KR20150104574A - Specimen Stage and of Precise Control Unit of Specimen Holder for Multipurpose 3 Dimensional Imaging by Transmission Electron Microscope - Google Patents

Abstract

The present invention relates to a goniometer (x, y, z, a) for multi-purpose three-dimensional imaging (atomic structure, electron diffraction, electronic tomography, etc.) of a nanostructure using a transmission electron microscope (TEM) And a double-tilting holder (?). According to the present invention, it is possible to automatically adjust the orientation of a sample in an electron microscope and to perform three-dimensional imaging of the nanostructure (atomic structure, electron diffraction, Electronic tomography, etc.) can be acquired quickly and easily.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a specimen stage and a specimen holder for precise control of a specimen holder for a multi-purpose three-dimensional imaging in a transmission electron microscope.

The present invention relates to a goniometer (x, y, z, a) for multi-purpose three-dimensional imaging (atomic structure, electron diffraction, electronic tomography, etc.) of a nanostructure using a transmission electron microscope (TEM) And a double-tilting holder (?) At the same time.

Several methods are known for obtaining superior three-dimensional images in TEM.

For example, Japanese Laid-Open Patent Publication No. 2006059687 (published on March 22, 2006) discloses a device for defocusing a sample by tilting the focus and downward, thereby obtaining a three- Japanese Patent Application Laid-Open No. 2003197142 (published on July 11, 2003) discloses a device for adjusting the incident direction of an electron beam and a method for obtaining an image at various angles without inclining the sample. However, since they are equipped with a device for changing the focusing position or incidence direction of the electron beam to control the function of the TEM itself, the apparatus is complicated and can affect the inherent functions of the TEM.

US 8089053 (registered Jan. 13, 2012) provides a dynamic tilting holder using MEMS (Micro Electro Mechanical Systems) and PZTs (piezoelectric transducers), which digitally controls the tilting holder.

In addition, a typical apparatus (method) for obtaining a three-dimensional image in the conventional TEM is to adjust the irradiation angle and irradiating position of the sample, fine movement of the holder itself on the x, y, and z axes, (?) Around the x-axis, and a double tilting holder for rotating the sample placed on the holder about the y-axis (?). By controlling the goniometer and the double tilting holder, one sample is observed (photographed) in various directions to construct a three-dimensional image.

The goniometer is one of the devices constituting the TEM and is fixedly mounted on the TEM itself, and there is a goniometer control device for controlling the three-axis movement and rotation (?) Thereof. FIG. 1 shows a goniometer disposed at the objective piece pole piece region of the TEM (the holder is also shown in the drawing). As shown in the figure, the goniometer has a structure in which the holder itself is finely and linearly moved in an axis (x axis) in the direction in which the holder is mounted, an axis (z axis) perpendicular to the x axis Rotate the holder around the axis (α) to control the position and observation angle of the sample. That is, the operator adjusts x, y, and z to determine a specific position of the sample to be observed (a point at which the electron beam should focus, hereinafter referred to as an observation point) And the observation point is observed at various angles.

To this end, the goniometer is provided with an x-axis drive motor, a y-axis drive motor, a z-axis drive motor, and an? Rotation drive motor (not shown). In this case, the movement range in each axial direction is very fine, about ± 2 mm in the x-axis direction and the y-axis direction and about ± 250 μm in the z-axis direction, and the rotation range of α is usually ± 60 to 70 °.

Separately, the double-tilting holder is paired with a holder control device for rotating the sample of the holder as one of the various holders used in the TEM. The double tilting holder is equipped with a driving motor (not shown) that rotates about the y-axis (?). The rotation range of? Is usually within a range of 20 to 45 degrees. The rotation direction and rotation range of? And? In the holder are shown in Fig.

Thus, the goniometer control device and the holder control device are separate devices without any structural or operational coherence.

