample to irradiate the sample, wherein:

the ion beam column comprises an ion source housed on a proximal side of the ion beam column and an ion optical system for irradiating the sample with the ion beam; and

the ion optical system comprises a first objective lens electrode for focusing the ion beam on the sample and a second objective lens electrode for focusing an ion beam accelerated with a second acceleration voltage, which is lower than a first acceleration voltage for accelerating the ion beam, on the sample.

2. A charged particle beam apparatus according to claim 1 , wherein the second objective lens electrode is disposed on a distal side of the ion beam column, relative to the first objective lens electrode.

3. A charged particle beam apparatus according to claim 1 , wherein the first objective lens electrode comprises a plurality of electrodes which have a grounded electrode disposed adjacent to the second objective lens electrode, and

wherein the grounded electrode, the second objective lens electrode, and a distal portion of the ion beam column, which is grounded, form a lens electric field for focusing the ion beam accelerated with the second acceleration voltage.

4. A charged particle beam apparatus according to claim 1 ,

wherein the ion optical system further comprises a deflection electrode for deflecting the ion beam, which is disposed on the proximal side of the ion beam column relative to the first objective lens electrode, and

wherein the deflection electrode deflects the ion beam accelerated with the first acceleration voltage so that the ion beam passes through a lens center of the first objective lens electrode, and deflects the ion beam accelerated with the second acceleration voltage so that the ion beam passes through a lens center of the second objective lens electrode.

5. A charged particle beam apparatus according to claim 1 ,

wherein the ion optical system further comprises a scanning electrode for scanning the ion beam, which is disposed on the proximal side of the ion beam column relative to the first objective lens, and

wherein the scanning electrode scans the ion beam accelerated with the first acceleration voltage so that the ion beam passes through a lens center of the first objective lens electrode, and scans the ion beam accelerated with the second acceleration voltage so that the ion beam passes through a lens center of the second objective lens electrode.

6. A charged particle beam apparatus according to claim 1 , wherein the ion optical system further comprising:

a focusing lens electrode for focusing the ion beam generated from the ion source; and

an astigmatism correction electrode for correcting astigmatism of the ion beam.

7. A charged particle beam apparatus according to claim 1 , further comprising:

an input unit for inputting the first acceleration voltage and the second acceleration voltage;

a storage unit for storing set values for the ion optical system, which correspond to the first acceleration voltage and the second acceleration voltage; and

a control unit for setting the set values for the ion optical system,

wherein the storage unit stores first set values corresponding to the first acceleration voltage and second set values corresponding to the second acceleration voltage, and

wherein the control unit sets the first set values for the ion optical system when the first acceleration voltage is input from the input unit, and sets the second set values for the ion optical system when the second acceleration voltage is input from the input unit.

8. A charged particle beam apparatus according to claim 7 ,

wherein the first set values comprise the set value for the first objective lens electrode indicating a constant voltage value, and the set value for the second objective lens electrode indicating 0, and

wherein the second set values comprise the set value for the first objective lens electrode indicating 0, and the set value for the second objective lens electrode indicating a constant voltage value.

9. A charged particle beam apparatus according to claim 7 , wherein the first set values and the second set values are set so that the ion beam accelerated with the first acceleration voltage and the ion beam accelerated with the second acceleration voltage irradiate the same area.

10. A charged particle beam apparatus according to claim 1 , wherein the second objective lens electrode comprises a hole portion for allowing the ion beam to pass therethrough, a plate portion having a plane substantially perpendicular to the ion beam, and a cylindrical portion for allowing the ion beam to pass therethrough.

11. A charged particle beam apparatus according to claim 1 , further comprising an electron beam column capable of irradiating, with an electron beam, an irradiation area of the ion beam on the sample,

wherein the electron beam column further comprises a coil of an objective lens for electron beam for focusing the electron beam on the sample, and

wherein a distance between a center of the coil of the objective lens for electron beam and the sample is larger than a distance between a center of the second objective lens electrode of the ion beam column and the sample.

12. A sample processing method, comprising:

a first processing step of accelerating an ion beam with a first acceleration voltage, focusing the ion beam by means of a first objective lens, and processing a sample; and

a second processing step of accelerating the ion beam with a second acceleration voltage, which is lower than the first acceleration voltage, focusing the ion beam by means of a second objective lens, which is disposed closer to the sample than the first objective lens, and processing the sample.

13. A sample processing method according to claim 12 , wherein the second processing step comprises removing a damaged portion formed in the sample in the first processing step.