JP2005174812A - Scanning electron microscope, control method of the same, and electron beam axis control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning electron microscope capable of easily controlling an electron beam axis, a control method of the scanning electron microscope, and an electron beam axis control method. <P>SOLUTION: The scanning electron microscope 100 is equipped with an electron beam source 1, an opening 6c, through which an electron beam 10 emitted from the electron beam source 1 passes, an object lens 6 converging the electron beam 10 on a sample 8 arranged at the back side of the opening 6c, an axis control means 4 controlling the axis of the electron beam 10, a scanning coil 5 scanning the electron beam 10, a detector 11 arranged at farther front side than the opening 6c of the object lens 6, and a control means 14 scanning the opening 6c of the object lens 6 by the electron beam 10, and controlling the axis control means 4 based on an image detected by the scanning. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a scanning electron microscope, a scanning electron microscope control method, and an electron beam axis adjustment method.

  In observation of a sample using a scanning electron microscope, an electron beam accelerated and emitted from an electron gun is focused on the sample by an objective lens and irradiated to obtain a detected sample image (detected image). Displayed and recorded on a storage medium as necessary.

  In such a scanning electron microscope, an axis adjustment operation for aligning the axis (optical axis) of the electron beam with the central axis of the objective lens is required. At this time, the axis of the electron beam that has passed through the aperture hole located between the electron gun and the objective lens is aligned with the central axis of the objective lens.

  This axis adjustment can be performed by periodically changing the excitation current of the objective lens to swing the focus position up and down, and finely adjusting the position of the stop so that the center position of the detected image remains stationary in that state. is there. In this case, if the electron beam passes through the center of the objective lens, even if the excitation current of the objective lens is slightly changed, the center of the detection image does not move.

  On the other hand, if the electron beam passes through a position deviating from the center of the objective lens, the center position of the detected image also moves vertically and horizontally on the screen when the excitation current of the objective lens is periodically changed. Move periodically. Using this phenomenon, the operator manually fine-tunes the position of the diaphragm while observing the detected image, or adjusts the excitation condition of the electromagnetic coil for axis adjustment.

  In such an electron beam axis adjustment method in a scanning electron microscope, when the excitation current of the objective lens is periodically changed, the detection image rotates. However, by correcting the scanning direction of the electron beam, Some stop rotation (see, for example, Patent Document 1).

  Also, there is a technique that detects the center of the diaphragm and changes the deflection signal so that the electron beam passes through the center of the diaphragm (see, for example, Patent Document 2).

JP-A-8-329870 JP-A-9-69350

  In the electron beam axis adjusting method in the scanning electron microscope described above, the adjustment work requires skill and the adjustment work is complicated.

  The present invention has been made in view of the above points, and provides a scanning electron microscope, a scanning electron microscope control method, and an electron beam axis adjustment method capable of easily adjusting an electron beam axis. With the goal.

  The scanning electron microscope according to the present invention has an electron beam source and an aperture through which the electron beam emitted from the electron beam source passes, and an objective lens that focuses the electron beam on a sample disposed behind the aperture A scanning electron microscope comprising: an axis adjusting unit that adjusts the axis of the electron beam; a scanning coil that scans the electron beam; and a detector that is positioned in front of the opening of the objective lens. And a control means for controlling the axis adjusting means based on an image detected by scanning the opening with an electron beam.

  The scanning electron microscope control method according to the present invention includes an electron beam source and an opening through which the electron beam emitted from the electron beam source passes, and the electron beam is placed on a sample disposed behind the opening. Of a scanning electron microscope comprising an objective lens for focusing the light, an axis adjusting means for adjusting the axis of the electron beam, a scanning coil for scanning the electron beam, and a detector positioned in front of the opening of the objective lens A first image detected by scanning an opening of an objective lens in a first direction with an electron beam, and a first image in which the opening is opposite to the first direction by an electron beam. A second image detected by scanning in two directions is acquired, and the first and second images are alternately displayed.

  Furthermore, another control method of the scanning electron microscope according to the present invention includes an electron beam source and an opening through which the electron beam emitted from the electron beam source passes, on a sample disposed behind the opening. A scanning electron microscope comprising an objective lens for focusing an electron beam, axis adjusting means for adjusting the axis of the electron beam, a scanning coil for scanning the electron beam, and a detector positioned in front of the opening of the objective lens The first image detected by scanning the aperture of the objective lens in the first direction with the electron beam and the first image obtained by rotating the first image by 180 degrees around the image center. A second image to be acquired, and the first and second images are alternately displayed.

