JP7562480B2 - Sample processing device and sample processing method - Google Patents

Description

The present invention relates to a sample processing device and a sample processing method.

Examples of sample processing devices that use ion beams to process samples include the Cross Section Polisher (registered trademark) for processing the cross section of a sample and the Ion Slicer (registered trademark) for producing thin film samples.

For example, Patent Document 1 discloses a sample preparation device that prepares a thin-film sample for a transmission electron microscope by placing a shielding belt on a bulk sample, irradiating the sample with an ion beam through the shielding belt, and ion milling the portion not shielded by the shielding belt.

In Patent Document 1, a CCD camera photographs the etched cross section of the sample, and an ion milling end determination circuit monitors changes in the shape of the sample. When the ion milling end determination circuit detects that a through hole has opened in the sample, the emission of the ion beam is stopped.

JP 2012-193962 A

In such sample processing equipment, a two-stage milling method is known as a method for preparing samples for cross-sectional observation of structures such as wiring and transistors formed on the wafer surface. The two-stage milling method involves a primary milling step to thin the sample overall, and a secondary milling step to thin the wafer surface on which the structures to be observed are formed to a thickness that can be observed with a transmission electron microscope.

In primary milling, the sample is placed under a shielding belt and the ion beam is irradiated from the front side of the wafer. In secondary milling, the sample is turned upside down and the ion beam is irradiated from the back side of the wafer. In this case, the ion beam is irradiated directly onto the sample without using a shielding belt. This causes the sample to gradually become thinner from the front side of the wafer. In secondary milling, processing is continued until the desired structure is thick enough to be observed with a transmission electron microscope.

By performing primary and secondary milling in this way, a sample can be produced that can be observed in cross section. Such sample processing equipment is required to be able to accurately determine the timing to end processing.

One aspect of the sample processing device according to the present invention is to
A sample processing apparatus for processing a sample by irradiating the sample with an ion beam, comprising:
an ion source for irradiating the sample with the ion beam;
A sample stage for holding the sample;
A camera for photographing the sample;
A processing unit that determines the end of processing based on the image captured by the camera;
Including,
The processing unit includes:
obtaining said image;
A process of acquiring information on a target position for processing;
A process of detecting an edge of a processing area in the image;
A process of detecting a hole formed in the processing area in the image;
determining whether the edge of the processing area or the hole has reached the target position;
a process of terminating the machining when it is determined that the edge of the machining area or the hole has reached the target position;
Do the following.

In such a sample processing device, the edge and holes of the processing area are detected, and processing ends when it is determined that the edge or hole of the processing area has reached the target position. Therefore, such a sample processing device can accurately determine the timing to end processing. Furthermore, such a sample processing device can process samples with high reproducibility.

One aspect of the sample processing method according to the present invention is to
A sample processing method using a sample processing apparatus that processes a sample by irradiating the sample with an ion beam, comprising the steps of:
acquiring an image of the sample taken by a camera;
acquiring information on a target position for processing;
detecting edges of a processing area in the image;
detecting a hole formed in the processing area in the image;
determining whether the edge of the processing area or the hole has reached the target position;
terminating the machining when it is determined that the edge of the machining area or the hole has reached the target position;
Includes.

In this type of sample processing method, the edge and holes of the processing area are detected, and processing ends when it is determined that the edge or hole of the processing area has reached the target position. Therefore, this type of sample processing method can accurately determine the timing to end processing. Furthermore, this type of sample processing method can process samples with high reproducibility.

FIG. 1 is a diagram showing the configuration of a sample processing device according to an embodiment. FIG. 2 is a diagram for explaining primary milling. FIG. 2 is a diagram for explaining primary milling. FIG. 2 is a diagram for explaining primary milling. FIG. 2 is a diagram showing an example of an image captured by a camera. FIG. 1 is a diagram for explaining secondary milling. FIG. 13 is a cross-sectional view showing a schematic diagram of a sample being processed in secondary milling. FIG. 4 is a diagram showing a schematic diagram of a cursor for designating a position for measuring a processing width. 4 is a flowchart illustrating an example of a primary milling process. FIG. 2 is a diagram illustrating an image captured by a camera. 5A and 5B are diagrams for explaining a process for measuring a processing width. 5A and 5B are diagrams for explaining a process for measuring a processing width. 5A and 5B are diagrams for explaining a process for measuring a processing width. 6A and 6B are diagrams for explaining a process for measuring the size of a gap. FIG. 13 is a diagram for explaining a method for predicting a processing end time. Graph plotting the coordinates of position P1 and the coordinates of position P2. 6A and 6B are diagrams for explaining a process for specifying a target position. 11 is a flowchart showing an example of a secondary milling process of the information processing device. FIG. 2 is a diagram illustrating an image captured by a camera. 6A and 6B are diagrams for explaining a process for detecting the edge at the bottom end of a processing area. FIG. 13 is a diagram for explaining a process for drawing the edge of a processing area in a predetermined color. 6A and 6B are diagrams for explaining a process for detecting a hole formed in a processing area. 6A and 6B are diagrams for explaining a process for detecting a hole formed in a processing area. FIG. 13 is a diagram for explaining a process for drawing holes in a predetermined color. 13 is a graph showing the relationship between the residual film thickness and the elapsed time from the start of processing. 10 is a flowchart showing a modified example of the secondary milling process of the information processing device.

Below, preferred embodiments of the present invention are described in detail with reference to the drawings. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

1. Sample processing device First, a sample processing device according to an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing the configuration of a sample processing device 100 according to this embodiment. Fig. 1 illustrates an X-axis, a Y-axis, and a Z-axis as three mutually orthogonal axes.

The sample processing device 100 is a device for processing the sample 2 by irradiating the sample 2 with an ion beam IB, and preparing a sample for observation or analysis. The sample processing device 100 can prepare a thin-film sample that can be observed with a transmission electron microscope.

As shown in FIG. 1, the sample processing device 100 includes an ion source 10, a control circuit 12, a sample stage 20, a shielding member 30, a transmitted illumination device 40, an illumination dimming circuit 42, a coaxial epi-illumination device 44, an illumination dimming circuit 46, an optical system 50, a camera 60, an information processing device 70 (an example of a processing unit), and a display unit 80.

The ion source 10 irradiates the sample 2 with an ion beam IB. The ion source 10 is attached to the top of a chamber (not shown) and irradiates the sample 2 housed in the chamber with the ion beam IB. The chamber is in a vacuum state. The ion source 10 is, for example, an ion gun that accelerates ions at a predetermined acceleration voltage and emits the ion beam IB. The ion source 10 irradiates the ion beam IB along the Z axis. For example, when irradiating the sample 2 with the ion beam IB, the ion source 10 oscillates around an axis parallel to the X axis as the rotation axis. The ion source 10 is controlled by a control circuit 12.

