JP2008215979A - Mask for ion milling sample manufacturing apparatus, and the sample manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mask for an ion milling sample manufacturing apparatus, capable of manufacturing a sample having a desired cross section of high positional accuracy, and to provide a sample manufacturing device. <P>SOLUTION: A mask of a several micron-several hundred micron unit is applied to the edge part of the mask for prescribing an ion irradiation region and an ion non-irradiation region and the positional relation of the mask, and the sample is confirmed, on the basis of the mark to facilitate the observation due to an optical microscope to manufacture a cross-sectional sample high in positional precision of about several microns. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mask disposed between an ion gun and a sample in an ion milling sample preparation apparatus, and an ion milling sample preparation apparatus thereof.

  Up to now, as an apparatus for producing a sample observed with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), for example, Japanese Patent Application Laid-Open No. 2005-62131 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2005-91094 ( An ion milling device as described in Patent Document 2) is known. In the ion milling sample preparation apparatus of Patent Document 1, as shown in FIG. 1, a plate-like mask 3 (shielding plate) having a straight side surface 4 is attached to a sample holder 8, and an ion beam generated by the ion source 1. 2 is configured to irradiate the sample 5. Since the sample 5 is etched with the side surface 4 of the mask 3 as a boundary, the hatched portion 6 in FIG. 1 is scraped off and a new sample cross section 7 is produced. This sample cross section 7 is observed by SEM or TEM.

JP 2005-62131 A JP2005-91094

  FIG. 2 is an enlarged view showing the positional relationship in the vicinity of the side surface 4 of the sample 5 and the mask 3 of the ion milling sample preparation apparatus shown in FIG. In this apparatus, a tiltable optical microscope 10 with illumination light is disposed in order to accurately position the edge portion 24 of the side surface 4 of the mask 3 directly above the target 9 on the sample 5. As will be described later, the optical microscope 10 is configured to be retractable from the ion beam optical axis when the sample 5 is ion milled.

Using the optical microscope 10, the sample position is adjusted so that the target 9 on the sample 5 coincides with the lower portion of the edge 24 of the mask 3, and the target 9 is positioned.
In this positioning, in order to produce a cross-sectional sample with a more accurate positional accuracy, the optical microscope 10 is required to have a positional accuracy in the order of several microns with the magnification of the optical microscope 10 being several tens to several hundreds.

  However, the wall of the side surface 4 having a height of about 1.5 mm that stands up almost vertically stands immediately before the target 9, and the observation with the optical microscope 10 shows that the mask has a height of 1.5 mm. 3 is performed in a very narrow range of the corner 11 created by the lower part of the edge portion 24 and the object 9 on the sample 5, and it can be said that it is extremely difficult to observe as in the observation at the foot of the lighthouse.

  The side surface 4 is applied to the optical axis of the ion beam 2 so that the ion beam 2 is uniformly irradiated to every corner of the target 9 and processing is performed correctly, and in order to facilitate observation with the optical microscope 10 from above. On the other hand, the angle is slightly opened to several degrees, and it has a fine trapezoidal shape and is polished to a mirror surface.

  Therefore, in the observation of the corner 11 with the optical microscope 10, the surface structure of the target 9 of the sample 5 is reflected by the edge portion 24, and a reflected image of the target 9 is projected on the edge 24.

As a result, the surface image of the target 9 and the reflection image of the target 9 by the edge portion 24 were observed in the image with the optical microscope 10 in an overlapping manner. For this reason, in the prior art, it has been extremely difficult to clearly recognize the boundary between the target 9 and the edge 24 of the mask 3. For these reasons, it can be said that the alignment of the mask and the sample by the optical microscope 10 is currently limited to about + -10 microns.
The present invention has been made in view of these points, and an object of the present invention is to provide a mask for an ion milling sample preparation device and a sample preparation device capable of producing a sample having a desired cross section with high positional accuracy.

