Sample Holder and Sample Processing Apparatus

A sample holder used for a sample processing apparatus that applies a charged particle beam to a sample to process the sample. The sample holder includes a holder base thermally connected to a cooling source, a rotating body rotatably supported on the holder base to hold the sample, and a drive unit that rotates the rotating body. The rotating body has a sliding surface that comes into slidable surface contact with the holder base.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2023-050125, filed Mar. 27, 2023, the disclosure of which is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a sample holder and a sample processing apparatus.

Description of Related Art

As a sample processing apparatus that uses an ion beam to process a sample, a Cross Section Polisher (registered trademark) for processing a cross section of the sample, an Ion Slicer (registered trademark) for producing a thin-film sample, and the like are known.

JP-A-2016-100111 discloses a sample processing apparatus including a sample holder capable of changing an incidence angle of an ion beam with respect to a sample.

As a technique of using an ion beam to process a sample, planar surface milling is known. In the planar surface milling, an ion beam is obliquely applied to a surface of a rotating sample to allow polishing flaws and crystal distortion caused by mechanical polishing to be removed in a wide range and allow an excellently smooth surface to be produced. By observing the sample produced using the planar surface milling with a scanning electron microscope, crystal information of an outermost surface of the sample can be obtained.

However, in a polymer or low-melting-point metal sample or the like sensitive to heat, an application of an ion beam causes thermal damage, and consequently, even when the planar surface milling is performed on the sample, an excellently smooth surface may not be able to be produced.

SUMMARY OF THE INVENTION

According to a first aspect of the present disclosure, there is provided a sample holder used for a sample processing apparatus that applies a charged particle beam to a sample to process the sample, the sample holder including:a holder base thermally connected to a cooling source;a rotating body rotatably supported on the holder base to hold the sample; anda drive unit that rotates the rotating body, andthe rotating body having a sliding surface that comes into slidable surface contact with the holder base.

According to a second aspect of the present disclosure, there is provided a sample processing apparatus including:the above sample holder; anda charged particle beam source that applies a charged particle beam to the sample held on the sample holder.

DESCRIPTION OF THE INVENTION

According to an embodiment of the present disclosure, there is provided a sample holder used for a sample processing apparatus that applies a charged particle beam to a sample to process the sample, the sample holder including:a holder base thermally connected to a cooling source;a rotating body rotatably supported on the holder base to hold the sample; anda drive unit that rotates the rotating body, andthe rotating body having a sliding surface that comes into slidable surface contact with the holder base.

In such a sample holder, a rotating body has a sliding surface that comes into slidable surface contact with a holder base, and accordingly it is possible to efficiently cool the holder, while rotating the holder. As a result, in such a sample holder, it is possible to reduce thermal damage given by an application of a charged particle beam to a sample and therefore produce an excellently smooth surface by planar surface milling.

According to an embodiment of the present disclosure, there is provided a sample processing apparatus including:the above sample holder; anda charged particle beam source that applies a charged particle beam to the sample held on the sample holder.

In such a sample processing apparatus, the sample holder described above is included, and accordingly it is possible to reduce thermal damage given by an application of a charged particle beam to the sample and produce an excellently smooth surface by the planar surface milling.

Now preferred embodiments of the invention will be described in detail below with reference to the drawings. The embodiments described below are not intended to unduly limit the scope of the invention as stated in the claims. Further, all of the components described below are not necessarily essential requirements of the invention.

1. First Embodiment

1.1. Configuration of Sample Holder

First, referring to the drawings, a description will be given of a sample holder according to the first embodiment.FIGS.1and2are perspective views schematically illustrating a sample holder100according to the first embodiment.FIG.3is a cross-sectional view schematically illustrating the sample holder100according to the first embodiment.FIG.4is a plan view schematically illustrating the sample holder100. Note thatFIG.3is a cross-sectional view along a line III-III inFIG.4.

The sample holder100is a sample holder for a sample processing apparatus that applies an ion beam to a sample S to process the sample S. As illustrated inFIGS.1to4, the sample holder100includes a base10, a holder base20, a holder30, a motor base40, a motor50, a first gear60, a magnet70, and a magnetic body80.

The base10has a wall portion12, a wall portion14, and a bottom portion16connecting the wall portion12and the wall portion14. The wall portion12and the wall portion14face each other. Between the wall portion12and the wall portion14, the holder base20is disposed.

The base10is configured to be detachable from the sample processing apparatus. For example, in the bottom portion16of the base10, a recessed portion15is formed. Into the recessed portion15, a protruding portion provided on a stage of the sample processing apparatus is fitted to allow the base10to be attached to the sample processing apparatus. Note that a method of attaching the base10to the sample processing apparatus is not particularly limited.

As illustrated inFIG.3, the base10is thermally connected to a cooling source2and cooled by heat transfer. The bottom portion16of the base10is in surface contact with the cooling source2. In the sample processing apparatus, a stage to which the base10is to be attached is cooled by a refrigerant such as liquid nitrogen, and the stage serves as the cooling source2.

The holder base20has a first wall portion22, a second wall portion24, and a bottom portion26connecting the first wall portion22and the second wall portion24. The first wall portion22and the second wall portion24face each other. Between the first wall portion22and the second wall portion24, the holder30that holds the sample S is disposed.