The sample stage 20 holds the sample 2. A shielding member 30 is attached to the sample stage 20. The shielding member 30 is placed on the sample 2 on the sample stage 20. The thickness of the shielding member 30 is, for example, about 10 μm, and the thickness of the sample 2 before processing is, for example, about 100 μm. The shielding member 30 is placed at the center of the sample 2 in the thickness direction.

The sample stage 20 is equipped with a swing mechanism that oscillates the sample 2 and the shielding member 30. The swing mechanism tilts the sample 2 and the shielding member 30 around a swing axis (tilt axis) that serves as the axis of rotation. The swing axis is, for example, parallel to the Y axis. The swing mechanism oscillates the sample 2 and the shielding member 30 at a constant period, for example.

The sample 2 held by the sample stage 20 has a plate-like shape. The sample 2 is, for example, a rectangular parallelepiped. The sample 2 will be described later.

The shielding member 30 shields the ion beam IB. The ion beam IB emitted from the ion source 10 is irradiated onto the sample 2 through the shielding member 30. The shielding member 30 is, for example, strip-shaped. The shielding member 30 is made of, for example, a material that is difficult to mill with the ion beam IB. The shielding member 30 is located above the sample 2 (in the +Z direction).

The transillumination device 40 emits illumination light that transmits and illuminates the sample 2. That is, the transillumination device 40 irradiates the sample 2 with illumination light from behind. The intensity of the illumination light emitted by the transillumination device 40 is controlled by the illumination dimming circuit 42.

The transmitted illumination device 40, sample 2, optical system 50, and camera 60 are arranged in this order along the Y axis.

The coaxial epi-illumination device 44 emits illumination light that illuminates the sample 2 coaxially. That is, the coaxial epi-illumination device 44 irradiates the sample 2 with illumination light along the optical axis of the camera 60. In the illustrated example, the optical system 50 has a half mirror 52, which is used to align the optical axis of the illumination light with the optical axis of the camera 60. The intensity of the illumination light emitted by the coaxial epi-illumination device 44 is controlled by the illumination dimming circuit 46.

The camera 60 photographs the sample 2 and the shielding member 30 via the optical system 50. The camera 60 is, for example, a digital camera such as a CCD camera or a CMOS camera. The optical system 50 is an optical system for photographing the sample 2 with the camera 60.

The information processing device 70 acquires the image captured by the camera 60 and performs processing to display the image on the display unit 80. The information processing device 70 also acquires the image captured by the camera 60 and performs processing to determine the end of processing based on the image. The information processing device 70 also controls the ion source 10 via the control circuit 12.

The information processing device 70 is, for example, a personal computer (PC) or the like, and includes a processor such as a CPU (Central Processing Unit), a storage device (memory) such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and an operation unit. The storage device stores programs and data for performing various image processing and control processing. The functions of the information processing device 70 (processing unit) can be realized by executing the programs in the processor. The operation unit is for the user to input operation information, and outputs the input operation information to the processor. The functions of the operation unit can be realized by hardware such as a keyboard, mouse, buttons, and touch panel.

The display unit 80 displays images acquired by the information processing device 70 and images generated by the information processing device 70. The function of the display unit 80 can be realized by an LCD, a CRT, a touch panel that also functions as an operation unit, etc.

2. Operation of the sample processing device 2.1. Two-stage milling method Two-stage milling method is a technique for preparing samples for observing, from the cross-sectional direction, for example, a thin film formed on a substrate, or a laminated film on a substrate on which wiring, transistors, etc. are formed. The two-stage milling method involves a primary milling process for thinning the sample overall, and a secondary milling process for thinning the thin film or laminated film to be processed to a thickness that can be observed with a transmission electron microscope.

2.2 Primary Milling Figures 2 to 4 are diagrams for explaining the primary milling. Figure 2 is a perspective view that shows a model of the sample 2 and the shielding member 30. Figure 3 is a diagram for explaining the oscillation operation of the sample 2. Figure 4 is a diagram for explaining the operation of the ion source 10.

As shown in FIG. 2, the sample 2 includes a substrate 4, a laminated film 6, and a protective member 8. The substrate 4 is, for example, a semiconductor substrate such as a silicon substrate or a compound substrate. The laminated film 6 includes, for example, wiring and transistors formed on the substrate 4 by semiconductor manufacturing technology. In the illustrated example, a sample for a transmission electron microscope for observing a cross section of the laminated film 6 formed on the substrate 4 can be prepared. The protective member 8 is a member for protecting the laminated film 6 during processing, and is, for example, a glass substrate. The protective member 8 is adhered to the laminated film 6 with epoxy resin or the like. The thickness of the protective member 8 is, for example, about 100 μm.

Sample 2 is pre-processed into a plate shape with a height (size in the Z direction) of 500 μm to 800 μm and a width (size in the Y direction) of approximately 100 μm.

The configuration of sample 2 is not limited to the example shown in Figure 2, and samples of various configurations can be processed using the two-stage milling method so that they can be observed with a transmission electron microscope.

In the primary milling, the sample 2 is positioned so that the first end 2a of the sample 2 is on the top and the second end 2b of the sample 2 is on the bottom. The first end 2a of the sample 2 is the end of the sample 2 on the protective member 8 side, and the second end 2b of the sample 2 is the end of the sample 2 on the substrate 4 side. The sample 2 is positioned under the shielding member 30, and the ion beam IB is irradiated from the first end 2a side of the sample 2. The ion beam IB is irradiated to the sample 2 through the shielding member 30.

When the sample 2 is processed by irradiating the ion beam IB, as shown in FIG. 3, the swing mechanism of the sample stage 20 is operated to swing the sample 2 and the shielding member 30 around axis A as the rotation axis. That is, the swing mechanism of the sample stage 20 causes the sample 2 and the shielding member 30 to perform a reciprocating tilt (rotation) motion around axis A as the tilt axis (rotation axis). Axis A is, for example, an axis parallel to the Y axis. Axis A is located, for example, at the boundary between the sample 2 and the shielding member 30.

Note that Figure 3 illustrates the cases when the tilt angle θ1 of the sample 2 is 0°, when the tilt angle θ1 of the sample 2 is -30°, and when the tilt angle θ1 of the sample 2 is +30°. Note that in Figure 3, the tilt angle θ1 is represented as "+" counterclockwise and "-" clockwise, with θ1 = 0° when the sample 2 is parallel to the X-axis.

When processing the sample 2, the ion source 10 is also oscillated as shown in FIG. 4. For example, the ion source 10 is tilted within a predetermined angle range with respect to the Z axis. By oscillating the ion source 10, the ion beam IB can be irradiated from an oblique direction onto the processing surface of the sample 2. For example, the ion source 10 is tilted so that the angle of incidence of the ion beam IB onto the processing surface of the sample 2 is about 0.4°. In other words, the range of the tilt angle θ2 of the ion source 10 is from -0.4° to +0.4°. The tilt angle θ2 of the ion source 10 can be changed as appropriate depending on, for example, the material of the sample 2.