  The electron beam axis adjusting method according to the present invention includes an electron beam source and an opening through which the electron beam emitted from the electron beam source passes, and the electron beam is placed on a sample disposed behind the opening. An electron in a scanning electron microscope comprising an objective lens for focusing the light, an axis adjusting means for adjusting the axis of the electron beam, a scanning coil for scanning the electron beam, and a detector positioned in front of the opening of the objective lens A method for adjusting the axis of a beam, wherein the opening of the objective lens is scanned with an electron beam, and the axis adjusting means is controlled based on an image detected thereby.

  In the present invention, the aperture of the objective lens is scanned with an electron beam, and the axis of the electron beam is adjusted based on the image detected thereby. At this time, if a first image detected by scanning the electron beam in the first direction and a second image corresponding to an inverted image at the image center of the first image are obtained, the electron beam is acquired. Can be easily adjusted.

  Hereinafter, a scanning electron microscope according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram showing a scanning electron microscope in the present invention. In FIG. 1, reference numeral 100 denotes a scanning electron microscope. The scanning electron microscope 100 includes an electron gun (electron beam source) 1 for accelerating and emitting an electron beam 10.

  The electron beam 10 emitted from the electron gun 1 is finely focused by the focusing lens 3 and the objective lens 6 and irradiated onto the sample 8. At this time, the scanning coil 5 causes the electron beam 10 to scan a predetermined area on the sample 8. Here, the objective lens 6 is a semi-in type objective lens, and includes an exciting coil 6 b and an opening 6 c through which the electron beam 10 passes at a tip portion facing the sample 8. The scanning coil 5 includes an upper scanning coil 5b disposed on the electron gun 1 side and a lower scanning coil 5c disposed on the sample 8 side.

  When the sample 8 is irradiated with the electron beam 10, detected electrons (not shown) such as secondary electrons are generated from the sample 8. The detected electrons generated from the sample 8 pass through the opening 6 c of the objective lens 6. The detected electrons that have passed through the opening 6 c of the objective lens 6 are detected by the detector 11.

  The detector 11 outputs a detection signal based on the detection result of the detected electrons. The detection signal output from the detector 11 is amplified and sent to the A / D converter 12 where it is converted into a digital signal. The detection signal converted into a digital signal by the A / D converter 12 is output to the bus line 13.

  An image forming unit 16 is connected to the bus line 13. The image forming unit 16 receives the digitized detection signal via the bus line 13 and forms an image (image) to be a scanned image. The image formed by the image forming unit 16 is sent to a display unit 19 composed of an LCD, a CRT or the like and displayed as a sample image. In addition, the formed image is sent to the storage unit 17 and stored as necessary.

  A gun alignment coil (axis adjusting means) for adjusting the axis of the electron beam 10 emitted from the electron gun 1 below (behind) the electron gun 1 and between the electron gun 1 and the focusing lens 3. 2 is arranged. Further, between the focusing lens 3 and the scanning coil 5, a diaphragm 9 and a beam alignment coil 4 (axis adjusting means) positioned below the diaphragm 9 are arranged.

  The diaphragm 9 is formed with a diaphragm hole 9a through which the electron beam 10 passes. The beam alignment coil 4 is for adjusting the axis of the electron beam 10 that has passed through the aperture 9 a of the aperture 9.

  The sample 8 is placed on the sample stage mechanism 7. The sample stage mechanism 7 moves the placed sample 8 in the horizontal direction (XY direction), the vertical direction (Z direction), the rotation direction, and the tilt direction.

  The electron gun 1, gun alignment coil 2, focusing lens 3, beam alignment coil 4, scanning coil 5, objective lens 6, and sample stage mechanism 7 are driven parts 1 to 7 by corresponding driving parts 1 a to 7 a, respectively. Drive controlled. Each drive unit 1 a to 7 a is connected to the bus line 13. Each component block connected to the bus line 13 including these drive units 1 a to 7 a is controlled by a control unit (control means) 14.

