Scanning charged-particle microscope

• US 20020079448A1
• Filed: 08/30/2001
• Published: 06/27/2002
• Est. Priority Date: 10/12/2000
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ishitani, Tohru, Sato, Mitsugu, Todokoro, Hideo
• Granted Patent: US 7,186,975 B2
• Time in Patent Office: Days
• US Class Current: 250/310
• CPC Class Codes: H01J 37/09 Diaphragms; Shields associated with electron or ion-optical arrangements; Compensation of disturbing fields
• CPC Class Codes: H01J 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence

Abstract

In orer to supply a scanning charged-particle microscope that can achieve both the improvement of resolution and that of focal depth at the same time, a scanning charged-particle microscope is supplied which is characterized in that a passage aperture for limiting the passage of the charged-particle optical beam is located between the charged-particle source and the scanning deflector, and in that a member for limiting the passage of the charged-particle optical beam is provided at least in the center of the passage aperture.

Claims

1. A scanning charged-particle microscope having

a charged-particle source,

a lens for focusing the charged-particle optical beam emitted from said charged-particle source, and

a scanning deflector for scanning said charged-particle optical beam in two-dimensional form on a sample,

wherein said scanning charged-particle microscope is characterized in that a passage aperture for limiting the passage of the charged-particle optical beam is located between the charged-particle source and said scanning deflector, and in that a member for limiting the passage of the charged-particle optical beam is provided at least in the center of said passage aperture.

2. A scanning charged-particle microscope as set forth in claim 1 above, wherein the scanning charged-particle microscope is characterized in that the half-opening angle of said aperture for said charged-particle optical beam focused on a sample by said focusing lens has a band with respect to specific values of α

_a and α

_b.

3. A scanning charged-particle microscope as set forth in claim 1 above, wherein the scanning charged-particle microscope is characterized in that said passage aperture is formed in a plate-like body, and in that said plate-like body is formed movably with respect to said charged-particle optical beam.

4. A scanning charged-particle microscope as set forth in claim 3 above, wherein the scanning charged-particle microscope is characterized in that said plate-like body is formed is provided with a circular aperture in addition to said passage aperture.

5. A scanning charged-particle microscope having

a charged-particle source,

a lens for focusing the charged-particle optical beam emitted from said charged-particle source, and

a scanning deflector for scanning said charged-particle optical beam in two-dimensional form on a sample,

wherein said scanning charged-particle microscope is characterized in that it has a means by which said charged-particle optical beam focused on said sample is radiated so that the half-opening angle of said aperture for the charged-particle optical beam will have a band with respect to specific values of α

_a and α

_b.

6. A scanning charged-particle microscope as set forth in claim 5 above, wherein the scanning charged-particle microscope is characterized in that a plate-like aperture body in which an annular aperture is formed is provided between said charged-particle source and said scanning deflector.

7. A scanning charged-particle microscope as set forth in claim 6 above, wherein the scanning charged-particle microscope is characterized in that in addition to said annular aperture, a circular aperture is provided in said plate-like aperture body, and in that there is provided a movement feature for positioning said annular aperture and said circular aperture on the orbit of said charged-particle optical beam.

8. A scanning charged-particle microscope having

a charged-particle source,

a lens for focusing the charged-particle optical beam emitted from said charged-particle source, and

a scanning deflector for scanning said charged-particle optical beam in two-dimensional form on a sample,

wherein said scanning charged-particle microscope is characterized in that an aperture for limiting the passage of said charged-particle optical beam is formed in two different places on the orbit thereof, and in that one of said two apertures is an annular aperture and the other is a circular aperture.

9. A scanning charged-particle microscope as set forth in claim 8 above, wherein the scanning charged-particle microscope is characterized in that said annular aperture is formed in a plate-like body, in that said plate-like body is also provided with a circular aperture, and in that there is provided a movement feature for positioning the annular aperture and the circular aperture on the orbit of said charged-particle optical beam.

10. A scanning charged-particle microscope as set forth in claim 8 above, wherein the scanning charged-particle microscope is characterized in that said circular aperture is formed in a plate-like body, in that said plate-like body is also provided with a charged-particle optical beam cutoff portion, and in that there is provided a movement feature for positioning said charged-particle optical beam cutoff portion and said circular aperture on the orbit of said charged-particle optical beam.

11. A scanning charged-particle microscope as set forth in claim 8 above, wherein the scanning charged-particle microscope is characterized in that said circular aperture and said annular aperture are formed in a first plate-like body and a second plate-like body, respectively, in that said first plate-like body is provided with a charged-particle optical beam cutoff portion in addition to the circular aperture and said second plate-like body is provided with a circular aperture in addition to the annular aperture, and in that both the first plate-like body and the second plate-like body are provided with a movement feature.

12. A samples image forming method using a scanning charged-particle microscope having

a charged-particle source,

a lens for focusing the charged-particle optical beam emitted from said charged-particle source, and

a scanning deflector for scanning said charged-particle optical beam in two-dimensional form on a sample,

wherein said samples image forming method is characterized in that the image of a sample that has been acquired with an annular aperture positioned on the orbit of the charged-particle optical beam and the image of a sample that has been acquired with a circular aperture positioned on the orbit of the charged-particle optical beam are combined to form a new samples image.