A method for quickly aligning a crystal ribbon axis

Abstract

The present invention relates to a method for fast alignment of crystal band axes, comprising the following steps: step S1: in an imaging mode, moving the target position of a sample to the center of a fluorescent screen, adjusting the sample Z height to the positive focus of the image, and recording the coordinates of the sample at this time; step S2: obtaining a Kikuchi diffraction pattern, marking a Kikuchi pole closest to the center of the fluorescent screen; step S3: measuring the length of the marked Kikuchi pole perpendicular to the X-axis and the Y-axis respectively, and estimating the tilt angle α and β values ​​of the sample stage respectively; step S4: calculating the sample coordinate X after tilting according to the estimated α and β values. t , Y t , Z t Step S5: In the imaging mode, enter the coordinate value X in the electron microscope operating software t , Y t , Z t As well as the tilt angle α and β values, the sample stage automatically translates and rotates the sample. At this time, the electron beam is close to the crystal zone axis corresponding to the kikuchi pole; step S6: converge the electron beam, and in the diffraction mode, fine-tune the sample stage α and β angles to move the kikuchi pole to the center of the fluorescent screen.

Description

Technical Field

[0001] The invention relates to the field of transmission electron microscope analysis, and in particular to a method for quickly aligning a crystal zone axis of a transmission electron microscope sample with an incident electron beam. Background Art

[0002] In the field of transmission electron microscopy analysis, determining the crystal orientation or measuring the high-resolution lattice image requires aligning the sample's crystal band axis with the incident electron beam. In the actual operation of aligning the crystal band axis with the electron beam, the electron microscope operator tilts the sample stage according to the diffraction pattern of the target position of the sample. For example, patent 202010168410.2 discloses a "method and system for aligning the crystal band axis", which uses the position of the zero-order Laue band (ZOLZ) of the sample to determine the degree of inclination of the crystal band axis, and then achieves alignment by tilting the sample stage. The system can automatically align the crystal band axis with the electron beam. However, this method is only applicable to the case where the crystal band axis deviates slightly from the electron beam. When a specific crystal band axis deviates greatly from the electron beam, the ZOLZ of the crystal band axis cannot be obtained. In the actual operation of aligning the crystal band axis with the electron beam, the tilting of the sample in a small range will also cause the sample position to shift. Therefore, electron microscope workers need to constantly switch between diffraction mode and imaging mode. That is, in the diffraction mode, the sample is tilted slightly to observe the changes in the diffraction pattern, and then switched to the imaging mode, the deviated target position is moved back to the initial position, and the sample is adjusted to the positive focus height, and the above steps are repeated until the crystal zone axis is aligned with the electron beam. Constantly switching between the imaging mode and the diffraction mode is extremely time-consuming. Moreover, when the sample is tilted in the diffraction mode, the sample position cannot be observed in real time, and when it returns to the imaging mode, the target position is often not recognizable. Therefore, it is necessary to develop a method to quickly align the sample crystal zone axis with the electron beam. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method for quickly aligning the crystal zone axis of a transmission electron microscope sample with the incident electron beam, which can quickly and effectively align the crystal zone axis of the mirror sample with the incident electron beam and improve the analysis efficiency of the transmission electron microscope.

[0004] To achieve the above object, the present invention adopts the following technical solution:

[0005] A method for rapid alignment of a crystal ribbon axis, comprising the following steps:

[0006] Step S1: In the transmission electron microscope imaging mode, move the target position of the sample to the center of the fluorescent screen, adjust the sample Z height to the positive focus of the image, and record the coordinates X0, Y0, Z0 of the sample at this time;

[0007] Step S2: The electron beam is converged to the target position of the sample, and in the diffraction mode, a Kikuchi diffraction pattern is recorded using a fluorescent screen, marking a Kikuchi pole closer to the center of the fluorescent screen;

[0008] Step S3: respectively measure the length of the marked Kikuchi pole perpendicular to the X-axis and Y-axis, and estimate the tilt angle α and β values ​​of the sample stage according to the lengths of the two respectively;