  The mask for an ion milling sample preparation apparatus of the present invention that achieves the above object is provided by ion milling arranged on a sample surface irradiated with an ion beam in order to form an ion irradiation region and an ion non-irradiation region on the sample surface. This is a mask for a sample preparation device, and marks on the edge of the mask that define the ion irradiation region and ion non-irradiation region are marked in units of several microns to several hundred microns. By confirming the relationship, observation with an optical microscope is facilitated, and a cross-sectional sample with high positional accuracy of about several microns is produced.

  Therefore, according to the present invention, it is possible to provide a mask for an ion milling sample preparation device and a sample preparation device capable of producing a sample having a cross section with a positional accuracy of several microns.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 3A and 3B are views showing an example of an ion milling sample preparation apparatus according to the present invention. (A) shows the state where the ion milling sample preparation apparatus is in the atmospheric state, and the sample is aligned using the optical microscope, and the sample and the mask are aligned. (B) is (A) After completion of the adjustment, vacuum evacuation is performed to show a state of sample preparation by an ion beam. In (B), since the configuration is the same as (A), the reference numerals of parts are omitted.

  In (A), 12 is a vacuum chamber, and the ion gun 1 is attached to the upper part of the vacuum chamber 12. A gas ion gun is used as the ion gun 1, for example, a gas ion gun that releases Ar ions by ionizing Ar gas by discharge.

  Reference numeral 13 denotes a sample stage drawing mechanism, and the sample stage drawing mechanism 13 is attached to the vacuum chamber 12 so as to be openable and closable. (A) is a state in which the sample stage drawing mechanism 13 is opened. A sample stage (tilt stage) 14 is mounted on the sample stage pull-out mechanism 13, and the sample stage 14 can tilt around the tilt axis K (the tilt axis K coincides with the Y-axis). 13 is attached. Reference numeral 15 denotes an inclination driving circuit for inclining the sample stage 14 with respect to the K axis.

  A sample position adjusting mechanism 16 is arranged on the sample stage 14, and the sample position adjusting mechanism 16 is configured to be movable in the X and Y axis directions. Further, the sample position adjusting mechanism 16 is configured to be rotatable around the optical axis of the ion beam, that is, the Z axis. In this figure, a sample holder 8 holding the sample 5 is attached to the sample position adjusting mechanism 16. A mask position adjusting mechanism 17 is installed on the sample stage 14. The mask position adjusting mechanism 17 is configured to be movable in the Y axis direction. A mask tilting mechanism 18 is disposed on the mask position adjusting mechanism 17, and a mask holding mechanism 19 that holds the mask 3 is mounted on the mask tilting mechanism 18, and the mask 3 is moved as shown by a dotted line about the axis Q. It has a structure of flipping up, and the mask 5 can be flipped up to align the sample 5.

  An optical microscope tilting mechanism 20 is attached to the upper end portion of the sample stage pulling mechanism 13. An optical microscope position adjusting mechanism 21 holding the optical microscope 10 with illumination light is attached on the optical microscope tilting mechanism 20. That is, the optical microscope position adjusting mechanism 21 has a structure that can be tilted about the axis R.

  In this way, after pulling out the sample stage drawing mechanism 13 into the atmosphere and using the optical microscope 10 with illumination light to align the object on the sample with the edge portion of the mask, the sample stage drawing mechanism 13 is moved. The sample is built in the vacuum chamber 12, evacuated by the evacuation device 22, and a sample is prepared with an ion beam as shown in (B). In this figure, the optical microscope 10 is shown tilted by the optical microscope tilting mechanism 20 so as not to interfere with the ion gun.

  FIG. 4 shows in detail the observation at the corner created by the edge plane of the mask and the sample surface in the present invention. As a feature thereof, a mark 23 is provided on the edge portion 24 of the mask 3, that is, the sample side end portion of the mask side surface 4. This figure shows a case where a plurality of elongated marks 23 are provided on the same straight line along the edge direction of the edge portion 24.

  FIG. 5 shows an embodiment of positioning of a marked mask and a sample according to the present invention. In FIG. 5A, a metal deposition mark having a length of 75 microns, a width of 5 microns, and a thickness of 1 micron is formed as a mark 23 on the edge 24 of the side surface 4 of the mask 3 by FIB deposition. A state in which the edge portion 24 of the mask 3 is correctly aligned with the target 9 on the sample 5 using the optical microscope 10 is shown.