  In addition, a calculation unit 15 and an image creation unit 18 are connected to the bus line 13. The calculation unit 15 is for performing calculations necessary for controlling the scanning electron microscope 100. The image creating unit 18 reads an image stored in the storage unit 17 and converts the image to create a new image. The image created by the image creating unit 18 is also displayed on the display unit 19 and stored in the storage unit 17 as necessary.

  Further, an input unit 20 is connected to the bus line 13. The input unit 20 includes a pointing device such as a joystick and a mouse, a keyboard, and the like.

  A method for adjusting the axis of the electron beam in the scanning electron microscope having such a configuration will be described below. In this embodiment, the axis of the electron beam 10 emitted from the electron beam 1 is aligned with the central axis of the focusing lens 3 behind the gun alignment coil 2 and is arranged behind the focusing lens 3. An example in which the axis of the electron beam 10 that has passed through the aperture 9a of the aperture 9 is aligned with the central axis of the objective lens 6 will be described.

  The electron beam 10 emitted from the electron gun 1 and having passed through the aperture 9a of the aperture 9 passes through the opening 6c of the objective lens 6. At this time, the scanning coil 5 is driven and controlled, and the aperture 6c is passed through the aperture 6c. The electron beam 10 is scanned using a predetermined region in the objective lens 6 including the scanning region as a scanning region. At this time, the supply of the excitation current to the excitation coil 6b of the objective lens 6 is stopped.

  Hereinafter, scanning of the electron beam 10 in the objective lens 6 at this time will be described with reference to FIG. Here, FIG. 2 is an enlarged view of a main part of the objective lens 6 of FIG.

  In FIG. 2, an opening 6c through which the electron beam 10 passes is formed at the tip of the objective lens 6 as described above. This tip portion is configured to face a sample 8 (see FIG. 1) disposed behind the objective lens 6. As a result, the sample 8 is positioned behind the opening 6c. The objective lens 6 has a function of focusing the electron beam 10 on the sample 8 arranged at this position. Although the positional relationship between the objective lens 6 and the sample 8 is as described above, it is not necessary to arrange the sample 8 in the axis adjustment of the electron beam 10 described in the present embodiment.

  The objective lens 6 includes an inner magnetic pole 6d and an outer magnetic pole 6e. The electron beam 10 travels toward the opening 6c through the electron beam passage space 6f in the objective lens 6. The inner magnetic pole 6d and the outer magnetic pole 6e are provided with a through hole 6g formed so as to communicate with and face the electron beam passage space 6f.

  A detector 11 for detecting the detected electrons 10a such as secondary electrons is disposed in the through hole 6g. The detector 11 is positioned above (front) the opening 6c through which the electron beam 10 passes. The detector 11 includes a scintillator 11a for receiving and detecting the detected electron 10a, a corona ring 11b, and a photomultiplier tube 11c.

  The opening 6c of the objective lens 6 having such a configuration is scanned by the scanning coil 5 (see FIG. 1). At this time, the scanning coil 5 is driven and controlled by the drive unit 5a (see FIG. 1), and the electron beam 10 uses the predetermined region of the inner surface 6h of the inner magnetic pole 6d including the opening 6c in the objective lens 6 as a scanning region. Scan. As a scanning condition, the deflection amount in scanning in the X direction is symmetric about the axis of the electron beam 10. The deflection amount in scanning in the Y direction is also symmetric about the axis of the electron beam 10. Note that it is not necessary to match the deflection amount in the X direction with the deflection amount in the Y direction.

  The scanning direction of the electron beam 10 at this time will be further described with reference to FIG. Here, FIG. 3 is a schematic view showing the opening 6c in the objective lens 6 and a part of the inner surface 6h of the inner magnetic pole 6d located around the opening 6c. That is, FIG. 3 is a view of the objective lens 6 as viewed from the electron beam passage space 6f side toward the opening 6c (that is, the traveling direction of the electron beam 10). The electron beam 10 scans the inner surface 6h of 6d.

