JP2004253232A - Sample fixing table - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a TEM (Transmission Electron Microscope) sample fixing table that allows highly accurate focused-ion-beam machining and TEM observation. <P>SOLUTION: The sample fixing table 10 is equipped with a sample fixing plate 110 and a sample mounting table 120. The sample mounting table 120 has in its lower side a circular arc for installing the sample fixing table 100 in a sample holder. The sample fixing plate 110 to adhere a TEM sample 140 is formed on the upper side of the sample mounting table 120. The thickness of the sample fixing plate 110 is thinner than that of the sample mounting table 120 by one space for adhering the TEM sample 140. The observing sample-surface 150 of the TEM sample is adhered to the fixing plate main surface 130 of the sample fixing plate 110 by tungsten 160 (tungsten deposition). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sample fixing table for fixing a sample for observation, particularly for fixing a sample (hereinafter also referred to as a TEM sample) for observation by a transmission electron microscope (TEM). Of the sample holder.
[0002]
[Prior art]
In recent years, a device equipped with a microprobe in a FIB (Focused Ion Beam) processing device has been developed and commercialized. In this apparatus, it is possible to produce a fine TEM sample having a size of several tens μm. This TEM sample is so small that it cannot be gripped with tweezers, but can be handled by manipulating the microprobe provided in the device and can be adhered to the sample fixing table. This sample holder can be attached to a TEM device or FIB device using a TEM sample holder or FIB sample holder. Therefore, the sample processed by the FIB device is observed and evaluated by the TEM device, and further processed by the FIB device based on the evaluation, whereby the processing and the evaluation can be repeatedly performed. Such a sample preparation method is called a microsampling method. By using the microsampling method, a desired portion in the bulk sample can be extracted. Examples of such a sample fixing table and a sample holder are described in Patent Documents 1 to 3, for example.
[0003]
[Patent Document 1]
JP-A-11-149896 [Patent Document 2]
JP-A-11-329325 [Patent Document 3]
JP-A-2002-150984
[Problems to be solved by the invention]
In order to cut out a desired observation point from a complicated device structure by FIB in the preparation of a sample for a semiconductor device, it is necessary to know an accurate orientation of the sample. Also, when observing the sample by TEM, it is necessary to know the exact orientation of the sample. In a semiconductor device that is being miniaturized, a shift in the orientation of the sample when the sample is processed by the FIB apparatus leads to a failure in sample preparation. In addition, if the orientation of the sample is deviated during the observation of the sample by the TEM device, the shape of the sample cannot be accurately grasped.
[0005]
When a plane sample is cut from a bulk sample using a conventional sample holder, first, gallium ions are incident in a direction perpendicular to the bottom surface of the bulk sample, and the sample is cut out by FIB (hereinafter, this cut-out surface is This is called the cut surface). Next, the cut sample is bonded (tungsten deposition) with tungsten so that the bottom surface of the sample is in close contact with the upper surface of the sample fixing table. After rotating the sample holder by 90 °, gallium ions are incident, and the direction of the sample is adjusted so that the beam of gallium ions is perpendicular to the cutout surface, thereby thinning the sample to produce a flat sample. Was.
[0006]
However, since the gallium ion beam has a certain spread, it is difficult to process the bulk sample so that the bottom surface of the sample and the cut surface are completely perpendicular. For this reason, there is a problem that it is difficult to make a desired portion in the bulk sample into a thin film to produce a planar sample.
[0007]
In order to observe the surface of a semiconductor device (for example, the direction of the surface of the semiconductor device is assumed to be the [100] direction) from the [100] direction using a conventional sample holder, an electron diffraction image of the device substrate must be obtained first. To obtain information about the orientation of the device substrate. Then, the TEM sample holder is tilted according to the azimuth information, and the direction of the surface of the semiconductor device is aligned with the [100] direction to perform TEM observation.
[0008]
However, in recent years, with the increase in the number of layers of a semiconductor device, a TEM observation of only the upper layer of the device substrate may be required in the semiconductor device. In such a case, since the device substrate is removed by the FIB, the azimuth information cannot be obtained from the device substrate. Therefore, there is a problem that it is difficult to accurately adjust the direction of the surface of the semiconductor device to the [100] direction.
