Focusing and positioning device for a particle-optical raster microscope

• US 20080315120A1
• Filed: 08/01/2008
• Published: 12/25/2008
• Est. Priority Date: 02/03/2006
• Status: Active Grant

• Current Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Original Assignee: CARL Zeiss SMT GmbH (Carl-Zeiss-Stiftung)
• Inventors: Albiez, Michael
• Granted Patent: US 7,888,643 B2
• Time in Patent Office: Days
• US Class Current: 250/491.1
• CPC Class Codes: H01J 2237/216 Automatic focusing methods
• CPC Class Codes: H01J 2237/2482 Optical means
• CPC Class Codes: H01J 37/20 Means for supporting or positioning the objects or the material; Means for adjusting diaphragms or lenses associated with the support introducing the objects H01J37/18
• CPC Class Codes: H01J 37/21 Means for adjusting the focus adjusting the focus while observing the image by photographic or optical means H01J37/22; means for observing the object or the point of impact on the object in tubes for the localised treatment of materials H01J37/3005
• CPC Class Codes: H01J 37/22 Optical or photographic arrangements associated with the tube using a CRT for the display of the image in a scanning electron microscope H01J37/28; observing the object or the point of impact on the object in tubes for the localised treatment of materials H01J37/3007
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

The invention relates to a focusing and positioning ancillary device for a particle-optical scanning microscope, a particle-optical scanning microscope including a corresponding positioning aid, and a method for focusing and positioning an object in a particle-optical scanning microscope. The focusing and positioning ancillary device includes an illuminating device, a camera, a display and a control unit. The illuminating device produces a collimated or focused light beam at an angle to the particle-optical beam axis which intersects the particle-optical beam axis at a predetermined position. The camera is sensitive to the wavelength of the light beam and records an image of the object, which is positioned on the object table, at a second angle to the particle-optical beam axis. The control unit produces an image captured by the camera on the display together with a marking which indicates the position of the particle-optical beam axis in the image.

Claims

1. A focusing and positioning ancillary device for a particle-optical raster microscope having an objective defining a particle-optical beam axis and an object table for accommodating an object thereon, the focusing and positioning ancillary device comprising:

an illuminating unit configured to generate at least one of a collimated light beam and a focused light beam at a first angle to said particle-optical beam axis with said light beam having a wavelength and intercepting said particle-optical beam axis at a predefined position;

a camera sensitive to said wavelength and configured to record an image of said object positioned on said object table at a second angle relative to said particle-optical beam axis;

a display; and

,

a control unit configured to cause said image recorded by said camera to be shown on said display together with a marking indicating the position of said particle-optical beam axis in said image.

2. The focusing and positioning ancillary device of claim 1, wherein said illuminating unit comprises a laser.

3. The focusing and positioning ancillary device of claim 2, wherein said laser is a diode laser and said illuminating unit further includes an optic disposed in front of said laser diode.

4. The focusing and positioning ancillary device of claim 1, wherein said marking extends longer in length in the direction of said particle-optical axis than perpendicular to said particle-optical beam axis.

5. The focusing and positioning ancillary device of claim 1, wherein said illuminating unit has a focus in the vicinity of the intersect point of said light beam with said particle-optical beam axis.

6. The focusing and positioning ancillary device of claim 1, wherein said light beam defines an axis along which said light beam travels;

and, wherein said device further comprises a displacement unit accommodating said illuminating unit thereon for adjusting said axis of said light beam perpendicularly to the course thereof.

7. A particle beam system comprising:

an objective lens defining a particle-optical beam axis;

a particle beam generator for generating a particle beam for travel along said particle-optical beam axis;

a specimen chamber;

an object table for accommodating an object thereon and said object table being mounted in said specimen chamber;

a focusing and positioning ancillary device including;

an illuminating unit configured to generate at least one of a collimated light beam and a focused light beam at a first angle to said particle-optical beam axis with said light beam having a wavelength and intercepting said particle-optical beam axis at a predefined position;

a camera sensitive to said wavelength and configured to record an image of said object positioned on said object table at a second angle relative to said particle-optical beam axis;

a display; and

,

a control unit configured to cause said image recorded by said camera to be shown on said display together with a marking indicating the position of said particle-optical beam axis in said image.

8. The particle beam system of claim 7, wherein said illuminating unit comprises a laser.

9. The particle beam system of claim 8, wherein said laser is a diode laser and said illuminating unit further includes an optic disposed in front of said laser diode.

10. The particle beam system of claim 7, wherein said marking extends longer in length in the direction of said particle-optical beam axis than perpendicular to said particle-optical beam axis.

11. The particle beam system of claim 7, wherein said illuminating unit has a focus in the vicinity of the intersect point of said light beam with said particle-optical beam axis.

12. The particle beam system of claim 7, wherein said light beam defines an axis along which said light beam travels;

and, wherein said device further comprises a displacement unit accommodating said illuminating unit thereon for adjusting said axis of said light beam perpendicularly to the course thereof.

13. A method of focusing and positioning an object in a particle-optical raster microscope including an objective defining a particle-optical beam axis and an object table, said method comprising the steps of:

(a) providing a light beam having a predetermined wavelength and intersecting said particle-optical beam axis at a predefined position;

(b) providing a camera sensitive to said wavelength;

(c) providing a display whereon the position of said particle-optical beam axis is marked;

(d) recording an image of said object positioned on said object table via said camera;

(e) positioning said object table in the direction of said particle-optical beam axis until said light beam intersects said object on said marking in the image of said object shown on said display; and

,

(f) switching over said particle-optical raster microscope to irradiation of said object with electrons and displaying an image of said object via detected particles or light quanta generated by said irradiation of said object with charged particles.

14. The method of claim 13, further comprising the additional step carried out between steps (e) and (f) of positioning said object table perpendicularly to said particle-optical beam axis until said light beam intersects a selected location of interest of said object in said image recorded by said camera and shown on said display.