JP4016970B2 - Sample preparation apparatus and sample preparation method - Google Patents

Description

  The present invention is a sample preparation apparatus that uses an ion beam and a transfer means to extract only a part necessary for analysis or observation from a sample piece, and fixes it to a sample holder to process it into a shape suitable for analysis or observation. And a sample preparation method.

  As the integration of semiconductors increases, the need for analysis increases even if the object to be analyzed or observed is so fine that it cannot be observed with the resolution of a scanning electron microscope (hereinafter abbreviated as SEM). Therefore, a transmission electron microscope (hereinafter abbreviated as TEM) having a high observation resolution is a promising apparatus.

  As a conventional TEM sample preparation method, a method using polishing or ion thinning is well known. However, it is almost impossible to prepare a sample by limiting a desired observation region at a μm level. At the same time, it took several days to make one sample.

  Recently, an example using a focused ion beam (hereinafter abbreviated as FIB) processing is being established. First, a strip-shaped pellet including a region to be observed is cut out from a sample such as a wafer by using a dicing apparatus. The size of the pellet is approximately 3 × 0.1 × 0.5 mm (0.5 mm is the thickness of the wafer). A part of the strip-shaped pellet is FIB processed into a thin wall shape to obtain a TEM sample. The FIB-processed sample for TEM observation (TEM sample) has a shape as shown in FIGS. 2 (a) 20 and (b) 20 '. The cross-sectional shape of a TEM sample may be an inverted T-shape or an L-shape, and may be variously modified. However, basically, a part of a strip-shaped test piece is processed into a thin wall for TEM observation. There is to be. The width of the upper part 21 of the sample is about 40 μm, the width of the lower part 22 is about 100 μm, the dimensions of the TEM observation parts 23 and 23 ′ are about 10 μm × 5 μm, and the thickness is about 0.1 μm. Using such a sample as a TEM sample, a TEM holder is mounted on a TEM stage and introduced into a TEM apparatus to observe the wall portions 23 and 23 '. This method makes it possible to locate a desired observation portion from the wafer or chip at the μm level.

  This technique is described, for example, by E.C.G.Kirk et al. In the collection of papers Microscopy of SEM iconducting Materials 1989, Institute of Physics Series No.100., P.501-506 (Prior Art 1).

  Recently, a sample stage that can be used both as an FIB apparatus and a TEM apparatus has been used. FIG. 2C shows a schematic shape of the sample stage, which is a side entry type sample stage. The grip portion 24 is a portion for holding the sample stage 7 ′ by hand when the sample stage 7 ′ is put in and out of the apparatus, and for adjusting the tilt of the sample. At the tip of the cylindrical portion 25, FIG. 2A and FIG. The sample 20 (or 20 ′) is fixed by fixing jigs 26 and 26 ′. As shown in FIG. 3, the sample stage 7 'is introduced into the FIB apparatus 31, and the position thereof is adjusted by the sample stage fine movement mechanism 8'. The FIB is irradiated with FIB parallel to the wall portions 23 and 23 'during the FIB processing, and the electron beam is irradiated perpendicularly to the wall surface during the TEM observation. Therefore, the sample stage 7' has an axis of 90 ° between the FIB processing and the TEM observation. Use by rotating. Such a sample stage 7 'makes it possible to immediately bring the sample processed in the FIB apparatus into the TEM apparatus and observe it. However, even if FIB processing is used, the processing time is 3 to 5 hours for one sample. As described above, TEM can be expected to provide high-resolution observation, but it has a large amount of time for sample preparation and a skillful manual operation that must be performed with a sharp nerve. This sample stage for both FIB and TEM is described in Japanese Patent Application Laid-Open No. 6-103947, “Focused Ion Beam Device” (known example 2). In this known example 2, this sample stage is not only TEM but also SEM, etching. It is described that it can be directly mounted on an apparatus, a vapor deposition apparatus, and a laser processing machine.

  Further, as a method of extracting a specific minute sample produced in a wafer using an ion beam with a probe, Japanese Patent Publication No. 2774884, “Method for separating sample and method for analyzing separated sample obtained by this separation method” (known example) 3).

In addition, as another method of extracting a small sample from a wafer, the 58th JSAP Scientific Lecture Proceedings (October 1997, Akita University) 3p-ZL-8, p.666, TEM sample preparation method using micromanipulation technology "(known example 4).
In addition, a method in which only a thin film for TEM observation is produced in a wafer using a focused ion beam, and only this thin film is transferred onto a TEM mesh using a glass needle to form a TEM sample, for example, Material Research Society Symposium Proceedings, 1997 vol. 480., p19-27 (known example 5).

JP-A-6-103947

As described above, when preparing a sample suitable for analysis, observation, and measurement, particularly, a TEM sample preparation, there are many problems as follows.
Problems associated with known examples 1 and 2 are as follows.
(1) In order to produce a TEM sample, a plurality of apparatuses such as an ion thinning and polishing machine, or a dicing apparatus and an FIB apparatus are required.
(2) The work from sample preparation to TEM observation was complicated and time consuming.
The problems with the known example 3 are as follows.
(3) Since the produced TEM sample is held by the probe, it is difficult to introduce it into the TEM apparatus.
Problems relating to the known examples 4 and 5 are as follows.
(4) In attaching the prepared sample to the TEM sample stage, the operator's nerves are used and there is a possibility of an accident such as dropping or loss. Moreover, the same danger is hidden when replacing with another sample after TEM observation.

  In view of the above problems, the first object of the present invention is that the operations from sample preparation to analysis, observation, and measurement are simple, sample preparation can be performed with a single device, and delivery of the prepared sample to the analyzer is easy. A second object of the present invention is to provide a sample preparation method in which operations from sample preparation to analysis, observation, and measurement are simple and delivery of the prepared sample to the analyzer is easy. It is to provide.

