Methods for determining the virtual source location of a liquid metal ion source

Patent metadata

Field	Value
Publication number	US-12237142-B2
Application number	US-202217807362-A
Country	US
Kind code	B2
Filing date	Jun 16, 2022
Priority date	Jun 16, 2022
Publication date	Feb 25, 2025
Grant date	Feb 25, 2025

Abstract

Variations in charged-particle-beam (CPB) source location are determined by scanning an alignment aperture that is fixed with respect to a beam defining aperture in a CPB, particularly at edges of a defocused CPB illumination disk. The alignment aperture is operable to transmit a CPB portion to a secondary emission surface that produces secondary emission directed to a scintillator element. Scintillation light produced in response is directed out of a vacuum enclosure associated with the CPB via a light guide to an external photodetection system.

First claim

We claim:

1. A charged particle beam (CPB) alignment apparatus, comprising:
an alignment aperture plate defining an alignment aperture;
a secondary emission element situated to receive a portion of a CPB transmitted by the alignment aperture and operable to produce secondary emission in response;
a scintillator element situated to receive at least a portion of the secondary emission and produce scintillation light in response; and
a photodetector situated to receive the scintillation light produced at the scintillator element,
wherein the alignment aperture is moveable so as to receive the charged particle beam so that the scintillation light is detected by the photodetector, whereby an axis of the charged particle beam may be located.

2. The charged particle beam alignment apparatus of claim 1 , further comprising an aperture plate fixed to a support member and defining at least one beam defining aperture.

3. The charged particle beam alignment apparatus of claim 1 , further comprising a support member having an inner end and an outer end, wherein the alignment aperture plate is secured to the support member and is situated at the inner end of the support member.

4. The charged particle beam alignment apparatus of claim 1 , further comprising a light guide situated to receive the scintillation light produced at the scintillator element and direct the scintillation light to the photodetector.

5. The charged particle beam alignment apparatus of claim 4 , wherein the light guide is an elongated cavity defined in a support member and the scintillator element is situated at an entrance end of the light guide.

6. The charged particle beam alignment apparatus of claim 5 , wherein the light guide is dielectric lightguide having an entrance end facing the scintillator element.

7. The charged particle beam alignment apparatus of claim 1 , wherein the secondary emission element is situated on an axis perpendicular to the alignment aperture plate and tilted at an angle of between 10 degrees and 80 degrees away from the scintillator element.

8. The charged particle beam alignment apparatus of claim 1 , further comprising a rod-shaped support member that extends along an axis and comprises a first conductive section situated at an interior end and an insulator section coupled to the first conductive section, wherein the first conductive section includes the alignment aperture and the secondary emission element and the insulator section defines an insulator cavity extending along the axis, wherein a light guide is situated in the insulator cavity.

9. The charged particle beam alignment apparatus of claim 8 , wherein the support member includes a second conductive section coupled to the insulator section and defining a conductive cavity extending along the axis, wherein the light guide is situated in the conductive cavity.

10. The charged particle beam alignment apparatus of claim 9 , wherein the second conductive section extends through the insulator cavity and is electrically coupled to the scintillator element.

11. The charged particle beam alignment apparatus of claim 10 , further comprising a translation feedthrough coupled to the second conductive section and operable to vary a position of the alignment aperture with respect to a CPB axis.

12. The charged particle beam alignment apparatus of claim 1 , wherein the scintillator element includes a conductive coating.

13. The charged particle beam alignment apparatus of claim 1 , further comprising:
a controller; and
an actuator, wherein the controller is coupled to the actuator to move the alignment aperture with respect to a CPB axis and determine an offset of the alignment aperture with respect to the CPB axis based on the scintillation light received by the photodetector.

14. The charged particle beam alignment apparatus of claim 13 , wherein the controller is coupled to a CPB optical column to adjust at least one of a CPB axis and a beam defining aperture based on the determined offset of the alignment aperture.

15. A method, comprising:
scanning an alignment aperture with respect to a charged particle beam (CPB);
producing scintillation light at a scintillator member in response to a portion of the CPB transmitted by the alignment aperture, the scintillator member situated to receive secondary emission produced by a secondary emission element situated to receive a portion of the CPB transmitted by the alignment aperture;
detecting the scintillation light produced by the scintillator member with a photodetector situated to receive the scintillation light;
determining a CPB axis based on the detected scintillation light; and
adjusting at least one of a CPB axis and a beam defining aperture based on the determined CPB axis.

16. The method of claim 15 , further comprising capturing at least a portion of the scintillation light in a light guide that directs the scintillation light to the photodetector.

17. The method of claim 15 , further comprising adjusting the beam defining aperture based on the determined CPB axis.

18. The method of claim 15 , wherein the alignment aperture and a beam defining aperture are secured to a rod-shaped member that is coupled to an actuator that translates the alignment aperture.

19. A charged particle beam (CPB) apparatus, comprising:
a vacuum enclosure;
a CPB source situated in the vacuum enclosure and operable to produce a CPB;
a CPB optical system situated to direct the CPB along a CPB axis;
a CPB alignment apparatus extending into the vacuum enclosure, wherein the CPB alignment apparatus includes:
a beam limiting aperture plate defining a beam limiting aperture;
an alignment aperture plate defining an alignment aperture fixed with respect the beam limiting aperture plate;
a secondary emission member situated to receive portions of the CPB transmitted by the alignment aperture; and
a scintillator member situated to receive secondary emission from the secondary emission member and produce scintillation light;

a mechanical vacuum feed through coupled to the CPB alignment apparatus and operable to move at least the alignment aperture with respect to a CPB axis; and
a controller coupled to the mechanical vacuum feed through and a photodetector system and operable to direct the mechanical vacuum feed through to move the alignment aperture with respect to the CPB axis and, based on a portion of the scintillation light, determine a CPB position.

20. The CPB apparatus of claim 19 , wherein the CPB alignment apparatus includes a rod-shape support member that comprises:
an inner conductive section that includes the beam limiting aperture plate, the alignment aperture plate, the secondary emission member, and the scintillator member;
an intermediate insulator section defining a cavity in which a light guide is situated to extend toward the scintillator member; and
an outer section coupled to the mechanical vacuum feed through, wherein the light guide extends to the scintillator member through the vacuum enclosure.

Assignees

• Fei Co

Inventors

• Kellogg Sean M
• Maazouz Mostafa
• Mcginn James B

Classifications

• H01J2237/221

  Image processing · CPC title

• H01J2237/2445

  Photon detectors for X-rays, light, e.g. photomultipliers · CPC title

• H01J2237/2443

  Scintillation detectors · CPC title

• H01J2237/0458

  movable, i.e. for changing between differently sized apertures · CPC title

• H01J37/244

  Detectors; Associated components or circuits therefor · CPC title