JP5657435B2 - Thin film sample preparation method - Google Patents

Description

  The present invention relates to a thin film sample preparation method for preparing a thin film sample observed with a transmission electron microscope or the like.

  As a method for preparing a thin film sample to be observed with a transmission electron microscope or the like, a shielding material is disposed on the sample, and the shielding material and the sample are irradiated with an ion beam from above the shielding material, and are not shielded by the shielding material. There is a method of forming a thin film sample that can transmit an electron beam by ion milling the sample portion.

  1 and 2 show an example of a thin film sample preparation apparatus for carrying out such a thin film sample preparation method. FIG. 1 shows an overall configuration of the thin film sample preparation apparatus, and FIG. The structure inside the vacuum chamber of a thin film sample preparation apparatus is shown. FIG. 1 is a YZ plane sectional view of FIG.

  In FIG. 1, reference numeral 1 denotes a vacuum chamber, and the inside of the vacuum chamber is evacuated by an exhaust device 2.

  In the figure, reference numeral 3 denotes a stage, which is attached to the stage tilting mechanism 4. The stage tilting mechanism is attached to the vacuum chamber 1 and tilts the stage 3 left and right around the Y axis. The stage has an ion beam passage opening 3a.

  A sample stage 5 is placed on the sample stage 3, and as shown in FIG. 2, a notch (ion beam passage part) 5a is formed in the sample stage. Guide pins 6a and 6b are fixed to the upper surface 5b of the sample stage so as to face each other with the notch 5a interposed therebetween.

  Furthermore, four pulleys 7a, 7b, 7c, and 7d are attached to the upper surface 5b of the sample table. Among these pulleys, the pulleys 7a to 7c are fixed to the upper surface 5b of the sample table 5, and the remaining pulley 7d is attached to the sample table so as to be pulled in the direction of arrow P by a spring (not shown). It is attached.

  A belt-shaped and ring-shaped ion beam shielding belt 8 is hooked on the pulleys 7a to 7d and the guide pins 6a and 6b. In this case, since the pulley 7d is pulled by the spring in the direction of arrow P as described above, the shielding belt 8 hooked on the pulley 7d is pulled without any slack over the entire circumference.

  The pulley 7d is configured to rotate about the axis Q by the rotation of the motor 9 incorporated in the sample table 5, and the shielding belt hooked on the pulley by the rotation of the pulley. 8 is configured to move. The shielding belt 8 is made of a material that is difficult to be milled by an ion beam (for example, an amorphous metal such as nickel-phosphorus).

  In FIG. 2, reference numeral 10 denotes a sample holder for holding the sample material 11, and is set in the notch 5 a portion of the sample table 5. The sample material 11 has a rectangular parallelepiped shape cut out from a bulk sample and roughly polished (for example, as shown in the lower part of FIG. 2, the vertical dimension d1 is 700 μm and the horizontal dimension d2 is 2. 5 mm and thickness d3 is 100 μm) and is attached to the sample holder 10 with an adhesive.

  Thus, by setting the sample holder 10 holding the sample material 11 and the shielding belt 8 on the sample table 5, the shielding belt guided by the guide pins 6a and 6b is perpendicular to the sample material 11. It will be placed upright. As shown in FIG. 1, the shielding belt is located on the Z axis, and the right side surface 8a and the left side surface 8b of the shielding belt are parallel to the Z axis.

  Further, in the state shown in FIG. 1, that is, in a state where the inclination of the stage is zero, the longitudinal direction of the shielding belt 8 stretched on the sample material 11 coincides with the X-axis direction.

  On the other hand, in the state shown in FIG. 1, the upper surface 11a of the sample material 11 is positioned perpendicular to the Z axis and on the Y axis.

  The gap between the upper surface 11a of the sample material 11 and the shielding belt 8 is extremely small (for example, about 10 to 30 μm). As shown in the lower part of FIG. 1, the ion beam non-irradiation surface 11b and the ion beam irradiation surfaces 11c and 11d are formed on the left and right sides thereof. The ion beam non-irradiated surface is a sample surface covered with the shielding belt 8 and is a surface not irradiated with an ion beam from an ion gun 12 described below.

