JP4675860B2 - Ion milling apparatus and method - Google Patents

Description

  The present invention relates to a novel ion milling apparatus and method for producing a sample observed with a scanning microscope (SEM), a transmission microscope (TEM), or the like.

  An ion milling device is a device for polishing the surface or cross section of metal, glass, ceramic, etc. by irradiating an argon ion beam, etc., and a pretreatment device for observing the surface or cross section of a sample with an electron microscope It is suitable as.

  In the cross-sectional observation of a sample with an electron microscope, conventionally, the vicinity of the part to be observed is cut using, for example, a diamond cutter, a thread saw, etc. I was observing.

  In the case of mechanical polishing, for example, a soft sample such as a polymer material or aluminum has a problem that the observation surface is crushed or deep scratches remain due to abrasive particles. In addition, for example, a hard sample such as glass or ceramic is difficult to polish, and a composite material in which a soft material and a hard material are laminated has a problem that cross-sectional processing is extremely difficult.

  On the other hand, ion milling can process a soft sample without damaging the surface, and can polish a hard sample and a composite material. A mirror-shaped cross section can be easily obtained.

  In Patent Document 1, when mounting and fixing a sample in an ion milling apparatus for processing a transmission electron microscope (TEM) sample, a sample holder for fixing the sample without using an adhesive, and a holder for fixing the holder It is described with respect to the fixture.

  Patent Document 2 discloses an ion beam irradiation means for irradiating a sample disposed in a vacuum chamber with an ion beam, a tilt stage disposed in the vacuum chamber and having a tilt axis in a direction substantially perpendicular to the ion beam, A sample holder disposed on the tilt stage and holding a sample, and a shielding material that is positioned on the tilt stage and blocks a part of the ion beam that irradiates the sample, while changing the tilt angle of the tilt stage, A sample preparation apparatus is shown in which an optical microscope for adjusting the position of a sample is attached to the upper end of a sample stage drawing mechanism so that the sample can be processed with a beam.

JP-A-9-293475 JP 2005-91094 A

  In the case of a conventional ion milling device, in order to match the sample holder and the sample stage, create a sample with the mask surface of the sample and the back surface to be pressed parallel to each other, and accurately align the center of the ion beam with the part you want to mirror-polish the sample. Is required. In addition, it is necessary to expose only the part of the sample to be mirror polished and to shield the other part with a mask. In an ion milling apparatus, the sample is usually fixed after being processed according to the mounting shape of the sample holder and the sample stage, and the sample holder is fixed to the sample holder fixture.

  It was not easy to accurately align the position of the mask with the processing surface of the sample on the sample holder fixture installed in the vacuum chamber. For this reason, as a result, it is not easy to accurately position the portion of the sample to be mirror polished and the center of the ion beam. Conventionally, when fixing a sample to the sample holder, the sample is sandwiched from both sides of the processing surface and brought into contact with the mask, so that it is not easy to process the sample according to the sample holder. Further, when the sample was not in close contact with the mask, in other words, when there was a gap between the sample and the mask, the target cross section was not obtained as the cross section to be observed.

  In any of the patent documents, the samples to be observed all have parallel surfaces, and the processing of the samples when they have non-parallel surfaces is not shown.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ion milling apparatus using a sample holder unit and a method thereof that can easily perform sample preparation without the need for parallel processing when the mask surface side of the sample and the mounting surface are non-parallel. Is to provide.

The present invention provides an ion milling apparatus that performs milling by irradiating an ion beam and fixing a flat sample to a sample holder unit in a vacuum chamber, and the sample holder unit has a structure to be described later. It has a fixing structure that can be fixed along the inclination on the back surface side with respect to the plane that is in contact with the mask that shields from the beam. That is, an adjustment mechanism is provided so that the upper surface of the sample and the lower surface of the mask can be brought into close contact with each other even if the fixing surface of the sample is not parallel.