In this manner, in the sample processing device 100, the sample 2 is oscillated and the ion source 10 is oscillated while irradiating the sample 2 with the ion beam IB to process the sample 2. In the primary milling, two inclined surfaces 3 and a processing area 5 between the two inclined surfaces 3 are formed by processing. In the primary milling, the processing area 5 is processed so that the entirety of the processing area 5 has approximately the same thickness as the shielding member 30. Note that in the primary milling, the processing area 5 may be processed so that the thickness is approximately the same as the shielding member 30, and the film thickness increases from the first end 2a to the second end 2b.

In the primary milling, processing is terminated when the second end 2b of the sample 2 has a thickness suitable for secondary milling. As described later, in the secondary milling, the sample 2 is arranged so that the second end 2b is on top and the first end 2a is on the bottom, and the ion beam IB is irradiated from the second end 2b side. Therefore, for example, if the thickness of the second end 2b side of the sample 2 is large, the amount of ion beam IB irradiated to the second end 2b side increases, and the second end 2b side is rapidly removed. As a result, there is a possibility that the sample 2 will disappear before the target laminated film 6 becomes thin. Therefore, in the primary milling, the second end 2b of the sample 2 must be made to a thickness suitable for secondary milling.

Here, the thickness of the second end 2b of the sample 2 cannot be confirmed from the image captured by the camera 60. Therefore, the width of the processing area 5 on the second end 2b side of the sample 2, that is, the processing width W shown in FIG. 2, is used as a guide to determine the timing to end the primary milling process. In the sample processing device 100, as the processing progresses, the processing area 5 of the sample 2 becomes thinner and the processing width W expands. Therefore, the thickness of the processing area 5 can be estimated from the processing width W.

For example, by setting the processing width W to approximately 300 μm to 600 μm, the thickness of the second end 2b of the sample 2 can be set to approximately 10 μm, which is a thickness suitable for secondary milling.

The state of the sample 2 during processing is photographed by the camera 60. The image of the sample 2 photographed by the camera 60 is sent to the information processing device 70. The information processing device 70 acquires the image photographed by the camera 60 and displays it on the display unit 80.

Figure 5 shows an example of an image I2 captured by the camera 60. Image I2 shown in Figure 5 is an image obtained by capturing, with the camera 60, a sample 2 illuminated by coaxial epi-illumination and transillumination.

Since the sample 2 is illuminated by coaxial epi-illumination, as shown in FIG. 5, the processed area 5 of the sample 2, the unprocessed area of the sample 2, and the shielding member 30 are bright, while the inclined surface 3 is dark, in image I2. This is because, with coaxial epi-illumination, the illumination light is reflected toward the camera 60 only from a surface perpendicular to the observation direction (the optical axis of the camera 60). Since the inclined surface 3 is not perpendicular to the observation direction, the illumination light reflected from the inclined surface 3 does not head toward the camera 60. Therefore, the inclined surface 3 is dark in image I2. In the sample processing device 100, even if the sample 2 is rocked, the orientation of the surfaces of each area of the sample 2 does not change. Therefore, with coaxial epi-illumination, even if the sample 2 is rocked during processing, an image in which the inclined surface 3 is always dark is obtained.

In addition, since the sample 2 is illuminated through the light, the illumination light leaks from the gap between the sample 2 and the shielding member 30 as shown in FIG. 5. The illumination light also wraps around from below the sample 2. Therefore, in image I2, the gap between the sample 2 and the shielding member 30 and the space below the sample 2 appear bright. As a result, only the inclined surface 3 appears dark in image I2.

The information processing device 70 takes advantage of the fact that only two inclined surfaces 3 are dark in the image I2, extracts the two inclined surfaces 3, and measures the processing width W by measuring the distance between the two extracted inclined surfaces 3.

2.3 Secondary Milling Fig. 6 is a diagram for explaining the secondary milling.

6, in the secondary milling, the sample 2 is arranged so that the second end 2b of the sample 2 is on the top and the first end 2a of the sample 2 is on the bottom. In the secondary milling, the ion beam IB is irradiated from the second end 2b side of the sample 2. In the secondary milling, the ion beam IB is irradiated directly onto the sample 2 without using a shielding member 30.

Figure 7 is a cross-sectional view that shows a schematic diagram of the processing of sample 2 during secondary milling.

As shown in FIG. 7, in the secondary milling, first, the protective member 8 is thinned. In the process of thinning the protective member 8, holes may be formed in the protective member 8 or the protective member 8 may be peeled off. Then, when the protective member 8 is removed, the epoxy resin layer (not shown) is thinned and removed, and finally, the target laminated film 6 is thinned.

3. Sample processing method 3.1. Preparation for primary milling 3.1.1. Setting the sample As shown in Figures 1 and 2, the sample 2 is set on the sample stage 20, and a shielding member 30 is placed on the sample 2. The chamber is then evacuated to a vacuum. The sample 2 and the shielding member 30 are illuminated by the transmitted illumination device 40 and illuminated by the coaxial epi-illumination device 44.

3.1.2. Noise Level Measurement The noise level of the image I2 captured by the camera 60 is measured. For example, the information processing device 70 measures the luminance of the same location within the field of view of the camera 60 multiple times, and determines the noise level as the value obtained by subtracting the minimum luminance from the maximum luminance. In this manner, the noise level is quantified.

The noise level varies depending on, for example, the brightness of the illumination light, the exposure time of the camera 60, and the adjustment of the gain of the camera 60. If the noise level of the image I2 is high, there is a high possibility that an erroneous judgment will be made in the process of determining the end of processing.

The information processing device 70 displays the measured noise level on the display unit 80, and if the noise level is higher than a preset threshold, displays a notification on the display unit 80 to readjust the illumination conditions of the sample 2 by the transmitted illumination device 40 and the coaxial epi-illumination device 44 and the settings of the camera 60.

In this way, the sample processing device 100 can optimize the lighting conditions for the sample 2 and the settings of the camera 60 by measuring the noise level. This allows an image I2 with less noise to be acquired, reducing the possibility of making an erroneous decision when determining the end of processing.

3.1.3 Designation of Position for Measuring Processing Width The user designates a position for measuring the processing width W in the image I2. Fig. 8 is a diagram showing a schematic diagram of a cursor C for designating a position for measuring the processing width W.

As shown in FIG. 8, the information processing device 70 displays a cursor C on the image I2 displayed on the display unit 80. The cursor C is used to specify the position in the image I2 at which the machining width W is to be measured. In the example shown, a line L is drawn on the cursor C, and the position indicated by the line L is the position at which the machining width W is to be measured. The position at which the machining width W is to be measured is specified by the user using the operation unit of the information processing device 70 to move the cursor C.

3.1.4. Designation of target machining width The user designates the target machining width TW. For example, the information processing device 70 displays a GUI (Graphical User Interface) screen on the display unit 80. The GUI screen displays the target machining width TW
When the user inputs the target machining width TW into the text box via the operation unit, information on the target machining width TW is input to the information processing device 70. When the target machining width TW is input, a marker M corresponding to the target machining width TW is displayed on the line L as shown in Fig. 8. Note that the method of setting the target machining width TW is not limited to this.

