JP6957002B2 - Charged particle beam device - Google Patents

Description

It relates to a charged particle beam device for observing a sample.

A precision stage equipped with a mechanism such as a linear motor or a linear encoder is used as the sample stage of the charged particle beam device. Since the precision stage can accurately move the sample to a specific position inside the apparatus, it is possible to realize highly accurate sample observation.
In a scanning electron microscope, the smaller the wagging distance, the higher the resolution of observation. Therefore, the sample is moved near the tip of the electron beam barrel by stage control to observe the sample. Therefore, in a composite charged particle beam apparatus provided with a focused ion beam lens barrel and an electron beam lens barrel, an arrangement and a stage configuration of a beam lens barrel capable of high-resolution observation with a small wagging distance have been proposed.

Japanese Unexamined Patent Publication No. 2011-216465

The control system of the stage generally limits the range of movement of the stage so that the sample or the stage does not collide with a member in the device such as a beam barrel or a detector.
However, if there is a malfunction of the user or a malfunction of the control system, the stage may collide with a member in the sample chamber without stopping even if the limit range is exceeded, and the member may be damaged.

Therefore, an object of the present invention is to provide a charged particle beam device that is provided with a stage having a power cutoff mechanism so that the members in the sample chamber are not damaged by the stage drive.

In order to achieve the above object, the charged particle beam device of the present invention irradiates a sample with a sample table for holding a sample, a stage having the sample table, a driving source for driving the sample table, and a sample. It has a charged particle beam lens barrel, a detector that detects charged particles generated from a sample by irradiation with a charged particle beam, and an image forming means that forms a charged particle image based on the signal detected by the detector. Provided a power cutoff mechanism for cutting off the power from the drive source to the sample table between the drive source and the sample table.

According to this charged particle beam device, when the sample table is moved and the sample or the sample table comes into contact with a member in the sample chamber, the movement of the sample table is stopped by cutting off the power from the drive source to the sample table. Can be made to.

According to the present invention, by providing the stage having the power cutoff mechanism, it is possible to avoid damage to the members in the sample chamber due to the stage drive.

It is a figure which shows the whole structure of the charged particle beam apparatus which concerns on embodiment of this invention. It is a figure which shows the structure of each lens barrel and a stage. It is a figure which shows the structure of the 2nd stage. It is a figure which shows the idling mechanism. It is a figure which shows the structure of the 2nd stage. It is a figure which shows the crushable mechanism.

The charged particle beam device 100 according to the embodiment of the present invention includes an electron beam barrel 2 as a charged particle beam barrel, a secondary electron detector 4 as a detector, an image forming unit 13 as an image forming means, and a sample table. It includes 36, a second stage 6 as a stage, a motor 31 as a drive source, and an idling mechanism 39 as a power cutoff mechanism.

The electron beam lens barrel 2 irradiates the sample 10 held on the sample table 36 with an electron beam. The secondary electron detector 4 detects secondary electrons generated from the sample 10 by electron beam irradiation. The image forming unit 13 forms a secondary electron image based on the secondary electron signal detected by the secondary electron detector 4 and the scanning signal of the electron beam. As a result, a secondary electron image of the sample 10 can be obtained.

The second stage 6 includes a sample table 36 for holding the sample 10, an inclined stage 35 for fixing the sample table 36, and a motor 31 for inclining the inclined stage 35. In the second stage 6, the sample 10 can be tilted with respect to the electron beam lens barrel 2 so that the sample 10 is arranged in a posture suitable for observation.

Further, the second stage 6 includes a rotating shaft 32 connected to the tilting stage 35, a motor 31 for rotating the rotating shaft 32, and an idling mechanism 39 of the rotating shaft 32 between the motor 31 and the tilting stage 35. The idling mechanism 39 idles the rotation of the rotating shaft 32 so that the power of the motor 31 is not transmitted to the inclined stage 35 when a constant external force is applied to the sample table 36. As a result, the driving force for tilting the sample table 36 can be cut off. Therefore, even when the sample table 36 is tilted to come into contact with the electron beam lens barrel 2, the idling mechanism 39 cuts off the driving force for tilting the sample table 36, so that the electron beam lens barrel 2 is erroneously mounted on the sample table 2. It is possible to prevent the tip of the electron beam lens barrel 2 from being damaged by being pressed against the 36.

Hereinafter, as an embodiment of the present invention, a charged particle beam device including an idling mechanism as a power cutoff mechanism will be described with reference to FIGS. 1, 2, 3, and 4.
FIG. 1 is a diagram showing an overall configuration of a charged particle beam device 100 according to an embodiment of the present invention. In FIG. 1, the charged particle beam device 100 includes a focused ion beam barrel 1 that irradiates a gallium ion beam, an electron beam barrel 2 that irradiates an electron beam, and an ion beam barrel 3 that irradiates an argon ion beam. It includes a secondary electron detector 4 for detecting secondary electrons, a first stage 5, and a second stage 6 held in the first stage 5. The inside of the sample chamber 9 is depressurized to a predetermined degree of vacuum.
The focused ion beam lens barrel 1 is arranged in the vertical direction, and the electron beam lens barrel 2 is arranged at an angle of 60 degrees with respect to the focused ion beam lens barrel 1. Here, the electron beam lens barrel 2 may be arranged in the vertical direction, and the focused ion beam lens barrel may be tilted. Further, the electron beam lens barrel 2 and the focused ion beam lens barrel 1 may be arranged at right angles.

