JP2006010397A - Sample preparation method and sample analysis method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of preparing easily a sample suitable for analyzing the surface state of a thin film and the state of a plane parallel to the surface. <P>SOLUTION: After forming an etching groove 16 reaching a soluble film 12 so as to enclose an analysis object domain 10R by irradiating FIB 15A, 15B toward a laminated film 10Z, a bottom part 12B which is a part in contact with an intermediate pattern 13 is dissolved and removed by using acid solution capable of dissolving only the soluble film 12 among a wafer 11, the soluble film 12 and an intermediate film 13Z, to thereby form the sample 10 for analysis. The acquired sample 10 for analysis is taken out by grasping its side surfaces 10W. Hereby, the sample 10 for analysis suitable for analyzing the surface state and the state of a plane parallel to the surface by using a SEM or a TEM can be formed easily and highly accurately without fouling the surface of an analysis object film pattern 14. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sample preparation method for cutting out an analysis sample including a thin film pattern having a predetermined shape from a thin film formed on a substrate, and a sample analysis method for analyzing the sample.

  2. Description of the Related Art Conventionally, when a minute portion of a thin film formed on a wafer is analyzed, observation with a transmission electron microscope (TEM) or a scanning electron microscope (SEM) has been performed. When analyzing a minute portion of a thin film using such a TEM or SEM, the thin film on the wafer is predetermined so as to include an area to be analyzed (analysis target area) for convenience of the apparatus configuration. It is necessary to cut out a thin film pattern of the size.

  As a method of cutting out the analysis sample including the thin film pattern, machining that cuts using a diamond saw or the like can be cited. However, in such machining, it has been difficult to obtain a size of about 100 μm or less due to the problem of dimensional accuracy. In addition, the damage given to the sample during processing was not small. In view of this, a method of cutting out an analysis sample having a minute dimension by irradiating a focused ion beam and selectively etching a thin film has been proposed (for example, refer to Patent Document 1).

In Patent Document 1, by irradiating FIB from two directions to a region to be analyzed in a thin film on a wafer, a block-shaped analysis sample including the surface of the thin film is cut out without damaging the wafer. ing. At this time, the probe from the outside is bonded in advance to the surface of the thin film before being cut out so as to support the cut-out analysis sample.
JP-A-5-52721

  By the way, it may be necessary to analyze the component analysis, density distribution, and film thickness distribution of the thin film formed on the wafer and in the film formation plane parallel to the surface.

  However, although the preparation method disclosed in Patent Document 1 can produce a sample suitable for cross-sectional analysis, it is suitable for analysis of the surface state of a thin film and a state in a film formation plane parallel to the surface. It was very difficult to prepare a sample for analysis.

  For example, when an SEM observation is performed on the surface of a thin film in an analysis sample of Patent Document 1, a probe is connected to the surface of the thin film, and a deposited film is formed as a fixing material with the probe. So it is virtually impossible to observe. Therefore, a method of cutting out an analysis sample having a larger surface area and securing a thin film surface on which no probe or deposited film is provided can be considered. However, when this method is employed, there is a problem that the processing time for forming the bottom surface (surface opposite to the surface) of the sample for analysis by etching increases depending on the size of the surface area. . In addition, it is impossible to make the incident direction of the focused ion beam parallel to the surface of the thin film, and it must be oblique, so that the bottom surface of the sample for analysis is necessarily inclined with respect to the surface of the thin film. End up. For this reason, since the increase in the surface area is accompanied by an increase in the thickness of the sample for analysis itself, the upper limit is actually about 20 μm square (that is, the surface area of the analysis target region is limited to the film thickness of the thin film). ) Even if such a method is adopted, the analysis sample has an inclined bottom surface, and is not suitable for SEM observation as it is. Therefore, in order to obtain a thin sample suitable for SEM observation, further additional processing is required.

  The present invention has been made in view of such a problem, and a first object of the present invention is to prepare a sample capable of easily producing a sample suitable for analyzing the surface state of a thin film and a state in a plane parallel to the surface. It is to provide a method. A second object of the present invention is to provide a sample analysis method capable of easily analyzing a surface state of a thin film and a state in a plane parallel to the surface using a sample obtained by such a manufacturing method. It is to provide.