The first purpose is to
(1) Ion beam irradiation optical system, secondary particle detection means for detecting secondary particles generated by ion beam irradiation, and transfer means for transferring an extracted sample obtained by separating a part of a sample piece to a sample holder; , Having at least a sample stage fine movement means for mounting and finely moving the side entry type sample stage, and the side entry type sample stage placing a first sample stage on which the sample piece is placed, and an extracted sample being placed This is realized by a sample preparation device constituted by a second sample stage to which a sample holder to be attached can be attached and detached. With this configuration, a sample can be prepared in one sample preparation device, and delivery to an analysis and observation device is simplified. Also,
(2) Ion beam irradiation optical system, secondary particle detection means for detecting secondary particles generated by ion beam irradiation, and deposition for supplying a source gas for forming a deposition film in the ion beam irradiation region Gas supply source, transfer means for transferring an excised sample from which a part of the sample piece has been separated to the sample holder, and a sample stage fine movement means for finely moving the side entry type sample stage mounted thereon, and further, side entry The mold sample stage is realized by a sample preparation apparatus including a first sample stage on which the sample piece is placed and a second sample stage on which a sample holder on which the extracted sample is placed can be attached and detached. With this configuration, the extracted sample can be transferred and fixed to the sample holder with the deposition film. Also,
(3) When the ion beam is at least one of a focused ion beam and a projected ion beam, accurate processing or high-speed processing is possible. In addition, (4) the first sample stage has a configuration in which the sample placement portion on which the sample piece is placed has a rotation mechanism that can rotate about an axis perpendicular to the first sample stage axis, thereby allowing the sample piece to be placed on the sample stage. Can be placed without worrying about the orientation of the desired cross section, and the desired cross section can be easily processed in the sample preparation apparatus. Also,
(5) The second sample stage is a focused ion beam device, a projection ion beam device, a transmission electron microscope, a scanning electron microscope, a scanning probe microscope, an Auger electron spectrometer, an electron probe X-ray microanalyzer, and an electron energy defect analysis. By setting it as a sample stage that can be loaded into any of an apparatus, a secondary ion mass spectrometer, a secondary neutral particle ionization mass spectrometer, an X-ray photoelectron spectrometer, or an electrical measurement device using a probe, Analysis, observation, etc. can be performed without changing the sample after sample preparation, and the possibility of sample breakage can be reduced. Also,
(6) The second sample stage is a focused ion beam device, a projection ion beam device, a transmission electron microscope, a scanning electron microscope, a scanning probe microscope, an Auger electron spectrometer, an electron probe X-ray microanalyzer, an electron energy defect analysis Place a sample holder for loading into any of the following devices: secondary ion mass spectrometer, secondary neutral particle ionization mass spectrometer, X-ray photoelectron spectrometer, or electrical measurement device using a probe By having a configuration having a holder installation part that performs the above, a prepared sample can be installed in a sample holder that is optimal for analysis and observation. Also,
(7) The first sample stage is a focused ion beam device, a projection ion beam device, a transmission electron microscope, a scanning electron microscope, a scanning probe microscope, an Auger electron spectrometer, an electron probe X-ray microanalyzer, an electron energy defect analysis By setting it as a sample stage that can be loaded into any of an apparatus, a secondary ion mass spectrometer, a secondary neutral particle ionization mass spectrometer, an X-ray photoelectron spectrometer, or an electrical measurement device using a probe, Sample cross-section analysis and observation can be performed easily. further,
(8) By having an etching gas supply source that supplies a gas that enables ion beam assisted accelerated etching of a sample, high-speed processing can be realized, and the sample preparation time can be reduced.
The second purpose is to
(9) The sample piece mounted on the first sample stage of the side entry method is processed by an ion beam, and the extracted sample obtained by extracting a part of the sample piece by the transfer means is temporarily held and changed to the first sample stage and side entry is performed. The second sample stage is loaded, the extracted sample is transferred to the sample holder on the second sample stage by the transfer means, and processed into a sample shape suitable for the desired analysis means, observation means or measurement means by the ion beam Therefore, it is possible to produce a sample in one apparatus. Also,
(10) The second sample stage loaded with the extracted sample is loaded into a desired analysis means, observation means, or measurement means, and analysis is performed in a short time after sample preparation by performing analysis by desired analysis, observation, or measurement. Observation becomes possible. Also,
(11) Analyzing means, observing means or measuring means are in particular focused ion beam devices, transmission electron microscopes, scanning electron microscopes, scanning probe microscopes, Auger electron spectroscopy analyzers, electron probe X-ray microanalyzers, electron energy Various sample analyzes are possible as long as it is one of a defect analyzer, secondary ion mass spectrometer, secondary neutral ionization mass spectrometer, X-ray photoelectron spectrometer, or electrical measurement device using a probe. It becomes possible. further,
(12) If the ion beam is a focused ion beam or a projected ion beam, accurate processing or high-speed processing is possible. In particular,
(13) Efficient sample preparation of a plurality of samples can be realized by mounting a plurality of test pieces on the first sample stage, extracting a part from each of the test pieces and transferring them onto the sample holder. ,
(14) A plurality of portions are extracted from one test piece mounted on the first sample stage and transferred to the sample holder installed on the second stage, so that it is intensive and efficient from one sample. Sample preparation is possible. In particular,
(15) A plurality of portions are extracted from one test piece mounted on the first sample stage and transferred to the same sample holder installed on the second stage, so that the analysis or observation apparatus can Multiple samples can be efficiently analyzed and observed simply by inserting two sample stages. Also,
(16) Marking that marks a sample for identifying a region to be analyzed or observed or measured with respect to a sample piece mounted on a first sample stage of a side entry method as a sample preparation method for observation, analysis, or measurement A step of forming a plurality of vertical holes around the mark by ion beam irradiation, a step of tilting the sample stage and forming an oblique groove with respect to the surface of the sample piece by ion beam irradiation, and The step of forming the wedge-shaped cantilever sample held by the support portion on the sample piece, the first sample stage is returned to the horizontal position, and a part of the transfer means is brought into contact with a part of the cantilever sample. Irradiating an ion beam to a region including a contact portion while supplying a deposition gas to form a deposition film, thereby fixing a part of the cantilever sample and the transfer means; A step of cutting the support portion by irradiating the film, a step of relatively separating the first sample stage and the transfer means, a step of pulling out the first sample stage from the apparatus, and a first sample stage instead of the first sample stage. (2) Inserting the sample stage into the apparatus; (2) moving the sample holder installed on the second stage so that it is located almost immediately below the extracted sample; Forming a deposition film by irradiating a portion of the contact portion between the sample holder and the sample to be extracted while forming a deposition film while supplying the deposition gas; A step of separating the transfer means and the extraction means by irradiating; and a step of producing an optimum sample for at least one of the analysis device, the observation device and the measurement device. One in a sample manufacturing apparatus Mukoto, analysis, simple sample can be prepared for analysis.