The sample holder unit of the present invention includes a main body portion, and the mask provided to be moved to the side one of the main body portion, and a sample holder for mounting the sample was provided through the said sample holder A ball plunger that can be inserted into the female screw and can adjust the protruding length along the inclination ; a rotating ring that is provided on the main body and is rotatably installed on the plane ; and on one side of the rotating ring A feed screw that is provided and presses the sample holder against the other side of the rotating ring, and a sample holder that is provided on the sample holder side of the feed screw and that fixes the sample holder in the rotating ring by pressing by the feed screw. that having a fixed bracket.

  The ion milling device according to the present invention is attached to the vacuum chamber and irradiates the ion beam with an ion beam source, an ion source control unit for controlling the current density of the ion beam, and vacuum exhaust for evacuating the vacuum chamber. System, an evacuation system controller for controlling the evacuation system, an opening provided on a side surface of the vacuum chamber, a flange for closing the opening, the sample holder, and an optical axis of the ion beam A sample holder unit moving mechanism that can be manually moved in the X and Y directions, and a sample movement that can be reciprocally rotated and tilted around the center of the sample holder unit moving mechanism, mounted on the flange and mounted on the sample holder unit moving mechanism. It has a base, and a sample movement control unit for controlling a rotation direction and an angle for reciprocating and tilting the sample.

The present invention is also directed to an ion milling method in which a sample having a flat surface is fixed to a sample holder unit in a vacuum chamber and is irradiated with an ion beam to mill the sample. The sample holder unit includes the sample holder unit described above. becomes, the surface in contact with the mask to shield from the ion beam of the sample and the plane, mounting the plane with contact with the mask, to the sample holder along the inclination of the rear surface side of the sample to the plane And fixed.

In the ion milling method of the present invention, the sample can be rotated around the axis about the irradiation direction of the ion beam irradiation by the above-described ion milling apparatus, and parallel to the processing surface of the sample by the ion beam irradiation. It is characterized in that it can be reciprocally rotated and tilted, and can be moved in the X direction and the Y direction around the irradiation direction of the ion beam irradiation.

According to the present invention, there is no need to process the sample upper surface and the sample fixing surface in parallel, and ion milling using a sample holder unit that can easily prepare a sample for observing the surface or cross section with an electron microscope or the like. An apparatus and method thereof can be provided .

  FIG. 1 is a configuration diagram of an ion milling apparatus according to the present invention, where (a) shows a state in which a sample is installed in a vacuum chamber, and (b) shows a state in which the sample is taken out from the vacuum chamber. The ion milling apparatus according to the present invention will be described with respect to the case of irradiating an argon ion beam from the ion source 1, but this embodiment is not limited to an argon ion beam.

  The current density of argon ions in the ion source 1 of argon ions is controlled by the ion source controller 7. The vacuum chamber 15 can be in a vacuum or atmospheric state by controlling the vacuum exhaust system 6 by the vacuum exhaust system controller 9 and can maintain the state.

  The sample moving base 5 is configured to fix a sample holder 23 for fixing the sample 2 and to reciprocate and tilt in parallel with the processing surface of the sample 3 irradiated with the ion beam about the center of the sample holder unit moving mechanism 4 as an axis. The direction and tilt angle for reciprocating rotation tilt are controlled by the sample movement control unit 8. By rotating and tilting the sample moving base 5, the sample 3 fixed by the sample holder 23 can be set at a predetermined angle with respect to the optical axis of the ion beam.

  The sample holder unit moving mechanism 4 is configured so that it can be manually moved by two feed screws in the front-rear and left-right directions, that is, the X direction and the Y direction with respect to the optical axis of the ion beam.

  The sample movement base 5 is disposed on a flange 10 that also serves as a part of the container wall of the vacuum chamber 15 via a rotation mechanism, and the vacuum chamber 15 is opened to the atmospheric state by pulling out the flange 10 along the linear guide 11. Sometimes, the sample moving base 5 is configured to be pulled out of the vacuum chamber 15. In this way, the sample stage drawing mechanism is configured.

  FIG. 2 is a perspective view (a) showing the configuration of the sample holder unit main body, and perspective views (b) and (c) of the sample holder. In this embodiment, at least the sample holder 23 and its rotation mechanism, and the mask 2 and its fine adjustment mechanism are integrally configured as a sample holder unit 21. In FIG. 2, a sample holder rotating ring 22 and a sample holder rotating screw 28 are provided as a rotating mechanism of the sample holder 23 so that the sample holder can be rotated perpendicularly to the optical axis of the ion beam.

