Charged particle optical apparatus with aberration corrector

Abstract

When an accelerating voltage and operating distance are changed, an excitation current and a pole voltage of an aberration corrector must also be changed. Moreover, different multipole voltages or currents must be added individually for each pole in order to superpose multipoles. In view of overcoming the problems explained above, the charged particle optical apparatus of the present invention comprises an excitation device including, to give excitation to form a multipole field to each pole of the multipole lens, electromagnetic type quadrupole of four stages arranged along an optical axis of charged particle beam, electromagnetic type quadrupole of two stages for superposing distribution of voltage similar to distribution of magnetic potential of the electromagnetic type quadrupole of two stages at the center of the electromagnetic type quadrupole of four stages, and electromagnetic type octupole for superposing magnetic potential at least to three multipoles among that of four stages and also comprises a first power supply group for driving the same excitation device and a second power supply group for impressing voltages.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing a structure of an example of an electron beam apparatus with aberration corrector to which the present invention is applied;

FIG. 2 shows an example of structure of an electromagnetic multipole lens of the aberration corrector;

FIG. 3 shows an example of structure of pole of the electromagnetic multipole lens;

FIG. 4 shows an example of structure of an electrostatic and electromagnetic complex type multipole lens of the aberration corrector;

FIG. 5 shows an example of structure of the electromagnetic and electrostatic complex type multipole lens.

FIG. 6 shows an example of structure of a scanning charged particle optical apparatus of a second embodiment;

FIG. 7 shows an example of structure of an electromagnetic multipole lens of the second embodiment;

FIG. 8 shows an example of structure of the electromagnetic and electrostatic complex type multipole lens of the second embodiment;

FIG. 9 shows an example of the other structure of the pole of the electromagnetic multipole lens;

FIG. 10 shows an example of structure of the pole of the electromagnetic and electrostatic complex type multipole lens; and

FIG. 11 shows an example of structure of a scanning charged particle optical apparatus of a third embodiment.

Claims

1. A scanning charged particle optical microscope comprising an irradiation optical system for scanning charged particle beam to a specimen, a specimen stage for setting the relevant specimen, and a detecting optical system for detecting secondary charged particle generated from said specimen with irradiation of said charged particle beam, wherein said irradiation optical system includes a charged particle gun, an objective lens, an aberration corrector arranged between said charged particle gun and said objective lens,said aberration corrector includes a couple of static-magnetic type multipole lens and a couple of complex type multipole lenses arranged between a couple of electromagnetic type multipole lenses,said electromagnetic type multipole lens and said complex type multipole lens include a plurality of poles arranged in the form of a ring, first coils provided to a plurality of relevant poles, and a first current input terminal for supplying a common current to the first coils provided to a plurality of said poles, andsaid complex type multipole lens includes a voltage input terminal, conductive wires for distributing the voltage impressed to said voltage input terminal among a plurality of said poles, and moreover, a first current source for supplying current to said first current input terminal and a voltage source for supplying voltage to said voltage input terminal.

2. A scanning charged particle optical microscope comprising an irradiation optical system for scanning the charged particle beam to a specimen, a specimen table for setting the relevant specimen, and a detecting optical system for detecting second charged particle generated from said specimen with irradiation of said charged particle beam, wherein said irradiation optical system includes a charged particle gun, an objective lens, and an aberration corrector arranged between said charged particle gun and said objective lens,said aberration corrector includes a first electromagnetic type mulitpole lens, a first complex type multipole lens arranged at the lower side of said first electromagnetic type multipole lens, a second complex type multipole lens arranged at the lower side of said first complex type multipole lens, and a second electromagnetic type multipole lens arranged at the lower side of said second complex type multipole lens,said first and second electromagnetic type multipole lenses and said first and second complex type multipole lenses include a plurality of poles arranged in the form of a ring, first coils provided to a plurality of said poles, and a first current input terminal for supplying a common current to said first coils provided to a plurality of said poles, andsaid complex type multipole lens further includes a voltage input terminal, conductive wires for distributing the voltage impressed to said voltage input terminal to a plurality of said poles, and moreover a first current source for supplying current to said first current input terminal and a voltage source for supplying voltage to said voltage input terminal.