The sample preparation method according to the present invention includes the following steps (1) to (3).
(1) A step of forming a laminated film in which a soluble film, an intermediate film, and an analysis target film including an analysis target region are sequentially stacked on the substrate from the substrate side.
(2) By selectively etching the laminated film using a dry etching method or a laser etching method, an etching groove reaching at least a soluble film is provided along the outer edge of the analysis target region, and the analysis target film pattern and the intermediate film Forming a pattern;
(3) By using a solvent capable of dissolving only the soluble film among the substrate, the soluble film and the intermediate film, by dissolving and removing at least a part of the soluble film in contact with the intermediate film pattern, Forming a sample for analysis comprising a film pattern;

  In the sample preparation method according to the present invention, an etching groove reaching at least the soluble film is continuously formed along the outer edge of the analysis target region in the analysis target film by the dry etching method or the laser etching method, and further the soluble groove is formed. The solvent capable of dissolving only the film dissolves and removes at least a portion of the soluble film in contact with the intermediate film pattern. As a result, the analysis sample is separated along the bottom surface of the intermediate film without being supported by other members or means.

  In the sample preparation method according to the present invention, it is preferable that the method further includes a step of taking out the analysis sample by grasping a side surface thereof.

  In the sample manufacturing method according to the present invention, an etching groove can be formed by irradiation with a focused ion beam or a laser beam. At that time, it is desirable to remove the soluble membrane until the thickness is less than half.

  In the sample preparation method according to the present invention, it is preferable that the method further includes a step of forming a buffer tank connected to the etching groove in a region excluding the analysis target region on the substrate, and particularly occupies a larger region than the etching groove. Thus, it is desirable to form the buffer tank.

In the sample preparation method according to the present invention, a soluble layer is formed using a metal material, and an acidic solution can be used as a solvent. In that case, it is desirable to form the substrate and the intermediate layer using aluminum oxide (Al ₂ O ₃ ). Furthermore, hydrochloric acid, nitric acid, aqua regia or sulfuric acid is used as an acidic solution, and aluminum (Al), gold (Au), cobalt (Co), chromium (Cr), copper (Cu), iron (as a metallic material) Fe containing at least one of nickel (Ni), palladium (Pd), platinum (Pt), rhodium (Rh), ruthenium (Ru), tantalum (Ta) and titanium (Ti) is used. it can.

In the sample preparation method according to the present invention, a soluble layer may be formed using silicon oxide (SiO ₂ ), and hydrofluoric acid may be used as a solvent. In that case, it is desirable to form the substrate and the intermediate layer using silicon (Si).

Further, in the sample preparation method according to the present invention, a soluble layer may be formed using aluminum oxide (Al ₂ O ₃ ), and an alkaline solution may be used as a solvent. Or while forming a soluble layer using an organic material, you may make it use an organic solvent as a solvent. In that case, a novolak resist or an acrylic resist is used as the organic material, and an organic solvent containing at least N-methylpyrrolidone is used.

The sample analysis method according to the present invention includes a sample preparation step for preparing an analysis sample and a sample analysis step for analyzing the analysis sample using a scanning electron microscope or a transmission electron microscope. is there. The sample preparation process includes the following processes (1) to (3).
(1) A step of forming a laminated film in which a soluble film, an intermediate film, and an analysis target film including an analysis target region are sequentially stacked on the substrate from the substrate side.
(2) By selectively etching the laminated film using a dry etching method or a laser etching method, an etching reaching at least a soluble film is provided along the outer edge of the analysis target region, and an analysis target film pattern and intermediate Forming a film pattern;
(3) By using a solvent capable of dissolving only the soluble film among the substrate, the soluble film and the intermediate film, by dissolving and removing at least a part of the soluble film in contact with the intermediate film pattern, Forming a sample for analysis comprising a film pattern;

  In the sample analysis method according to the present invention, in the sample preparation process, an etching groove reaching at least the soluble film is continuously formed along the outer edge of the analysis target region in the analysis target film by a dry etching method or a laser etching method. Furthermore, at least a part of the soluble film in contact with the intermediate film pattern is dissolved and removed by a solvent capable of dissolving only the soluble film. As a result, the analysis sample is separated along the bottom surface of the intermediate film.

  In the sample analysis method according to the present invention, it is desirable that the sample preparation step further includes a step of taking out the analysis sample by gripping the side surface.

  According to the sample preparation method of the present invention, an etching groove reaching at least a soluble film is continuously formed along the outer edge of the analysis target region in the analysis target film by a dry etching method or a laser etching method. Since at least a part of the soluble film in contact with the intermediate film pattern is dissolved and removed by a solvent capable of dissolving only the dissolved film, an analysis sample having a flat bottom surface can be produced. By controlling the thicknesses of the intermediate film and the analysis target film during film formation, an analysis sample having a desired thickness can be obtained. Therefore, it is possible to obtain a sample for analysis according to the purpose and application of the analysis without additional processing.