  With the sample preparation device or the sample preparation method according to the present invention, a necessary part can be extracted from a sample piece placed on a side entry type stage and mounted on a sample stage suitable for various analysis devices. In addition, except that the initial sample piece is placed on the first stage, since the sample is not directly touched by hand, there is an effect that there is no fear of damaging the sample.

Embodiments of the sample preparation apparatus according to the present invention include an ion beam irradiation optical system, secondary particle detection means for detecting secondary particles generated by ion beam irradiation, and an extracted sample from which a part of a sample piece is separated. And a transfer means for transferring the sample piece to the sample holder, and a side entry type first sample stage on which the sample piece is placed and a side entry type second sample stage on which the extracted sample is placed. It is set as the structure which has the sample stage drive mechanism mounted. First, the first stage is mounted on the stage drive mechanism, the target sample is extracted from the placed sample, is attached to the transfer means, the first stage is pulled out, and the second stage is replaced with the stage. Attach to the drive mechanism. The extracted sample extracted first is installed in the sample holder installed in the second stage. The processed sample is processed into a shape suitable for the intended analyzer. After the processing is completed, the second stage can be pulled out and loaded into the intended analyzer to analyze the desired region of the extracted sample. Hereinafter, specific examples will be described.
<Embodiment 1>
FIG. 1 is a schematic configuration diagram showing an embodiment of a sample preparation apparatus according to the present invention. Here, a TEM sample preparation method for TEM observation will be described as an example of an analysis means.

  The sample preparation apparatus 1 includes an irradiation optical system 4 of an ion beam 3 that processes and observes a sample piece 2, a secondary particle detector 5 that detects secondary particles generated by irradiation of the ion beam 3, and the ion beam. A deposition gas supply source 6 for supplying a source gas for forming a deposition film in the irradiation region 3; a sample stage fine movement mechanism 8 for finely moving a sample stage 7 on which a sample is placed in a side entry type; It has a structure having at least a transfer means 10 for transferring the extracted sample from which a part of the sample piece 2 is separated to the sample holder 9, and the side entry type sample stage 7 is a first stage on which the sample piece 2 is placed. -There are two types, the stage 7A and the second stage 7B on which the extracted sample is placed, and the sample stage fine movement means 8 can be replaced and mounted. A sample holder 9 for fixing the extracted sample can be attached to and detached from the second stage 7B. The second stage 7B is taken out from the sample stage fine movement mechanism 8 part of the sample preparation apparatus 1 as shown in FIG. For example, it can be loaded directly into the sample stage inlet 42 of the transmission electron microscope (TEM) 41. The sample stage 7B is a dual-purpose stage that can be loaded into other analysis devices such as a scanning electron microscope (SEM), a secondary ion mass spectrometer (SIMS), an Auger electron spectrometer (AES), and an electric circuit measurement device. It is. The sample preparation apparatus 1 further includes an ion beam control unit 11 that controls the irradiation optical system 4 of the ion beam 3, a secondary particle detector control unit 12 that adjusts an applied voltage to the secondary particle detector 5, and the like. Deposition gas supply source control means 13 for controlling the temperature adjustment of the deposition gas supply source 6 and opening / closing of the valve, a stage control section 14 for controlling the sample stage fine movement mechanism 8, and a transfer means 10 for driving It has a transfer means control section 15, an image display section 16 for displaying an image of the sample piece 2, the transfer means 10, etc., and these control sections are controlled by a calculation processing section 17.

  The sample piece 2 to be used is a small piece obtained by dividing a semiconductor wafer or an electronic device into several millimeters square. That is, the dimensions are such that they do not protrude from the sample placement portion of the first stage 7A.

  The ion beam irradiation optical system 4 is a well-known optical system. In the case of a focused ion beam (hereinafter abbreviated as FIB) as an example of the ion beam 3, a liquid metal ion source, a beam limiting aperture, and a focusing lens are used. FIB with a beam diameter of about 10 nm to about 100 nm can be formed by passing through the objective lens. By scanning the FIB over the sample using a deflector, processing corresponding to the scanning shape of the μm to sub-μm level can be performed on the sample surface. Processing here refers to forming a recess by sputtering, forming a film by FIB-assisted deposition, or changing the original shape of the sample by combining these. By detecting and imaging secondary particles such as secondary electrons and secondary ions generated during FIB irradiation with the secondary particle detector 5, it is possible to observe the processing region of the sample, the transfer means, and the like.

  The deposition gas supply source 6 is for supplying a gas to the sample as needed in order to deposit a gas component in the ion beam irradiation region, and the tip can intensively release the gas to a desired region. When the gas raw material is solid or powder, it has a heating part for heating and gasifying, a valve for controlling gas release, a nozzle position adjusting part, and the like. The deposition film to be formed is bonded to connect the probe (needle-like member) 18 at the tip of the transfer means 10 and the sample piece 2 or to fix the extracted micron-sized extracted sample to the sample holder 9. Use instead of wood. The material of the deposition film may be a metal material such as tungsten, copper or platinum.