  As shown in FIG. 1, the ion gun is held by an ion gun tilting mechanism 13 attached to the upper part of the vacuum chamber 1. The ion gun tilting mechanism tilts the ion gun 12 left and right around the X axis, that is, tilts the ion gun in the −Y direction and the Y direction with respect to the Z axis.

  In FIG. 1, reference numeral 14 denotes a central controller, which includes an ion gun control circuit 14a, an ion gun tilt control circuit 14b, a stage tilt control circuit 14c, and an ion milling end determination circuit 14d. In addition, the central control unit is electrically connected to the power source 15 of the ion gun 12, the driving source 16 of the ion gun tilting mechanism 13, the driving source 17 of the stage tilting mechanism 4, and the input means 18 including a keyboard and a mouse. Connected.

  Further, in FIG. 1, reference numeral 19 denotes a CCD camera for observing the etching cross section of the sample material 11 from the −Y direction, which is attached to the vacuum chamber 1 and the video signal from the camera is the ion signal. This is input to the milling end determination circuit 14d.

  With the thin film sample preparation apparatus having such a configuration, the thin film sample preparation is performed as follows.

  First, when an operator instructs the start of ion milling with the input means 18, the ion gun tilt control circuit 14b of the central controller 14 turns the ion gun 12 to the left (−Y direction) by an angle θ1 (for example, 1.5 degrees). ) A tilt signal for tilting is sent to the tilt drive source 16. The tilt driving source tilts the ion gun tilting mechanism 13 based on the tilt signal. As a result, the ion gun 12 is inclined to the left by the angle θ1 with respect to the Z axis.

  At the same time, the stage tilt control circuit 14c provides a tilt signal θs for repeatedly tilting the stage 3 around the Y axis (for example, one reciprocal tilt of ± 30 degrees and one reciprocating tilt 30 seconds). It is sent to the tilt drive source 17. The tilt drive source tilts the stage tilt mechanism 4 based on the tilt signal. As a result, as shown in FIG. 3, the sample material 11 is reciprocally inclined at a constant speed as indicated by an arrow R together with the shielding belt 8.

  At this time, the ion gun control circuit 14 a sends a signal for emitting the ion beam IB from the ion gun 12 to the ion gun power supply 15. Then, since the power source applies a predetermined voltage for emitting an ion beam between the electrodes of the ion gun 12, as shown in FIG. 4A, the power source is inclined to the left by an angle θ1. An ion beam IB is emitted from the ion gun 12.

  As shown in FIG. 4A, the ion beam is applied to the shielding belt and the sample material 11 from obliquely above and to the left of the shielding belt 8. Since the ion beam irradiation is performed for a predetermined time (for example, 5 minutes), the sample material 11 is ion milled while being tilted about the Y axis. FIG. 4B shows the sample material 11 after a predetermined time from the start of ion milling. The ion beam irradiated surfaces 11c and 11d irradiated with the ion beam are milled and covered with the shielding belt 8 to be covered with the ion beam. The non-irradiated ion beam non-irradiated surface 11b remains without being milled. Since the sample material 11 is irradiated with the ion beam obliquely from the upper left side of the shielding belt 8, the ion beam irradiation surface 11c side is milled more than the ion beam irradiation surface 11d. The ion beam irradiation surface 11c side is deeply milled inward (Z-axis side) from the ion beam irradiation surface 11d.

  Next, the ion gun tilt control circuit 14 b sends a tilt signal for tilting the ion gun 12 to the right (Y direction) by an angle θ 1 to the tilt drive source 16. The tilt driving source tilts the ion gun tilting mechanism 13 based on the tilt signal. As a result, the ion gun 12 is inclined to the right by the angle θ1 with respect to the Z axis.