[0009] Step S4: Calculate the sample coordinates X after tilting by matrix transformation according to the estimated α and β values t , Y t , Z t ;

[0010] Step S5: In the imaging mode, input the coordinate value X in the electron microscope operating software. t , Y t , Z t As well as the tilt angle α and β values, the sample stage automatically translates and rotates the sample, and at this time the electron beam is close to the crystal zone axis corresponding to the kikuchi pole;

[0011] Step S6: Converge the electron beam, and in the diffraction mode, fine-tune the angles α and β of the sample stage, and move the kikuchi pole to the center of the fluorescent screen. At this time, the crystal axis of the sample is aligned with the incident electron beam.

[0012] Furthermore, the step S3 is specifically as follows: respectively measure the lengths AB and BO of the marked Kikuchi pole perpendicular to the X-axis and the Y-axis, divide AB and BO by the camera length PO to obtain the values ​​L and M respectively; and according to the conversion relationship between radians and degrees, obtain the tilt angles α≈L×180÷π, β≈M×180÷π.

[0013] Further, the step S4 is specifically as follows: after determining the tilt angles α and β of the double-tilt sample stage, according to the matrix transformation relationship of the coordinate tilt, the new coordinates X after the sample is tilted are t , Y t , Z t Calculated according to the following formula:

[0014] .

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] The present invention can quickly and effectively realize the alignment of the mirror sample crystal zone axis with the incident electron beam, thereby improving the analysis efficiency of the transmission electron microscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the principle of the present invention;

[0018] Figure 2is a transmission electron microscopic image of an aluminum oxide sample in one embodiment of the present invention;

[0019] Figure 3 In one embodiment of the present invention, the electron beam converges at the sample target position;

[0020] Figure 4 is a Kikuchi diffraction pattern at a target position in one embodiment of the present invention;

[0021] Figure 5 is the Kikuchi diffraction pattern after the sample is tilted in one embodiment of the present invention;

[0022] Figure 6 It is a Kikuchi pattern when the crystal zone axis of the sample is aligned with the electron beam in one embodiment of the present invention;

[0023] Figure 7 It is a selected area electron diffraction pattern of a target position in one embodiment of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0025] Please refer to Figure 1 The present invention provides a method for rapid alignment of a crystal band axis, comprising the following steps:

[0026] Step S1: In the transmission electron microscope imaging mode, move the target position of the sample to the center of the fluorescent screen, adjust the sample Z height to the positive focus of the image, and record the coordinates X0, Y0, Z0 of the sample at this time;

[0027] Step S2: The electron beam is converged to the target position of the sample, and in the diffraction mode, a Kikuchi diffraction pattern is recorded using a fluorescent screen, marking a Kikuchi pole closer to the center of the fluorescent screen;

[0028] Step S3: Measure the lengths AB and BO of the marked Kikuchi pole perpendicular to the X-axis and the Y-axis respectively, divide AB and BO by the camera length PO to obtain the values ​​L and M respectively; and according to the conversion relationship between radians and degrees, obtain the tilt angles α≈L×180÷π, β≈M×180÷π;

[0029] Step S4: After the tilt angles α and β of the double-tilt sample stage are determined, the new coordinates X after the sample is tilted are calculated according to the matrix transformation relationship of the coordinate tilt. t , Y t , Z t Calculated according to the following formula:

[0030] ;

[0031] Step S5: In the imaging mode, input the coordinate value X in the electron microscope operating software. t , Yt , Z t As well as the tilt angle α and β values, the sample stage automatically translates and rotates the sample, and at this time the electron beam is close to the crystal zone axis corresponding to the kikuchi pole;

[0032] Step S6: Converge the electron beam, and in the diffraction mode, fine-tune the angles α and β of the sample stage, and move the kikuchi pole to the center of the fluorescent screen. At this time, the crystal axis of the sample is aligned with the incident electron beam.

[0033] Embodiment 1:

[0034] This embodiment takes an aluminum oxide sample as an example to illustrate the specific operation process of the present invention.