The sample stage 7 is a side entry method and can be installed without releasing the vacuum in the sample chamber 19 of the apparatus. Further, when it is desired to extract the sample chamber 19, the sample chamber 19 can be extracted without breaking the vacuum. The side entry type sample stage has been used in TEM and in-lens type SEMs so far, and the principle of the side entry type stage and its driving mechanism is well known, but the sample stage 7 used here is a key related to the present invention. Since it is a point, it explains in full detail here.
A sample stage 7 used in the sample preparation apparatus 1 is installed to process a first stage 7A on which a small sample piece 2 including a region to be analyzed is mounted, and a micro sample having a shape suitable for the analysis apparatus. The second stage 7B is used. Both the first stage 7A and the second stage 7B have a shape that can be mounted on the sample stage fine movement mechanism 8, and each sample stage has such a dimension that the sample or the sample holder appears in the field of view by the ion beam. The second sample stage 7B can also be loaded into the analysis apparatus, and may be the sample stage 7 ′ (FIG. 3) used for both the FIB and the TEM described above. Since it has such a shape, it is also a great feature that TEM observation can be performed immediately by simply inserting / removing the sample stage 7 carrying the observation sample processed in the sample preparation apparatus 1 from the sample stage fine movement mechanism 8. In other words, a small sample extracted from a sample piece is processed into a sample shape suitable for analysis and observation without any special sample processing equipment or manual work requiring tension and skill, and the sample stage is inserted and removed. You can immediately move to analysis and observation.

  FIG. 5A is a perspective view of the first stage 7A. The first stage 7A includes a cylindrical part 51, a grip part 52 for holding or operating the sample stage 7A, a sample setting part 53 for mounting a sample piece 2 cut from a wafer or a chip, It includes small protrusions 54 for supporting the load of the first stage 7A, reducing vibrations, and preventing the rotation of the rotating shaft. Further, the grip portion 52 has an in-plane rotation adjusting portion 55 for causing the sample setting portion 53 to rotate around an axis parallel to the ion optical axis. By providing a rotation mechanism in the sample setting portion 53 so that the sample piece 2 can be rotated in the plane, the sample piece 2 can be adjusted in the in-plane rotation, and a desired observation surface (analysis surface or measurement surface) of the sample piece 2 can be obtained. It can be set parallel to the axis of the sample stage, and when the extracted sample is transferred to the second stage 7B, it is not necessary to cause the transfer means to make a complicated movement such as rotation. The movement in the direction perpendicular to the axis of the first stage 7A, that is, the direction perpendicular to and parallel to the ion beam axis, and the shaft rotation can be controlled by the sample stage fine movement mechanism 8. With such a mechanism and configuration, the sample piece 2 placed on the sample placement surface 53 can be rotationally corrected in a desired direction or moved, so that a desired fine portion can be observed and processed by the FIB.

  The second stage 7B is a stage for processing the extracted sample so as to be suitable for the analysis apparatus. FIG. 2B is a perspective view of the second stage 7B. Here, the analysis device corresponds to a TEM, and is a sample stage that serves as both the sample preparation device 1 and the TEM. FIG. 2C is an enlarged view near the tip of the second stage 7B, and the sample holder 9 for directly fixing the extracted sample is fixed by the fixing jigs 56 and 56 '. The sample holder used here is a rectangular thin piece 9a shown in FIG. 2 (d), and the dimensions are, for example, 1 mm in length, 5 mm in width, and 30 μm in thickness. The extracted sample 2a is fixed to the upper surface of the rectangular thin piece 9a. The shape and dimensions of the sample holder 9 are not limited to those shown here, but the basic process is to make the sample fixing surface as smooth as possible and to make the width as thin as possible, and to prevent obstructing the electron beam path during TEM observation. Thus, as long as such a concept is disclosed, many modifications are easy.

Next, the sample stage fine movement mechanism 8 can be finely moved in the ion beam axis direction and its vertical direction by the stage control device 11 while holding the sample stage axis horizontally. Since fine movement control in the axial rotation direction can also be performed, a rectangular concave portion is formed on the extracted sample by FIB, and then rotated about 30 ° to observe the side surface of the rectangular concave portion, that is, the cross section of the sample.
FIG. 3 shows the detailed structure of the transfer means 10 used in this embodiment. The transfer means 10 is composed of two parts, a coarse movement part 60 and a fine movement part 61. The tip is attached with a sharpened probe 18 that directly touches the extracted sample. In the coarse movement part 60, the support 63 can be moved in the XYZ axis direction by three encoders 64X, 64Z, 64Y (not shown) with the narrowed part 62 as a fulcrum. The coarse stroke and the moving resolution depend on the performance of the encoder and the ratio of the distance from the narrowed portion 62 to the encoder and the tip of the probe 18, but in this embodiment, it has a 5 mm stroke and a resolution of 2 μm. The springs 65a and 65b are used to resist the force generated by the encoder. The drive system of the coarse movement unit 60 is on the atmosphere side through the port of the sample chamber 19, and the vacuum is blocked by a vacuum seal 66 such as a gasket and a bellows 67.

  The fine movement part 61 uses only the Z axis and uses a bimorph piezoelectric element 68. The bimorph piezoelectric element 68 has an advantage that it has a relatively large stroke (several hundred μm or more) compared to other piezoelectric elements. For this reason, it is not necessary to require high positional accuracy for the coarse movement portion 60. Although the coarse moving part 60 used in this example has a vibration of several μm when driven, the vibration at rest is almost negligible. Therefore, the fine moving part 61 is used to make the closest approach to the sample piece and contact it. . At this time, since the position control of the tip of the tip probe 18 only needs to have a resolution of the order of μm, even a bimorph piezoelectric element having a relatively low resolution among piezoelectric elements can be sufficiently handled and can be manufactured at low cost.