[0009]
Further, there is also a problem that the azimuth alignment accuracy of the sample is lowered because the tilting function of the TEM sample holder and the FIB sample holder is insufficient.
[0010]
The present invention has been made in order to solve the above problems, and an object of the present invention is to provide a sample fixing table capable of performing highly accurate FIB processing and TEM observation.
[0011]
[Means for Solving the Problems]
The sample fixing table according to the invention according to claim 1 is a sample fixing table for fixing a sample having an observation surface for observation with an electron microscope, and a sample fixing plate for bonding the observation surface of the sample, A sample mounting table for mounting on a sample holder, the sample fixing plate protruding in a notch shape;
[0012]
The sample fixing table according to the invention according to claim 3 is a sample fixing table for fixing a sample having an observation surface for observation with an electron microscope, the sample fixing table having a portion for fixing the sample, and attached to a sample holder. And a mark for observation position alignment formed on the sample mounting table.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
<Embodiment 1>
FIG. 1 is a diagram showing a sample fixing table 100 according to Embodiment 1 of the present invention. 1A, 1B, and 1C are a top view, a front view, and a side view, respectively, of the sample fixing table 100. FIG. 2 shows a perspective view of the sample fixing table 100.
[0014]
The sample fixing table 100 includes a sample fixing plate 110 and a sample mounting table 120. The sample mounting table 120 has a lower part in an arc shape, and has a function of mounting the sample fixing table 100 to the sample holder 170 as shown in FIG. The sample holder 170 has a function of mounting the TEM sample 140 adhered to the sample fixing plate 110 to a TEM device or a FIB device (neither is shown).
[0015]
Further, a sample fixing plate 110 for bonding the TEM sample 140 is formed on the upper portion of the sample mounting table 120. The thickness of the sample fixing plate 110 is smaller than the thickness of the sample mounting table 120 by the space for bonding the TEM sample 140. That is, the sample fixing plate 110 protrudes from the upper surface of the sample mounting table 120 in a notch shape. Therefore, as shown in FIG. 1C, the side view of the cutout portion of the sample fixing table 100 is L-shaped.
[0016]
As shown in FIG. 1, a sample observation surface 150, which is an observation surface of a TEM sample 140, is adhered (tungsten deposition) on a fixing plate main surface 130, which is a main surface of the sample fixing plate 110, by tungsten 160. That is, the sample is adhered to the sample fixing plate such that the back surface of the sample observation surface is cut in parallel with the observation surface.
[0017]
Next, a procedure for cutting out a planar sample from the bulk sample 200 by FIB using the sample fixing table 100 will be described.
[0018]
As shown in FIG. 4, a tungsten film 220 is formed on the surface of the bulk sample 200. The tungsten film 220 functions as a protective film for protecting the TEM sample 140 located below (in the depth direction of the paper) from gallium ion irradiation described below.
[0019]
Next, in FIG. 5, by irradiating the bulk sample 200 with gallium ions from above (on the front side of the paper surface), a region around the TEM sample 140 is shaved off to form a groove 230. The bulk sample 200 and the TEM sample 140 are connected to each other by the support 240. The bulk sample 200 is cut so that the bottom surface is parallel to the paper surface.
[0020]
Next, as shown in FIG. 6, the microprobe 250 built in the FIB device is operated to bring its tip into contact with the upper surface of the tungsten film 220. Then, a tungsten film 260 is formed at a contact portion between the tungsten film 220 and the microprobe 250. The TEM sample 140 and the microprobe 250 are bonded to each other by the tungsten film 260.
[0021]
Next, as shown in FIG. 7, gallium ions are irradiated to completely separate the support portion 240 and the TEM sample 140. Next, the TEM sample 140 is extracted from the bulk sample 200 by operating the microprobe 250. FIG. 8 is a cross-sectional view of the cross section taken along line AA shown in FIG. As shown in FIG. 1, the bottom surface of the TEM sample 140 is bonded to the fixed plate main surface 130 with tungsten 160 as a sample observation surface 150, and the microprobe 250 is cut.