The first stage 5 can be moved in the XYZ direction by the stage drive mechanism 7, and can be tilted by the stage tilt mechanism 8. The first stage 5 can be tilted 5 degrees to the electron beam barrel 2 side and 60 degrees to the opposite side. Further, the first stage 5 can be rotated about the Z-axis direction.

Further, the charged particle beam device 100 includes a control unit 11. The control unit 11 includes a beam control unit 12 that controls irradiation of each beam, an image forming unit 13 that forms an observation image based on a detection signal and a beam scanning signal, and a stage control unit 14 that drives and controls the stage. Further, the charged particle beam device 100 includes an input unit 15 such as a keyboard for acquiring an input instruction of a user, and a display unit 16 for displaying an observation image or the like.

FIG. 2 is a diagram showing a configuration of each lens barrel and a stage. The second stage 6 includes a sample table 36 for fixing the sample 10, an inclined stage 35 for fixing the sample table 36 and inclining the sample table 36, a motor 31 as a drive source for inclining the inclined stage 35, and a motor 31. A rotating shaft 32 that is connected to the tilting stage 35 and tilts the tilting stage 35 by the driving force of the motor 31, and a rotating shaft support portion 34 that supports the rotating shaft 32.

The focused ion beam irradiation axis 1a, the electron beam irradiation axis 2a, and the gas ion beam irradiation axis 3a intersect on the sample 10. The first stage 5 can be tilted about the tilt axis 8a. The direction parallel to the inclination axis 8a is defined as the X-axis direction 21, and the Y-axis direction 22 and the Z-axis direction 23 are defined.
The second stage 6 can be tilted independently of the first stage 5. Here, the rotation shafts 32 and 33, which are the tilt shafts of the second stage, can be arranged so as to be parallel to the tilt shaft 8a of the first stage 5. As a result, the second stage 6 can be tilted in addition to the tilt of the first stage 5. Therefore, the sample 10 can be tilted beyond the tilt range of the first stage 5. Further, since the second stage 6 is smaller than the first stage 5, even if the first stage 5 is tilted and interferes with the members in the sample chamber 9, the second stage 6 can be tilted. It can be tilted to the desired angle without interference.

FIG. 3 is a diagram showing the configuration of the second stage 6. In FIG. 3, the second stage 6 holds a base 40 fixed to the first stage 5, a motor 31 that generates a rotational driving force, a rotary shaft 32 that transmits a rotational driving force from the motor 31, and a sample 10. The sample table 36 is provided, and an inclined stage 35 that inclines the sample table 36 by the rotation of the rotating shaft 32. The second stage 6 is fixed to the base 40 and supports the rotating shafts 32 and 33, and the stage supporting portion 37 fixed to the inclined stage 35 and supporting the rotating shafts 32 and 33, respectively. It is provided with a part 38. The stage support portion 37 includes an idling mechanism 39 that cuts off the driving force from the motor 31.

FIG. 4 is a diagram showing the configuration of the idling mechanism 39. In FIG. 4, the idling mechanism 39 includes a rotating shaft 32 having a groove 32a, a support member 41 to be inserted into the groove 32a, and a spring 42 that supports and expands and contracts the support member 41.

As shown in FIG. 4A, the support member 41 maintains the connection between the rotary shaft 32 and the rotary shaft support portion 34 in a state where the support member 41 is inserted into the groove 32 a of the rotary shaft 32 by the spring 42. That is, the spring 42 presses the support member 41 against the groove 32a of the rotating shaft 32. In this case, the rotating shaft 32, the rotating shaft 33, the tilting stage 35, the sample base 36, the support portion 37, the support portion 38, and the idling mechanism 39 rotate integrally by the driving force from the motor 31. Further, depending on the direction of the driving force, the rotation shaft 32 has two rotation directions, hourly and counterclockwise.

When the sample 10 or the sample table 36 comes into contact with a member in the sample chamber 9, that is, a member other than the second stage 6, and an external force is applied to the sample table 36 when the sample table 36 is tilted, the motor 31 is driven. The torque applied to the rotating shaft 32 becomes larger, and as shown in FIG. 4B, the spring 42 contracts the support member 41 and pushes it out of the groove 32a. As a result, the rotation shaft 32 idles. In this case, the driving force from the motor 31 is cut off, and the inclination of the sample table 36 is stopped.