The wall portion12of the base10and the first wall portion22of the holder base20face each other and, between the wall portion12and the first wall portion22, there is a gap. The wall portion14of the base10and the second wall portion24of the holder base20face each other and, between the wall portion14and the second wall portion24, there is a gap. The bottom portion16of the base10and the bottom portion26of the holder base20face each other and, between the bottom portion16and the bottom portion26, there is a gap.

The holder base20is thermally connected to the base10. The holder base20is thermally connected to the cooling source2via the base10and cooled by heat transfer. The first wall portion22is provided with a first protruding portion23protruding toward the wall portion12of the base10. A leading end surface23aof the first protruding portion23is in slidable surface contact with the wall portion12. The second wall portion24is provided with a second protruding portion25protruding toward the wall portion14of the base10. A leading end surface25aof the second protruding portion25is in slidable surface contact with the wall portion14. The surface contact of the first protruding portion23and the second protruding portion25with the base10thermally connects the holder base20to the base10. Thus, the holder base20is thermally connected to the cooling source2via the base10.

In the bottom portion26of the holder base20, a hole28is formed to guide a shaft portion36of the holder30. In addition, the bottom portion26has a bottom surface27with which a sliding surface30aof the holder30comes into slidable surface contact.

The holder base20is connected to the base10to be able to be inclined. The holder base20is inclined using an axis A illustrated inFIG.3as an inclination axis. The first protruding portion23and the second protruding portion25are rotatably connected to the base10via rod-shaped shaft members each extending along the axis A. This allows the holder base20to be inclined using the axis A as the inclination axis. The holder base20may also be inclined manually or using the motor not shown as power. By inclining the holder base20, it is possible to incline the holder30, the motor base40, and the motor50. By inclining the holder base20, it is possible to incline the sample S.

The holder30holds the sample S serving as a processing target. The holder30is rotatably supported on the holder base20. The holder30is a rotating body rotated by a drive of the motor50. The holder30has the sliding surface30athat comes into slidable surface contact with the holder base20.

The holder30has a sample holding portion32, a columnar portion33, a second gear34, and the shaft portion36. For example, the sample holding portion32, the columnar portion33, the second gear34, and the shaft portion36are integrally configured.

The sample holding portion32holds the sample S. The sample holding portion32is located between the first wall portion22and the second wall portion24of the holder base20. The sample S is fixed to the sample holding portion32such that the axis A serving as the inclination axis of the holder base20passes through a surface Sa of the sample S. The sample S may be fixed to the sample holding portion32by using, e.g., a resin or an adhesive, and may also be fixed to the sample holding portion32by using a spring, a screw, or the like. A shape of the sample holding portion32is a circle when viewed in a direction along an axis B. Note that the shape of the sample holding portion32is not particularly limited, and may also be a polygon when viewed in the direction along the axis B.

The columnar portion33is a column-shaped portion extending along the axis B. The shape of the columnar portion33is a columnar shape around the axis B serving as a center axis. To one end of the columnar portion33, the sample holding portion32is connected while, to another end of the columnar portion33, the second gear34and the shaft portion36are connected.

The second gear34meshes with the first gear60. The second gear34is rotated by power transmitted thereto from the first gear60. The second gear34is, e.g., a spur gear. A center of the second gear34is located on the axis B serving as a rotation axis of the holder30. The second gear34has the sliding surface30athat comes into slidable surface contact with the holder base20. The sliding surface30ais a circular region around the axis B. A plurality of teeth included in the second gear34are formed around the sliding surface30a.

A maximum diameter (maximal diameter) D of the second gear34illustrated inFIG.4is larger than a maximum width W of the sample holding portion32. The maximum width W of the sample holding portion32has a dimension in a direction perpendicular to the axis B of the sample holding portion32. The shape of the sample holding portion32is the circle herein when viewed in the direction along the axis B, and the maximum width W is a maximum diameter of the sample holding portion32.

When viewed in the direction along the axis B, the second gear34has a largest width (dimension in the direction perpendicular to the axis B) in the holder30. In other words, when viewed in the direction along the axis B, the maximum diameter D of the second gear34is larger than each of the maximum width W of the sample holding portion32, a maximum width (maximum diameter) of the columnar portion33, and a maximum width (maximum diameter) of the shaft portion36. By setting the maximum diameter D of the second gear34large, it is possible to increase an area of the sliding surface30a. This can increase an area over which the holder30and the holder base20are in surface contact with each other, and increase a cooling efficiency.

The shaft portion36is inserted in the hole28of the holder base20. By inserting the shaft portion36into the hole28, the holder30can be attached to the holder base20. The holder30rotates, while being guided by the hole28in which the shaft portion36is inserted. A center axis of the shaft portion36overlaps the axis B. The holder30rotates around the axis B serving as the rotation axis.

To the shaft portion36, the magnet70is fixed. In the illustrated example, the magnet70is fixed to the shaft portion36with a nut72. The nut72screws over a male screw formed in the shaft portion36. For example, the magnet70has a circular shape when viewed in the direction along the axis B, and the shaft portion36passes through a center of a circle. Meanwhile, into the hole28of the holder base20, the magnetic body (ferromagnetic body)80is fixed. For example, the magnetic body80has a circular shape when viewed in the direction along the axis B, and the shaft portion36passes through a center of a circle.

By a magnetic force generated by the magnet70, the sliding surface30aof the holder30comes into close contact with the bottom surface27of the holder base20. By an attraction force acting between the magnet70and the magnetic body80, the sliding surface30ais pressed against the bottom surface27to come into close contact with the bottom surface27. The sliding surface30ais pressed by a predetermined magnetic force of the magnet70against the bottom surface27.