The tip of the bimorph piezoelectric element 68 was connected to the probe 18 processed into a needle shape with a thin tungsten wire having a diameter of 50 μm to a tip radius of about 0.5 μm, and connected to the coarse movement part 60 by a column 63. By applying a voltage to the bimorph piezoelectric element 68, the tip of the probe 18 slightly moves in the Z direction. Reference numeral 69 denotes a voltage introduction terminal for applying a voltage to the piezoelectric element.
According to the known example 2, the transport means for transporting the separated sample comprises three bimorph piezoelectric elements corresponding to the XYZ axes. Since the bimorph piezoelectric element moves so that the other end bends at one end as a fulcrum, the other end draws an arc according to the applied voltage. When this bimorph piezoelectric element is assembled with three axes, it moves in a complicated manner. For example, in the movement in the XY plane, it is very difficult to move the probe to a desired position because the probe at the tip of the transport means does not move linearly in one axial direction only by the operation of one bimorph piezoelectric element. Therefore, when the fine movement part is constituted by three bimorph piezoelectric elements, in order to move the probe tip to a desired position, the three bimorph piezoelectric elements must be controlled in a complicated manner. On the other hand, in this embodiment, a coarse movement mechanism that moves three axes orthogonally is provided, and the bimorph piezoelectric element is used only for one axis of the fine movement portion, thereby reducing the complexity of positioning the probe.

  In the present invention, the transfer means 10 is independent of the sample stage 7 so as not to interfere with each other's operation. Further, the coarse moving part 60, which tends to be large in size, is installed as far as possible from the sample substrate, and the fine moving part 61 is composed of a fine moving mechanism of only the Z axis so as to be used for the secondary particle detector 5 or deposition. Interference with other surrounding structures such as the gas supply source 6 is avoided. As described above, the transfer means 10 must sufficiently consider the configuration, size, and installation position, but the sample preparation apparatus according to the present invention solves all of these.

  As described above, the sample preparation device having the configuration of the present embodiment can extract a micro sample at an arbitrary location from a sample piece divided into several mm square in the device, and can be fixed to a sample holder adapted to the analysis device. It is easy to process a sample suitable for the desired analysis, and the conventional manual work related to sample preparation that requires skill and time to analyze, observe, and measure is to place the sample piece on the sample installation surface first. This is realized only by changing the mounting of the sample holder without the operator touching the sample directly or reworking the mesh, such as refining the nerve and sharpening the nerve. As described above, the sample preparation device of the present invention has the effect of greatly reducing the time and freeing from mental pressure during sample preparation.

  Furthermore, as for the TEM sample, as a result of the TEM observation of the prepared sample, when the wall portion is not thick or the desired shape is obtained, the sample stage is simply pulled out from the TEM and inserted into the sample preparation apparatus again. The observation efficiency is very high because it has the convenience of being able to immediately perform additional work by FIB.

Although the FIB has been described here as a form of ion beam, it is also possible to perform regular processing using a projection ion beam using a stencil mask having an opening of a desired shape. The signal to be detected is not limited to secondary electrons, but may be secondary ions.
<Embodiment 2>
In the second embodiment, a sample preparation method using the sample preparation apparatus according to the present invention will be described with reference to FIGS.

  In order to extract a part of the micro sample from the sample piece, it is essential to separate the micro sample from the substrate. In the method of the known example 2, there are five cut surfaces, and processing time is required. Moreover, when the bottom surface is separated, the bottom surface of the extracted sample is inclined with an ion beam incident angle and a processing aspect ratio. In order to form a cross section or wall that is almost perpendicular to the surface of the sample piece, it is essential to reduce the bottom slope and stand the sample piece vertically on the top surface of the sample holder. There must be. Therefore, it is desirable to have a sample preparation method in which the processing time as aimed by the present invention is short, and when the extracted sample is transferred to a sample holder, which is another member, an operation such as greatly tilting the sample stage is minimized.

The specific procedure of the sample preparation method according to the present invention will be described below. Here, as a sample example, a method for preparing a sample for TEM observation will be described in which all steps from marking of a region to be observed to final wall processing are performed in the same apparatus.
The sample piece 2 is mounted on a first stage dedicated to mounting a small sample including the region to be analyzed, and is a semiconductor element of approximately 5 mm × 5 mm. Below, the process of producing the TEM sample for TEM observation of the cross section about the specific area | region of this sample piece is demonstrated corresponding to a figure.
FIG. 7A: First, the sample stage fine adjustment mechanism 8 is adjusted so that a desired region of the sample piece 2 mounted on the first stage enters the FIB irradiation region. Marks 71a and 71b for specifying the TEM observation surface 70 are attached on the sample piece 2 by the FIB 3a. The space between the two marks 71a and 71b is the TEM observation surface 70, and the distance between them is approximately 10 μm. In this embodiment, the + (plus) mark is used, but the present invention is not limited to this. Adjustment is performed by a rotation mechanism built in the sample stage 7A so that the straight line connecting the two marks is parallel to the tilt axis of the sample stage. With this adjustment, when the extracted sample is placed in the sample holder, the transfer means is not forced to move in a complicated manner. At this time, a deposition film is formed as a protective film so as to cover the TEM observation surface 70.
FIG. 7B: Two rectangular holes 72a and 72b are formed by FIB 3a on both sides of the two marks 71a and 71b.

  The opening size of the rectangular holes is, for example, 10 × 7 μm, the depth is about 15 μm, and the distance between both rectangular holes is 30 μm. In either case, the FIB 3a was processed with a large current FIB 3a having a diameter of about 0.15 μm and a current of about 10 nA in order to complete in a short time. The processing time was approximately 7 minutes.