  According to the sample preparation method of the present invention, in particular, when the sample is taken out by grasping the side surface of the sample for analysis, the sample for analysis can be easily taken out without touching the surface of the analysis target film pattern. Therefore, a sample suitable for analyzing the surface state of the analysis target film and the state in a plane parallel to the surface of the analysis target film can be obtained.

  According to the sample analysis method according to the present invention, in the sample preparation step, an analysis sample having a flat bottom surface and a thickness suitable for analysis in a scanning electron microscope or a transmission electron microscope can be prepared. Samples can be easily analyzed.

  According to the sample analysis method of the present invention, in the sample preparation process, in particular, when the analysis sample is taken out by grasping the side surface, the sample for analysis can be easily prepared without touching the surface of the analysis target film pattern. It can be taken out. Therefore, accurate analysis of the surface state of the analysis target film and the state in a plane parallel to the surface of the analysis target film can be easily performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  Initially, with reference to FIGS. 1-6, the sample preparation method which concerns on one embodiment of this invention is demonstrated. As shown in FIG. 1, the sample preparation method of the present embodiment takes out a portion corresponding to an analysis target region (analysis target region) 10R from a laminated film 10Z formed on a predetermined wafer. The analysis sample 10 (FIG. 5) is prepared. In particular, in the present embodiment, a focused ion beam (FIB) etching method and a chemical etching method are used in combination.

Specifically, first, as shown in FIG. 2, a soluble film 12 and an intermediate layer are formed on a wafer 11 made of, for example, aluminum oxide (Al ₂ O ₃ ) or AlTiC (Al ₂ O ₃ .TiC). The laminated film 10Z is formed by sequentially laminating the film 13Z and the analysis target film 14Z. Here, for example, a sputtering method can be used.

The analysis target film 14Z is, for example, a single layer film or a laminated film made of metal, and a specific example is a magnetoresistive element in a thin film magnetic head. The soluble film 12 is made of aluminum (Al), gold (Au), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), palladium (Pd), platinum (Pt). , Rhodium (Rh), ruthenium (Ru), tantalum (Ta) and titanium (Ti), or a metal material such as an alloy in which these elements are arbitrarily combined. For example, when the magnetoresistive film is the analysis target film 14Z as described above, a thin film magnetic head shield layer (for example, 2 μm thickness) and electrode film (for example, a laminated film of a 5 nm thick titanium layer and a 50 nm thick copper layer) ) Corresponds to the soluble membrane 12. The intermediate film 13Z is an Al ₂ O ₃ layer having a thickness of ₃₀ nm to 50 nm, for example. When the analysis target film 14Z is a writing magnetic pole tip (pole) in the thin film magnetic head and the fusible film 12 is a shield layer, the intermediate film 13Z has an Al ₂ thickness of, for example, ₂ μm to 3 μm. O ₃ layer. The intermediate film 13Z is desirably 5 μm or less in order to ensure ease of sample preparation.

  After forming the laminated film 10Z, a focused ion beam (FIB) is irradiated while scanning so as to surround the analysis target region 10R in the analysis target film 14Z. Here, the analysis target region 10R is, for example, a square having a side of 200 μm. As shown in FIG. 3, the FIB 15A is irradiated along the square outline in a direction perpendicular to the surface of the laminated film 10Z (that is, the surface of the analysis target film 14Z) 14S, and the angle θ with the FIB 15A is set. By irradiating the formed FIB 15B, the film is selectively removed from the surface 14S of the laminated film 10Z until reaching the soluble film 12 in the thickness direction. Here, it is desirable to remove the soluble membrane 12 until the thickness is less than half of the original thickness. As a result, the etching groove 16 is formed so as to surround the analysis target region 10R, and the analysis target film pattern 14 and the intermediate film pattern 13 are formed. At this time, since the FIB 15A and the FIB 15B make an angle θ with each other, the cross-sectional shape of the etching groove 16 becomes a wedge shape whose width increases toward the surface 14S. By setting it as such a cross-sectional shape, injection | pouring of the etching liquid 17 (FIG. 4) at the following process becomes easy, and workability | operativity at the time of taking out the analysis sample 10 finally obtained improves.