  Due to the inclination of the ion gun, as shown in FIG. 5A, an ion beam IB inclined to the right by θ1 with respect to the Z axis irradiates the shielding belt 8 and the sample material 11. The ion beam irradiation is performed for a predetermined time (for example, 5 minutes), and the sample material 11 is ion milled while being tilted together with the shielding belt 8 as described above. FIG. 5B shows the sample material 11 after a predetermined time from the start of ion milling with the ion gun 12 tilted to the right. This time, the ion beam irradiation surface 11d side is the ion beam irradiation surface. The ion beam non-irradiated surface 11b that has been milled more than 11c and is not irradiated with the ion beam covered with the shielding belt 8 remains without being milled.

  Thereafter, the ion gun 12 is repeatedly tilted to the left and right in the same manner as described above, and the sample material 11 is milled by ion beams tilted by θ1 to the left and right with respect to the Z axis.

  FIG. 6 is a view showing the sample material 11 that is ion-milled. After (b) in FIG. 5, the sample material is milled as shown in FIG. After a), the sample material is milled as shown in FIG. Thereafter, the ion gun 12 is tilted to the left and right several times to perform ion milling of the sample material 11, and the sample material is milled as shown in FIG.

  As shown in FIGS. 6A to 6C, the non-irradiated surface 11b of the sample material 11 remains without being milled, but around the non-irradiated surface of the ion beam. The sample material portion is gradually milled, and as shown in FIG. 6C, the portion A becomes thinner from the non-irradiated surface 11b toward the lower side (−Z direction).

  FIG. 6D shows a state in which the direction of the ion gun 12 is changed and further the ion beam irradiation is performed on the sample material 11 after FIG. 6C. The ion milling of the A portion of the sample material 11 shown in (c) of FIG. 6 proceeds, and a through hole H is opened in the sample material. The position of the through hole H is a distance HL (for example, about 300 μm) from the upper surface of the sample material 11. The opening position of the through-hole H is closely related to the inclination angle of the ion gun 12, and the through-hole is opened depending on from which direction the ion beam is applied to the shielding belt 8 and the sample material 11. The position changes.

  FIG. 6E is a view of the sample material 11 of FIG. 6D viewed from the −Y direction (from the CCD camera 19 side).

  The CCD camera 23 has photographed the sample material 11 from the front from the start of ion milling, and the image signal is sent to the ion milling end determination circuit 14d.

  The ion milling end judging circuit constantly monitors the shape change of the sample material 11 based on the image signal, and the through hole H is opened in the sample material as shown in FIG. 6 (d). Is detected, a milling end signal is sent to the ion gun control circuit 14a.

  Then, the ion gun control circuit sends a signal for stopping the ion irradiation to the power source 15, so that the ion beam emission from the ion gun 12 is stopped.

  At the same time, the ion milling end signal from the ion milling end determination circuit 14d is also sent to the ion gun tilt control circuit 14b and the stage tilt control circuit 14c, whereby these control circuits send tilt stop signals to the respective drive sources 16. , 17, the tilt of the ion gun 12 and the tilt of the stage 3 are stopped.

  As described above, the thin film sample shown in FIGS. 6D and 6E is completed. The A portion of the completed sample is thinner as it goes downward from the non-irradiated surface 11b, and the peripheral portion K of the through hole H is a thin film of about 100 mm suitable for transmission electron microscope observation.

Japanese Patent No. 4486462

  However, the thin film portion of about 100 mm suitable for the transmission electron microscope observation, that is, the peripheral portion K of the through hole H is a very small region.

  Therefore, when such a sample is used as a sample for a transmission electron microscope, the observation field of view is limited to the very peripheral portion of the through-hole H, and not only the use efficiency for sample observation is remarkably low. Cannot observe and analyze himself sufficiently.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a novel thin film sample preparation method capable of preparing a thin film sample having a wider observable region as a sample such as a transmission electron microscope.