Next, a width of about 2 μm, a length of about 30 μm, and a depth of about 2 μm apart from a straight line connecting the marks 71a and 71b, intersecting with one rectangular hole 72b and not intersecting the other rectangular hole 72a. A 10 μm narrow groove 73 is formed. The scanning direction of the beam is set so that the fine grooves 73 and the rectangular holes 72a and 72b are not filled with sputtered particles generated when the FIB 3a irradiates the sample piece 2. A small region that does not intersect with the rectangular hole 72a serves as a support portion 74 that supports a sample to be extracted later.
FIG. 7C: Next, the sample surface is tilted by rotating the first stage 7A. In this embodiment, the angle is 20 °. Here, since the straight line connecting the two marks 71a and 71b is set parallel to the tilt axis of the sample stage, it is tilted in the direction in which the narrow groove 73 is lowered. Therefore, an oblique groove 75 having a width of about 2 μm, a length of about 32 μm, and a depth of about 15 μm is formed on the surface of the sample piece 2 so as to connect the rectangular holes 72a and 72b with a distance of about 2 μm from the straight line connecting the marks 71a and 71b. It is formed by FIB 3a incident from an oblique direction. Scanning is performed so as not to fill the rectangular holes 72a and 72b formed by the sputtered particles by the FIB 3a irradiation. The oblique groove 75 intersects the previously formed narrow groove 73. The wedge-shaped sample 76 to be extracted, which includes the marks 71a and 71b and has a right triangle cross section with an apex angle of 20 °, is held only by the support portion 74.
FIG. 7D: Next, the sample stage 7A is returned to the horizontal position, and the probe 18 at the tip of the transfer means is brought into contact with the end opposite to the support 74 on the upper surface of the sample 76 to be extracted. Contact can be sensed by the electrical connection between the sample and the probe and the change in capacitance between them. In the present embodiment, detection was made by conduction between the two. In addition, in order to avoid damaging the sample 76 to be extracted and the probe 18 by careless pressing of the probe 18, the probe 18 has a function of stopping driving in the Z direction when the probe 18 contacts the sample.
FIG. 7E: Next, in order to fix the probe 18 to the sample 76 to be extracted, a deposition film 77 is formed in an area of about 2 μm square including the tip of the probe 18. Thereby, the probe 18 and the sample 76 to be extracted are connected. Next, in order to extract the sample 76 to be extracted from the sample piece 2, the supporting portion 74 is sputtered away by irradiation with the FIB 3a, thereby releasing the supporting state. Since the support 74 is 2 μm square and about 10 μm deep when viewed from above the sample surface, it can be removed by FIB 3a scanning for 2 to 3 minutes. Since the process of forming the rectangular holes 72a, 72b, the narrow grooves 73, and the oblique grooves 75 does not greatly affect the observation surface, it is wise to process quickly even if a slight displacement occurs in the FIB 3a with a large current. .
FIG. 7 (f): The extracted sample 2 a completely separated from the sample piece 2 is raised (moved in the + Z direction) while being kept away from the sample stage.
Here, the first stage 7A and the second stage 7B are interchanged. By mounting the second stage 7B, the vicinity of the center of the sample holder 9 enters the SIM image field of view.
FIG. 8A: In order to bring the extracted sample 2a into contact with the sample holder 9, the probe 18 is lowered (moved in the −Z direction) and brought close to the sample holder 9. Contact between the extracted sample 2a and the sample holder 9 can be detected by conduction.
FIG. 8B: After confirming that the extracted sample 2 a is in contact with the sample holder 9, a deposition film 80 is formed on the contact portion between the extracted sample 2 a and the sample holder 9, and the extracted sample 2 a is fixed to the sample holder 9. . The size of the deposition film 80 is about 3 μm square, and a part of the deposition film 80 is attached to the sample holder 9 and a part is attached to the side surface of the extracted sample 2a, and both are fixed.

Further, although it is desired that the TEM observation region of the sample is disposed on the rotation center axis of the sample stage 7B, the extracted sample 2a to be fixed is as small as several μm to 20 μm. If the holder 9 is arranged so that the upper surface of the holder 9 is on the axis of the sample stage, the TEM observation region can be easily provided in the TEM visual field.
FIG. 8C: Next, after stopping the introduction of the deposition gas, the FIB 3a is irradiated to the deposition film 77 connecting the probe 18 and the extracted sample 2a to remove the sputter, whereby the probe 18 is removed. It can be separated from the extracted sample 2a. By this operation, the extracted sample 2a becomes independent on the sample holder 9.
FIG. 8D: Finally, the observation part by TEM is irradiated with FIB 3a, and finish processing is performed so that the thickness of the observation region finally becomes the wall 81 of about 100 nm or less. At this time, since one of the side surfaces in the longitudinal direction of the extracted sample 2a is a vertical surface, when determining the irradiation area of the FIB 3a for wall processing, the vertical surface is used as a reference so that it is substantially perpendicular to the surface of the sample substrate. A wall 81 can be formed. As a result of this wall processing, a wall 81 having a width of about 15 μm, a depth of about 10 μm, and a width of 0.1 μm or less can be formed, and a TEM observation region is completed. As described above, the processing time from the marking to the completion of the wall processing is about 1 hour, which can be shortened to a fraction of that of the conventional TEM sample manufacturing method.

  Finally, after wall processing, the second stage 7B is pulled out from the sample preparation apparatus 1 and mounted in the sample chamber of the TEM. At this time, the second stage 7B is inserted by being rotated by 90 ° so that the electron beam path and the wall surface are perpendicular to each other. Since the subsequent TEM observation technique is well known, it is omitted here. Since the second stage 7B is a side entry type for both FIB and TEM, the sample stage can be pulled out immediately after wall processing and introduced into the TEM. If additional processing is required for the observation sample, the sample preparation device 1 can be used immediately. There is an effect that it can be returned and processed.