  Next, as shown in FIG. 4, an etching solution 17 is injected into the etching groove 16. At that time, the etching solution 17 does not contaminate the surface 14S of the analysis target film 14Z. The etching solution 17 is an acidic solution that can dissolve only the soluble film 12 among the wafer 11, the soluble film 12, and the intermediate film 13Z. Specifically, hydrochloric acid, nitric acid, aqua regia or sulfuric acid is used. By injecting such an etchant 17, the portion (bottom portion 12 </ b> B) in contact with the intermediate film pattern 13 and the peripheral portion of the soluble film 12 can be dissolved and removed (see FIG. 5). At this time, an etching solution 17 is additionally injected as necessary.

  By dissolving the bottom 12B, the periphery of the intermediate film 13Z and the analysis target film 14Z in the analysis target region 10R is all removed and isolated, and the analysis sample 10 is formed. The analysis sample 10 is a laminate of the intermediate film pattern 13 and the analysis target film pattern 14 and has a side surface 10W and a bottom surface 10B. Here, after injecting the etching solution 17, the dissolution of the bottom 12 </ b> B may be promoted by applying vibration by adding ultrasonic waves or the like.

  After the bottom portion 12B is sufficiently dissolved, the analysis sample 10 is taken out with tweezers or the like as shown in FIG. At this time, if both side surfaces 10W of the analysis sample 10 are gripped, they can be taken out without touching the surface 14S. Further, since the cross-sectional shape of the etching groove 16 is a wedge shape so that the width does not increase toward the surface 14S, the etching groove 16 can be taken out relatively easily. As described above, it is possible to obtain the analysis sample 10 in which the surface 14S of the analysis target film pattern 14 is not contaminated. When the internal structure of the analysis target film pattern 14 is observed using a TEM or the like, the analysis sample 10 is further subjected to several tens of times by electrolytic polishing or the like as necessary in order to transmit the electron beam. Adjust to a thickness of ˜100 nm.

  Further, as shown in FIGS. 7A and 7B, a buffer tank 18 connected to the etching groove 16 by a flow path 19 is provided in advance in a region excluding the analysis target region 10R on the wafer 11. Is preferred. FIG. 7A illustrates a planar configuration, and FIG. 7B illustrates a cross-sectional configuration in the arrow direction along the VII-VII cutting line illustrated in FIG. The buffer tank 18 occupies a larger area than the etching groove 16 and has a substantially circular planar shape. The flow path 19 is shallower than the bottom surface of the buffer tank 18, and is elongated in the direction connecting the buffer tank 18 and the etching groove 16. For this reason, by injecting the etching solution 17 into the buffer tank 18 away from the analysis target region 10 </ b> R, it can be indirectly injected into the etching groove 16 through the flow path 19. Furthermore, since the bottom surface of the flow path 19 is shallower than the bottom surface of the buffer tank 18, when the liquid level height of the etching solution 17 poured into the buffer tank 18 is set higher than the bottom surface 19B of the flow path 19, Implantation into the etching groove 16 is performed. Therefore, by appropriately adding the etching liquid 17 to the buffer tank 18 while comparing the liquid level heights of both in the buffer tank 18 and the etching groove 16, a necessary amount of the etching liquid 17 is passed through the flow path 19. Can be met. At this time, since the buffer tank 18 occupies a larger area than the etching groove 16, the change in the liquid level is moderate as compared with the case where the buffer tank 18 is poured directly into the etching groove 16. Therefore, excessive care for preventing the surface 14S from becoming dirty is unnecessary, and the etching solution 17 can be injected relatively easily. In addition, the planar shape of the buffer tank 18 is not limited to a circle, and may be a square or other polygons.

  Subsequently, a sample analysis method according to an embodiment of the present invention will be described with reference to FIGS. 8 and 9. In the sample analysis method of the present embodiment, the analysis sample 10 obtained by the above-described sample preparation method is analyzed using SEM or TEM.

  FIG. 8 shows the configuration of the SEM 20 used in the sample analysis method of the present embodiment. The SEM 20 is used to observe the microstructure on the surface using secondary electrons (from the analysis sample 10) obtained by irradiating the analysis sample 10 with an electron beam. Unlike a TEM, a stereoscopic image can be obtained, and even when the surface 14S of the analysis sample 10 has large irregularities, it is possible to focus on almost the entire observation area. Further, the analysis sample 10 irradiated with the electron beam emits reflected electrons, Auger electrons or X-rays (characteristic X-rays and continuous X-rays) in addition to secondary electrons, and this is detected by a predetermined detector. By doing so, various types of analysis are possible. For example, by detecting the characteristic X, elemental analysis (elemental qualitative analysis and element distribution state investigation) can be performed.