Therefore, in order to form a three-dimensional image of a specific portion of the sample, imaging is required in various orientations of the same sample. An example of the image is shown in FIG. In order to move the sample in the azimuth direction, a skilled operator must repeat the operation of the goniometer control device and the operation of the holder control device independently from several times to several tens of times. As a skilled operator, it is not only a day of trouble, but also a time consuming task. Because of this reality, it is very difficult to repeatedly observe one specific sample repeatedly in several orientations.

The present invention can automatically adjust the orientation of a desired sample by simply inputting a target coordinate value (i.e., a position and an azimuth angle of a specific portion of the sample) to which the sample is to be moved by allowing the Goniometer and the holder to be controlled simultaneously in the TEM, (Sample holder orientation navigator) that enables TEM observation.

In order to achieve the above-mentioned object, the present invention is characterized in that (A) an x-axis driving motor, a y-axis driving motor, a z-axis driving motor, a rotation driving motor and a predetermined double tilting holder Rotation driving motor of the double tilting holder, and independently drives each of the driving motors in accordance with an operation signal of the controller; (B) The rotation angle (current angle) of the gyrometer's x-axis driving motor, y-axis driving motor, z-axis driving motor, alpha -rotation driving motor and beta -rotation driving motor shaft of the double tilting holder is measured, A sensor unit for transmitting the signal to the control unit; (C) a rotation angle of each driving motor shaft of the goniometer, corresponding x, y, z and a values, (2) a code of the double tilting holder and a rotation angle of the The stored storage unit; (D) an input unit for receiving the [x, y, z] value of the target sample position and the target azimuth [?,?] Value, the code value of the double tilting holder, and a run signal; (E) if there is an operation signal of the input unit, the control unit refers to the storage unit to determine a target rotation of each driving motor shaft with respect to the input x, y, z, and a value of the double tilting holder corresponding to the input code A controller for extracting an angle and transmitting an operation signal to the drive unit until the current rotation angle of each drive motor transmitted from the sensor unit coincides with the target rotation angle; And (F) a display unit for displaying information including x, y, z, alpha and beta values for the input target position and orientation and the current x, y, z, alpha and beta values of the sample And is a precision control device for three-dimensional imaging in a transmission electron microscope.

As described above, according to the present invention, a "sample orientation automatic adjustment device" capable of automatically adjusting the orientation of a sample in an electron microscope becomes possible.

Dimensional image (atomic structure, electron diffraction, electronic tomography, etc.) of a nanostructure which can not be analyzed in conventional X-ray and neutron and which is difficult to realize even in TEM by using the "automatic sample- So that it can be acquired quickly and easily. Therefore, by using the precise control device according to the present invention, it is possible to make a great contribution to the shape analysis technique and the atomic arrangement structure of the low dimensional fused composite nano material.

1 is a conceptual view showing a goniometer installed in a TEM;
2 is a view showing rotation directions and rotation ranges of and in a conventional double tilting holder;
Figure 3 is an example of sample orientation movement and imaging for three-dimensional imaging of the same sample.
4 is a schematic configuration view showing the configuration and the relevance of each of the drive motors of the precision control device and the goniometer and the holder according to the present invention.
5 and 6 are diagrams showing a part of different examples of a touch screen in which an input unit and a display unit are integrated in the precision control apparatus according to the present invention.
FIG. 7 is an example of a Wulff net showing reference values for the crystallographic orientation of a sample, which is utilized in the technical field to which the present invention belongs.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the appended drawings illustrate only the contents and scope of technology of the present invention, and the technical scope of the present invention is not limited thereto. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the technical idea of the present invention based on these examples.

The present invention relates to a device (automatic sample orientation adjusting device) for multi-purpose three-dimensional imaging in a transmission electron microscope, which comprises a goniometer as a component for operating a sample in a TEM, Is a precise control device that can integrally control the double tilting holder to be replaced with a double tilting holder. A precision control device according to the present invention comprises a driving unit, a sensor unit, a storage unit, an input unit, a control unit, and a display unit. Fig. 4 shows the schematic configuration and the relevance of the precision control device according to the present invention and the drive motors of the goniometer and the holder.