The holder30is held on the holder base20by the attraction force between the magnet70and the magnetic body80. Accordingly, the holder30is detachable from the holder base20. Therefore, in the sample holder100, the sample S can be fixed to the holder30in a state where the holder30is detached from the holder base20. In addition, when the holder30is worn out, the holder30can be replaced.

A material of the base10and the holder base20is, e.g., aluminum, while a material of the holder30is, e.g., copper. By using different types of metals as the material of the holder base20and the material of the holder30, it is possible to prevent galling. Note that the materials of the base10, the holder base20, and the holder30are not particularly limited as long as the materials have high heat conductivities. For example, it may be possible to cover each of a base material of the holder base20and a base material of the holder30with a plate layer to allow each of the bottom surface27of the holder base20and the sliding surface30aof the holder30to have a plated layer surface. For example, it may also be possible to use a plated layer surface with a high slidability and a high heat conductivity as each of the bottom surface27of the holder base20and the sliding surface30aof the holder30.

The motor base40holds the motor50. The motor base40is connected to the holder base20. The motor50is connected to the first gear60. The motor50rotates the first gear60. The motor50functions as a drive unit for rotating the holder30. The first gear60is, e.g., a spur gears.

1.2. Operation of Sample Holder

In the sample holder100, by inclining the holder base20by using the axis A as the inclination axis, it is possible to adjust an incidence angle of an ion beam with respect to the surface Sa of the sample S.

When the first gear60is rotated by rotation of the motor50, the second gear34meshing with the first gear60is rotated. Thus, the holder30rotates around the axis B serving as the rotation axis, and the sample S held by the sample holding portion32rotates around the axis B serving as the rotation axis. For example, the motor50continuously rotates the holder30in a predetermined direction. In other words, the motor50rotates the holder30plurality of times in the same direction.

As a result of the rotation of the holder30, the sliding surface30aof the holder30slides, while being in surface contact with the bottom surface27. Since the base10is in contact with the cooling source2herein, the base10is cooled herein by heat transfer. By the cooling of the base10, the holder base20thermally connected to the base10is cooled. Since the sliding surface30aof the holder30is in slidable surface contact with the holder base20, it is possible to cool the holder30, while rotating the holder30. At this time, by the attraction force acting between the magnet70fixed to the holder30and the magnetic body80fixed to the holder base20, the sliding surface30ais pressed with a predetermined force against the bottom surface27. This can bring the sliding surface30aand the bottom surface27into close contact with each other.

The sample holder100includes the holder base20thermally connected to the cooling source2, the holder30rotatably supported on the holder base20and holding the sample S, and the motor50that rotates the holder30. Meanwhile, the holder30has the sliding surface30athat comes into slidable surface contact with the holder base20. Thus, in the sample holder100, the holder30has the sliding surface30athat comes into slidable surface contact with the holder base20, and therefore it is possible to efficiently cool the holder30, while rotating the holder30. As a result, in the sample holder100, it is possible to reduce thermal damage given by the application of the ion beam to the sample S, and therefore it is possible to produce an excellently smooth surface by the planar surface milling even when the sample is a polymer or low-melting-point metal sample or the like sensitive to heat.

For example, when the holder30is rotatably supported on the holder base20via a bearing, between the holder base20and the holder30, a portion in point contact with a ball of the bearing is included. As a result, when the holder30is supported on the holder base20via the bearing, heat transfer is poor, and the holder30cannot efficiently be cooled. By contrast, in the sample holder100, the holder30and the holder base20are in surface contact with each other, and accordingly heat transfer is excellent, and the holder30can efficiently be cooled.

The sample holder100includes the magnet70that brings the holder30into close contact with the holder base20by a magnetic force generated by the magnet70. In the sample holder100, the magnet70is fixed to the holder30, while the magnetic body80is fixed to the holder base20. Thus, in the sample holder100, it is possible to magnetically bring the sliding surface30aof the holder30into close contact with the holder base20, and therefore it is possible to reduce a contact thermal resistance between the sliding surface30aand the holder base20and efficiently cool the holder30.

In addition, in the sample holder100, the sliding surface30aof the holder30is brought into close contact with the holder base20by the magnetic force generated by the magnet70, and therefore the sliding surface30acan be pressed with a predetermined force. This can reduce fluctuations in frictional force occurring across the sliding surface30aand can reduce fluctuations in contact thermal resistance between the sliding surface30aand the bottom surface27.

For example, when the sliding surface30ais brought into close contact with the holder base20by using an elastic member such as a spring, a magnitude of a resilient force of the spring is proportional to an amount of extension/contraction of the spring from a natural length thereof, and therefore it is difficult to press the sliding surface30awith a predetermined force. By contrast, in the sample holder100, the sliding surface30aof the holder30is magnetically brought into close contact with the holder base20, and accordingly the sliding surface30acan be pressed with a predetermined given force. This can reduce the frictional force fluctuations caused across the sliding surface30a. In addition, it is possible to reduce the contact thermal resistance fluctuations between the sliding surface30aand the holder base20. As a result, in the sample holder100, the holder30can be rotated at a predetermined speed, while a temperature of the holder30can be held constant.

The sample holder100includes the first gear60rotated by the rotation of the motor50. Meanwhile, the holder30includes the sample holding portion32that holds the sample S and the second gear34rotated by the power transmitted thereto from the first gear60. Consequently, in the sample holder100, the holder30can continuously be rotated in a predetermined direction.