[0022]
In FIG. 1A, the TEM sample 140 adhered to the main surface 130 of the fixing plate is thinned by a gallium ion beam incident from a front side of the drawing to produce a flat sample. At this time, by performing SIM (Scanning Ion Microscope) observation of the upper surface of the sample fixing table 100 using the incident gallium ion beam, the sample observation surface 150 becomes parallel to the gallium ion beam. The fixed base 100 can be inclined. That is, in FIG. 1A, since the gallium ion beam is incident from the near side of the paper surface, when the sample observation surface 150 is parallel to the gallium ion beam, the observation shape of the sample fixing table 100 is the upper and lower sides. (Edges) have the same rectangular shape. In this rectangle, the upper side (edge) corresponds to the back surface of the sample holder 100, and the lower side (edge) corresponds to the front surface of the sample holder 100. However, if the sample observation surface 150 is not parallel to the gallium ion beam, one of the upper and lower edges of this rectangle is observed in an arc shape, and the shapes of the upper and lower edges are not the same. Therefore, the orientation of the TEM sample 140 can be adjusted by inclining the sample fixing table 100 so that the shapes of the upper and lower edges become the same by SIM observation.
[0023]
In addition, in FIG. 1B, TEM observation is performed by irradiating an electron beam from the depth direction of the paper surface to the TEM sample 140 whose orientation has been aligned.
[0024]
Thus, in sample holding table 100 according to the present embodiment, sample observation surface 150 of TEM sample 140 and main surface of fixed plate 130 of sample fixed plate 110 are bonded, so that orientation of TEM sample 140 can be adjusted. Accuracy can be increased. Therefore, highly accurate FIB processing and TEM observation can be performed.
[0025]
<Embodiment 2>
In the sample holder 100 according to the first embodiment, the TEM sample 140 is obtained by performing SIM observation on the upper surface of the sample holder 100 and inclining the sample holder 100 so that the upper and lower edges have the same shape. The direction is adjusted.
[0026]
However, since it is difficult to observe the edge portion of the sample fixing table 100 in detail by SIM, there has been a problem that the accuracy of the azimuth alignment is reduced.
[0027]
9A, 9B, and 9C are a top view, a front view, and a side view, respectively, of a sample fixture 300 according to the second embodiment of the present invention. The sample fixing table 300 is obtained by disposing a square pyramid mark for observation position alignment, that is, a pyramid mark section 310 on the upper surface of the sample mounting table 120 in the sample fixing table 100. 9, the same elements as those in FIG. 1 are denoted by the same reference numerals, and a detailed description thereof will be omitted. For simplicity, the TEM sample 140 is omitted.
[0028]
At the time of FIB processing, in FIG. 9A, not the edge of the sample fixing table 300 but the pyramid-shaped mark 310 is observed by SIM. That is, the sample observation surface 150 can be made parallel to the gallium ion beam by inclining the sample fixing table 300 so that all four triangles forming the pyramid-shaped mark portion 310 have the same shape.
[0029]
Also, at the time of TEM observation, the height of the pyramid-shaped mark portion 310, that is, the distance between the bottom surface and the apex, is measured, and the sample fixing table is adjusted so that the measured value matches the actual height of the pyramid-shaped mark portion 310. By inclining 300, the orientation of TEM sample 140 can be adjusted so that an electron beam is incident on sample observation surface 150 perpendicularly.
[0030]
If the electron beam does not pass through the pyramid-shaped mark portion 310 or the sample fixing plate 110 and cannot be observed by TEM, use a scanning electron microscope (SEM) function incorporated in the TEM device. Thereby, the pyramid-shaped mark portion 310 can be observed.
[0031]
As described above, the sample fixing table 300 according to the present embodiment has a structure in which the pyramid-shaped mark portion 310 for observation position alignment is arranged on the upper surface of the sample mounting table 120 in the sample fixing table 100. The orientation of the sample 140 can be more precisely aligned. Therefore, more accurate FIB processing and TEM observation can be performed.