The driving unit is connected to the x-axis, y-axis, z-axis driving motor and the? -Rotation driving motor of the goniometer and the? -Rotation driving motor of the holder when a predetermined double tilting holder is mounted on the TEM, And drives the drive motors independently.

Each of the x-, y-, and z-axis driving motors moves the sample position linearly on each axis by the rotation of the motor, and the azimuth angle of the sample is changed by the rotation of the motor in the α rotation drive motor and the β rotation drive motor .

In the present invention, the goniometer control device and the holder control device, which are originally mounted on the TEM, can be used as they are or after being modified, or the connections between the goniometer control device and the holder control device are all cut off, It can also be used.

The sensor unit is configured such that the (focused) electron beam is focused on the sample at any position (position on the x, y, and z axes) of the sample ultimately required to be observed and the sample is rotated at any angle ) In order to detect how these positions and angles have changed. On the other hand, the positional change on the x-, y-, and z-axes (in a straight line) corresponds to the rotation angle (or the rotation amount; hereinafter simply referred to as rotation angle) of the x-, y-, and corresponds to the rotation angle (or rotation amount) of the? -rotation and? -rotation drive motor shaft. Therefore, in the present invention, the sensor unit measures the rotation angle (current angle) of the x-axis drive motor, y-axis drive motor, z-axis drive motor,? -Rotation drive motor and? And transmits the information to the control unit.

The sensor unit may be configured in various ways, and may operate, for example, in the following configuration. That is, the sensor unit includes: (1) a resistor whose resistance changes in association with the rotation of each drive motor drive shaft; (2) a constant voltage supplier that supplies a constant voltage to the resistor; and (3) a voltmeter that measures a voltage output from each resistor. And the rotation angle of each of the drive motor shafts is expressed by a voltage value measured by a voltmeter of each of the drive motors. As the resistor, a potentiometer known in the art can be used.

In the present invention, the sensors of the Goniometer or the holder of the TEM may be used as they are, or they may be blocked or removed, and a newly manufactured sensor may be used.

The storage unit stores (1) the rotation angles of the x, y, and z axis drive motor shafts of the goniometer and the position values x, y, z of the x, y, z axes Of the double tilting holder mounted on the current electron microscope and the azimuth angle value? Of the sample corresponding to the azimuth angle value? Of the sample and the code (unique number) of the double tilting holder mounted on the current electron microscope and the rotation angle of the? .

The input unit receives the code value of the double tilting holder mounted on the electron microscope, the position of the target (to be observed) and the azimuth angle x, y, z, alpha and beta values, And transmits a run signal to the control unit.

The control unit receives the code value of the double tilting holder, the position of the sample and the azimuth angles x, y, z, alpha and beta in the input unit, and if there is an operation signal, Extracting a target rotation angle of each drive motor shaft with respect to a position and an azimuth angle x, y, z, and a value of the double tilting holder and a value of a double tilting holder corresponding to the input code, And (3) transmitting an operation signal to the drive unit until the current rotation angle of each drive motor coincides with the target rotation angle.

The display unit displays information including the input target x, y, z, alpha and beta values and x, y, z, alpha and beta values of the current sample position and azimuth angle.

The precision control apparatus for multi-purpose three-dimensional imaging according to the present invention as described above is typically used (operated) as follows.

The operator attaches a predetermined double tilting holder on which the sample is placed to the electron microscope, and inputs the code value of the double tilting holder to the input unit. Next, the operator inputs the [x, y, z] value of the target sample position and the target sample azimuth angle [alpha, beta] value to the input unit and then presses the run button.

The input unit receiving the operation button signal transmits the values [x, y, z] and [alpha, beta] to the control unit.

The sensor unit measures in real time the rotational angle (current angle) of the gyrometer's x-axis drive motor, y-axis drive motor, z-axis drive motor,? -Rotation drive motor and? do.

