Electron beam apparatus for visualizing a displacement of an electric field

Patent metadata

Field	Value
Publication number	US-9208994-B2
Application number	US-201113817086-A
Country	US
Kind code	B2
Filing date	Jul 7, 2011
Priority date	Aug 18, 2010
Publication date	Dec 8, 2015
Grant date	Dec 8, 2015

Abstract

The present invention provides an electron beam apparatus comprising a means for visualizing an axial displacement of a retarding electric field, and a means for adjusting axial displacement. The axial displacement visualizing means includes a reflective plate ( 6 ), and an optical system ( 2, 3 ) for converging a secondary electron beam ( 9 ) on the reflective plate ( 6 ), and the axial displacement adjusting means includes an incline rotation mechanism ( 8 ) for a sample stage ( 5 ). With this configuration, in electron beam apparatuses such as SEM and the like, such problems as visual field displacement caused by displacement of the axial symmetry of the electric field between an objective lens ( 3 ) and a sample ( 4 ) and inability to measure secondary electrons and reflected electrons that provide desired information can be eliminated.

First claim

The invention claimed is:

1. An electron beam apparatus which is provided with at least an electron gun, an electron lens that includes an objective lens, and accelerates and converges an electron discharged from the electron gun to form the electron into a probe electron beam, a deflector that deflects the probe electron beam, a sample stage on which an observation sample is mounted, display means that displays an observed image of the observation sample, and a controller that controls the functions, and converges the probe electron beam on the observation sample to detect the electron generated from the observation sample for observation of a microstructure of the observation sample, comprising:
a visualizing means that is selected from the group consisting of a reflective plate, an optical system, and/or a detector having a hole or a dead zone at a center thereof, the visualizing means including a retarding power source that applies an electric field for decelerating the probe electron beam between the objective lens and the observation sample, and visualizes a displacement, that arises from an irregular cross-sectional shape of the observation sample surface, of a retarding electric field from an axial symmetry in a region through which the probe electron beam passes between the objective lens and the observation sample upon application of a retarding voltage, and
displacement reducing means that reduces the displacement of the electric field based on a result of the visualization, wherein
the displacement reducing means is a mechanism that inclines the sample stage, and includes 2-axis or 1-axis inclination and 1-axis rotation,
the visualizing means includes first means that directly detects the electron generated from the observation sample using the detector, which is located above the observation sample, or second detection means that detects an electron generated from a plate with a circular hole, which has been generated as a result of impingement of the electron generated from the sample on the plate, and
the controller has a function of setting a deflection range of the probe electron beam and a lens condition of the electron lens for convergence so as to provide a circular dark region representing that the electron generated from the observation sample is in the hole or the dead zone of the first means, or the hole of the plate, and a bright region or a bright annular region representing that the detection electron is increased by irradiating a sensitive zone of the first means or a rim of the hole of the plate, and controlling the inclination mechanism of the sample stage so that the annular region is brought to a center of the image, and further has a control panel or a switch for activating the function.

2. An electron beam apparatus which is provided with at least an electron gun, an electron lens that includes an objective lens, and accelerates and converges an electron discharged from the electron gun to form the electron into a probe electron beam, a deflector that deflects the probe electron beam, a sample stage on which an observation sample is mounted, display means that displays an observed image of the observation sample, and a controller that controls the functions, and converges the probe electron beam on the observation sample to detect the electron generated from the observation sample for observation of a microstructure of the observation sample, comprising:
a visualizing means that is selected from the group consisting of a reflective plate, an optical system, and/or a detector having a hole or a dead zone at a center thereof, the visualizing means including a retarding power source that applies an electric field for decelerating the probe electron beam between the objective lens and the observation sample, and visualizes a displacement, that arises from an irregular cross-sectional shape of the observation sample surface of a retarding electric field from an axial symmetry in a region through which the probe electron beam passes between the objective lens and the observation sample upon application of a retarding voltage, and
displacement reducing means that reduces the displacement of the electric field based on a result of the visualization, wherein
the visualizing means has a function that changes the retarding voltage to have a desired period to visualize a visual field displacement of the observed image; and
the controller has a function that controls a sample stage inclination mechanism so that an oscillation of the observed image is set to zero or minimized, and includes a control panel or a switch for activating the functions.

3. The electron beam apparatus according to claim 1 , wherein the visualizing means changes the retarding voltage, and visualizes the displacement of the electric field as a non-symmetry of the observed image under a mirror condition in which an energy generated upon incidence of the probe electron beam to the sample is set to a value around 0 eV, and application of the probe electron beam to the sample is not allowed.

4. The electron beam apparatus according to claim 1 , wherein a function that automatically adjusts an inclination of the sample stage is provided so that the displacement from the axial symmetry is minimized.

5. The electron beam apparatus according to claim 2 , wherein a function that automatically adjusts an inclination of the sample stage is provided so that the displacement from the axial symmetry is minimized.

6. The electron beam apparatus according to claim 3 , wherein a function that adjusts an inclination of the sample stage is provided so that the displacement from the axial symmetry is minimized.

7. The electron beam apparatus according to claim 4 , wherein the visualizing means further includes a function that changes the retarding voltage to have a desired period and visualizes the visual field displacement of the observed image.

8. The electron beam apparatus according to claim 4 , wherein the visualizing means further changes the retarding voltage, and visualizes the displacement of the electric field as a non-symmetry of the observed image under a mirror condition in which an energy generated upon incidence of the probe electron beam to the sample is set to a value around 0 eV, and application of the probe electron beam to the sample is not allowed.

9. The electron beam apparatus according to claim 5 , wherein the visualizing means further changes the retarding voltage, and visualizes the displacement of the electric field as a non-symmetry of the observed image under a mirror condition in which an energy generated upon incidence of the probe electron beam to the sample is set to a value around 0 eV, and application of the probe electron beam to the sample is not allowed.

10. The electron beam apparatus according to claim 7 , wherein the visualizing means further changes the retarding voltage, and visualizes the displacement of the electric field as a non-symmetry of the observed image under a mirror condition in which an energy generated upon incidence of the probe electron beam to the sample is set to a value around 0 eV, and application of the probe electron beam to the sample is not allowed.

11. The electron beam apparatus according to claim 3 , wherein means for changing an incident energy of the probe electron beam to the observation sample is allowed to select at least three points of the retarding voltage.

12. The electron beam apparatus according to claim 4 , wherein means for changing the incident energy of the probe electron beam to the observation sample is allowed to select at least three points of the retarding voltage.

13. The electron beam apparatus accordi

Assignees

• Ohshima Takashi
• Hatano Michio
• Morishita Hideo
• Hitachi High Tech Corp

Inventors

• Ohshima Takashi
• Hatano Michio
• Morishita Hideo

Classifications

• H01J37/265 Primary

  Controlling the tube; circuit arrangements adapted to a particular application not otherwise provided, e.g. bright-field-dark-field illumination · CPC title

• H01J2237/202

  Movement · CPC title

• H01J37/28

  with scanning beams {(H01J37/268, H01J37/292, H01J37/2955 take precedence)} · CPC title

• H01J2237/153

  Correcting image defects, e.g. stigmators · CPC title

• H01J2237/20207

  Tilt · CPC title