3. The scanning charged particle optical microscope according to claim 1, wherein said first current source and voltage source are constituted with the identical power supply.

4. The scanning charged particle optical microscope according to claim 1, comprising an aberration corrector controlling means for controlling said aberration corrector, wherein said aberration corrector controlling means switches operation of said complex type multipole lens to operation of the electromagnetic field type multipole lens in accordance with an accelerating voltage of said charged particle beam.

5. The scanning charged particle optical microscope according to claim 1, comprising a voltage source controlling means for controlling said voltage source, wherein said voltage source controlling means stops supply of voltage to said voltage input terminal when an accelerating voltage of said charged particle beam is equal to or higher than the predetermined value.

6. The scanning charged particle optical microscope according to claim 1, wherein said electromagnetic type multipole lens and said complex type multipole lens include second coils provided to a plurality of said poles and a second current input terminal for supplying a common current to the second coils provided to a plurality of poles.

7. The scanning charged particle optical microscope according to claim 1, wherein said electromagnetic type multipole lens and said complex type multipole lens include third coils provided to a plurality of said poles and a third current input terminal for supplying a common current to said third coils provided to a plurality of said poles.

8. The scanning charged particle microscope according to claim 7, wherein said poles provided with said first coils, second coils, and third coils provided to said electromagnetic multipole lens are respectively form a dipole lens, quadrupole lens, and an octupole lens.

9. In the scanning charged particle optical microscope according to claim 7, said poles provided with said first coils, second coils, and third coils provided to said complex type multipole lens respectively form a quadrupole lens, octupole lens, and dodecapole lens.

10. A scanning charged particle optical apparatus comprising the functions for irradiating charged particle beam to a specimen on which a circuit pattern is formed, detecting secondary electron or backscattered electron generated by said irradiation of charged particle beam with a detector, and for conducting critical dimension or inspection of said circuit pattern using a detecting signal of said detector, comprising a scanning charged particle optical microscope including the function for detecting said charged particle beam irradiation, said second electron or said backscattered electron and an information processing means including the function to conduct critical dimension or inspection using said detecting signal, whereinsaid scanning charged particle optical microscope includes a charged particle gun, an objective lens, and an aberration corrector arranged between said charged particle gun and said objective lens,said aberration corrector includes a couple of electromagnetic type multipole lenses and a couple of complex type multipole lens arranged between a couple of said electromagnetic type multipole lenses,said electromagnetic multipole pole and said complex type multipole lens include a plurality of poles arranged in the form or a ring, first coils provided to a plurality of said poles, a first current input terminal for supplying a common current among first coils provided to a plurality of said poles, andsaid complex type multipole lens includes a voltage input terminal and conductive wires for distributing voltage impressed to said voltage input terminal to a plurality of said poles and further a first current source for supplying current to said first current input terminal and a voltage source for supplying voltage to said voltage input terminal.

11. The scanning charged particle optical apparatus according to claim 10, wherein said first current source and voltage source are constituted with the identical power supply.

12. The scanning charged particle optical apparatus according to claim 11, comprising an aberration corrector controlling means for controlling said aberration corrector, wherein said aberration corrector controlling means switches operation of said complex type multipole lens to the operation of an electromagnetic field type multipole lens in accordance with an accelerating voltage of said charged particle beam.

13. The scanning charged particle optical apparatus according to claim 11, comprising a voltage source controlling means for controlling said voltage source, wherein said voltage source controlling means stops supply of voltage to said voltage input terminal when an accelerating voltage of said charged particle beam is equal to or higher than the predetermined value.

14. The scanning charged particle optical apparatus according to claim 11, wherein said information processing means stops supply of voltage to said voltage input terminal when an accelerating voltage of said charged particle beam is equal to or higher than the predetermined value.

15. The scanning charged particle optical apparatus according to claim 14, comprising an information inputting means used for inputting said predetermined value to said information processing means and an image displaying means for displaying a result of input with said information inputting means.