The sample preparation method is not limited to a TEM sample, but other analysis and observation methods such as Auger electron spectroscopy, electron probe X-ray microanalysis, electron energy deficiency analysis, secondary ion mass spectrometry, secondary neutral particles Ionization mass spectrometry, X-ray photoelectron spectroscopic analysis, transmission electron microscope, scanning electron microscope, scanning probe microscope, and measuring means can be used for sample preparation for electrical measurement using a probe.
The sample preparation method according to the present invention and the sample separation method according to the known example 3 are significantly different from each other in (1) the beam irradiation method for sample extraction (separation). In the present invention, the sample extraction is made as thin as possible. In order to easily separate the bottom surface, the side surface in the longitudinal direction (parallel to the TEM observation surface) is inclined, and (2) the extracted sample is transferred to a sample holder which is a member different from the transfer means. (3) The sample stage is a side-entry type, in which the original sample to be extracted is placed separately from the stage to be introduced into the analyzer, and two stages are inserted and removed during sample preparation. Therefore, the time from sample preparation to subsequent material analysis such as observation is greatly reduced.
In the above embodiment, the sample to be observed (analyzed) is extracted from the sample piece 2 by being adhered to the probe 18 by the deposition film 77 and fixed to the sample holder 9. In the basic apparatus configuration of the present application, The method can also be applied.
That is, a sample in the final form to be observed (analyzed) (for example, only a thin film for TEM observation) is prepared on the sample piece 2 on the first stage 7A, and the sample in the final form is formed by electrostatic force with the probe 18. Is adsorbed and removed. Next, the first stage is pulled out and the second stage is inserted. Here, as shown in FIG. 9, the second stage 7B ′ has a fixing jig 91 and a holding spring 92, and is a conventional TEM sample holding mesh (for example, a wire mesh) 90 coated with a thin film that easily transmits electrons such as carbon. Can be installed. On the mesh 90, the above-described final form sample extracted by the probe 18 is placed. The final sample and the mesh 90 are also adsorbed by electrostatic force. Thereafter, the second stage 7B ′ can be pulled out of the sample preparation apparatus 1 and inserted into the TEM as it is for TEM observation. Of course, other analysis can be performed by inserting into an analysis device other than TEM.

  In this way, by using this sample preparation method, a desired location on a device chip or a semiconductor wafer is marked on the spot, and it can be used for TEM observation or the like in the same apparatus without manual work requiring skill and tension. Samples for analysis, measurement, and observation can be prepared.

<Embodiment 3>
The present embodiment is an example in which the second stage is mounted on an analyzer other than TEM.
In the first embodiment, the second stage 2B is a stage that serves both as a TEM apparatus and a sample preparation apparatus. However, the analysis apparatus is not limited to a TEM, and an in-lens SEM (scanning electron microscope), In-lens SIMS (Secondary Ion Mass Spectrometer), AES (Auger Electron Spectrometer), circuit characteristic measuring device may be used. Of course, EDX (Electron X-ray Diffraction Spectrometer) function is added to TEM and SEM. The sample stage may be used for elemental analysis.

In particular, here, an example in which four sections of an excised sample are observed with an SEM is shown. A region including a desired observation surface is extracted from the sample placed on the first stage 2A. The means for extraction is as shown in Embodiment 1 (FIG. 1), and the method of extraction is as shown in Embodiment 2 (FIGS. 7 (a) to (f) and FIGS. 8 (a) to (c)). It is. After confirming that the extracted sample 2a is attached to the tip of the probe 18, the probe 18 is once moved away from the first stage 7A to prevent unexpected danger such as contact. Next, the first stage 7A is pulled out, and a second stage 7B that can also be installed in the SEM is inserted and stopped at a predetermined position. The probe 18 withdrawn first is brought close to the sample holder 9 mounted on the second stage 7B, carefully brought into contact with the sample holder 9, and fixed. The fixing method is also shown in Embodiment 2 (FIGS. 8B and 8C). Next, the periphery is deleted by an ion beam so that a desired observation surface remains on the fixed extracted sample 2a. Here, since the purpose is to observe four cross sections of the plug in the semiconductor device by SEM, the projection shape 100 as shown in FIG. 10 is processed by an ion beam so that the desired four cross sections remain. After the processing, the second stage 7B is pulled out from the sample preparation apparatus 1, and the second stage 7B is introduced into the SEM with the extracted sample 2a ′ after the processing attached.
Through the above steps, four cross sections of the protrusion shape 100 can be observed with an SEM.

  The second stage 7B includes a focused ion beam device, a transmission electron microscope, a scanning electron microscope, a scanning probe microscope, an Auger electron spectroscopic analyzer, an electron probe X-ray microanalyzer, an electron energy defect analyzer, a secondary ion. Since it is also used as a sample stage for a mass spectrometer, secondary neutral ionization mass spectrometer, X-ray photoelectron spectrometer, or electrical measurement device using a probe, the above microscope and various analyzes are performed prior to TEM sample preparation. Performing elemental analysis and observation with the device has the advantage that only the sample stage can be inserted and removed.

<Embodiment example 4>
The present embodiment is an example in which the first stage is mounted on the analysis apparatus.
In particular, here, an example in which a sample cross section is observed with an SEM is shown. That is, the first stage 7A is a stage that combines the sample preparation apparatus 1 and the SEM. FIG. 11A is an enlarged view of the distal end portion of the first stage 7A, and shows a state where the sample piece 2 to be observed is placed on the sample setting portion 53 and is introduced into the sample preparation device 1. FIG. The sample piece 2 ′ is processed by the FIB 3a to form a desired observation cross section 110 as shown in FIG. 11B, which is an enlarged view of the sample piece 2 ′. After processing, the first stage 7A is taken out from the sample preparation apparatus 1 and introduced into the SEM as it is. FIG. 11C is an enlarged view of the distal end portion of the first stage 7A introduced into the SEM. As shown in the enlarged view of the sample piece 2 ′ in FIG. 11D, the observation electron beam 112 of the SEM is desired. The cross section can be observed by tilting the first stage 7A so that the observation cross section 110 is irradiated. Since the first stage 7A has a rotation mechanism in the sample setting part 53, for example, when it is desired to observe the cross section 111 in FIG. 11B, the cross section 111 is rotated so as to be parallel to the tilt axis of the first stage 7A in the SEM. By adjusting and tilting the first stage 7A so that the electron beam 112 is irradiated onto the cross section 111, SEM observation can be easily performed. Here, if additional machining is required, the first stage 7A can be returned to the sample processing apparatus 1 as it is, reprocessed, and returned to the SEM for easy observation.
By using the first stage 7A as a stage for both the sample processing apparatus and the SEM in this way, it is possible to easily observe the sample without repositioning the sample on the SEM-dedicated stage after the cross-section processing as in the prior art. Become. In addition, the first stage can be introduced into another analysis apparatus as described in the third embodiment, so that observation can be performed with high efficiency as in the case of the SEM.