In FIG. 3, a region 30 surrounded by a dotted line shows an example of a scanning region when the axis of the electron beam 10 and the central axis of the objective lens 6 do not match. As described above, the scanning condition of the electron beam 10 is such that the amount of deflection in the X direction and the amount of deflection in the Y direction are symmetric about the axis, respectively. Coincides with the center 33 of. Further, the central axis of the objective lens 6 coincides with the center 34 of the opening 6c. Accordingly, if the axis adjustment is performed so that the center 33 of the scanning region 30 by the electron beam 10 under the scanning condition and the center 34 of the opening 6c coincide with each other, the axis of the electron beam 10 and the objective lens 6 are aligned. Will be aligned with the central axis. It is assumed that the pre-alignment (coarse adjustment) between the electron beam 10 and the central axis of the objective lens 6 has been completed, and the scanning region 30 includes the opening 34.
Under the above scanning conditions, first, the direction indicated by the one-dot chain line arrow 31 in FIG. That is, in the scanning region 30 in FIG. 3, the electron beam 10 is scanned from the upper left in the direction of the arrow 31 (X direction in the figure). After the scanning of one scanning line is completed, the scanning line is sequentially shifted in the direction from the upper part to the lower part (the −Y direction in the figure), and scanning with the electron beam 10 is executed in the direction indicated by the arrow 31. Go.

  When the scanning region 30 including the opening 6c is scanned with the electron beam 10 in this way, detected electrons 10a are generated from the scanning region 30 on the inner surface 6h of the inner magnetic pole 6d excluding the portion of the opening 6c. The generated detected electron 10a is detected by the detector 11, and the detector 11 outputs a detection signal based on the detection result. The detection signal output from the detector 11 is amplified and sent to the A / D converter 12 where it is converted into a digital signal. Since the supply of the excitation current to the excitation coil 6b of the objective lens 6 is stopped, the objective lens 6 is not excited, and the sample 8 is temporarily arranged behind the objective lens 6. However, the electron beam 10 is not focused and irradiated on the sample 8, and the detected electrons are not detected from the sample 8 by the detector 11.

  The detection signal converted into a digital signal by the A / D conversion unit 12 is sent to the image forming unit 16 via the bus line 13. The image forming unit 16 receives the detection signal and forms an image to be a scanned image. The image thus formed is sent to the display unit 19 for display and sent to the storage unit 17 for storage.

  An example of the scanned image at this time is shown in FIG. Here, FIG. 4 is a diagram illustrating an example of a scanned image in a case where there is a deviation between the axis of the electron beam 10 and the central axis of the objective lens 6. As shown in FIG. 4A, the scanning image (first image) 41 is formed corresponding to the scanning region 30 in FIG.

  In the scanning image 41, the opening image 6i of the opening 6c is detected by being shifted from the image center 35 of the scanning image 41 (corresponding to the center 33 of the scanning region 30) in the upper left direction in FIG. Here, since the detected electrons 10a are not generated from the opening 6c, the opening image 6i is in a dark state.

  As described above, after the scanning image 41 to be the first image is detected and acquired, and is displayed and stored in the storage unit 17, a second image corresponding to the reverse image of the scanning image 41 is now displayed. Detect and obtain as follows.

  By changing the driving condition of the scanning coil 5 by the driving unit 5a, the scanning direction of the electron beam 10 is changed in the reverse direction without changing the scanning region 30. Note that the deflection amount in the X direction and the deflection amount in the Y direction with respect to the axis of the electron beam 10 are not changed from the conditions for obtaining the first image. The scanning direction of the electron beam 10 when acquiring the second image will be described with reference to FIG.

  In FIG. 3, a two-dot chain line arrow 32 is a scanning direction of the electron beam 10 when the second image is acquired. That is, in the scanning region 30 in FIG. 3 (which coincides with the scanning region when the first image is acquired), the electron beam 10 is scanned from the lower right portion in the direction of the arrow 32 (the −X direction in FIG. 3). To do. After the scanning of one scanning line is completed, the scanning line is sequentially shifted from the lower part to the upper part (Y direction in the figure), and scanning with the electron beam 10 in the direction of the arrow 32 is executed.

  When the scanning region 30 is scanned with the electron beam 10 in this way, the detected electrons 10a (see FIG. 2) are generated from the scanning region 30 as described above. The generated detected electron 10a is detected by the detector 11, and the detector 11 outputs a detection signal based on the detection result. The detection signal output from the detector 11 is amplified and sent to the A / D converter 12 where it is converted into a digital signal. Also at this time, since the supply of the excitation current to the excitation coil 6b of the objective lens 6 is stopped, the objective lens 6 is not excited, and the sample 8 is temporarily arranged behind the objective lens 6. Even if the electron beam 10 is focused, the electron beam 10 is not focused and irradiated, and the detected electrons are not detected from the sample 8 by the detector 11.