In the sample holder100, the sliding surface30ais a surface of the second gear34. In addition, the plurality of teeth of the second gear34are formed around the sliding surface30a. Consequently, in the sample holder100, as a result of the rotation of the holder30, the sliding surface30aslides, while being in surface contact with the holder base20. Therefore, in the sample holder100, it is possible to bring the holder30into surface contact with the holder base20, while rotating the holder30.

In the sample holder100, when viewed in the direction along the axis B, the maximum diameter D of the second gear34is larger than the maximum width W of the sample holding portion32. Accordingly, in the sample holder100, compared to a case where, e.g., the maximum diameter D of the second gear34is equal to or less than the maximum width W of the sample holding portion32, the area of the sliding surface30acan be increased to be able to enhance the efficiency of cooling of the holder30.

In the sample holder100, the motor50continuously rotates the holder30in a predetermined direction. As a result, in the sample holder100, it is possible to reduce uneven processing of the surface Sa of the sample S in the planar surface milling and produce the excellently smooth surface.

For example, when the holder30is cooled by connecting the holder30and the cooling source2with a flat stranded wire, when the holder30is continuously rotated in a predetermined direction, the flat stranded wire may be twisted, and consequently the holder30cannot continuously be rotated in a predetermined direction. By contrast, in the sample holder100, the sliding surface30aof the holder30is allowed to slide, while being kept in surface contact with the holder base20, and consequently it is possible to continuously rotate the holder30in a predetermined direction, while cooling the holder30.

The sample holder100includes the base10thermally connected to the cooling source2, the holder base20is thermally connected to the cooling source2via the base10, and the holder base20is connected to the base10to be able to be inclined. Therefore, in the sample holder100, it is possible to adjust the incidence angle of the ion beam with respect to the surface Sa of the sample S.

1.4.1. First Modification

FIG.5is a cross-sectional view schematically illustrating a sample holder101according to a first modification. Hereinbelow, in the sample holder101, members having the same functions as those of the constituent members of the sample holder100described above are denoted by the same reference signs, and a detailed description thereof is omitted.

In the sample holder100described above, as illustrated inFIG.3, the magnet70is fixed to the holder30, while the magnetic body80is fixed to the holder base20. By contrast, in the sample holder101, as illustrated inFIG.5, the magnet70is fixed to the holder base20, while the magnetic body80is fixed to the holder30.

The sample holder101can achieve the same functions/effects as those achieved by the sample holder100.

1.4.2. Second Modification

FIG.6is a cross-sectional view schematically illustrating a sample holder102according to the second modification. Hereinbelow, in the sample holder102, members having the same functions as those of the constituent members of the sample holder100described above are denoted by the same reference signs, and a detailed description thereof is omitted.

In the sample holder100described above, as illustrated inFIG.3, the magnet70is fixed to the holder30, while the magnetic body80is fixed to the holder base20. Accordingly, in the sample holder100, a distance between the magnet70and the magnetic body80is constant.

By contrast, in the sample holder102, as illustrated inFIG.6, the magnetic body80can move along the axis B. Consequently, in the sample holder102, the distance between the magnet70and the magnetic body80can be varied. The magnet70is fixed to the holder30.

In an inner surface of the hole28formed in the bottom portion26of the holder base20, a female screw is formed while, in an outer surface of the magnetic body80, a male screw is formed. By thus providing the magnetic body80and the hole28with a screw structure, it is possible to move the magnetic body80along the axis B. This allows the distance between the magnet70and the magnetic body80to be varied.

Alternatively, the magnetic body80may also be screwed in place in a direction perpendicular to the axis B, though not shown. Still alternatively, after the distance between the magnet70and the magnetic body80is adjusted, the magnetic body80may also be bonded and fixed.

The sample holder102can achieve the same functions/effects as those achieved by the sample holder100. In addition, in the sample holder102, the distance between the magnet70and the magnetic body80is variable. Accordingly, in the sample holder102, a magnitude of the attraction force between the magnet70and the magnetic body80can be adjusted. Therefore, in the sample holder102, a force to press the sliding surface30aof the holder30against the holder base20can be adjusted.

Note that, as illustrated inFIG.5, it may also be possible to fix the magnetic body80to the holder30and allow the magnet70to move along the axis B. This allows the distance between the magnet70and the magnetic body80to be varied.

1.4.3. Third Modification

FIG.7is a cross-sectional view schematically illustrating a sample holder103according to a third modification. Hereinbelow, in the sample holder103, members having the same functions as those of the constituent members of the sample holder100described above are denoted by the same reference signs, and a detailed description thereof is omitted.

In the sample holder100described above, when viewed in the direction along the axis B, the magnet70has the circular shape. By contrast, in the sample holder103, a plurality of the magnets70are held by a circular holding member74and arranged around the shaft portion36.

FIG.8is a perspective view schematically illustrating the holding member74. When viewed in the direction along the axis B, the holding member74has a circular shape, and the shaft portion36passes through a center of a circle. The holding member74is fixed to the shaft portion36with the nut72. As illustrated inFIG.8, the holding member74holds the plurality of magnets70. For example, the magnets70are equidistantly arranged around the axis B. In the illustrated example, the holding member74holds the four magnets70, but the number of the magnets70to be held by the holding member74is not particularly limited. Locations of the magnets70are also not particularly limited, and the magnets70can be disposed at any positions. The sample holder103can achieve the same functions/effects as those achieved by the sample holder100.