The controller inquires of the storage unit as the input x, y, z, alpha and beta values and extracts a target rotation angle of each drive motor shaft for each value. Next, the target rotation angle of each drive motor shaft is compared with the current rotation angle of each drive motor shaft transmitted from the sensor unit, and an operation signal for driving each drive motor is transmitted to the drive unit until the difference becomes zero.

The drive unit receiving the individual operation signals for each drive motor independently drives the corresponding drive motor. At this time, the current rotation angle of each drive motor is measured by the sensor unit in real time and transmitted to the control unit.

On the other hand, the rotation angle of each driving motor shaft of the goniometer and corresponding x, y, z and a values, the code of the double tilting holder, and the? Rotation driving The rotation angle of the motor shaft and the corresponding? Value are measured and stored in the storage unit. It is preferable that each corresponding value stored in the storage section is calibrated periodically or intermittently automatically or manually by the operator.

As described above, the combination of x, y, and z determines the position of the sample, and α and β determine the crystallographic azimuth of the sample to be observed. Normally, the operator first determines the observation point of the sample, then determines the observation orientation of the sample, analyzes the imaging (atomic structure, electron diffraction) of the sample, determines the new observation orientation again and analyzes the image of the sample. In some situations, however, there is a need to look back at the orientation of the sample that has been observed before. However, in the conventional TEM, it was impossible to return accurately to the point and angle observed before, and it had to depend on the operator's sense and manipulation technique.

In order to solve this inconvenience, the present invention can be modified as follows. That is, the input unit is provided with a storage button for storing the current position and the azimuth information of the sample, and a recall button for recalling the past position and the azimuth information of the stored sample. (X, y, z,?,?) Of the current sample and the azimuth information (x, y, z,?,?) Of the sample stored in the storage unit x, y, z, alpha, beta) to determine the target x, y, z, alpha and beta values.

(X, y, z,?,?) Or a predetermined number of samples in accordance with the storage button depression signal, or the azimuth information The azimuth information (?,?) At the specific sample position is stored together with a predetermined identification symbol (for example, an alphabetical order, a stored time or a name input by the operator), and if the recall button pushing signal is repeated, Y, z, alpha, beta) of the predetermined number of stored samples and the azimuth information (alpha, beta) at the specific sample position by sequentially calling the azimuth information (x, And the beta value.

As a result, the operator can reproduce the position and the azimuth angle as it was before, so that the sample observing operation can be performed more efficiently.

5 and 6 show a part of another example of the touch screen in which the input unit and the display unit are integrated, reflecting the above functions. In the figure, only rotation angles, that is, α and β which designate the azimuth angle of the sample are expressed. It is to be understood that what is shown is merely an example, and that various touch screens that operate in a manner different from that described below will be possible. In FIG. 5, press 'HOLDER CODE' indicated by a square at the upper left corner, and then press the numeric keypad to record the code value of the mounted holder. 'Present' shows current α and β values. When the operator presses the α marked with a rectangle and presses the number plate to enter the desired target α value, presses the square marked β, presses the number plate and inputs the desired target β value, and the target value is displayed in 'Target'. If you press 'MEMORY' indicated by a square at the top, current α and β values are stored in the memory unit. If you press 'RECALL' marked with a square, α and β values stored in the memory unit are displayed immediately below and 'SEL' The value is selected as the target value and displayed in 'Target'. When 'Step' is toggled, it is decided to skip as much as the angle indicated in 'Step' to go continuously from the current value to the target value. When 'RUN' is pressed, the sample is rotated at the angle recorded in 'Target', so that the α and β values of 'Present' and 'Target' coincide positively.

Mechanical backlash can occur due to the instability of the goniometer and the holder. Therefore, 'Present' value and 'Target' value may be slightly different from each other when RUN is performed once.

In order to prevent this, the operator is required to repeat the 'RUN' 2-3 times or, if the 'RUN' is inputted once in software, the 'RUN' is automatically repeated 2-3 times .

