Sample height regulating method, sample observing method, sample processing method and charged particle beam apparatus

• US 7,423,266 B2
• Filed: 02/23/2006
• Issued: 09/09/2008
• Est. Priority Date: 02/25/2005
• Status: Active Grant

• Current Assignee: Hitachi High-Tech Science Corporation (Hitachi, Ltd.), Innovative Fiber LLC
• Original Assignee: SII NanoTechnology Inc. (Hitachi, Ltd.)
• Inventors: Tashiro, Junichi, Sato, Makoto, Ikku, Yutaka
• Primary Examiner(s): Souw; Bernard E
• Application Number:
  US11/360,948
• Publication Number:
  US 20060192118A1
• Time in Patent Office: 929 Days
• Field of Search: 250/310, 250/306, 250/307, 250309-311, 250/559.29, 250/559.3, 250/548, 250/396.R, 250397-400, 250/491.1, 250/492.1, 250/492.2, 250/492.21, 250/492.22, 250/492.3, 356/138, 356/139, 356/139.07, 356399-401, 356/601, 356/607, 356/608
• US Class Current: 250/310
• CPC Class Codes: G01N 23/2251 using incident electron beams, e.g. scanning electron microscopy [SEM]
• CPC Class Codes: H01J 2237/20235 Z movement or adjustment
• CPC Class Codes: H01J 2237/216 Automatic focusing methods
• CPC Class Codes: H01J 2237/221 Image processing
• CPC Class Codes: H01J 2237/31745 for preparing specimen to be viewed in microscopes or analyzed in microanalysers
• 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 37/28 with scanning beams H01J37/268, H01J37/292, H01J37/2955 take precedence
• 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 37/3056 for microworking, e.g. etching of gratings, trimming of electrical components trimming of resistors H01C17/22

Abstract

In a sample height regulating method, an area including the observation point on the sample is scan-irradiated with a first charged particle beam to obtain a first secondary electron image including the observation point. An area including the observation point on the sample is then scan-irradiated with a second charged particle beam to obtain a second secondary electron image including the observation point. Thereafter, based on magnifications of the first secondary electron image and the second secondary electron image and a distance between the observation point in the first secondary electron image and the observation point in the second secondary electron image, a height of the sample required for focusing the first charged particle beam and the second charged particle beam on the observation point is calculated. A sample stage supporting the sample is then displaced so as to position the sample at the calculated sample height.

Claims

1. A sample height regulating method for irradiating an observation point on a sample with two charged particle beams from different angles, comprising the steps of:

scan-irradiating an area including the observation point on the sample with a first charged particle beam to obtain a first secondary electron image including the observation point;

scan-irradiating an area including the observation point on the sample with a second charged particle beam to obtain a second secondary electron image including the observation point;

calculating, based on magnifications of the first secondary electron image and the second secondary electron image and a distance between the observation point in the first secondary electron image and the observation point in the second secondary electron image, a height of the sample required for focusing the first charged particle beam and the second charged particle beam on the observation point; and

displacing a sample stage so as to position the sample at the calculated sample height.

2. A sample observing method comprising the steps of:

executing a sample height regulating method according to claim 1 at a desired observation area or in a vicinity thereof; and

scan-irradiating the observation area or the vicinity thereof with the first charged particle beam to obtain a secondary electron image of the observation area.

3. A sample height regulating method according to claim 1;

wherein the first charged particle beam is an electron beam and the second charged particle beam is an ion beam.

4. A sample processing method comprising the steps of:

executing a sample height regulating method according to claim 3 at a desired process area or in a vicinity thereof; and

scan-irradiating the process area or the vicinity thereof with the ion beam to etch the process area.

5. A sample processing method comprising the steps of:

executing a sample height regulating method according to claim 3 at a desired process area or in a vicinity thereof;

scan-irradiating the process area or the vicinity thereof with the ion beam to etch the process area; and

scan-irradiating a cross-section of the etched process area or vicinity thereof with the electron beam to observe the cross section.

9. A sample height regulating method according to claim 1;

wherein the step of scan-irradiating with the first charged particle beam comprises scan-irradiating with the first charged particle beam using a first charged particle source; and

wherein the step of scan-irradiating with the second charged particle beam comprises scan-irradiating with the second charged particle beam using a second charged particle source different from the first charged particle source.

10. A sample height regulating method according to claim 9;

wherein the first charged particle source is a scanning electron microscope and the second charged particle source is a focused ion beam apparatus.