3.2 Primary Milling 3.2.1 Flow of Primary Milling In the sample processing device 100, the information processing device 70 performs a primary milling process for processing the sample 2 by primary milling. Fig. 9 is a flow chart showing an example of the primary milling process of the information processing device 70.

When the user inputs an instruction to start primary milling to the information processing device 70, the information processing device 70 acquires information on the position at which the machining width W is to be measured (S100). The user can specify the position at which the machining width W is to be measured by moving the position of the cursor C via the operation unit. The information processing device 70 acquires information on the position at which the machining width W is to be measured, which is specified by the cursor C, via the operation unit.

The information processing device 70 also acquires information on the target machining width TW (S102). The user can specify the target machining width TW by inputting the value of the target machining width TW via the operation unit. The information processing device 70 acquires the information on the input target machining width TW via the operation unit.

Next, the information processing device 70 performs a process to start irradiating the ion beam IB (S104). Specifically, the information processing device 70 generates a control signal for irradiating the ion beam IB and sends it to the control circuit 12. The control circuit 12 generates a drive signal based on the control signal and outputs it to the ion source 10. This causes the ion source 10 to irradiate the ion beam IB onto the sample 2. At this time, the swing mechanism of the sample stage 20 swings the sample 2 and the shielding member 30.

As described above, in the sample processing device 100, the sample 2 and the shielding member 30 are oscillated while the ion beam IB is irradiated onto the sample 2 through the shielding member 30 to process the sample 2. While the sample 2 is being processed, the camera 60 photographs the sample 2.

When processing (irradiation of ion beam IB) begins, the information processing device 70 acquires an image I2 of the sample 2 captured by the camera 60 (S106).

Figure 10 is a schematic diagram showing image I2 captured by camera 60.

As shown in FIG. 10, the information processing device 70 acquires an image I2 captured by the camera 60 when the sample 2 is horizontal. This makes it unnecessary to take into account the inclination of the sample 2 in the image processing described below. Furthermore, the information processing device 70 acquires an image I2 once per period of the rocking motion of the sample 2.

For example, in the example shown in FIG. 3, if image I2 is captured with sample 2 tilted at tilt angle θ1 = -30° and then held horizontal (tilt angle θ1 = 0°), and if image I2 is captured with sample 2 tilted at tilt angle θ1 = +30° and then held horizontal (tilt angle θ1 = 0°), there may be a misalignment between the images due to mechanical backlash in the swing mechanism. As described above, by acquiring image I2 once per period of the swinging motion of sample 2, it is possible to reduce the misalignment between images due to backlash.

Next, the information processing device 70 measures the size of the gap between the sample 2 and the shielding member 30, and determines whether the gap has expanded (S108). Details of the process S108 for determining whether the gap has expanded will be described later in "3.2.2. Process for determining whether the gap has expanded."

If the information processing device 70 determines that the gap has expanded (Yes in S108), it stops irradiating the ion beam IB and ends the processing (S120).

The information processing device 70 generates a control signal for stopping the irradiation of the ion beam IB and sends it to the control circuit 12. The control circuit 12 stops the output of the drive signal based on the control signal. This causes the ion source 10 to stop irradiating the ion beam IB. At this time, the information processing device 70 may display a notification on the display unit 80 that the processing has not progressed normally.

If the information processing device 70 determines that the gap has not expanded (No in S108), it measures the processing width W on image I2.

Figures 11 to 13 are diagrams for explaining the process of measuring the processing width W.

In the process of measuring the processing width W, the information processing device 70 first binarizes the image I2 (S110).

As shown in FIG. 11, the information processing device 70 sets a threshold value so that the minimum luminance peak is selected from the luminance histogram of image I2, and binarizes image I2. This makes it possible to generate a binarized image I2B shown in FIG. 12. Note that image processing may be performed to remove noise from image I2 before binarizing image I2.

In this case, since the sample 2 is illuminated by coaxial epi-illumination and transillumination, only the inclined surface 3 appears dark in the image I2. Therefore, the inclined surface 3 can be extracted by selecting the minimum luminance peak from the luminance histogram of the image I2 and binarizing it. In the example shown in FIG. 12, image I2 is binarized by making pixels with a luminance below the threshold white and pixels with a luminance above the threshold black.

Next, the information processing device 70 identifies clusters of white pixels corresponding to the inclined surface 3 in the binarized image I2B, and determines whether the number of clusters is two or not (S112).

At the beginning of processing, the processing area 5 has not yet reached the second end 2b of the sample 2, so the number of aggregates is one. When the processing area 5 reaches the second end 2b of the sample 2, the number of aggregates becomes two.

In addition, in the early stages of processing, since inclined surface 3 is small, it may not be possible to select a peak corresponding to inclined surface 3 in the brightness histogram. In such cases, the number of aggregates will be three or more. Therefore, by determining whether the number of aggregates is two or not, it is possible to determine whether inclined surface 3 has been extracted.

Whether or not the inclined surface 3 has been extracted is determined based on whether the number of aggregates is two or not, but other conditions may be used for the determination. For example, it may be determined that the inclined surface 3 has not been extracted if the number of pixels constituting the aggregate is less than a predetermined number, if the processing time is shorter than a set time, or if there is a large change in the area of the aggregate.

If the information processing device 70 determines that the number of aggregates is not two (No in S112), it returns to process S106 to acquire image I2.

If the information processing device 70 determines that there are two aggregates (Yes in S112), it linearly approximates the edges of each of the two aggregates and draws approximation lines L1 and L2, as shown in FIG. 13 (S114).

The information processing device 70 identifies a position P on the binarized image I2B where the machining width W is to be measured from the information on the position where the machining width W is to be measured acquired in process S100, and measures the machining width W by measuring the distance between the approximation line L1 and the approximation line L2 at position P (S116).

The position P at which the processing width W is measured is identified, for example, by the vertical position coordinate of the binarized image I2B.

Next, the information processing device 70 determines whether the measured machining width W is equal to or greater than the target machining width TW (S118). In other words, the information processing device 70 determines whether W≧TW is satisfied.

If the information processing device 70 determines that W≧TW is not satisfied (No in S118), it returns to process S106 to acquire image I2.

The information processing device 70 repeats the process S106 of acquiring an image, the process S108 of determining whether the gap is widening, the binarization process S110, the process S112 of determining whether there are two aggregates, the process S114 of calculating a straight line approximation of the edge of the aggregate, the process S116 of measuring the processing width W, and the process S118 of determining whether W≧TW is satisfied, until it is determined that W≧TW is satisfied or the gap is widening.

If the information processing device 70 determines that the gap is widening (Yes in S108) or that W≧TW is satisfied (Yes in S118), it stops irradiating the ion beam IB to the ion source 10 (S120).

By performing the above processing, the information processing device 70 ends the primary milling process.