1.4.4. Fourth Modification

FIG.9is a cross-sectional view schematically illustrating a sample holder104according to a fourth modification. Hereinbelow, in the sample holder104, members having the same functions as those of the constituent members of the sample holder100described above are denoted by the same reference signs, and a detailed description thereof is omitted.

In the sample holder100described above, as illustrated inFIG.3, the sliding surface30aof the holder30is a circular region around the axis B serving as t-he rotation axis of the holder30. By contrast, in the sample holder104, as illustrated inFIG.9, the sliding surface30aof the holder30is a circle around the axis B.

The sliding surface30ais provided on the shaft portion36. The sliding surface30ais an end surface of the shaft portion36. When viewed in, e.g., the direction along the axis B, the magnet70has a circular shape, and the shaft portion36passes through a center of a circle. The sliding surface30ais surrounded by the magnet70when viewed in the direction along the axis B. In other words, the sliding surface30ais located inside the circular magnet70when viewed in the direction along the axis B. The magnet70is fixed by a fixing member76to the holder30. Note that a method of fixing the magnet70is not particularly limited, and the magnet70may also be fixed to the holder30with, e.g., an adhesive or the like.

The magnetic body80is disposed in a region facing the magnet70. When viewed in the direction along the axis B, the magnetic body80overlaps the magnet70. In the illustrated example, when viewed in, e.g., the direction along the axis B, the magnetic body80has a circular shape. For example, the diameter of the magnet70and the diameter of the magnetic body80are equal. The bottom surface27of the holder base20that comes into surface contact with the sliding surface30aof the holder30is surrounded by the magnetic body80. In other words, the bottom surface27of the holder base20is located inside the circular magnetic body80when viewed in the direction along the axis B.

The sample holder104can achieve the same functions/effects as those achieved by the sample holder100.

FIG.10is a perspective view schematically illustrating a sample holder105according to a fifth modification. Hereinbelow, in the sample holder105, members having the same functions as those of the constituent members of the sample holder100described above are denoted by the same reference signs, and a detailed description thereof is omitted.

As illustrated inFIG.10, in the sample holder105, the first gear60and the second gear34are bevel gears.

Each of the first gear60and the second gear34is the bevel gear in which a plurality of teeth are formed in a side surface of a truncated cone. The first gear60and the second gear34are in upside down relation. In the illustrated example, the first gear60is disposed such that a top surface with a small area is at the bottom and a bottom surface with a large area is at the top, while the second gear34is disposed such that a top surface is at the top and a bottom surface is at the bottom. An axis C serving as a rotation axis of the first gear60and the axis B serving as a rotation axis of the second gear34are parallel to each other.

By using the first gear60and the second gear34which are thus in upside down relation, on the second gear34to which power has been transmitted from the first gear60, a force to press the sliding surface30aof the holder30against the holder base20acts. Accordingly, in the sample holder105, not only the magnetic force from the magnet70, but also a force generated by the second gear34as a result of transmission of power from the first gear60allow the sliding surface30ato be brought into close contact with the holder base20.

The sample holder105can achieve the same functions/effects as those achieved by the sample holder100. In addition, in the sample holder105, the second gear34generates the force to press the sliding surface30aof the holder30against the holder base20with the power transmitted from the first gear60. Consequently, in the sample holder105, it is possible to bring the sliding surface30ainto closer contact with the holder base20and improve the efficiency of cooling of the holder30.

While the description has been given above of a case where the first gear60and the second gear34are the bevel gears, the first gear60and the second gear34are not particularly limited as long as the second gear34generates the force to press the sliding surface30aagainst the holder base20.

For example, the first gear60and the second gear34may also be helical gears having helical tooth traces with respect to rotation axes. This allows the second gear34to generate the force to press the sliding surface30aagainst the holder base20in the same manner as in a case where the first gear60and the second gear34are bevel gears. In addition, by using the helical gears as the first gear60and the second gear34, it is possible to allow the holder30to be detachable.

FIG.11is a cross-sectional view schematically illustrating a sample holder106according to a sixth modification. Hereinbelow, in the sample holder106, members having the same functions as those of the constituent members of the sample holder100described above are denoted by the same reference signs, and a detailed description thereof is omitted.

As illustrated inFIG.11, the sample holder106includes a heater38disposed on the holder30.

The first wall portion22and the second wall portion24are thermally connected to the base10thermally connected to the cooling source2, and are accordingly cooled by heat transfer. The sample S held herein by the sample holding portion32is disposed between the first wall portion22and the second wall portion24. Therefore, it is possible to allow the first wall portion22and the second wall portion24to function as a cooling trap that adsorbs molecules of hydrocarbon or the like serving as a contamination source for the sample S and reduces sample contamination.

The heater38is a heater for heating the sample S. The heater38is attached to the holder30. In the illustrated example, the heater38is disposed so as to come into contact with the sample holding portion32, but a position at which the heater38is to be attached is not particularly limited. The heater38, which is attached to the holder30, can raise a temperature of the sample S held by the sample holding portion32before raising temperatures of the first wall portion22and the second wall portion24. To the holder30, a thermometer for measuring the temperature of the sample S may also be attached, though not shown. This allows the temperature of the sample S to be known.

To the stage of the sample processing apparatus, a heater for heating the sample holder100is attached, though not shown.

In the sample holder106, when the sample S is processed by applying the ion beam to the sample S, while the sample S is cooled, the first wall portion22and the second wall portion24are allowed to function as the cooling trap. Accordingly, it is possible to reduce contamination of the sample S.