  In the thin film sample preparation method of the present invention, an ion beam non-irradiated surface on a sample material and a shielding material for forming an ion beam irradiated surface around the sample material are disposed on the sample material, and the shielding is performed from above the shielding material. A sample preparation method in which an ion beam is irradiated to a material and the sample material, and the ion beam non-irradiated surface is left without being ion milled, and the surrounding ion beam irradiated surface is ion milled. The ion beam irradiation direction is set so that the sample becomes thinner as it goes downward from the non-irradiated surface, and finally a through hole is formed, and ions are applied from different directions toward the shielding material and the sample material. While irradiating the beam, the sample material is tilted around an axis orthogonal to the plane of the thin film to be produced or an axis parallel to the axis. In the thin film sample preparation method, when the sample material is irradiated, the ion beam irradiation to the sample material is stopped when a through-hole is opened in the sample material portion below the non-irradiated surface of the ion beam. In the inclination, the sample material is temporarily stopped at at least one inclination angle.

  In the thin film sample preparation method of the present invention, a shielding material for forming an ion beam non-irradiated surface on the sample material and an ion beam irradiated surface around the sample material is disposed on the sample material, and from above the shielding material. A sample preparation method in which the shielding material and the sample material are irradiated with an ion beam, the ion beam non-irradiated surface is left without being ion milled, and the surrounding ion beam irradiated surface is ion milled. Different directions toward the shielding material and the sample material by setting the irradiation direction of the ion beam so that the sample becomes thinner from the non-irradiated surface of the ion beam and finally a sample having a through hole is formed. The sample material is tilted at a predetermined speed around an axis orthogonal to the surface of the thin film to be produced or an axis parallel to the axis. In the thin film sample preparation method, the sample material is irradiated with an ion beam, and the ion beam irradiation to the sample material is stopped when a through hole is opened in the sample material portion below the non-irradiated surface of the ion beam. In the inclination of the sample material, the sample material is inclined at an extremely low speed in a slight inclination angle range of at least one of the inclination angles changing at the predetermined speed.

  According to the present invention, a thin film sample in which a thin film portion suitable for observation with a transmission electron microscope or the like is widely formed can be produced.

The whole structure of a thin film sample preparation apparatus is shown. 2 shows an example of a structure in a vacuum chamber of the thin film sample manufacturing apparatus shown in FIG. The state of repeated reciprocating inclination of the sample material is shown. The shielding belt, the ion beam irradiation state on the sample material, and the milling state of the sample material when the ion gun is tilted to the left with respect to the Z axis are shown. The ion belt irradiation state and the sample material milling state when the ion gun is tilted to the right with respect to the Z axis are shown. A state in which the sample material is ion milled is shown. The ion beam irradiation area | region to the sample material in the typical inclination angle of a sample material is shown. The locus of the ion beam irradiation area QA on the sample material is shown. The ion beam irradiation area to the sample material when the sample material is inclined at the maximum angle is shown. The locus | trajectory of ion beam irradiation area | region QA, QA 'and QA' 'to the sample raw material in the thin film sample preparation method of this invention is shown.

  Prior to the description of the embodiments of the present invention, the principle of the present invention will be described.

  First, the present inventor considered the cause of the problems of the conventional thin film manufacturing method.

  In the conventional thin film manufacturing method, the stage 3 is repeatedly reciprocated around the Y axis. That is, as shown in FIG. 3, the sample material 11 is repeatedly reciprocated and inclined as shown by the arrow R together with the shielding belt 8. When the ion beam irradiation area to the sample material 11 at each inclination angle in this reciprocating inclination is searched, it can be considered as follows.

  FIGS. 7A to 7E show ion beam irradiation regions on the sample material 11 at typical inclination angles. FIG. 7A shows the case of FIG. 7C shows the maximum tilt angle in the clockwise direction, FIG. 7E shows the maximum tilt angle in the counterclockwise direction, and FIG. 7B shows the maximum tilt angle of 0 degrees clockwise. (D) of FIG. 7 shows the case where the tilt angle is between 0 degrees and the maximum angle in the counterclockwise direction.