  FIG. 5B shows an image obtained by the optical microscope 10. The lower half portion indicated by J in the main image is a surface image of the target 9, and the upper half portion indicated by I in the image reflects the surface image of the target 9 on the edge 24 of the mask 3. It is a reflection image. Thus, the surface image of the target 9 and its reflection image are observed simultaneously, and the band-like portion H at the boundary between the surface image and the reflection image is displayed as a wide black portion, and the edge 24 of the mask 3 and the target 9 are displayed. It is difficult to find the exact boundary.

  A particularly bright horizontal short straight line portion indicated by an arrow 23 is observed in the center of the main image, and this is the mark by the FIB deposition described above. Light irradiation in the thickness direction of the mark 23 is performed by light irradiation for optical microscope observation from above, and the portion of the mark 23 is observed as a bright white line in the black belt-like boundary portion H with high contrast. I understand that.

  In this way, the boundary between the edge portion 24 of the mask 3 and the target 9 on the sample 5 can be clearly known with the bright white line of the mark 23 as a reference, and accurate alignment between the two is possible.

  Of course, it is important that these marks 23 have values corresponding to the magnification used by the optical microscope, such as the size and interval, and are several microns high and several tens to several hundred microns long. In consideration of complicated light reflection at the corner 11 in a narrow area, it is preferable to have a convex structure having a thickness of several microns. That is, the mark 23 should be formed on the sample side edge portion 24 of the side surface 4 so that the thickness from the side surface 4 of the mask 3 is about several microns.

  The formation of the mark 23 is not limited to a metal deposition method using a focused ion beam (FIB), and a sputtered film deposition method using an exposure technique, a plating method, or the like may be used.

It is a figure for demonstrating the conventional ion milling sample preparation apparatus. It is a figure for demonstrating the conventional mask position alignment. It is a figure for demonstrating the conventional ion milling apparatus. It is a figure for demonstrating the mask with a mark of this invention. It is a figure for demonstrating the mask with a mark of this invention.

Explanation of symbols

(Those that perform the same or similar operations are denoted by a common reference.)
1 ion source 2 ion beam 3 mask 4 side surface 5 sample 6 deletion part 7 sample cross section 8 sample holder 9 object 10 optical microscope 11 corner 12 vacuum chamber 13 stage extraction mechanism 14 sample stage 15 tilt drive circuit 16 sample position adjustment mechanism 17 mask Position adjusting mechanism 18 Mask tilting mechanism 19 Mask holding mechanism 20 Optical microscope tilting mechanism 21 Optical microscope position adjusting mechanism 22 Vacuum exhaust device 23 Mark 24 Edge portion H Boundary portion I Reflected image J Surface image

Claims (5)

  A mask for an ion milling sample preparation device disposed on a sample surface irradiated with an ion beam to form an ion beam irradiation region and an ion beam non-irradiation region on the sample surface, the ion beam on the sample surface A mask for an ion milling sample preparation apparatus, wherein marks for observation with an optical microscope are formed at an edge portion of a mask that defines a boundary between an irradiation region and an ion beam non-irradiation region.   The mask has a side surface substantially parallel to the ion beam, the boundary is defined by a sample-side edge portion of the side surface, and the mark is attached to the sample-side edge portion. 2. A mask for an ion milling sample preparation apparatus according to 1.   3. The ion milling sample preparation apparatus mask according to claim 1, wherein the mark is formed in a convex shape.   4. The mask for an ion milling sample preparation apparatus according to claim 1, wherein a plurality of the marks are formed on the same straight line along an edge direction of the edge portion. 5.   An ion gun for irradiating a sample with an ion beam, and a mask disposed on the sample surface irradiated with the ion beam to form an ion irradiation region and an ion non-irradiation region on the sample surface In the sample preparation device, a mark for optical microscope observation is formed on an edge portion of the mask that defines a boundary between an ion irradiation region and an ion non-irradiation region on the sample surface.

Images