ELECTRON BEAM IRRADIATION APPARATUS AND ELECTRON BEAM DYNAMIC FOCUS ADJUSTMENT METHOD

• US 20180284620A1
• Filed: 02/13/2018
• Published: 10/04/2018
• Est. Priority Date: 03/30/2017
• Status: Active Grant

• Current Assignee: NuFlare Technology, Inc. (Toshiba Corporation)
• Original Assignee: NuFlare Technology, Inc. (Toshiba Corporation)
• Inventors: OGASAWARA, Munehiro
• Granted Patent: US 10,451,976 B2
• Time in Patent Office: Days
• CPC Class Codes: G03F 1/78 by charged particle beam [CPB], e.g. electron beam patterning of masks
• CPC Class Codes: G03F 7/2063 for the production of exposure masks or reticles
• CPC Class Codes: G03F 7/70383 Direct write, i.e. pattern is written directly without the use of a mask by one or multiple beams maskless lithography using a programmable mask G03F7/70291
• CPC Class Codes: H01J 2237/022 Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
• CPC Class Codes: H01J 2237/04926 combined
• CPC Class Codes: H01J 2237/20228 Mechanical X-Y scanning
• CPC Class Codes: H01J 2237/31776 Shaped beam
• CPC Class Codes: H01J 37/12 electrostatic
• CPC Class Codes: H01J 37/21 Means for adjusting the focus
• CPC Class Codes: H01J 37/304 Controlling tubes by information coming from the objects or from the beam, e.g. correction signals
• CPC Class Codes: H01J 37/3174 Particle-beam lithography, e.g. electron beam lithography
• CPC Class Codes: H01L 21/0277 Electrolithographic processes

Abstract

An electron beam irradiation apparatus includes a first electrode being annular, arranged along the optical axis of the electron beam, at the downstream from the deflector, and in the magnetic field of the objective lens, to which a first potential being positive is variably applied, a second electrode being annular, arranged in the magnetic field of the objective lens and between the deflector and the first electrode, to which a second potential being positive and higher than the first potential is applied, and a third electrode being annular, arranged in the magnetic field of the objective lens and to be opposite to the second electrode with respect to the first electrode, to which a third potential lower than the first potential is applied.

Claims

1. An electron beam irradiation apparatus comprising:

an emission source configured to emit an electron beam;

a deflector configured to deflect the electron beam to a desired position on a surface of a target object;

an objective lens configured to focus the electron beam to form an image on the surface of the target object;

a first electrode being annular, arranged along an optical axis of the electron beam, at a position downstream from the deflector, and in a magnetic field of the objective lens, in which a first aperture is formed in a central portion such that the electron beam passes through it, and to which a first potential being positive is variably applied;

a second electrode being annular, arranged in the magnetic field of the objective lens and between the deflector and the first electrode, in which a second aperture is formed in a central portion such that the electron beam passes through it, and to which a second potential being positive and higher than the first potential is applied; and

a third electrode being annular, arranged in the magnetic field of the objective lens and at a position opposite to the second electrode with respect to the first electrode, in which a third aperture is formed in a central portion such that the electron beam passes through it, and to which a third potential lower than the first potential is applied.

2. The apparatus according to claim 1, further comprising:

a fourth electrode being annular, arranged between the deflector and the second electrode, to which a negative potential is applied.

3. The apparatus according to claim 1, wherein the second electrode is arranged in the magnetic field of the objective lens and at a position where a magnetic flux density on a central axis of the magnetic field is lower than that of the first electrode.

4. The apparatus according to claim 1, further comprising:

a supply port configured to supply ozone to a back side of the second electrode.

5. The apparatus according to claim 1, wherein potential of the first electrode is variably controlled in a range lower than potential of the second electrode.

6. The apparatus according to claim 2, wherein the second electrode is formed such that its peripheral shape tapers toward the first electrode.

7. The apparatus according to claim 1, wherein the second electrode is formed such that its portion at a side of the first electrode is a honeycomb structure.

8. The apparatus according to claim 1, wherein the second electrode is formed such that its portion at a side of the first electrode is a corrugated structure.

9. The apparatus according to claim 1, wherein the first electrode and the second electrode are formed using carbon material.

10. An electron beam dynamic focus adjustment method comprising:

adjusting a focus of an electron beam dynamically depending on unevenness of a surface of a target object in a state where the electron beam has been focused on the surface of the target object by an objective lens, using an annular multi-stage electrode composed of a first-stage electrode, a second-stage electrode, and a third-stage electrode, by variably changing a first potential being positive applied to the second-stage electrode, and making a second potential applied to the first-stage electrode and a third potential applied to the third-stage electrode fixed; and

making the second potential applied to the first-stage electrode be a positive potential higher than the first potential, and removing an electron of a low energy component which floats at a side of an optical axis of the second-stage electrode to a side of the first-stage electrode.