3.2.2. Process for determining whether the gap is expanding Generally, when processing proceeds normally, the milled sample 2 and the like adhere to the gap between the sample 2 and the shielding member 30, and the gap becomes smaller. In contrast, when the gap becomes larger as processing proceeds, there is a possibility that the upper end of the processing region 5 of the sample 2 has been milled away from directly below the shielding member 30. In other words, there is a high possibility that processing is not proceeding normally.

Therefore, the information processing device 70 measures the size of the gap based on, for example, the brightness of each pixel of the image I2. For example, the size of the gap is measured from the vertical brightness profile of the image I2. Here, the size of the gap is the size of the gap in the vertical direction of the image I2. In other words, the size of the gap is the distance between the sample 2 and the shielding member 30.

Figure 14 is a diagram for explaining the process of measuring the size of the gap. Figure 14 shows the luminance profile of the area corresponding to the gap in image I2.

As shown in Fig. 14, the size of the gap can be measured based on the vertical brightness profile of image I2. For example, the size G of the gap is calculated by utilizing the fact that the brightness of the gap is maximum. Specifically, a position E1 where the brightness is lower by an intensity S1 than the brightness of the peak PK and a position E2 where the brightness is lower by an intensity S2 than the brightness of the peak PK are calculated, and |E2-E1| is calculated to calculate the size G of the gap.

The determination of whether the gap is widening is performed as follows. First, a first image that serves as a reference and is taken by the camera 60, and a second image that is taken after the first image are obtained. Next, the size G1 of the gap in the first image is measured, and the size G2 of the gap in the second image is measured. Next, the size G1 of the gap in the second image is compared with the size G2 of the gap in the first image, and if the size G2 of the gap in the second image is larger than the size G1 of the gap in the first image (G2>G1), it is determined that the gap is widening.

It may be determined that the gap is expanding when the value (G2-G1) obtained by subtracting the size of the gap in the first image G1 from the size of the gap in the second image G2 is equal to or greater than a predetermined value. In addition, for example, the measurement results of the size of the gap G may be plotted to obtain a function showing the relationship between the size of the gap G and the elapsed time of processing, and it may be determined from the function whether the gap is expanding or not.

In the above, it is determined whether the size of the gap is expanding, but it may be determined whether the size G of the gap is within a predetermined range. The size G of the gap between the sample 2 and the shielding member 30 has a range suitable for sample preparation. For example, it is preferable that the size G of the gap is approximately 40 μm or more and 80 μm or less. If the size G of the gap is outside this range, there is a high possibility that the processing will not proceed normally. Therefore, the information processing device 70 may determine whether the size G of the gap is outside the predetermined range, and if it is outside the range, notify the user of this fact and perform processing to end the processing.

3.2.3. Processing for predicting machining end time The information processing device 70 performs processing for predicting the machining end time in parallel with the above-mentioned primary milling processing.

For example, the information processing device 70 acquires information on the machining width W measured in process S116 for measuring the machining width W, and calculates the increasing speed at which the machining width W increases. The end time of machining is calculated from this increasing speed.

The information processing device 70 may display on the display unit 80 the progress of the machining width W approaching the target machining width TW using a progress bar or the like. This allows the user to grasp the progress of the machining.

The information processing device 70 may also create a graph of the change in the machining width W, with the horizontal axis representing time and the vertical axis representing the machining width W, and display it on the display unit 80. At this time, the information processing device 70 may display the graph of the current change in the machining width W alongside a graph of the change in the machining width W that was created in the past. This makes it possible to determine whether the machining is proceeding normally. For example, by comparing the current graph with the past graph, it is possible to notice any abnormality in the machining speed.

Note that, during the time from when processing begins until two inclined surfaces 3 are formed, it is not possible to obtain information on the processing width W measured in process S116 for measuring the processing width W. Therefore, when there is one aggregate in the binarized image I2B, the information processing device 70 may predict the end time of processing from the change in the position of the outer edge of the aggregate or the change in the position of the inner edge of the aggregate.

Figure 15 is a diagram to explain a method for predicting the end time of processing.

When there is one collection of binary image I2B, the coordinates of position P2 of the outer edge of the collection are plotted, and the end time of processing is predicted based on the change in position P2. Then, when the processing progresses and the inner edge of the collection becomes clear, the coordinates of position P1 of the inner edge of the collection are plotted, and the end time of processing is predicted based on the change in position P1. Position P1 is, for example, the position where the inner edge of the collection intersects with one of two straight lines extending vertically and drawn at an interval corresponding to the target processing width TW. Position P2 is the position where the outer edge of the collection intersects with one of two straight lines extending vertically and drawn at an interval corresponding to the target processing width TW.

Figure 16 is a graph plotting the coordinates of position P1 and the coordinates of position P2. The horizontal axis of the graph shown in Figure 16 is the elapsed time from the start of processing (irradiation of ion beam IB), and the vertical axis is the processing depth. The processing depth of position P1 is the distance between position P1 and the first end 2a of the sample 2, and the processing depth of position P2 is the distance between position P2 and the first end 2a.

When predicting the end time based on the change in position P1, for example, the speed at which the distance between position P1 and position P where the processing width W is measured is calculated, and the time at which position P1 reaches position P is calculated based on that speed, thereby predicting the end time of processing.

When predicting the end time based on the change in position P2, for example, the speed at which the distance between position P2 and position P decreases is calculated. Then, from the calculated speed, the speed at which the distance between position P1 and position P decreases is estimated, and the end time of processing is predicted.

In the example shown in FIG. 16, the machining area 5 on the inside of the inclined surface 3 is not formed until 40 minutes after machining has started, so the machining end time T is predicted based on the change in position P2. This makes it possible to predict the machining end time T even in the early stages of machining.

After 40 minutes from when processing starts, the end time T of processing is predicted based on position P1. This makes it possible to predict the end time T of processing based on position P1.

If the thickness of the sample 2 before processing begins is always the same, the distance between the inner edge position P1 and the outer edge position P2 is approximately constant. Therefore, at all times during processing, the inner edge position P1 may be calculated from the outer edge position P2 to predict the processing end time T.

Normally, the outer edge of the aggregate is clearer than the inner edge of the aggregate. This is because the boundary between the inclined surface 3 and the processing area 5 is gently inclined due to the distribution of the intensity of the ion beam IB. Therefore, in the binarized image, the outer edge of the aggregate is clearer than the inner edge of the aggregate. In other words, position P2 can be located more accurately than position P1. Therefore, at all times during processing, by predicting the processing end time T based on position P2, the processing end time T can be accurately predicted.

3.3. Preparation for secondary milling 3.3.1. Setting of the sample After the primary milling is completed and before the secondary milling is started, as shown in Fig. 6, the sample 2 is turned upside down so that the second end 2b of the sample 2 is on the top and the first end 2a is on the bottom. For example, after opening the chamber to the atmosphere, the user turns the sample 2 placed on the sample stage 20 upside down. After turning the sample 2 upside down and fixing the sample 2 to the sample stage 20, the shielding member 3 is attached to the sample stage 20.
Then, evacuate the chamber.

