Apparatus and method for observing sample using electron beam

• US 20030089852A1
• Filed: 05/22/2002
• Published: 05/15/2003
• Est. Priority Date: 11/13/2001
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ishitani, Tohru, Koike, Hidemi, Tomimatsu, Satoshi, Sato, Mitsugu, Fukuda, Muneyuki, Ochiai, Isao
• Granted Patent: US 6,627,889 B2
• Time in Patent Office: Days
• US Class Current: 250/310
• CPC Class Codes: H01J 2237/2561 electron
• CPC Class Codes: H01J 2237/31745 for preparing specimen to be viewed in microscopes or analyzed in microanalysers
• CPC Class Codes: H01J 37/256 using scanning beams

Abstract

An apparatus and method for observing a sample that is capable of making observations by irradiating an electron beam to a sample in the form of a thin film, and making elemental analysis accurately and with increased resolution while reducing background noise. A particular portion of the sample is observed by the electron beam by disposing a light element piece having a hole provided immediately behind the thin film sample. According to the present invention, it is possible to reduce the x-rays generated from portions other than the sample and electron beam incident on the sample after being scattered to portions other than the sample when observing the thin film sample by irradiating the electron beam. It is therefore possible to make secondary electron observation and elemental analysis with increased accuracy and sensitivity. Thus, an apparatus and a method for observing samples is provided that allows for the accurate and high-resolution internal observation of LSI devices.

Claims

1. An apparatus for observing a sample using an electron beam, comprising:

an electron beam for irradiating on the sample;

a sample stage on which the sample is placed;

an x-ray detector for detecting x-rays generated from a micro sample taken from the sample as the electron beam irradiates the micro sample; and

a shielding piece comprised of a light elemental material provided between the sample stage and the micro sample for reducing x-rays.

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

a first holder for holding the micro sample; and

a second holder for holding the shielding piece.

3. The apparatus according to claim 1, wherein said shielding piece is incorporated into a portion of said sample stage, further wherein said micro sample is in contact with said shielding piece portion of the sample stage.

4. The apparatus according to claim 3, further comprising:

at least one additional shielding piece comprised of a light elemental material incorporated into at least a second portion of said sample stage.

5. The apparatus according to claim 1, wherein said electron beam for irradiating the sample comprises:

an electron source emitting an electron beam;

a lens for focusing the electron beam;

a deflector for scanning the electron beam; and

an objective lens for irradiating the electron beam on the sample.

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

a second sample stage provided on the first sample stage, wherein said shielding piece is made a part of the second sample stage.

7. The apparatus according to claim 1 wherein the shielding piece includes a hole with the walls of the hole defined by said light elemental material.

8. The apparatus according to claim 5, further comprising:

a holder provided to the sample stage for holding said sample, said holder including said shielding piece including a tube-like projection into said shielding piece with walls made of a light elemental material.

9. The apparatus according to claim 8, wherein the holder is disposed inside the objective lens.

10. The apparatus of claim 1, further comprising:

a focused ion beam irradiation optical system; and

a manipulator for separating the micro sample from the sample using the focused ion beam to separate the micro sample.

11. The apparatus according to claim 10, wherein said focused ion beam irradiation optical system comprises an ion beam source, a lens for focusing said ion beam, and a deflector for scanning the ion beam.

12. The apparatus according to claim 1, wherein said stage is adapted to be rotated and translated.

13. The apparatus according to claim 6, wherein said second sample stage is adapted to hold a plurality of micro samples.

14. The apparatus according to claim 6, wherein said shielding piece is mounted perpendicular to a surface of said second stage, said micro sample is mounted adjacent to said shielding piece on said second stage surface, and said electron beam is adapted to irradiate the micro sample parallel to said surface of said second stage and perpendicular to said shielding piece.

15. The apparatus according to claim 14, further comprising:

a focused ion beam irradiation optical system; and

a manipulator for separating a micro sample from the sample using the focused ion beam to separate the micro sample.

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

a controller to control the movement of said first holder.

17. A method for observing a sample using an electron beam, comprising steps of:

placing a sample on a sample stage;

separating a micro sample from the sample;

setting a shielding piece comprised of a light elemental material for reducing x-rays between the sample stage and the micro sample;

irradiating the electron beam on the micro sample;

detecting x-rays generated from the micro sample.

18. The method according to claim 17, wherein said separating step is accomplished using a focused ion beam irradiation optical system comprising an ion beam source, a lens for focusing said ion beam, and a deflector for scanning the ion beam.

19. The method according to claim 17, wherein said shielding piece includes a hole defined by walls made of said light elemental material.

20. The method according to claim 17, further comprising the step of:

before said irradiation step, attaching said separated micro sample to a holder; and

moving said micro sample via said holder into contact with a second stage which includes said shielding piece.