[0032]
In the above description, one pyramid-shaped mark is arranged on the upper surface of the sample mounting table as a mark for observation position alignment. However, the shape of the mark is not limited to the pyramid shape, but is limited to a three-dimensional shape. However, the number is not limited to one. For example, as shown in Embodiment Mode 3, as long as alignment for observation is possible, a planar mark such as a square diagonal mark or a plurality of marks may be arranged.
[0033]
Further, in the above description, the sample fixing table including both the sample fixing plate and the sample mounting table has been described. However, even if the sample fixing table includes only the sample mounting table, the observation position alignment mark is provided on the sample mounting table. The same effect is obtained by forming.
[0034]
<Embodiment 3>
The sample fixing table 300 according to the second embodiment has a structure in which a pyramid mark 310 for observation position alignment is arranged on the upper surface of the sample mounting table 120 in the sample fixing table 100. Instead of the mark section 310, a planar square diagonal mark section 320 may be used.
[0035]
FIGS. 10A, 10B, and 10C are a top view, a front view, and a side view, respectively, of a sample fixing table 400 according to Embodiment 3 of the present invention. The sample fixing table 400 is obtained by disposing a square diagonal mark 320 for observation position alignment on the upper surface, the front surface, and the back surface of the sample mounting table 120 in the sample fixing table 100 (not shown in FIG. 10). A square diagonal mark 320 is also arranged on the back side.) The square diagonal mark 320 is formed by engraving a groove in the sample mounting table 120 using FIB or the like. 10, the same elements as those of FIG. 1 are denoted by the same reference numerals, and a detailed description thereof will be omitted. For simplicity, the TEM sample 140 is omitted.
[0036]
At the time of FIB processing, the square diagonal mark 320 on the upper surface of the sample mounting table 120 is observed with SIM in FIG. That is, the sample observation surface 150 can be made parallel to the gallium ion beam by inclining the sample fixing table 400 so that all four triangles forming the square diagonal mark 320 have the same shape.
[0037]
Further, at the time of TEM observation, the square diagonal mark portions 320 on the front surface and the rear surface of the sample mounting table 120 are observed, and the sample fixing table 400 is set so that all four triangles forming the square diagonal mark portions 320 have the same shape. By tilting, the orientation of the TEM sample 140 can be adjusted so that the electron beam enters the sample observation surface 150 perpendicularly.
[0038]
When the electron beam does not pass through the sample mounting table 120 and cannot be observed by a TEM, a square diagonal mark portion is obtained by using a SEM (Scanning Electron Microscope) function incorporated in the TEM device. 320 can be observed.
[0039]
As described above, in the sample fixing table 400 according to the present embodiment, in the sample fixing table 100, the square diagonal mark portion 320 for observation position alignment is planarly provided on the upper surface, the front surface, and the back surface of the sample mounting table 120. Take the arranged structure. Therefore, since the square diagonal mark portion 320 can be formed by using FIB or the like, in addition to the effect of the second embodiment, there is an effect that the manufacturing cost can be reduced.
[0040]
In the above description, the square diagonal mark portion 320 is arranged on the front and back of the sample mounting table. However, the same effect can be obtained even if the square diagonal mark 320 is arranged on either the front or the back. Have.
[0041]
<Embodiment 4>
The sample mounting table 300 according to the second embodiment has a structure in which a pyramid-shaped mark portion 310 for observation position alignment is arranged on the upper surface of the sample mounting table 120 in the sample mounting table 100. The pyramid-shaped mark portions 310 may be arranged on the front surface and the back surface instead of the upper surface.
[0042]
FIGS. 11A, 11B, and 11C are a top view, a front view, and a side view, respectively, of a sample fixture 500 according to Embodiment 4 of the present invention. The sample fixing table 500 is obtained by disposing a pyramid-shaped mark 310 for observation position alignment on the front and back of the sample mounting table 120 in the sample fixing table 100. 11, the same elements as those of FIG. 1 are denoted by the same reference numerals, and a detailed description thereof will be omitted. For simplicity, the TEM sample 140 is omitted.