The sample stage 20 may have an inversion mechanism for inverting the sample 2 upside down. This allows the sample 2 to be inverted upside down without opening the chamber to the atmosphere.

3.3.2. Designation of target position FIG. 17 is a diagram for explaining the process of designating a target position TP.

The user specifies the target position TP for machining. In secondary milling, machining ends when the edge of the machining area 5 or the hole formed in the machining area 5 reaches the specified target position TP.

The information processing device 70 displays a GUI screen on the display unit 80. An image I2 and a cursor C for inputting a target position TP for processing are displayed in a window on the GUI screen. In addition to the cursor C, an arrow C2 indicating the direction in which processing will proceed is also displayed in the window. The user can specify the target position TP by moving the cursor C via the operation unit. When the user specifies the target position TP with the cursor C, information on the target position TP is input to the information processing device 70. Note that the method for setting the target position TP is not limited to this.

The image I2 used when specifying the target position TP is, for example, an image obtained by photographing the sample 2 illuminated by transillumination and coaxial epi-illumination. Note that the sample 2 is transilluminated during processing by secondary milling.

3.4. Secondary Milling 3.4.1. Flow of Secondary Milling In the sample processing device 100, the information processing device 70 performs a secondary milling process for processing the sample 2 by secondary milling. Fig. 18 is a flow chart showing an example of the secondary milling process of the information processing device 70.

When the user inputs an instruction to start secondary milling into the information processing device 70, the information processing device 70 acquires information on the target position TP (S200). The user can specify the target position TP by moving the position of the cursor C via the operation unit. The information processing device 70 acquires information on the target position TP specified by the cursor C via the operation unit.

Next, the information processing device 70 performs a process to start irradiating the ion beam IB (S202). This causes the ion beam IB to be irradiated from the ion source 10 to the sample 2. At this time, the swing mechanism of the sample stage 20 swings the sample 2.

As described above, the sample processing device 100 processes the sample 2 by irradiating the sample 2 with the ion beam IB while oscillating the sample 2. While the sample 2 is being processed, the camera 60 photographs the sample 2.

When processing begins, the information processing device 70 acquires an image I2 of the sample 2 captured by the camera 60 (S204).

Figure 19 is a schematic diagram showing image I2 captured by camera 60.

The image I2 captured during processing is an image obtained by capturing an image of the sample 2 that has been transmitted and illuminated. As shown in Fig. 19, the information processing device 70 captures the image I2 captured by the camera 60 at the timing when the sample 2 becomes horizontal. This makes it unnecessary to take into account the inclination of the sample 2 in the image processing described below. Furthermore, the information processing device 70 captures the image I2 once per period of the rocking motion of the sample 2. This makes it possible to reduce the misalignment between images caused by operational backlash.

The circular cursor shown in FIG. 19 is used to define the range in which processing is performed in the process of detecting the edges of the processing area 5 and the process of detecting holes, which will be described later. The user can change the range in which processing is performed by moving the position of the cursor via the operation unit. It is also possible to perform processing on the entire image I2 without defining the range in which processing is performed with the cursor.

Next, the information processing device 70 detects the edge of the processing area 5 in the image I2 (S206).

Figure 20 is a diagram for explaining the process of detecting the edge E at the bottom end of the processing area 5. In Figure 20, the line for acquiring the luminance profile for detecting the edge E at the bottom end of the processing area 5 is shown by a dashed line.

As shown in FIG. 20, the information processing device 70 acquires multiple vertical luminance profiles of the image I2 and identifies the position of the edge E at the bottom end of the processing area 5. In the vertical luminance profile of the image I2, the luminance changes significantly at the edge E at the bottom end of the processing area 5, so the edge E is detected from this change in luminance. The information processing device 70 identifies the edge E0 that is the shortest distance from the target position TP from the detection results of the edge E in the multiple luminance profiles. The information processing device 70 calculates the distance D1 between the edge E0 and the target position TP.

Figure 21 is a diagram explaining the process of drawing edge E in a specified color.

As shown in FIG. 21, in order to emphasize the detected edge E, the information processing device 70 draws the area 9 adjacent to the edge E in the image I2 in a predetermined color. This makes it possible to emphasize the edge E. In the illustrated example, the area 9 in the image I2 is an area that corresponds to the space below the sample 2.

Note that the method for emphasizing the edge E is not limited to this. For example, the edge E may be drawn in a specified color.

Next, the information processing device 70 detects holes formed in the processing area 5 in the image I2 (S208).

Figures 22 and 23 are diagrams for explaining the process of detecting a hole H formed in the processing area 5. In Figure 22, a dashed line indicates a line for acquiring a luminance profile for detecting the hole H. Figure 23 shows an example of a luminance profile.

As shown in FIG. 22, as machining proceeds, a hole H may be formed between the edge E of the machining area 5 and the target position TP.

The information processing device 70 acquires multiple horizontal brightness profiles of the image I2 and detects the hole H formed in the processing area 5.

For example, when determining whether an arbitrary first region A1 of an image I2 is a hole H, the determination as to whether the first region A1 is a hole H is based on the brightness of the first region A1 and the brightness of the second region A2 and the third region A3 that sandwich the first region A1.
may be one pixel or a set of multiple pixels. The distance between the first region A1 and the second region A2, and the distance between the first region A1 and the third region A3 can be set appropriately.

Specifically, as shown in FIG. 23, the difference between the luminance Lu1 of the first region A1 and the average value of the luminance Lu2 of the second region A2 and the luminance Lu3 of the third region A3 is defined as the signal strength of the first region A1. That is, the signal strength of the first region A1 is expressed as signal strength = Lu1 - (Lu2 + Lu3) / 2. The process of changing the position of the first region A1 and finding the signal strength is performed for all regions of image I2. As a result, the signal strength of all regions of image I2 is obtained.

Next, information on the maximum signal intensity is obtained from the signal intensity of the entire region of image I2. The maximum value is, for example, the signal intensity of the region where the transmitted illumination light is directly detected. Next, the information processing device 70 determines that the region where the signal intensity is equal to or greater than a predetermined value is a hole H. The predetermined value is, for example, 90% of the maximum acquired signal intensity.

Here, an area where the signal strength is locally high due to noise or the like may be determined to be a hole H. Therefore, if the area of an area where the signal strength is equal to or greater than a predetermined value is greater than a set value, it may be determined to be a hole H. The set value can be set arbitrarily. In addition, before obtaining the above brightness profile, a filter may be applied to image I2 to remove noise and gradual brightness unevenness.

When the information processing device 70 detects hole H, it calculates the distance (shortest distance) D2 between hole H and the target position TP.

The information processing device 70 also renders the detected holes H in a predetermined color. Figure 24 is a diagram for explaining the process of rendering the edges E in a predetermined color.

As shown in FIG. 24, the information processing device 70 renders the detected hole H in a predetermined color on the image I2. This makes it possible to highlight the hole H.

Next, the information processing device 70 determines whether the edge E or hole H of the processing area 5 has reached the target position TP (S210).