As another way to minimize the mechanical error caused by backlash, it is also good to decelerate the drive motor as 'Present' value approaches 'Target' value when 'RUN' is input. Accordingly, as the 'Present' value approaches 'Target' value, the speed of the driving motor is lowered so that no backlash occurs.

Particularly, in the electronic tomography analysis, it is necessary to observe the sample while changing only one of the target x, y, z, alpha and beta values. In contrast, in the present invention, the input unit may further include an increase button and a decrease button for all or a part of x, y, z, alpha and beta values, and the control unit may further include: And transmits an operation signal to the drive unit to cause the drive motor corresponding to the decrement button pressing signal to rotate forward or backward by a predetermined rotation angle.

FIG. 6 shows a portion of an example of a touch screen (input and display) in which an increase (+) button and a decrease (-) button are introduced. In this inputting part (the other is the same as in FIG. 5), for example, when the α button marked by a quadrangle (or the α button on the left side of FIG. 5 when this is omitted) Unlike the case described above, only the rotation drive motor rotates in the positive (+) direction or the negative (-) direction without any change in the other values.

Although briefly mentioned in the description of FIG. 5 above, for example, when the observation orientation is changed from the first orientation to the second orientation of the sample, it may move continuously immediately, but any one or two of the? It may be necessary to observe the sample while moving in a stepwise manner at predetermined intervals.

To this end, in the precision control apparatus according to the present invention, a selection button (a step drive button or a continuous drive button) which can select a continuous movement and a step movement by a toggle, for example, may be added to the input unit. In this case, if there is a step-driving button depression signal, the control unit may step-up from the current azimuths? And? Of the sample to the target azimuths? And? To a predetermined angle And transmits an operation signal to the drive unit so as to continuously move from the current azimuths? And? Of the sample to the target azimuths? And? If there is a continuous drive button depression signal, Further,

On the other hand, the double tilt holder has an accuracy of about ± 1 °, and the error (the difference between the input value and the actual value) varies depending on the mounted double tilting holder. That is, when an operation signal corresponding to a predetermined rotation angle t is inputted to the? Tilting drive motor of the double tilting holder, the rotation angle? O of the actual double tilting holder, Beta] t-beta) is generated in the actual value [beta] = actual beta value). The generation of the error and the method of measuring the error are described in detail in a prior application (Patent Publication No. 10-2008-0059694) of the present inventors, so that further explanation is omitted.

Therefore, in the precise control apparatus according to the present invention, the storage section further stores an error (? =? T -?) Between the target rotation angle? T and the actual rotation angle? 0 of the double tilting holder to be mounted, It is preferable that the control unit further include a function of correcting the β of the double tilting holder corresponding to the input code by the error when extracting the target turning angle of the driving motor shaft.

On the other hand, when the sample is moved to the respective sample orientations on the electron microscope after the observation position of the sample is determined, that is, after the sample is fixed at the specific x, y and z, Axial drive is required. Conventionally, the operator has to rotate the sample to the desired direction while pressing the α and β axis buttons while alternately pressing the α and β axis buttons while viewing the display screen on which the angle with respect to each axis is displayed. It was difficult.

However, according to the present invention, when the α and β values are inputted to the 'Target' of FIG. 5 or 6 and 'RUN' is pressed, the operator moves to the direction of the desired sample without manually adjusting the α and β values manually, Imaging (atomic structure, electron diffraction) can be analyzed easily and quickly.