In the sample holder106, the heater38attached to the holder30is included, and can therefore independently heat the holder30. Thus, it is possible to prevent molecules adsorbed by the first wall portion22and the second wall portion24, each functioning as the cooling trap, to serve as the contamination source from adhering again to the sample S.

For example, in the sample holder106, the sample S can be processed by applying the ion beam to the sample S, while the first wall portion22and the second wall portion24are cooled to function as the cooling trap. After the processing is ended, when the sample S is to be returned to a room temperature, the sample S is heated first with the heater38attached to the holder30. Then, with the heater attached to the stage, the base10and the holder base20are heated. Thus, when the sample S is to be returned to the room temperature, the temperature of the sample S can constantly be set higher than the temperatures of the first wall portion22and the second wall portion24. As a result, it is possible to prevent the molecules adsorbed by the first wall portion22and the second wall portion24to serve as the contamination source from adhering again to the sample S.

In the sample holder100illustrated inFIG.3, the sliding surface30aof the holder30and the bottom surface27of the holder base20may also be coated with a lubricant. The lubricant may also be held between the sliding surface30aand the bottom surface27. As the lubricant, e.g., a conductive lubricant such as an ionic liquid can be used. This can reduce friction between the holder30and the holder base20and improve the efficiency of cooling of the holder30.

In the sample holder100illustrated inFIGS.1to4, the first gear60is rotated by the rotation of the motor50, and the power is transmitted from the first gear60to rotate the second gear34, but a first rotation transmission member rotated by the rotation of the motor50and a second rotation transmission member rotated by the power transmitted thereto from the first rotation transmission member are not limited to the first gear60and the second gear34.

It may also be possible to use pulleys as the first rotation transmission member connected to the motor50and the second rotation transmission member provided on the holder30and connect the first rotation transmission member and the second rotation transmission member with a belt. This can transmit the drive of the motor50to the holder30via the first rotation transmission member and the second rotation transmission member and rotate the holder30.

2. Second Embodiment

2.1. Configuration of Sample Holder

Next, referring to the drawings, a description will be given of a sample holder according to the second embodiment.FIGS.12and13are perspective views schematically illustrating a sample holder200according to the second embodiment.FIG.14is a cross-sectional view schematically illustrating the sample holder200according to the second embodiment. Hereinbelow, in the sample holder200according to the second embodiment, members having the same functions as those of the constituent members of the sample holder100according to the first embodiment are denoted by the same reference signs, and a detailed description thereof is omitted.

In the sample holder100described above, the rotating body rotatably supported on the holder base20is formed of the holder30. By contrast, in the sample holder200, as illustrated inFIGS.12to14, a rotating body202includes the holder30, a rotating base210, and a multi-layer foil220.

The sample holder200includes the rotating base210, the multi-layer foil220, and a bearing230. The holder30, the rotating base210, and the multi-layer foil220are included in the rotating body202rotated by the drive of the motor50.

The rotating base210is supported on the holder base20to be rotatable around the axis B serving as a rotation axis. The rotating base210is fixed into the hole28of the holder base20via the bearing230. Thus, the rotating base210is rotatably supported on the holder base20. The rotating base210rotates around the axis B serving as the rotation axis.

In the rotating base210, a hole211is formed around the axis B serving as a center axis. Into the hole211, the shaft portion36of the holder30is inserted. The holder30is in surface contact with the rotating base210. A surface35of the holder30surrounded by the plurality of teeth of the second gear34is in surface contact with an upper surface212of the rotating base210. To the rotating base210, the magnetic body80is fixed. To the holder30, the magnet70is fixed. Under an attraction force acting between the magnet70fixed to the holder30and the magnetic body80fixed to the rotating base210, the surface35of the holder30is in close contact with the upper surface212of the rotating base210.

The holder30is fixed to the rotating base210with the magnetic force generated by the magnet70, and accordingly the holder30is detachable from the rotating base210. The holder30and the rotating base210integrally rotate around the axis B serving as the rotation axis.

The multi-layer foil220is fixed to the rotating base210. The multi-layer foil220rotates together with the rotating base210. A surface of the multi-layer foil220has a circular shape around the axis B. The multi-layer foil220is, e.g., copper foils laminated in multiple layers. The multi-layer foil220is disposed between the rotating base210and the holder base20.

The surface of the multi-layer foil220serves as the sliding surface30a. In other words, the surface of the multi-layer foil220comes into slidable surface contact with the bottom surface27of the holder base20. Compared to, e.g., bulk metal, the multi-layer foil220is more susceptible to elastic deformation. Accordingly, by using the surface of the multi-layer foil220as the sliding surface30a, it is possible to rotate the rotating body202, while bringing the sliding surface30ainto close contact with the holder base20.

For example, when a surface of bulk metal with high rigidity is used as the sliding surface30a, a frictional resistance increases when a position of the rotating base210is close to the holder base20, and the rotating body202cannot rotate. Meanwhile, when the position of the rotating base210is away from the holder base20, the rotating body202cannot be brought into close contact with the holder base20, and the holder30cannot be cooled. When the surface of the bulk metal with the high rigidity is thus used as the sliding surface30a, it is difficult to rotate the rotating body202, while keeping the sliding surface30ain close contact with the holder base20. By contrast, by using the surface of the multi-layer foil220susceptible to elastic deformation as the sliding surface30a, it is possible to rotate the rotating body202, while keeping the sliding surface30ain close contact with the holder base20.