Here, an embodiment in which the second stage 6 is tilted and the cross-sectional processing observation of the sample 10 is performed will be described. First, the sample 10 is scanned and irradiated with a gallium ion beam from the focused ion beam lens barrel 1, and the sample 10 is etched to form a cross section. At this time, the first stage 5 may be tilted 60 degrees from the horizontal state to the side opposite to the electron beam irradiation shaft 2, and the second stage 6 may be tilted 10 degrees. As a result, the sample 10 can be tilted beyond the tiltable range of the first stage 5, so that the sample 10 can be processed by irradiating the sample surface with a gallium ion beam at an incident angle of 70 degrees. .. Next, the inclinations of the first stage 5 and the second stage 6 are restored.

Next, in order to perform high-resolution observation with the electron beam, the first stage 5 is driven to bring the sample 10 closer to the tip of the electron beam lens barrel 2. Next, the second stage 6 is driven so that the cross section of the sample 10 is perpendicular to the electron beam irradiation axis 2a, and the sample 10 is tilted. In this state, the cross section is irradiated with an electron beam to obtain a secondary electron image of the cross section.

Here, the sample 10 is tilted at a position close to the tip of the electron beam lens barrel 2 and adjusted by the second stage 6 so as to have an optimum observation posture. Even if the sample table 36 is brought into contact with the tip of the electron beam lens barrel 2 due to a malfunction of the user or a malfunction of the control system, the driving force to the sample table 36 is cut off by the above-mentioned idling mechanism 39 in the second stage 6. Since the sample table 36 is stopped, damage to the tip of the electron beam lens barrel 2 can be avoided.

As an embodiment of the present invention, a charged particle beam device including a crushable mechanism instead of the idling mechanism as the power cutoff mechanism will be described.
FIG. 5 is a diagram showing the configuration of the second stage 6. In FIG. 5, the first stage 6 is provided with a crushable mechanism 50 that cuts off the driving force from the motor 31 on the rotating shaft support portion 34 instead of the idling mechanism 39.

FIG. 6 is a cross-sectional view taken along the line AA shown in FIG. Depending on the direction of the driving force, the rotation shaft 32 has two rotation directions, hourly and counterclockwise. Here, the mechanism of power interruption will be described by taking the case where the rotating shaft 32 rotates clockwise as an example.

As shown in FIG. 6A, the crushable mechanism 50 has a structure of being inserted between the rotating shaft 32 and the rotating support portion 34. A driving force is transmitted from the rotary shaft 32 to the rotary support 34 through the crushable mechanism 50, and the rotary support 34 rotates together with other components connected to the rotary support 34.

When the sample 10 or the sample table 36 is tilted, the torque transmitted from the rotation shaft 32 to the rotation support portion 34 is crushable when an external force is applied so as to interfere with other members and prevent the sample table 36 from tilting. When the torque upper limit value that the mechanism 50 can withstand is exceeded, the crushable mechanism 50 is cracked and separated into a crushable mechanism fragment 50A and a crushable mechanism fragment 50B. In this case, the driving force cannot be transmitted from the rotating shaft 32 to the support portion 34.

In the above embodiment, the device in which the crushable mechanism is installed on the rotation support portion 34 has been described, but the present invention is also effective when the crushable mechanism is installed on the rotation shaft 32.

Further, in the above embodiment, the device provided with the power cutoff mechanism for the tilt control of the second stage 6 has been described, but the present invention is also effective when the power cutoff mechanism is provided for the movement control of the first stage 5. Play.

It goes without saying that the present invention is not limited to the above embodiments and extends to various modifications and equivalents included in the idea and scope of the present invention.

1 ... Focused ion beam barrel, 2 ... Electron beam barrel, 3 ... Gas ion beam barrel, 5 ... First stage, 6 ... Second stage, 10 ... Sample, 31 ... Motor, 32 ... Rotation axis, 34 ... Rotating shaft support, 35 ... Tilt stage, 36 ... Sample stand

Claims (3)

A sample table for holding the sample and
A stage having the sample table and
The drive source that drives the sample table and
A charged particle beam lens barrel that irradiates the sample with a charged particle beam,
A detector that detects charged particles generated from the sample by irradiation with the charged particle beam, and
It has an image forming means for forming a charged particle image based on a signal detected by the detector.
The stage includes a power cutoff mechanism that cuts off power from the drive source to the sample table between the drive source and the sample table .
The stage has a rotating shaft for rotating the sample table between the drive source and the sample table.
The power cutoff mechanism is a charged particle beam device characterized by being an idling mechanism that idles the rotation of the rotating shaft. A sample table for holding the sample and
A stage having the sample table and
The drive source that drives the sample table and
A charged particle beam lens barrel that irradiates the sample with a charged particle beam,
A detector that detects charged particles generated from the sample by irradiation with the charged particle beam, and
It has an image forming means for forming a charged particle image based on a signal detected by the detector.
The stage includes a power cutoff mechanism that cuts off power from the drive source to the sample table between the drive source and the sample table.
The stage has a rotating shaft for rotating the sample table between the drive source and the sample table.
The power cutoff mechanism, load electrostatic particle beam device you and separating the connecting member between the sample stage and the driving source if certain force is applied to the rotating shaft. The charged particle beam device according to claim 1 or 2 , wherein the sample table can be tilted with respect to the stage.

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