  The sample holder unit 21 has a mechanism that can finely adjust the position and rotation angle of the mask 2, and can be attached to and detached from the sample holder unit fine movement mechanism 4.

  The mask 2 is fixed to the mask holder 25 by a mask fixing screw 27. The mask holder 25 can be moved in the protruding length direction of the sample along the linear guide 24 by operating a mask fine adjustment mechanism 26 having a screw structure for adjusting the position of the mask 2. The position of 2 is finely adjusted. The sample holder 23 is inserted and fixed into the sample holder rotating ring 22 from the lower side. The sample 3 is fixed by the sample holder 23 and the mask 2.

  The sample holder rotating ring 22 is configured to rotate by turning the sample holder rotating screw 28, and reverse rotation is returned by the spring pressure of a spring (not shown).

  2B and 2C are perspective views showing details of the sample holder 23 on which the sample 3 is placed, and FIG. 2B is a view seen from the ion irradiation surface side of the sample holder 23 to which the sample 3 is fixed. c) is a view from the opposite side of the ion irradiation surface. As shown in FIGS. 2B and 2C, four ball plungers 12 are inserted into the sample holder 23 through the female screw 13 so that the ion irradiation side adheres to the mask 2 along the inclination of the sample 3 described later. The protruding length of each ball plunger 12 is adjusted. The ball plunger 12 has a male screw that is inserted through the female screw 13 and has a hemispherical tip.

  Four female screws 13 are formed in the same direction as the feed direction of the feed screw 14 in parallel to the mounting surface of the sample 3 of the sample holder 23.

  FIG. 3 is a plan view (a) and a front view (b) showing the configuration of the sample holder unit according to the present invention. In the present embodiment, at least the sample holder 23 and its rotation mechanism, and the mask 2 and its fine adjustment mechanism are integrally configured as a sample holder unit 21. In FIG. 3, a sample holder rotating ring 22 that rotates around the optical axis of the ion beam and a sample holder rotating screw 28 that rotates the sample holder 23 are provided as a rotating mechanism of the sample holder 23. On the other hand, the plane of the sample 3 can be rotated horizontally.

The sample holder unit 21 includes a sample holder 23, a mask 2, a ball plunger 12, a sample holder fixing bracket 1 6 , a sample holder 23, a main body 18, a sample holder rotating ring 22 rotatably provided on the main body 18, a sample holder The feed screw 14 provided on the rotary ring 22 is detachably fixed to the sample fine movement base 5 fixed to the flange 10.

  The sample holder fixing bracket 16 has a U-shape so as to be pressed in contact with the left and right of the sample holder 23 so as not to receive the ion beam irradiation.

  As shown in FIG. 3, the sample 3 is mounted on a sample holder 23 provided with a ball plunger 12 so that the thickness thereof is inclined to the back of the processed surface and the flat surface can be in close contact with the mask 2. Has been. The flat surface of the sample 3 is brought into close contact with the mask 2, the protruding length of the ball plunger 12 is adjusted along the inclination, and then the sample holder 23 is attached to the ball plunger 12 by the sample holder fixing bracket 16 sent by the feed screw 14. The portion of the sample 3 to be processed is protruded from the mask 2 so that it can be milled by an ion beam.

  If the sample holder unit 21 according to this configuration is used and the sample is processed to the size of the sample holder 23, the sample 3 having various shapes can be handled.

  The sample holder unit 21 has a mechanism that can finely adjust the position and rotation angle of the mask 2, and can be attached to and detached from the sample holder unit fine movement mechanism 4.

  The mask 2 is fixed to the mask holder 25 by a mask fixing screw 27. The mask holder 25 moves along the linear guide 24 by operating a mask fine adjustment mechanism (that is, a mask position adjustment unit) 26, thereby finely adjusting the positions of the sample 3 and the mask 2. The sample holder 23 is inserted into the sample holder rotating ring 22 from the lower side and fixed.