Note that the multi-layer foil220needs only to be disposed between the rotating base210and the holder base20. Accordingly, it may also be possible to fix the multi-layer foil220to the holder base20and use the bottom surface27of the holder base20as the surface of the multi-layer foil220.

While the description has been given herein of the case where the multi-layer foil220is used as a member to be used as the sliding surface30a, the member to be used as the sliding surface30ais not limited to the multi-layer foil220. The member to be used as the sliding surface30aneeds only to be an elastic body having a high heat conductivity and susceptible to elastic deformation, and may also be a flat stranded wire made of copper or the like.

In the sample holder200, when the rotating body202is fixed to the holder base20via the bearing230, a force with which the sliding surface30aof the rotating body202presses the holder base20can be adjusted depending on the position at which the rotating body202is to be fixed.

An operation of the sample holder200is the same as the operation of the sample holder100except that the rotating body202including the holder30, the rotating base210, and the multi-layer foil220is rotated by the drive of the motor50, and a description thereof is omitted.

In the sample holder200, the rotating body202includes the holder30that holds the sample S, the rotating base210that detachably holds the holder30and is rotatably supported on the holder base20, and the multi-layer foil220having the surface serving as the sliding surface30a. In addition, in the sample holder200, the rotating base210is rotatably supported on the holder base20via the bearing230. Consequently, in the sample holder200, it is possible to bring the sliding surface30aof the rotating body202into slidable surface contact with the holder base20, while rotatably supporting the rotating body202via the bearing230. Therefore, the sample holder200can achieve the same functions/effects as those achieved by the sample holder100.

3.1. Sample Processing Apparatus

Next, referring to the drawings, a description will be given of a sample processing apparatus according to the third embodiment.FIG.15is a diagram illustrating a configuration of a sample processing apparatus300according to the third embodiment.

The sample processing apparatus300can produce a sample for a scanning electron microscope by applying an ion beam IB to the sample S and processing the sample S. The sample processing apparatus300can process the sample S by planar surface milling in which the ion beam IB is obliquely applied to the surface Sa of the sample S.

The sample processing apparatus300includes the sample holder100illustrated inFIGS.1to4, a stage310, a liquid nitrogen tank320, an ion source330, a vacuum chamber340, and a camera350.

The sample holder100is attached to the stage310. In the example illustrated inFIG.15, an attachment surface312of the stage310to which the sample holder100is to be attached faces a horizontal direction. The sample holder100is attached to the attachment surface312such that the bottom portion16of the base10comes into surface contact with the attachment surface312. The sample holder100is attached to the attachment surface312of the stage310such that the axis A serving as the inclination axis illustrated inFIG.3is horizontal. To an intersection of the axis A with the axis B, the ion beam IB is applied.

The stage310is thermally connected via a heat transfer portion interposed between the stage310and the liquid nitrogen tank320in which liquid nitrogen serving as a refrigerant is pooled. Accordingly, it is possible to cool the stage310and cause the stage310to function as the cooling source2. In addition, to the stage310, a connection/disconnection mechanism for switching between connection and disconnection in the heat transfer portion connected to the liquid nitrogen tank and a heater for heating the stage310are attached, though not illustrated. As a result, in the sample processing apparatus300, a temperature of the stage310can be controlled to an intended temperature.

In the sample holder100, by using the axis A as the inclination axis, the holder base20can be inclined. Thus, by inclining the holder base20, it is possible to adjust the incidence angle of the ion beam IB with respect to the surface Sa of the sample S.

The ion source330applies the ion beam IB to the sample S. The ion source330is attached to an upper portion of the vacuum chamber340. For example, the ion source330is an ion gun that accelerates the ion beam IB with a predetermined acceleration voltage to emit the ion beam IB. For example, the ion source330ionizes argon gas to emit the argon ion beam IB.

In the vacuum chamber340, the sample holder100is contained. In the vacuum chamber340, to the sample S held on the sample holder100, the ion beam IB is applied. The vacuum chamber340is internally evacuated by using an exhaust device not shown.

The camera350is a camera for observing the sample S held on the sample holder100. The camera350allows a status of processing of the sample S to be checked.

3.2. Sample Processing Method

3.2.1. Planar Surface Milling

In the sample processing apparatus300, the surface Sa of the sample S can be processed by the planar surface milling. The planar surface milling is a technique of obliquely applying the ion beam IB to the surface Sa of the rotating sample S to process the surface Sa of the sample S. For example, in or to the surface Sa of the sample S subjected to preprocessing by mechanical polishing, a polishing flaw, crystal distortion, or the like occurs or a residue of an abrasive adheres, and accordingly it is difficult to obtain information on a state or unevenness of an outermost surface of the sample by using the scanning electronic microscope. By performing the planar surface milling as a final finish on the mechanically polished surface of the sample, it is possible to remove the polishing flaw, the residue of the abrasive, the crystal distortion, or the like in a wide range.

For example, when the ion beam IB is applied at a shallow angle of 10 degrees or less to the surface Sa of the sample S, a less uneven surface at which an etching rate difference due to a crystal orientation or a composition has been reduced can be obtained. This allows an image with an enhanced channeling contrast to be observed in the scanning electron microscope. Meanwhile, when the ion beam IB is applied at a deep angle of 30 degrees or more to the sample surface, an etching rate difference due to the crystal orientation or composition is produced, and therefore an image with enhanced unevenness can be observed in the scanning electron microscope.