[0035] (1) As attached Figure 2 As shown, in the electron microscope imaging mode, the target grain 201 image is moved to the center of the fluorescent screen. The Z height is adjusted to make the image in focus. At this time, the coordinates X0, Y0, and Z0 of the sample are -367.41 μm, -18.07 μm, and 9.75 μm, respectively.

[0036] (2) Focus the electron beam on the target grain, such as Figure 3 Central 301 location.

[0037] (3) In the diffraction mode, select an appropriate camera length. In this example, the camera length is 98 mm. Figure 4 The Kikuchi diffraction pattern is shown. Determine a Kikuchi pole as A. Measure the lengths of AB and BO and divide them by the camera length 98 mm to obtain the angles α and β, which are approximately equal to 0.138 rad and -0.1 rad, respectively, which are 7.9° and -5.7° in degrees.

[0038] (4) Based on the matrix transformation relationship of the tilt, the initial coordinates X0, Y0, Z0, and α and β, calculate the new coordinates X after the tilt t , Y t , Z t The calculation formula is as follows, and the obtained values ​​are -366.56μm, -14.22μm, and -29.02μm respectively.

[0039]

[0040] (5) In imaging mode, enter the calculated coordinate value X in the electron microscope operating software. t , Y t , Z t As well as the tilt angles α and β, the sample stage automatically translates and rotates the sample. At this time, the electron beam is close to the crystal zone axis corresponding to the Kikuchi pole A.

[0041] (6) Converging electron beam, in diffraction mode, from Figure 5 It can be seen that at this time, the Kikuchi pole A is very close to the center of the fluorescent screen O, and only the angles α and β of the sample stage need to be fine-tuned. After fine-tuning, the angles α and β are 8.29° and -5.87° respectively. Figure 6 As shown, at this time, the Kikuchi pole A is already in the center of the fluorescent screen, and the crystal axis of the sample is aligned with the incident electron beam. Figure 7 After aligning the electron beam to the crystal axis, Figure 2 Selected area electron diffraction at position 201 in the image. The pattern is very symmetrical, indicating that the crystal zone axis is aligned with the incident electron beam.

[0042] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for rapid alignment of a crystal band axis, characterized in that: The following steps are involved: Step S1: In the transmission electron microscope imaging mode, move the target position of the sample to the center of the fluorescent screen, adjust the sample Z height to the image focus, and record the coordinates X0, Y0, Z0 of the sample at this time; Step S2: The electron beam is converged to the target position of the sample, and in the diffraction mode, a Kikuchi diffraction pattern is recorded using a fluorescent screen, marking a Kikuchi pole closest to the center of the fluorescent screen; Step S3: respectively measure the length of the marked Kikuchi pole perpendicular to the X-axis and Y-axis, and estimate the tilt angle α and β values ​​of the sample stage according to the lengths of the two respectively; Step S4: Calculate the sample coordinates X after tilting by matrix transformation according to the estimated α and β values t , Y t , Z t ; Step S5: In the imaging mode, input the coordinate value X in the electron microscope operating software. t , Y t , Z t As well as the tilt angle α and β values, the sample stage automatically translates and rotates the sample, and at this time the electron beam is close to the crystal zone axis corresponding to the Kikuchi pole; Step S6: Converging the electron beam, in the diffraction mode, fine-tuning the angles α and β of the sample stage, moving the kikuchi pole to the center of the fluorescent screen, at which point the crystal zone axis of the sample is aligned with the incident electron beam; The step S3 is specifically as follows: respectively measure the lengths AB and BO of the marked kikuchi pole perpendicular to the X-axis and the Y-axis, divide AB and BO by the camera length PO to obtain the values ​​L and M respectively; and according to the conversion relationship between radians and degrees, obtain the tilt angles α≈L×180÷π, β≈M×180÷π.

2. The method for rapid alignment of a crystal zone axis according to claim 1, characterized in that: The step S4 specifically includes: after determining the tilt angles α and β of the dual-tilt sample stage, according to the matrix transformation relationship of the coordinate tilt, the new coordinates X after the sample is tilted are t , Y t , Z t Calculated according to the following formula: 。

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