[0043]
At the time of FIB processing, in FIG. 11A, the pyramid-shaped mark portion 310 is observed by SIM. That is, by measuring the height of the pyramid-shaped mark portion 310, that is, the distance between the bottom surface and the apex, and inclining the sample fixing table 500 so that the measured value matches the actual height of the pyramid-shaped mark portion 310, The sample observation surface 150 can be parallel to the gallium ion beam.
[0044]
Further, at the time of TEM observation, the pyramid-shaped mark portions 310 on the front surface and the back surface of the sample mounting table 120 are observed, and the sample fixing table 500 is set so that all four triangles forming the pyramid-shaped mark portions 310 have the same shape. By tilting, the orientation of the TEM sample 140 can be adjusted so that the electron beam enters the sample observation surface 150 perpendicularly.
[0045]
If the electron beam does not pass through the pyramid-shaped mark portion 310 or the sample mounting table 120 and cannot be observed by TEM, use a scanning electron microscope (SEM) function incorporated in the TEM device. Thereby, the pyramid-shaped mark portion 310 can be observed.
[0046]
As described above, the sample fixing table 500 according to the present embodiment has a structure in which the pyramid-shaped mark portions 310 for observation position alignment are arranged on the front surface and the rear surface of the sample mounting table 120 in the sample fixing table 100. Therefore, the third embodiment has the same effect as the second embodiment.
[0047]
In the above description, the pyramid-shaped mark portion 310 is arranged on the front and the back of the sample mounting table. However, the same effect can be obtained by disposing the pyramid-shaped mark 310 on either the front or the back. Have.
[0048]
<Embodiment 5>
In sample holding table 600 according to the fifth embodiment of the present invention, pyramid-shaped mark portions 310 for observation position alignment are arranged on the upper surface, the front surface, and the back surface of sample mounting table 120 in sample holding table 100, respectively. Take the structure. That is, a structure in which the sample fixing table 300 according to the second embodiment and the sample fixing table 500 according to the fourth embodiment are combined is adopted.
[0049]
FIGS. 12A, 12B, and 12C are a top view, a front view, and a side view, respectively, of the sample fixture 600 according to the present embodiment. 12, the same elements as those in FIG. 1 are denoted by the same reference numerals, and a detailed description thereof will be omitted. For simplicity, the TEM sample 140 is omitted.
[0050]
At the time of FIB processing, in FIG. 12A, the pyramid-shaped mark portion 310 is observed by SIM. That is, the sample observation surface 150 can be made parallel to the gallium ion beam by inclining the sample fixing table 600 so that all four triangles forming the pyramid-shaped mark portion 310a have the same shape.
[0051]
Alternatively, the height of the pyramid-shaped mark portion 310b, that is, the distance between the bottom surface and the apex is measured, and the sample fixing table 600 is inclined so that the measured value matches the actual height of the pyramid-shaped mark portion 310b. The sample observation surface 150 can be made parallel to the gallium ion beam.
[0052]
In the TEM observation, the pyramid-shaped mark portions 310b on the front surface and the back surface of the sample mounting table 120 are observed, and the sample fixing table 600 is set so that all four triangles forming the pyramid-shaped mark portions 310b have the same shape. By tilting, the orientation of the TEM sample 140 can be adjusted so that the electron beam enters the sample observation surface 150 perpendicularly.
[0053]
Alternatively, the height of the pyramid-shaped mark portion 310a, that is, the distance between the bottom surface and the vertex is measured, and the sample fixing table 600 is inclined so that the measured value matches the actual height of the pyramid-shaped mark portion 310a. The orientation of the TEM sample 140 can be adjusted so that the electron beam enters the sample observation surface 150 perpendicularly.
[0054]
If the electron beam does not pass through the pyramid-shaped mark portions 310a and 310b, the sample fixing plate 110, and the sample mounting table 120 and cannot be observed with a TEM, an SEM (Scanning Electron Microscope: scanning type) incorporated in the TEM device is used. By using the (electron microscope) function, the pyramid-shaped mark portion 310 can be observed.