It is a schematic block diagram for demonstrating the sample preparation apparatus by this invention. It is a figure for demonstrating the conventional TEM sample preparation method, (a) is an inverted T-shaped sample, (b) is an L-shaped sample, (c) is an external view of a FIB-TEM combined stage. . It is a figure for demonstrating the introduction state to the FIB of the conventional FIB-TEM combined stage. It is a conceptual diagram for demonstrating delivery of the sample stage between the sample preparation apparatus and TEM by this invention. It is a figure for demonstrating an example of the sample stage used for the sample preparation apparatus of this invention, (a) is a 1st stage, (b) is a 2nd stage, (c) is a 2nd stage front end enlarged view. (D) is for demonstrating the sample holder mounted in a 2nd stage. It is sectional drawing for demonstrating an example of the transfer means used for the sample preparation apparatus of this invention. It is a figure for demonstrating the process using a 1st stage among the series of procedures of the sample preparation method of this invention. It is a figure for demonstrating the process using a 2nd stage among the series of procedures of the sample preparation method of this invention. It is an example of the tip enlarged view of the 2nd stage used for the sample preparation device of the present invention, and is a figure for explaining the 2nd stage which can fix a mesh especially. It is a figure for demonstrating an example of the sample preparation method for SEM cross section observation by the 2nd stage used for the sample preparation apparatus of this invention. It is a figure for demonstrating an example of the sample preparation method for SEM cross-section observation by the 1st stage used for the sample preparation apparatus of this invention, and (a) is the 1st stage front-end | tip part at the time of sample processing apparatus introduction especially (B) is a cross-sectional processing state, (c) is an external appearance of the tip of the first stage when the SEM is introduced, and (d) is a cross-sectional observation state. It is a schematic block diagram for demonstrating the sample preparation apparatus by this invention, and is a figure which shows the apparatus structure which has the storage chamber of the sample stage which is not used especially.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sample preparation apparatus, 2 ... Sample piece, 2a ... Extracted sample, 3 ... Ion beam, 3a ... FIB, 4 ... Irradiation optical system, 5 ... Secondary particle detector, 6 ... Deposition gas supply source, 7 ... Sample stage, 7A ... first stage, 7B ... second stage, 8 ... sample stage fine movement mechanism, 9 ... sample holder, 9a ... rectangular slice, 10 ... transfer means, 11 ... ion beam controller, 12 ... secondary particles Detector control section, 13 ... deposition gas supply source control means, 14 ... stage control section, 15 ... transfer means control section, 16 ... image display section, 17 ... calculation processing section, 18 ... probe (needle-like member), DESCRIPTION OF SYMBOLS 19 ... Sample chamber, 41 ... TEM, 42 ... Sample stage introduction port, 51 ... Cylindrical part, 52 ... Grip part, 53 ... Sample installation part, 55 ... In-plane rotation adjustment part, 56 ... Fixing jig, 60 ... Coarse movement 61, fine movement, 62 ... constriction, 63 ... support 64X, 64Y, 64Z ... encoder, 65a, 65b ... spring, 68 ... bimorph piezoelectric element, 70 ... TEM observation surface, 71a, 71b ... mark, 72a, 72b ... rectangular hole, 73 ... narrow groove, 74 ... support part, 75 ... Diagonal groove, 76 ... Sample to be extracted, 77, 80 ... Deposition film, 81 ... Wall, 90 ... Mesh, 91 ... Fixing jig, 92 ... Holding spring, 100 ... Projection shape, 110 ... Observation cross section, 111 ... section, 112 ... electron beam.

Claims (4)

An irradiation optical system for generating an ion beam;
Secondary particle detecting means for detecting secondary particles generated by irradiation of the ion beam;
A side entry type first sample stage on which a sample is placed;
A sample stage fine movement mechanism for mounting and finely moving the side entry type first sample stage;
A sample chamber for storing the sample in a state of being placed on the side entry type first sample stage;
A transfer means for extracting and holding a sample piece prepared from the sample by processing with the ion beam;
The sample chamber has a structure in which a side entry type second sample stage on which a sample holding mesh on which the extracted sample piece is transferred is mounted can be replaced with the first sample stage and mounted on the fine movement mechanism. And
The transfer means, the sample pieces were held by suction by electrostatic force, said from the side entry type first sample stage, sample processing, characterized by transferring the second sample stage of the side entry type apparatus. The sample processing apparatus according to claim 1,
A sample processing apparatus, wherein the holding mesh is coated with carbon. In sample processing method of work made fine small sample piece from the sample stored in the sample chamber by ion beam irradiation,
A side entry type first sample stage on which the sample is placed is inserted into the sample chamber;
Wherein the sample placed on the sample stage by irradiating an ion beam to create made the sample piece,
The the acting made by sample pieces were held excised adsorbed by electrostatic force,
In place of the first sample stage, a side entry type second sample stage equipped with a sample holding mesh on which the extracted sample piece is transferred is inserted,
Sample processing method characterized by transferring the excised sample piece to the sample holding mesh in the sample chamber. In the sample processing method of Claim 3,
Sample processing method characterized by adsorbing the excised sample piece to the sample holding mesh by electrostatic force.

Images