The information processing device 70 first compares the distance between edge E0 and the target position TP with the distance between hole H and the target position TP. If the distance between edge E0 and the target position TP is smaller than the distance between hole H and the target position TP, the information processing device 70 determines whether edge E0 has reached the target position TP based on the coordinates of edge E0 and the coordinates of the target position TP in image I2. For example, it can be determined whether edge E0 has reached the target position TP from the coordinates of edge E0 and the coordinates of the target position TP in the vertical direction of image I2.

When the distance between the hole H and the target position TP is smaller than the distance between the edge E0 and the target position TP, the information processing device 70 determines whether the hole H has reached the target position TP based on the coordinates of the hole H and the coordinates of the target position TP in the image I2.

If the information processing device 70 determines that the edge E or hole H of the processing area 5 has not reached the target position TP (No in S210), it returns to process S204 to acquire image I2.

The information processing device 70 repeats process S204 for acquiring an image, process S206 for detecting the edge E of the processing area 5, process S208 for detecting the hole H, and process S210 for determining whether the target position TP has been reached, until it is determined that the edge E or hole H of the processing area 5 has reached the target position TP.

When the information processing device 70 determines that the edge E or hole H of the processing area 5 has reached the target position TP (Yes in S210), it stops irradiating the ion beam IB to the ion source 10 (S212).

By performing the above processing, the information processing device 70 ends the secondary milling process.

3.4.2. Processing for predicting machining end time The information processing device 70 performs processing for predicting the machining end time in parallel with the above-mentioned secondary milling processing.

For example, the information processing device 70 determines the residual film thickness as the smaller of the distance between the edge E of the processing area 5 and the target position TP and the distance between the hole H and the target position TP, and predicts the end time of processing based on the change in the residual film thickness.

Figure 25 is a graph showing the relationship between the residual film thickness and the time elapsed since the start of processing.

As shown in FIG. 25, by calculating the residual film thickness and plotting it on a graph with the horizontal axis showing the elapsed time and the vertical axis showing the residual film thickness, a function showing the relationship between the residual film thickness and the elapsed time can be calculated. In the example shown in FIG. 25, a function showing the relationship between the residual film thickness and the elapsed time is calculated by linear approximation calculation. Using this function, the time at which the residual film thickness will become zero can be calculated. The information processing device 70 displays the time at which the residual film thickness will become zero, i.e., the planned end time of processing, on the GUI screen.

The information processing device 70 may display on the display unit 80 a progress bar or the like that indicates how the residual film thickness approaches zero. This allows the user to grasp the progress of the processing.

18, the user sets the target position TP by specifying the target position TP using the cursor C, as shown in Fig. 17. Alternatively, the information processing device 70 may set the target position TP automatically. For example, the information processing device 70 automatically sets the target position TP at the boundary between the laminated film 6 and the protective member 8.

Figure 26 is a flowchart showing a modified example of the secondary milling process of the information processing device 70.

The modified example of the secondary milling process shown in FIG. 26 differs from the secondary milling process shown in FIG. 18 in that after the process S208 for detecting holes, a process S209 for setting a target position TP is performed. The other processes are similar to the processes shown in FIG. 18, and therefore a description thereof will be omitted.

In process S209 for setting the target position TP, similar to process S206 for detecting the edge E of the processing area 5 shown in FIG. 20, multiple vertical luminance profiles of the image I2 are acquired, and the boundary is detected from the change in luminance at the boundary between the laminated film 6 and the protective member 8. The information processing device 70 sets the detected boundary as the target position TP. After setting the boundary in this manner, the information processing device 70 displays a marker indicating the target position TP at a position on the image I2 that corresponds to the boundary.

In this way, the information processing device 70 can automatically set the target position TP.

4. Effects 4.1 Effects in primary milling In the sample processing device 100, the information processing device 70 performs the following processes: acquiring information on the target processing width TW; acquiring an image I2 obtained by photographing the coaxially epi-illuminated sample 2; measuring the processing width W in the acquired image I2; and terminating processing when the measured processing width W becomes equal to or larger than the target processing width TW.

As described above, by illuminating the sample 2 with coaxial epi-illumination, as shown in FIG. 5, in image I2, the processed area 5 of the sample 2, the unprocessed area of the sample 2, and the shielding member 30 appear bright, while the inclined surface 3 appears dark. Therefore, in image I2, the inclined surface 3 can be easily extracted, and the processed area 5 sandwiched between the two inclined surfaces 3 can be easily identified. Therefore, with the sample processing device 100, the processing width W can be accurately measured, and the timing to end processing can be accurately determined based on the processing width W. As a result, the sample 2 can be processed with high reproducibility and precision in the primary milling, improving the success rate of sample preparation in the secondary milling.

In the sample processing device 100, the information processing device 70, in the process of measuring the processing width W, binarizes the image I2 to generate a binary image I2B, and measures the processing width W in the binary image I2B. In the image I2 obtained by photographing the sample 2 illuminated with coaxial epi-illumination, the processing area 5 appears bright and the inclined surface 3 appears dark, so that the inclined surface 3 can be extracted by the binarization process. Therefore, the processing area 5 sandwiched between the two inclined surfaces 3 can be easily identified, and the processing width W can be accurately measured.

In the sample processing device 100, in the process of measuring the processing width W, the information processing device 70 binarizes the image I2 to extract the inclined surfaces 3 formed by processing, determines whether the number of extracted inclined surfaces 3 is two or not, and if there are two inclined surfaces 3, measures the processing width W by measuring the distance between the two inclined surfaces 3. Therefore, in the sample processing device 100, the processing area 5 sandwiched between the two inclined surfaces 3 can be easily identified, and the processing width W can be accurately measured.

In the sample processing device 100, the information processing device 70 includes a transillumination device 40 that emits illumination light that transmits and illuminates the sample 2, and the camera 60 captures the sample 2 that has been coaxially illuminated and transilluminated. By transilluminating the sample 2, the gap between the sample 2 and the shielding member 30 and the space below the sample 2 become bright in the image I2. As a result, only the inclined surface 3 becomes dark in the image I2, and the processing area 5 sandwiched between the two inclined surfaces 3 can be easily identified.

In the sample processing device 100, the information processing device 70 performs a process to predict the end time of processing based on the measurement results of the processing width W. Therefore, the sample processing device 100 can reduce the burden on the user.

In the sample processing device 100, the information processing device 70 acquires the image I2 captured by the camera 60 at the timing when the sample 2 becomes horizontal in the process of acquiring the image I2. Therefore, in the sample processing device 100, the inclination of the sample 2 does not need to be taken into account in the image processing of the image I2.

In the sample processing device 100, the information processing device 70 acquires a first image and a second image captured after the first image in a process of acquiring an image I2 captured by the camera 60, and performs a process of measuring the size of the gap in the first image, a process of measuring the size of the gap in the second image, a process of comparing the size of the gap in the second image with the size of the gap in the first image, and a process of terminating processing if the size of the gap in the second image is larger than the size of the gap in the first image. Therefore, the sample processing device 100 can automatically stop processing if the processing of the sample 2 is not proceeding normally.