  The detection signal converted into a digital signal by the A / D conversion unit 12 is sent to the image forming unit 16 via the bus line 13. The image forming unit 16 receives the detection signal and forms an image to be a scanned image. The image thus formed is sent to the display unit 19 for display and sent to the storage unit 17 for storage.

  A scanned image at this time is shown in FIG. As shown in FIG. 4B, the scanning image (second image) 42 is formed corresponding to the scanning region 30 in FIG. 3, but is an image corresponding to the inverted image of the first image 41. It has become. Here, the inverted image refers to an image obtained by rotating the first image 41 by 180 degrees around the center of the image.

  In the scanned image 42 shown in FIG. 4B, the opening image 6i of the opening 6c is shifted from the image center 35 of the scanning image 41 (corresponding to the center 33 of the scanning region 30) in the lower right direction in FIG. Has been detected. Also in this case, since the detected electrons 10a are not generated from the opening 6c, the opening image 6i is in a dark state.

  In this manner, the scanning image 42 as the second image is detected and acquired, and is displayed and stored in the storage unit 17. Thereafter, the comparison between the first image 41 and the second image 42 is performed as follows.

  Under the control of the control unit 14 (see FIG. 1), the first image 41 and the second image 42 stored in the storage unit 17 are read and sent to the calculation unit 15. The calculation unit 15 calculates the coordinates on the image of the center position 6j (see FIG. 4A) of the opening image 6i in the first image 41 and the center of the opening image 6i in the second image 42. The coordinates on the image of the position 6j (see FIG. 4B) are calculated.

  And the calculating part 15 calculates the difference amount of the coordinate of these two center positions 6j about the X direction and the Y direction from the coordinates of both the said center positions 6j, respectively.

  Thereafter, the control unit 14 controls the driving unit 4a to adjust the excitation condition of the beam alignment coil 4, move the axis of the electron beam 10 from the diaphragm 9, perform the above-described process again, and perform the first process. The apparatus is controlled to acquire the image 41 and the second image 42 and calculate the difference amount. And the control part 14 repeats this operation control, and controls the axis | shaft of the electron beam 10 so that the said difference amount may be set to zero.

  The first and second images when the difference amount becomes zero and the center position 6j of the opening image 6i in the first image 41 coincides with the center position 6j of the opening image 6i in the second image 42. 41 and 42 are shown in FIG. Here, FIG. 5 is a diagram illustrating a state in which the opening image 6i in the first image 41 and the opening image 6i in the second image 42 overlap each other.

  As shown in FIG. 5, in a state where both the opening images 6i in the first and second images 42 are overlapped and both the center positions 6j are coincident with each other, the center position 6j is a scanning region by the electron beam 10 at that time. Corresponds to 30 centers 33. Therefore, in this state, the center 33 of the scanning region 30 by the electron beam 10 coincides with the center 34 of the opening 6 c in the objective lens 6, and the axis of the electron beam 10 and the center axis of the objective lens 6 match. It becomes.

  Thus, in the present invention, the opening 6c of the objective lens 6 is scanned with the electron beam 10, and the axis of the electron beam is adjusted based on the image detected thereby. At this time, it corresponds to a first image 41 detected by scanning the electron beam 10 in the first direction 31 (see arrow 31 in FIG. 3) and a reverse image at the image center in the first image. The second image 41 to be acquired is acquired and the images 41 and 42 are compared to perform the axis adjustment, so that the axis adjustment of the electron beam 10 can be easily performed.

  Here, the drive control method of the scanning coil 5 when acquiring the first image 41 and when acquiring the second image 42 will be described.

  When acquiring the first image 41, as described above, the electron beam 10 is scanned in the direction of the arrow 31 in FIG. At this time, for example, the electron beam 10 is scanned by the upper scanning coil 5 b constituting the scanning coil 5.

  Further, when the second image 42 is acquired, as described above, the electron beam 10 is scanned in the direction of the arrow 32 in FIG. 3 (the direction opposite to the arrow 31). At this time, for example, the electron beam 10 is scanned by the lower scanning coil 5 c constituting the scanning coil 5.