  In FIGS. 7A to 7E, a band-like region QA is an ion beam irradiation region around HL from the upper surface of the sample material 11, and QB is an ion beam irradiation region above and below the ion beam irradiation region QA. The former region QA has a higher ion milling rate than the latter region QB.

FIG. 8 depicts a trajectory of the former ion beam irradiation area QA on the sample material 11. The central portion CR of the trajectory is always irradiated with an ion beam, and the through-hole K opens in this portion. The very peripheral portion of the through-hole is extremely thin (a thin film of about 50 nm suitable for observation with a transmission electron microscope or the like), and the other locus regions are not milled to a thickness suitable for observation with a transmission electron microscope or the like. .
Therefore, the present inventors produce a thin film region suitable for observation with a transmission electron microscope or the like not only in the very periphery of the through hole K but also in the locus portion of the ion beam irradiation region QA having a relatively high ion milling rate. If the stage is temporarily stopped at a certain tilt angle in the reciprocating tilt of the stage, the ion beam irradiation region QA having a relatively high ion milling rate at the tilt angle is searched. The ion milling rate was significantly increased, and this region was considered to be a thin film region suitable for observation with a transmission electron microscope or the like. Note that when the beam is temporarily stopped at many tilt angles, the ion milling rate of the central portion CR, which is constantly irradiated with the ion beam, becomes extremely large in a short time, and the ion beam irradiation region QA at the pause angle of tilt becomes a transmission electron microscope or the like. Since the through hole K is opened in the central portion CR before it becomes a thin film suitable for the observation, it seems to be better to pause at one to several places. Alternatively, instead of temporarily stopping, if the sample stage is tilted at an extremely low speed within a narrow tilt angle range where the tilt angle is changing at a constant speed, the relatively ion milling in the tilt angle range is performed. It is considered that the ion milling rate of the ion beam irradiation area QA having a high rate is remarkably increased.
The present invention has been made based on such an idea, and an embodiment of the thin film sample preparation method of the present invention will be described below with reference to the drawings.
The thin film sample preparation apparatus for carrying out the thin film sample preparation method of the present invention has almost the same configuration as that shown in FIGS. The different components are the central controller 14 ', a stage tilt control circuit 14c' that receives commands from the central controller, and a tilt drive source 17 'that operates with a tilt signal from the stage tilt control circuit. That is, the central control unit 14 'sends the stage tilt control circuit 14c' a command to repeatedly reciprocate the stage 3 while temporarily stopping the stage 3 at each positive and negative maximum tilt angle for a predetermined time. Is configured to send a tilt signal to the tilt drive source 17 'to repeatedly tilt back and forth while temporarily suspending the stage 3 at a positive and negative maximum tilt angle.

  With the thin film sample preparation apparatus having such a configuration, the thin film sample preparation is performed as follows.

  First, when an operator instructs to start ion milling with the input means 18, the ion gun tilt control circuit 14b of the central control device 14 'tilts the ion gun 12 to tilt to the left (-Y direction) by an angle θ1. A signal is sent to the tilt drive source 16. The tilt driving source tilts the ion gun tilting mechanism 13 based on the tilt signal. As a result, the ion gun 12 is inclined to the left by the angle θ1 with respect to the Z axis.

  At the same time, the central controller 14 'sends a command to the stage inclination control circuit 14c' to repeatedly reciprocate around the Y axis while temporarily suspending the stage 3 at each positive and negative maximum inclination angle for a predetermined time. The control circuit sends to the tilt drive source 17 'a tilt signal for repeatedly tilting the stage tilt mechanism 4 reciprocatingly about the Y axis while pausing the stage tilt mechanism 4 at positive and negative maximum tilt angles for a predetermined time. Therefore, the tilt drive source tilts the stage tilt mechanism 4 based on the tilt signal. As a result, the sample material 11 is repeatedly reciprocated and tilted around the Y axis together with the shielding belt 8 while temporarily stopping for a predetermined time at each positive and negative maximum inclination angle.