[0055]
As described above, the sample fixing table 600 according to the present embodiment has a structure in which the sample fixing table 300 according to the second embodiment and the sample fixing table 500 according to the fourth embodiment are combined. It has the same effect as 2.
[0056]
【The invention's effect】
As described above, the sample fixing table according to the first aspect of the present invention is a sample fixing table for fixing a sample having an observation surface for observation with an electron microscope, and the observation surface of the sample is Since a sample fixing plate to be adhered and a sample mounting table for mounting the sample fixing plate on the sample holder, the sample fixing plate protruding in a notch shape are provided, the accuracy of the orientation of the sample can be improved. Therefore, highly accurate FIB processing and TEM observation are possible.
[0057]
Further, the sample fixing table according to the invention according to claim 3 is a sample fixing table for fixing a sample having an observation surface for observation with an electron microscope, the sample fixing table having a portion for fixing the sample, and a sample holder. Since a sample mounting table for mounting on the sample mounting table and an observation position alignment mark formed on the sample mounting table are provided, the accuracy of azimuth alignment of the sample can be improved. Therefore, highly accurate FIB processing and TEM observation are possible.
[Brief description of the drawings]
FIG. 1 is a top view, a front view, and a side view of a sample fixing table according to Embodiment 1.
FIG. 2 is a perspective view of a sample fixing table according to the first embodiment.
FIG. 3 is a front view of the sample holder according to the first embodiment.
FIG. 4 is a diagram showing a procedure of sample processing according to the first embodiment.
FIG. 5 is a diagram showing a procedure of sample processing according to the first embodiment.
FIG. 6 is a diagram showing a procedure of sample processing according to the first embodiment.
FIG. 7 is a view showing a procedure of sample processing according to the first embodiment.
FIG. 8 is a diagram showing a procedure of sample processing according to the first embodiment.
FIG. 9 is a top view, a front view, and a side view of the sample fixing table according to the second embodiment.
FIG. 10 is a top view, a front view, and a side view of the sample fixing table according to the third embodiment.
FIG. 11 is a top view, a front view, and a side view of a sample fixing table according to a fourth embodiment.
FIG. 12 is a top view, a front view, and a side view of a sample fixing table according to a fifth embodiment.
[Explanation of symbols]
100, 300, 400, 500, 600 sample fixing table, 110 sample fixing plate, 120 sample mounting table, 130 fixing plate main surface, 140 TEM sample, 150 sample observation surface, 160 tungsten, 170, sample holder, 200 bulk sample, 220, 260 Tungsten film, 230 groove, 240 support, 250 microprobe, 310, 310a, 310b Pyramid mark, 320 square diagonal mark.

Claims (9)

A sample fixing table for fixing a sample having an observation surface for observation by an electron microscope,
A sample fixing plate for bonding the observation surface of the sample,
A sample fixing table comprising: a sample mounting table for mounting the sample fixing plate on a sample holder, the sample fixing table protruding in a notch shape. The sample fixing table according to claim 1, wherein
A sample fixing table further comprising an observation position alignment mark formed on the sample mounting table. A sample fixing table for fixing a sample having an observation surface for observation by an electron microscope,
Having a portion to which the sample is fixed, a sample mounting table for mounting on a sample holder,
A sample fixing table including an observation position alignment mark formed on the sample mounting table. It is a sample fixing stand according to claim 2 or claim 3,
A sample fixing table in which the observation position alignment mark has four triangles. The sample fixing table according to claim 4, wherein
A sample fixing table, wherein the observation position alignment mark is a three-dimensional square pyramid mark. The sample fixing table according to claim 5, wherein
A sample fixing table in which the square pyramid mark is formed on an upper surface of the sample mounting table. The sample fixing table according to claim 5, wherein
A sample fixing table in which the square pyramid mark is formed on a front surface or a rear surface of the sample mounting table. The sample fixing table according to claim 4, wherein
A sample fixing table, wherein the observation position alignment mark is a planar square diagonal mark. The sample fixing table according to claim 8, wherein
A sample fixing table, wherein the square diagonal line mark is formed on an upper surface of the sample mounting table and on a front surface or a rear surface thereof.

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