  As described above, the upper / lower scanning coils 5b and 5c for scanning the electron beam 10 are selected and driven each time depending on the scanning direction of the electron beam 10, thereby simplifying the setting of scanning conditions. be able to. Instead of selecting the upper / lower scanning coils 5b and 5c in accordance with the scanning direction of the electron beam 10, the entire scanning coil 5 composed of the upper / lower scanning coils 5b and 5c is driven and controlled, and the electron beam is controlled. There is no problem even if the scanning direction of 10 is changed.

  In the above-described example, after acquiring the first image 41, the electron beam 10 is scanned in the reverse direction again to acquire the second image. It is not limited to examples.

  That is, after acquiring the first image 41 and temporarily storing the image 41 in the storage unit 17, the image 41 is read from the storage unit 17 and sent to the image creation unit 18 under the control of the control unit 14. The image creation unit 18 converts the image 41 and creates a reverse image obtained by rotating the image 41 about the image center by 180 degrees as a second image.

  Thereafter, the calculation unit 15 performs the above-described calculation process based on the first image 41 stored in the storage unit 17 and the second image created by the image creation unit 18.

  In this way, if the second image is obtained by converting the first image 41, the electron beam 10 is scanned in the reverse direction again to obtain the second image, and the scanned image is obtained. There is no need to get. Therefore, in this case, the conditions for driving and controlling the scanning coil 5 become simpler, and the processing time can be shortened.

  In each of the above-described embodiments, the axis adjustment of the electron beam 10 is automatically performed, but a scanning image including the opening 6c of the objective lens 6 is acquired even when the axis adjustment is manually performed. Thus, the axis of the electron beam 10 can be adjusted. Below, the Example in the axial adjustment of the electron beam 10 manually is described.

  In this case, the first image 41 obtained by the same method as in the above-described embodiment and the second image 42 or the first image obtained by scanning the electron beam 10 in the reverse direction are converted. After obtaining the second image obtained in this manner, the first and second images are alternately and repeatedly displayed on the display unit 19.

  A display image by the display unit 19 at this time is shown in FIG. Here, FIG. 6 is a diagram showing a display image when the first and second images are alternately and repeatedly displayed.

  In FIG. 6, reference numeral 50 denotes a display image. The display image 50 is formed by alternately and repeatedly displaying the first image and the second image, and therefore the opening image 6i in the first image. And the opening image 6i in the second image are alternately and repeatedly displayed.

  At this time, if the cycle of the repeated display of the first image and the second image by the display unit 19 is shortened, the eyes of the operator who is visually confirming the display unit 19 will see the opening image in both images. 6i will alternately enter in a short cycle. As a result, an afterimage 51 corresponding to the opening image 6i in the first image and an afterimage 52 corresponding to the opening image 6i in the second image remain in the eyes of the operator. The operator operates the input unit 20 to adjust the axis of the electron beam 10 by exciting the beam alignment coil 4 so that the afterimages 51 and 52 overlap each other while confirming both afterimages 51 and 52.

  Thus, in the present invention, the opening 6c of the objective lens 6 is scanned with the electron beam 10, and the axis of the electron beam 10 is adjusted by controlling the beam alignment coil 4 based on the image detected thereby. . At this time, the first image detected by scanning the electron beam in the first direction and the second image corresponding to the reverse image at the center of the image are acquired and compared, and the comparison result is obtained. Since the beam alignment coil 4 is controlled based on this, the axis adjustment of the electron beam 10 can be easily executed. Further, even in the axis adjustment of the electron beam 10 by manual operation, the axis adjustment can be easily performed without requiring operator skill.

  In each of the above-described embodiments, an example in which the axis of the electron beam 10 that has passed through the aperture 9a of the aperture 9 is adjusted to the central axis of the objective lens 6 by adjusting the excitation condition of the beam alignment coil 4 has been described. However, the present invention is not limited to such an example. In addition to this example, for example, the present invention is applied to the case where the axis of the electron beam 10 emitted from the electron gun 1 is adjusted to the central axis of the focusing lens 3 by adjusting the excitation condition of the gun alignment coil 2. be able to.