  At this time, the ion gun control circuit 14 a sends a signal for emitting the ion beam IB from the ion gun 12 to the ion gun power supply 15. Then, since the power supply applies a predetermined voltage for emitting an ion beam between the electrodes of the ion gun 12, the ion beam IB is emitted from the ion gun 12 inclined at an angle θ1 to the left with respect to the Z axis. The

  Since the ion beam is applied to the shielding belt and the sample material 11 from the upper left of the shielding belt 8, the sample material 11 is ion milled while being tilted about the Y axis.

  At this time, the specimen material 11 is temporarily stopped for a predetermined time when it is tilted by the maximum angle in the clockwise direction and when tilted by the maximum angle in the counterclockwise direction. 9A shows the ion beam irradiation region when the sample material 11 is temporarily stopped at the maximum inclination angle in the clockwise direction, and FIG. 9B shows the maximum inclination of the sample material 11 in the counterclockwise direction. The ion beam irradiation area when temporarily stopped at an angle is shown. At any time, the ion beam irradiation areas QA ′ and QA ″ around the HL from the upper surface of the sample material 11 are at other tilt angles. The ion milling rate is considerably higher than that of the ion beam irradiation area QA at the same position. Accordingly, as shown in FIG. 10 showing the locus of the ion beam irradiation region around HL from the upper surface of the sample material 11, the ion beam is not as much as the central portion CR of the locus where the ion beam is constantly irradiated. The trajectory portions (solid line portions) corresponding to the beam irradiation areas QA ′ and QA ″ have a considerably higher ion milling rate than the other trajectory portions.

  Next, the ion gun tilt control circuit 14 b sends a tilt signal for tilting the ion gun 12 to the right (Y direction) by an angle θ 1 to the tilt drive source 16. The tilt driving source tilts the ion gun tilting mechanism 13 based on the tilt signal. As a result, the ion gun 12 is inclined to the right by the angle θ1 with respect to the Z axis.

  Due to the inclination of the ion gun, the shielding belt 8 and the sample material 11 are irradiated by the ion beam IB inclined to the right by θ1 with respect to the Z axis. In the ion beam irradiation, the sample material 11 is ion milled while being tilted together with the shielding belt 8 as described above.

  At this time, similarly to the above, when the sample material 11 is tilted at the maximum angle in the clockwise direction and when it is tilted at the maximum angle in the counterclockwise direction, the sample material 11 is temporarily stopped for a predetermined time. The ion beam irradiation areas QA ′ and QA ″ around HL from the upper surface of each sample material 11 when the sample material 11 is temporarily stopped at the tilt angle and when the sample material 11 is stopped at the maximum tilt angle counterclockwise are other tilts. The ion milling rate is considerably higher than that of the same ion beam irradiation area QA at the angle.

  Thereafter, the ion gun 12 is repeatedly tilted to the left and right in the same manner as described above, and the sample material 11 is milled by ion beams tilted by θ1 to the left and right with respect to the Z axis.

  In such an ion milling process, when an image signal indicating that the through hole H is opened in the sample material 11 is sent from the CCD camera 23 to the ion milling end determination circuit 14d, the ion milling end determination circuit Based on the image signal, an ion milling end signal for the sample material 11 is sent to the ion gun control circuit 14a.

  Then, the ion gun control circuit sends a signal for stopping the ion irradiation to the power source 15, so that the ion beam emission from the ion gun 12 is stopped.

  At the same time, the ion milling end signal from the ion milling end determination circuit 14d is also sent to the ion gun tilt control circuit 14b and the stage tilt control circuit 14c ', so that these control circuits send tilt stop signals to the respective drive sources. 16 and 17 ', the inclination of the ion gun 12 and the inclination of the stage 3 are stopped.