  FIG. 4 is a cross-sectional view in which the cross section of the sample is mirror-polished with an ion beam. When the sample 3 is irradiated with the argon ion beam 21, a portion not covered with the mask 2 can be removed in the depth direction along the mask 2, and the surface of the cross section of the sample 3 can be mirror-polished. . The mask 2 is also damaged by being irradiated with the argon ion beam 21, and a damaged portion 17 is formed.

  As described above, in this embodiment, in order to shield the sample 3 processed easily in accordance with the size of the sample holder 5 with the mask 2 without making the back surface of the sample 3 parallel to the surface to be masked 2, A sample holder 23 provided with a ball plunger 4 as an adjustment mechanism, a sample holder fixing bracket 16, and a sample holder unit 21 fixed by a feed screw 14 are mounted on a sample moving base 5 provided on the flange 9. .

  According to the present embodiment, by providing an adjustment mechanism in the sample holder unit 21, the surface to which the sample 3 is fixed and the upper surface of the sample 3 can be brought into close contact with the mask 2 without being processed into parallel surfaces. In the case of producing the sample 3, if only the surface in contact with the mask 2 is made flat and processed into a size that can be mounted on the sample holder 5, the sample 3 can be fixed to the sample holder 5. There is no need to process the fixed surface of the sample 3 in parallel, and the sample 3 for observation can be easily manufactured.

  Further, in consideration of damage to the sample 3, a fixing method in which a force is applied to the sample 3 by using a fixture or the like from the lower side of the sample 3 is not used, and the sample holder 23 having the ball plunger 12 is pressed with a finger. The sample 2 can be pressed from the side surface of the sample holder 23 with the feed screw 14 and the sample holder fixing bracket 16 without pressing the sample 2 as much as possible.

  Further, the alignment operation for aligning the position of the mask 2 with the portion of the sample 3 to be mirror-polished can be easily performed.

  In recent years, particularly in the semiconductor field, it has become important to observe a cross-section of a composite material with an electron microscope, and the importance of mirror-polishing the cross-section of the composite material has increased. According to this example, it is easy to fix the sample to the site where the sample is to be prepared and the cross section of the sample is desired to be observed. In the present embodiment, if a plurality of sample holder units are provided, it is possible to prepare a large number of samples in a state where the processing positions are finely adjusted in advance, which is very efficient.

It is a block diagram of the ion milling apparatus which concerns on this invention. It is a perspective view of a sample holder unit (a) and sample holders (b) and (c) according to the present invention. It is the top view (a) of the sample holder unit which concerns on this invention, and its front view (b). It is sectional drawing explaining the cross-sectional grinding | polishing method of the sample by the ion milling which concerns on this invention.

Explanation of symbols

1 ... ion source, 2 ... a mask, 3 ... sample, 4 ... sample holder unit moving mechanism, 5 ... sample moving base, 6 ... evacuation system, 7 ... ion source controller, 8 ... sample moving control unit, 9 ... Vacuum exhaust system control unit, 10 ... flange, 11 ... linear guide, 12 ... ball plunger, 13 ... female screw, 14 ... feed screw, 15 ... vacuum chamber, 16 ... sample holder fixing bracket, 17 ... damaged part, 18 ... main body part 21 ... Sample holder unit, 22 ... Sample holder rotating ring, 23 ... Sample holder, 24 ... Linear guide, 25 ... Mask holder, 26 ... Mask fine adjustment mechanism, 27 ... Mask fixing screw, 28 ... Sample holder rotating screw.

Claims (12)