3.2.2. Flow of Sample Processing

FIG.16is a flow chart illustrating an example of a sample processing method using the sample processing apparatus300including the sample holder100. Hereinbelow, referring toFIGS.1to4andFIG.15, a description will be given of a case where the planar surface milling is performed on the sample S.

First, the sample S is set in the sample holder100(S100). In the sample holder100, the holder30is detachable from the holder base20. Accordingly, it is possible to detach the holder30from the holder base20and fix the sample S to the holder30. Specifically, as illustrated inFIG.3, the sample S is fixed to the sample holding portion32such that the intersection of the axis A with the axis B is located at a center of the surface Sa of the sample S. After the sample S is fixed to the sample holding portion32, the holder30is attached to the holder base20.

Note that, in the sample holder100, the holder30is detachable, and accordingly it may also be possible to prepare a plurality of the holders30at different heights and use the holder30according to the height of the sample S.

Next, as illustrated inFIG.15, the sample holder100is attached to the stage310(S102). At this time, the position of the sample holder100with respect to an optical axis of the ion source330is adjusted such that the ion beam IB is applied to the intersection of the axis A with the axis B. In addition, the incidence angle of the ion beam IB with respect to the surface Sa of the sample S is adjusted. The adjustment of the incidence angle of the ion beam IB with respect to the surface Sa of the sample S is performed by inclining the holder base20by using the axis A as the inclination axis.

Next, the vacuum chamber340is internally evacuated to bring the inside of the vacuum chamber340into a vacuum state (depressurized state) (S104).

Next, cooling of the sample S is started (S106). By supplying the liquid nitrogen to the liquid nitrogen tank320, the stage310can be cooled. By the cooling of the stage310, the base10thermally connected to the stage310and the holder base20thermally connected to the base10are cooled. In addition, since the holder base20and the holder30are in surface contact with each other, the holder30is also cooled. Thus, the sample S can be cooled. It may also be possible to operate the heater attached to the stage310and thereby control the temperature of the sample S.

Next, the sample S is processed with the ion beam IB (S108). By operating the motor50, the holder30is continuously rotated in the given direction around the axis B serving as the rotation axis via the first gear60and the second gear34. As a result of the rotation of the holder30, the sliding surface30aof the holder30slides, while being kept in surface contact with the bottom surface27of the holder base20. In addition, by the magnetic force generated by the magnet70, the sliding surface30ais pressed against the bottom surface27. Accordingly, even when the holder30is rotated, the holder30can efficiently be cooled. Furthermore, due to the magnetic force generated by the magnet70, the sliding surface30ais pressed against the bottom surface27with a predetermined force, and consequently fluctuations in contact thermal resistance can be reduced to allow the temperature of the sample S to be held constant.

In a state where the sample S is rotated, the ion source330is caused to emit the ion beam IB, and the ion beam IB is applied to the surface Sa of the sample S. Thus, it is possible to apply the ion beam IB to the sample S and process the surface Sa of the sample S, while rotating and cooling the sample S. By the foregoing steps, the planar surface milling can be performed on the sample S.

After the processing of the sample S is ended, the stage310is heated with the heater attached to the stage310to return the sample holder100to a room temperature. As a result, it is possible to retrieve the sample holder100from within the vacuum chamber340.

Note that, while the description has been given above of a case where the sample S is processed by the planar surface milling using the sample processing apparatus300, the sample S can also be processed using the sample processing apparatus300and a technique other than the planar surface milling.

The sample processing apparatus300includes the sample holder100, and therefore it is possible to produce an excellently smooth surface by the planar surface milling even when the sample S is a polymer or low-melting-point metal sample or the like sensitive to heat.

3.4.1. First Modification

In the third embodiment described above, the description has been given of the case where the sample processing apparatus300includes the sample holder100, but the sample processing apparatus300may also include, e.g., a sample holder106illustrated inFIG.11. This allows the first wall portion22and the second wall portion24to be used as a cooling trap in Step S108of processing the sample S with the ion beam IB. In addition, when the sample holder100is to be retrieved from the vacuum chamber340, after the temperature of the holder30is increased with the heater38, the holder base20can be heated with the heater attached to the stage310. This can prevent molecules adsorbed by the first wall portion22and the second wall portion24to serve as a contamination source from adhering again to the sample S.

Note that the sample processing apparatus300may also include the other sample holders101,102,103,104,105, and200described above.

3.4.2. Second Modification

In the third embodiment described above, the description has been given of the case where the sample processing apparatus300includes the ion source330that applies the ion beam IB to the sample S, but the sample processing apparatus300may also include a charged particle beam source that applies a charged particle beam other than the ion beam IB, such as an electron beam, to the sample S.

Note that the embodiments and modifications described above are examples, and are not limited thereto. For example, the individual embodiments and the individual modifications can appropriately be combined with each other.

The invention is not limited to the above-described embodiments, and various modifications can be made. For example, the invention includes configurations that are substantially the same as the configurations described in the embodiments. Substantially same configurations mean configurations having the same functions, methods and results, or configurations having the same objectives and effects as those of the configurations described in the embodiments, for example. The invention also includes configurations obtained by replacing non-essential elements of the configurations described in the embodiments with other elements. The invention also includes configurations having the same effects as those of the configurations described in the embodiments, or configurations capable of achieving the same objectives as those of the configurations described in the embodiments. The invention further includes configurations obtained by adding known art to the configurations described in the embodiments.