  A thin film sample is completed as described above. The completed sample is not only the very peripheral portion of the through-hole H, but also an ion beam irradiation region when the sample material is tilted to the maximum in the clockwise direction and an ion beam irradiation region when the sample material is tilted to the maximum in the counterclockwise direction. It is a thin film of about 50 nm suitable for observation with a transmission electron microscope.

  In the previous example, the sample material is paused when the sample material is tilted maximum clockwise and when it is tilted maximum counterclockwise. However, the sample material is temporarily stopped at one or more other tilt angles. May be. However, the ion beam irradiation region in the sample material in which the ion milling rate is increased in addition to the through hole changes depending on the angle at which the beam is temporarily stopped.

  Also, instead of pausing the sample material at a certain tilt angle, the sample material is tilted at a very low speed in one or more slight tilt angle ranges of the tilt angle changing at a predetermined speed. You may make it raise the etching rate of the ion beam irradiation area | region around HL from the upper surface of a sample raw material in the inclination angle range.

  1: Vacuum chamber, 2: Exhaust device, 3: Stage, 4: Stage tilt mechanism, 5: Sample stage, 5a: Notch, 6a, 6b: Guide pin, 7a, 7b, 7c, 7d: Pulley, 8: Shielding Belt: 9: Motor, 10: Sample holder, 11: Sample material, 12: Ion gun, 13: Ion gun tilt mechanism, 14: Central controller, 14a: Ion gun control circuit, 14b: Ion gun tilt control circuit, 14c : Stage tilt control circuit, 14d: Ion milling completion determination circuit, 15: Power source, 16: Drive source, 17: Drive source, 18: Input means, 19: CCD camera

Claims (5)

A shielding material for forming an ion beam non-irradiation surface on the sample material and an ion beam irradiation surface around the surface is disposed on the sample material, and an ion beam is applied to the shielding material and the sample material from above the shielding material. Irradiating and leaving the ion beam non-irradiated surface without ion milling, and a sample preparation method in which the surrounding ion beam irradiated surface is ion milled, as it goes downward from the ion beam non-irradiated surface The ion beam irradiation direction is set so that the sample is thinned and finally the through hole is opened, and the ion beam is irradiated from different directions toward the shielding material and the sample material. The sample material is irradiated with an ion beam while the sample material is tilted about an axis orthogonal to the surface of the thin film to be produced or an axis parallel to the axis. In the thin film sample manufacturing method in which the ion beam irradiation to the sample material is stopped when a through hole is opened in the sample material portion below the non-ion beam irradiation surface, at least one inclination of the sample material is inclined. A method for preparing a thin film sample, characterized in that the sample material is temporarily stopped at a corner. A shielding material for forming an ion beam non-irradiation surface on the sample material and an ion beam irradiation surface around the surface is disposed on the sample material, and an ion beam is applied to the shielding material and the sample material from above the shielding material. Irradiating and leaving the ion beam non-irradiated surface without ion milling, and a sample preparation method in which the surrounding ion beam irradiated surface is ion milled, as it goes downward from the ion beam non-irradiated surface The ion beam irradiation direction is set so that the sample is thinned and finally the through hole is opened, and the ion beam is irradiated from different directions toward the shielding material and the sample material. An ion beam is applied to the sample material while tilting the sample material at a predetermined speed about an axis orthogonal to the surface of the thin film to be produced or an axis parallel to the axis. In the thin film sample preparation method, the ion beam irradiation to the sample material is stopped when a through hole is opened in the sample material portion below the non-ion beam irradiation surface. A thin film sample preparation method characterized in that the sample material is inclined at an extremely low speed in a slight inclination angle range of at least one of the inclination angles changing at the above-mentioned speed. 3. The method for preparing a thin film sample according to claim 1, wherein the shielding material is formed in a belt shape. 3. The thin film sample manufacturing method according to claim 1, wherein the sample material and the shielding material are inclined together. 2. The thin film sample manufacturing method according to claim 1, wherein the sample material is temporarily stopped at two maximum inclination angles in the inclination of the sample material.

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