In an ion milling apparatus for fixing a sample having a flat surface to a sample holder unit in a vacuum chamber and performing milling by irradiating with an ion beam,
The sample holder unit, through a body portion, and a mask provided to be moved to the side one of the main body portion, and a sample holder for mounting the sample, in internal thread which penetrates the said sample holder A ball plunger capable of adjusting the protruding length along the inclination, a rotating ring provided on the main body portion and rotatably installed in parallel to the plane, and provided on one side of the rotating ring. A feed screw that presses the sample holder against the other side of the rotating ring, and a sample holder fixing bracket that is provided on the sample holder side of the feed screw and that fixes the sample holder in the rotating ring by pressing by the feed screw. And
The sample, ion milling device according to claim Rukoto fixed along the inclination of the back surface side with respect to the plane tangent to the mask to shield from the ion beam. 2. The ion milling device according to claim 1 , wherein a plurality of the female screws are formed in the same direction as the feed direction of the feed screw in parallel with the sample mounting surface of the sample holder. 3. The ion milling device according to claim 1 , wherein the number of ball plungers is the same as the number of female threads. In claim 1, wherein the sample holder fixing bracket is characterized by having the pressing to Rukono-shape in contact with the left and right of the sample holder so as not to receive the ion beam irradiation Ion milling equipment. In any one of claims 1 to 4, wherein the mask is an ion milling apparatus, characterized in that is movable in the direction of the pressing. In any one of claims 1-5, attached to the vacuum chamber, an ion beam source for irradiating the ion beam, an ion source controller for controlling the current density of the ion beam, to evacuate the vacuum chamber An evacuation system, an evacuation system controller for controlling the evacuation system, an opening provided on a side surface of the vacuum chamber, a flange for closing the opening, the sample holder, and the ion beam A sample holder unit moving mechanism that can be manually moved in the X direction and the Y direction with respect to the optical axis, and the sample holder unit moving mechanism that is fixed to the flange can be mounted and reciprocally rotated and tilted around the center of the sample holder unit moving mechanism. Ion millin comprising a sample movement base and a sample movement control unit for controlling the rotation direction and angle for reciprocating and tilting the sample Equipment. In an ion milling method in which a sample having a flat surface is fixed to a sample holder unit in a vacuum chamber and irradiated with an ion beam to mill the sample,
The sample holder unit, through a body portion, and a mask provided to be moved to the side one of the main body portion, and a sample holder for mounting the sample, in internal thread which penetrates the said sample holder A ball plunger capable of adjusting the protruding length along the inclination, a rotating ring provided on the main body portion and rotatably installed in parallel to the plane, and provided on one side of the rotating ring. A feed screw that presses the sample holder against the other side of the rotating ring, and a sample holder fixing bracket that is provided on the sample holder side of the feed screw and that fixes the sample holder in the rotating ring by pressing by the feed screw. And
The surface of the sample that is in contact with the mask that shields the ion beam is the flat surface, the flat surface is in contact with the mask, and the sample is mounted on and fixed to the sample holder along an inclination on the back surface side with respect to the flat surface. An ion milling method characterized by the above. 8. The ion milling method according to claim 7 , wherein the rotating ring is used to rotate the sample together with the sample holder so as to be rotatable about the irradiation direction of the ion beam irradiation. Ion milling method, wherein according to claim 7 or 8, wherein the mask is movable protruding length direction of the sample. In any one of Claims 7-9 ,
The sample holder fixing bracket, possess the pressing to Rukono-shape in contact with the left and right of the sample holder so as not to receive the ion beam irradiation,
An ion milling method, wherein the sample is fixed by pressing left and right of the sample holder so as not to receive the ion beam irradiation. In any one of claims 7 to 10, wherein the fixing by adjusting the protruding length of the plurality of ball plunger provided the plane of the sample mounted on the sample holder in the sample holder so as to be in contact with the mask An ion milling method characterized by: In any one of Claims 7-11 ,
An ion beam source that is attached to the vacuum chamber and irradiates the ion beam, an ion source controller that controls a current density of the ion beam, a vacuum exhaust system that evacuates the vacuum chamber, and a vacuum exhaust system. An evacuation system controller to be controlled, an opening provided on a side surface of the vacuum chamber, a flange for closing the opening, the sample holder, and the X and Y directions with respect to the optical axis of the ion beam A sample holder unit moving mechanism that can be moved manually, a sample moving base that is fixed to the flange and mounted with the sample holder unit moving mechanism, and that can reciprocate and tilt around the center of the sample holder unit moving mechanism, and reciprocally rotate the sample possess a sample movement control unit for controlling the rotational direction and angle of tilting,
The sample is installed so as to be able to reciprocate and tilt in parallel with the processing surface of the sample by ion beam irradiation, and to be installed so as to be movable in the X direction and the Y direction about the irradiation direction of the ion beam irradiation. A featured ion milling method.

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