6. A charged particle beam apparatus comprising:

a first charged particle source for generating first charged particles;

a first charged particle optical system for focusing the first charged particles into a first charged particle beam and irradiating an area including an observation point on a surface of a sample with the first charged particle beam under a scanning motion;

a second charged particle source for generating second charged particles;

a second charged particle optical system for focusing the second charged particles into a second charged particle beam and irradiating the area including the observation point on the surface of the sample with the second charged particle beam under a scanning motion;

a secondary electron detector that detects secondary electrons generated by irradiating the sample surface with the first charged particle beam or the second charged particle beam;

display means for displaying a secondary electron image based on the secondary electrons detected by the secondary electron detector;

calculation means for calculating a height of the sample required for focusing the first charged particle beam and the second charged particle beam on the observation point on the surface of the sample;

a sample stage for supporting the sample; and

displacement means for displacing the sample stage to position the sample at the height calculated by the calculation means.

7. A charged particle beam apparatus according to claim 6;

wherein the calculation means calculates the height of the sample based on magnification of a first secondary electron image obtained by scan-irradiating the observation point on the surface of the sample with the first charged particle beam, magnification of a second secondary electron image obtained by scan-irradiating the observation point on the surface of the sample with the second charged particle beam, and a distance between the observation point in the first secondary electron image and the observation point in the second secondary electron image.

8. A charged particle beam apparatus according to claim 6;

wherein the first charged particle beam is an electron beam and the second charged particle beam is an ion beam.

11. A charged particle beam apparatus according to claim 6;

wherein the first charged particle source is a scanning electron microscope and the second charged particle source is a focused ion beam apparatus.

12. A charged particle beam apparatus according to claim 11;

wherein the first charged particle beam is an electron beam and the second charged particle beam is an ion beam.

13. A charged particle beam apparatus according to claim 7;

wherein the first charged particle beam is an electron beam and the second charged particle beam is an ion beam.

14. A charged particle beam apparatus comprising:

a first charged particle source that generates first charged particles and focuses them into a first charged particle beam that is irradiated on an area including an observation point on a surface of a sample using a scanning motion of the first charged particle beam;

a second charged particle source that generates second charged particles and focuses them into a second charged particle beam that is irradiated on the area of the sample surface including the observation point using a scanning motion of the second charged particle beam;

a secondary electron detector that detects secondary electrons generated when the sample surface is irradiated with the first charged particle beam or the second charged particle beam;

a display that displays a secondary electron image in accordance with the secondary electrons detected by the secondary electron detector;

a calculating device that calculates a height of the sample required for focusing the first charged particle beam and the second charged particle beam on the observation point on the sample surface; and

a displacement device that displaces the sample to position the sample at the height calculated by the calculating device.

15. A charged particle beam apparatus according to claim 14;

wherein the first charged particle beam is an electron beam and the second charged particle beam is an ion beam.

16. A charged particle beam apparatus according to claim 14;

wherein the first charged particle source is a scanning electron microscope and the second charged particle source is a focused ion beam apparatus.

17. A charged particle beam apparatus according to claim 16;

wherein the first charged particle beam is an electron beam and the second charged particle beam is an ion beam.

18. A charged particle beam apparatus according to claim 14;

wherein the calculation device calculates the height of the sample based on magnification of a first secondary electron image obtained by scan-irradiating the observation point on the surface of the sample with the first charged particle beam, magnification of a second secondary electron image obtained by scan-irradiating the observation point on the surface of the sample with the second charged particle beam, and a distance between the observation point in the magnified first secondary electron image and the observation point in the magnified second secondary electron image.

19. A charged particle beam apparatus according to claim 14;

further comprising a sample stage that supports the sample; and

wherein the displacement device displaces the sample stage to position sample at the height of the sample calculated by the calculating device.

20. A sample height regulating method comprising:

focusing first charged particles into a first charged particle beam and irradiating the first charged particle beam on an area including an observation point on a surface of a sample using a scanning motion of the first charged particle beam;

focusing second charged particles different from the first charged particles into a second charged particle beam and irradiating the second charged particle beam on the area of the sample surface including the observation point using a scanning motion of the second charged particle beam;

detecting secondary electrons generated when the sample surface is irradiated with the first charged particle beam or the second charged particle beam;

calculating a height of the sample required for focusing the first charged particle beam and the second charged particle beam on the observation point on the sample surface; and

positioning the sample at the calculated height.