Claims (9)

(A) is connected to the β-rotation driving motor of the double tilting holder when a given double tilting holder is mounted on the goniometer's x-axis driving motor, y-axis driving motor, z-axis driving motor, A driving unit for independently driving each of the driving motors in accordance with an operation signal of the control unit;
(B) measures the rotation angle of the x-axis driving motor, the y-axis driving motor, the z-axis driving motor, the? -Rotating driving motor and the? -Rotating driving motor shaft of the double tilting holder of the goniometer and transfers the information to the controller A sensor unit;
(C) a rotation angle of each driving motor shaft of the goniometer, corresponding x, y, z and a values, (2) a code of the double tilting holder and a rotation angle of the The stored storage unit;
(D) an input unit for receiving a [x, y, z] value of a target sample position and a target azimuth angle [?,?] Value, a code value of the double tilting holder, and a run signal;
(E) if there is an operation signal of the input unit, the control unit refers to the storage unit to determine a target rotation of each driving motor shaft with respect to the input x, y, z, and a value of the double tilting holder corresponding to the input code A controller for extracting an angle and transmitting an operation signal to the drive unit until the current rotation angle of each drive motor transmitted from the sensor unit coincides with the target rotation angle; And
(F) a display unit for displaying information including x, y, z, alpha and beta values of the input target position and orientation and the current x, y, z, alpha and beta values of the sample;
And a controller for controlling the three-dimensional imaging in the transmission electron microscope. The method according to claim 1,
The sensor unit includes: (1) a resistor whose resistance changes in association with the rotation of each drive motor drive shaft; (2) a constant voltage supplier that supplies a constant voltage to the resistor; and (3) a voltmeter that measures a voltage output from each resistor.
Wherein the rotation angle of each of the drive motor shafts is expressed by a voltage value measured in a voltmeter of each of the drive motors. 3. The method according to claim 1 or 2,
The input unit is further provided with a storage button for storing the current position and the azimuth information of the sample and a recall button for recalling the past position and azimuth information of the stored sample.
The control unit stores the position and azimuth angle information (x, y, z, alpha, beta) of the current sample in the storage unit when the storage button depression signal is present in the input unit. If the recall button depression signal is present, Y, z, alpha, and beta values by calling the position and azimuth information (x, y, z, alpha, Control device. The method of claim 3,
Wherein,
Stores a predetermined number of combinations of sample position and azimuth information (x, y, z,?,?) In the storage unit according to the storage button pressing signal,
Y, z,?,?) Combinations of the predetermined number of sample positions and azimuth information (x, y, z,?,?) Stored in the storage unit when the recall button depression signal is repeated, And the value of the parameter is determined as the value of the parameter. 3. The method according to claim 1 or 2,
Wherein the input unit further has an increase button and a decrease button for all or a part of x, y, z, alpha and beta values,
The control unit transmits an operation signal to the drive unit to cause the drive motor corresponding to the value to be rotated forward or backward by a predetermined rotation angle to the drive unit when the increase button or the decrease button press signal of the value of the input unit is received Precision control device for three - dimensional imaging in transmission electron microscope. 3. The method according to claim 1 or 2,
A step drive button or a continuous drive button is added to the input unit,
The control unit transmits an operation signal to the drive unit so as to stepwise rotate from the current azimuths? And? Of the sample to the target azimuths? And? Characterized in that an operating signal is transmitted to the driving unit so as to continuously move from the current azimuths? And? Of the sample to the target azimuths? And? If there is a continuous driving button pressing signal Precision control device for 3D imaging. 3. The method according to claim 1 or 2,
The storage unit further stores an error (? =? T -? O) between the target rotation angle? T of the double tilting holder to be mounted and the actual rotation angle?
Wherein the control unit further has a function of correcting the target turning angle of the driving motor shaft to the error with respect to the value of the double tilting holder corresponding to the input code by the error. Precision control device for. 3. The method according to claim 1 or 2,
Wherein,
Wherein when the operating signal of the input unit is once, the operating signal is transmitted to the driving unit two or three times with a time difference until the current rotational angle of each driving motor coincides with the target rotational angle. Precision control device for 3D imaging of. 3. The method according to claim 1 or 2,
Wherein,
Further comprising a function of decelerating a rotational speed of the driving motor as the current rotational angle of each of the driving motors approaches the target rotational angle.

Images