4.2. Effect in secondary milling In the sample processing device 100, the information processing device 70 performs the following processes: acquiring an image I2, acquiring information on a target position TP of processing, detecting an edge E of the processing area 5 in the image I2, detecting a hole H formed in the processing area 5 in the image I2, determining whether or not the edge E or hole H of the processing area 5 has reached the target position TP, and terminating processing when it is determined that the edge E or hole H of the processing area 5 has reached the target position TP.

In this way, the sample processing device 100 detects the edge E and hole H of the processing area 5, and ends processing when it is determined that the edge E or hole H of the processing area 5 has reached the target position TP. Therefore, the sample processing device 100 can accurately determine the timing to end processing. Furthermore, the sample processing device 100 can process the sample 2 with high reproducibility.

In the sample processing device 100, the information processing device 70, in the process of detecting hole H, determines whether the first region A1 is a hole H based on the brightness of the first region A1 of the image I2 and the brightness of the second region A2 and the third region A3 which sandwich the first region A1. Specifically, the information processing device 70 determines the difference between the brightness of the first region A1 and the average value of the brightness of the second region A2 and the third region A3 as the signal strength of the first region A1, and if the signal strength is equal to or greater than a predetermined value, determines that the first region A1 is a hole H. This allows the hole H to be identified.

In the sample processing device 100, the information processing device 70 performs a process to predict the end time of processing based on the distance between the edge E of the processing area 5 and the target position TP when the distance between the edge E of the processing area 5 and the target position TP is smaller than the distance between the hole H and the target position TP. In addition, the information processing device 70 performs a process to predict the end time of processing based on the distance between the hole H and the target position TP when the distance between the hole H and the target position TP is smaller than the distance between the edge E of the processing area 5 and the target position TP. Therefore, the sample processing device 100 can accurately predict the end time of processing.

In the sample processing device 100, the sample 2 includes a laminated film 6, which is the object to be processed, and a protective member 8 adhered to the object to be processed, and in the process of acquiring information on the target position TP, the information processing device 70 identifies the boundary between the laminated film 6 and the protective member 8 on the image I2, and sets the position of the boundary as the target position TP. In this way, the sample processing device 100 can automatically set the target position TP.

In the above-described embodiment, the acceleration voltage may be changed stepwise in the secondary milling depending on the thickness of the sample 2. For example, the acceleration voltage may be lowered as the sample 2 becomes thinner. This can reduce the effect of damage to the sample 2 caused by irradiation with the ion beam IB.

For example, the residual film thickness, which is the smaller of the distance between the edge E of the processing area 5 and the target position TP and the distance between the hole H and the target position TP, corresponds to the thickness of the sample 2.

Therefore, the acceleration voltage is changed in stages according to the measured residual film thickness. In other words, the acceleration voltage is decreased in stages as the residual film thickness decreases. This makes it possible to prepare a sample that is less damaged by irradiation with the ion beam IB.

5.2. Second Modification In the primary milling process shown in FIG. 9, the information processing device 70 may perform a process of correcting the positional deviation of the image I2.

For example, when the sample 2 is cooled to reduce damage caused by irradiation with the ion beam IB, a position shift may occur in the captured image I2 due to a change in temperature of the sample 2 or the sample stage 20. In addition, a position shift may occur in the captured image I2 due to mechanical play in the swing mechanism of the sample stage 20, for example.

Therefore, the sample processing device 100 uses the first acquired image I2 as a reference and corrects the positional shift of the image I2 captured afterwards. For example, in each of the two images I2, the position of the gap between the sample 2 and the shielding member 30 and the edge of the sample 2 are identified using a brightness profile or the like, and the positional shift is corrected. Note that the positional shift may also be corrected by performing pattern matching on the two images I2.

By correcting the positional shift of image I2, the positional shift of position P where processing width W is measured can be corrected.

Similarly, in the secondary milling process shown in FIG. 18, the information processing device 70 may also perform a process to correct the positional deviation of the image I2. By correcting the positional deviation of the image I2, the positional deviation of the target position TP can be corrected.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as the configurations described in the embodiments. Substantially the same configurations are, for example, configurations that have the same functions, methods, and results, or configurations that have the same purpose and effect. The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that have the same effects as the configurations described in the embodiments, or that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

2...sample, 2a...first end, 2b...second end, 3...inclined surface, 4...substrate, 5...processing area, 6...laminated film, 8...protective member, 10...ion source, 12...control circuit, 20...sample stage, 30...shielding member, 40...transmitted illumination device, 42...illumination dimming circuit, 44...coaxial epi-illumination device, 46...illumination dimming circuit, 50...optical system, 52...half mirror, 60...camera, 70...information processing device, 80...display, 100...sample processing device

Claims (6)

A sample processing apparatus for processing a sample by irradiating the sample with an ion beam, comprising:
an ion source for irradiating the sample with the ion beam;
A sample stage for holding the sample;
A camera for photographing the sample;
A processing unit that determines the end of processing based on the image captured by the camera;
Including,
The processing unit includes:
obtaining said image;
A process of acquiring information on a target position for processing;
A process of detecting an edge of a processing area in the image;
A process of detecting a hole formed in the processing area in the image;
determining whether the edge of the processing area or the hole has reached the target position;
a process of terminating the machining when it is determined that the edge of the machining area or the hole has reached the target position;
This is a sample processing device. In claim 1,
The processing unit, in the process of detecting the hole,
A sample processing device that determines whether the first region is a hole or not based on the brightness of the first region of the image and the brightness of second and third regions that sandwich the first region. In claim 2,
The processing unit determines the difference between the brightness of the first region and the average brightness of the second region and the third region as the signal strength of the first region, and judges the first region to be a hole if the signal strength is greater than or equal to a predetermined value. In any one of claims 1 to 3,
The processing unit includes:
When the distance between the edge of the processing area and the target position is smaller than the distance between the hole and the target position, a process of predicting a processing end time is performed based on the distance between the edge of the processing area and the target position;
A sample processing device that performs a process of predicting the completion time of processing based on the distance between the hole and the target position when the distance between the hole and the target position is smaller than the distance between the edge of the processing area and the target position. In any one of claims 1 to 4,
The sample includes an object to be processed and a protective member adhered to the object to be processed,
The processing unit, in the process of acquiring information on the target position,
Identifying a boundary between the object to be processed and the protective member on the image;
A sample processing device that sets the position of the boundary to the target position. A sample processing method using a sample processing apparatus that processes a sample by irradiating the sample with an ion beam, comprising the steps of:
acquiring an image of the sample taken by a camera;
acquiring information on a target position for processing;
detecting edges of a processing area in the image;
detecting a hole formed in the processing area in the image;
determining whether the edge of the processing area or the hole has reached the target position;
terminating the machining when it is determined that the edge of the machining area or the hole has reached the target position;
A sample processing method comprising:

Images