It is a schematic block diagram which shows the scanning electron microscope in this invention. It is an enlarged view of the principal part in the objective lens of FIG. It is the schematic which shows the opening part in an objective lens, and a part of inner surface of the inner side magnetic pole located in the circumference | surroundings. It is a figure which shows an example of the scanning image in case the shift | offset | difference has arisen between the axis | shaft of an electron beam, and the central axis of an objective lens. It is a figure which shows the state with which the opening part image in a 1st image and the opening part image in a 2nd image overlapped. It is a figure which shows a display image when the 1st and 2nd image is displayed by repeating alternately.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electron gun (electron beam source), 2 ... Gun alignment coil (axis adjustment means), 3 ... Focusing lens, 4 ... Beam alignment coil (axis adjustment means), 5 ... Scanning coil, 6 ... Objective lens, 7 ... Sample Stage mechanism, 8 ... sample, 9 ... aperture, 10 ... electron beam, 11 ... detector, 12 ... A / D conversion unit, 13 ... bus line, 14 ... control unit (control means), 15 ... calculation unit, 16 ... Image forming unit 17 ... Storage unit 18 ... Image creating unit 19 ... Display unit 20 ... Input unit

Claims (8)

An electron beam source, an objective lens that has an aperture through which the electron beam emitted from the electron beam source passes, and that focuses the electron beam on a sample disposed behind the aperture, and an axis of the electron beam are adjusted A scanning electron microscope comprising: an axis adjusting unit that performs scanning; a scanning coil that scans an electron beam; and a detector that is positioned in front of the opening of the objective lens. A scanning electron microscope comprising control means for controlling the axis adjusting means based on an image detected thereby. The control means has a first image detected by scanning the opening of the objective lens in the first direction with an electron beam, and the opening is in a direction opposite to the first direction by the electron beam. 2. The second image detected by scanning in the second direction is acquired, and the axis adjusting means is controlled based on a comparison between the first and second images. The scanning electron microscope as described. The control means is obtained by rotating a first image detected by scanning the aperture of the objective lens in a first direction with an electron beam and the first image rotated 180 degrees around the image center. The scanning electron microscope according to claim 1, wherein the second image is acquired and the axis adjusting unit is controlled based on a comparison between the first and second images. An electron beam source, an objective lens that has an aperture through which the electron beam emitted from the electron beam source passes, and that focuses the electron beam on a sample disposed behind the aperture, and an axis of the electron beam are adjusted A method for controlling a scanning electron microscope comprising: an axis adjusting means for performing scanning; a scanning coil for scanning an electron beam; and a detector positioned in front of the opening of the objective lens. And a second image detected by scanning the opening in a second direction opposite to the first direction by an electron beam. And a method for controlling the scanning electron microscope, wherein the first and second images are alternately displayed. An electron beam source, an objective lens that has an aperture through which the electron beam emitted from the electron beam source passes, and that focuses the electron beam on a sample disposed behind the aperture, and an axis of the electron beam are adjusted A method for controlling a scanning electron microscope comprising: an axis adjusting means for performing scanning; a scanning coil for scanning an electron beam; and a detector positioned in front of the opening of the objective lens. To obtain a first image detected by scanning in the first direction and a second image obtained by rotating the first image around the image center by 180 degrees. A method for controlling a scanning electron microscope, wherein two images are alternately displayed. An electron beam source, an objective lens that has an aperture through which the electron beam emitted from the electron beam source passes, and that focuses the electron beam on a sample disposed behind the aperture, and an axis of the electron beam are adjusted A method for adjusting an axis of an electron beam in a scanning electron microscope comprising: an axis adjusting means for performing scanning; a scanning coil for scanning an electron beam; and a detector positioned in front of the opening of the objective lens. A method of adjusting an axis of an electron beam, comprising: scanning an aperture with an electron beam; and controlling the axis adjusting unit based on an image detected thereby. A first image detected by scanning the opening of the objective lens in the first direction with an electron beam, and a second direction that is opposite to the first direction with the electron beam. 7. The electron beam according to claim 6, wherein a second image detected by scanning is acquired, and the axis adjusting means is controlled based on a comparison between the first and second images. Axis adjustment method. A first image detected by scanning the aperture of the objective lens in the first direction with an electron beam, and a second image obtained by rotating the first image by 180 degrees around the image center 7. The electron beam axis adjusting method according to claim 6, wherein the axis adjusting unit is controlled based on a comparison between the first and second images.

Images