  The SEM 20 includes a scanning coil 22, an objective lens 23, a focusing lens 24, and an electron gun 25 along the optical axis Z1 in order from the analysis sample 10 side, and a housing (not shown) together with the analysis sample 10. Is housed in. Further, a detector 26 for detecting secondary electrons or the like from the analysis sample 10 is provided in the casing. The detector 26 is connected to a cathode ray tube (CRT) 28 via a video amplifier 27 such as a photomultiplier tube (PMT).

  The electron gun 25 is an electron beam source called a thermionic emission type, and mainly includes a cathode (filament) 25A, a Wehnelt 25B, and an anode (acceleration electrode) 25C. The cathode 25A is made of tungsten (W), for example, and is heated by application of a voltage to emit electrons. Further, a negative voltage is applied to the cathode 25A with the anode 25C as the ground potential. A minus voltage (bias voltage) slightly lower than that of the cathode 25A is applied to the Wehnelt 25B. The Wehnelt 25B focuses electrons from the cathode 25A to form an electron beam bundle having a high electron density. The diameter of the electron beam bundle immediately after passing through the Wehnelt 25B is, for example, about 10 μm to 30 μm. The anode 25C functions to accelerate the electron beam bundle from the Wehnelt 25B.

  The objective lens 23 and the focusing lens 24 are called electron lenses, and generate an electric field or a magnetic field, so that the electron beam bundle from the electron gun 25 is finally irradiated onto the surface 14S of the analysis sample 10. The size is reduced so that the spot diameter is about several nm. You may make it provide an electronic aperture as needed.

  The scanning coil 22 is a set of deflection coils for scanning the electron beam bundle from the electron gun 25 in an arbitrary direction by generating a magnetic field. As shown in FIG. 8, the scanning coil 22 may be disposed closer to the sample 10 for analysis than the objective lens 23, or may be disposed between the focusing lens 24 and the objective lens 23. .

  In the SEM 20 having such a configuration, first, the inside of the housing is evacuated. Next, the cathode 25A is heated to emit electrons, and the electrons are focused at the Wehnelt 25B to form an electron beam bundle. Further, the electron beam bundle is accelerated by the anode 25C and emitted toward the focusing lens 24. The electron beam bundle is narrowed down to a minute spot diameter by passing through the focusing lens 24 and the objective lens 23, and is guided to a desired region in the analysis target film pattern 14 of the analysis sample 10 by the scanning coil 22. By irradiating the analysis sample 10 with the electron beam bundle, secondary electrons and the like are emitted, and these are captured by the detector 26. The secondary electrons that collide with the phosphor screen in the detector 26 are converted into light. After this light is amplified by the video amplifier 27 and then input to the cathode ray tube 28, an observation image of the surface 14S of the analysis sample 10 can be displayed on the screen.

  On the other hand, FIG. 9 shows the configuration of the TEM 30 used in the sample analysis method of the present embodiment. The TEM 30 is for observing the internal fine structure using an electron beam having information of the analysis sample 10 obtained by transmitting the analysis sample 10. In TEM, it is possible to observe at the atomic level by obtaining a projection image of several tens of thousands times or more, and in the same manner as in SEM, by irradiating an electron beam, the analysis sample 10 is reflected electrons, Auger electrons or X-rays ( Characteristic X-rays and continuous X-rays) are emitted, and various analyzes can be performed using this. In the TEM 30, an electron gun 31 as an electron beam source, an irradiation lens system 32, an imaging lens system 33, and an image sensor 34 are sequentially arranged in a housing (not shown). The analysis sample 10 is provided between the irradiation lens system 32 and the imaging lens system 33. The electron gun 31 has the same configuration as the electron gun 25 in the SEM 20, and includes a cathode 31A, a Wehnelt 31B, and an anode 31C. The irradiation lens system 32 has first and second focusing lenses 32A and 32B, and irradiates the sample 10 for analysis with the electron beam bundle from the electron gun 31. The imaging lens system 33 includes an objective lens 33A and an intermediate lens 33B for enlarging the electron beam bundle that has passed through the analysis sample 10, and a projection lens 33C for forming an image on the image sensor 34. . The imaging device 34 is, for example, a charge coupled device (CCD).

  In the TEM 30 having such a configuration, first, the inside of the housing is evacuated. Next, the cathode 31A is heated to emit electrons, which are converged in the Wehnelt 31B to form an electron beam bundle having a high electron density. Further, the electron beam bundle is accelerated by the anode 31C and directed to the irradiation lens system 32. To radiate. The electron beam bundle is narrowed down to a minute spot diameter by the irradiation lens system 32 and irradiated to the analysis sample 10. Since the irradiated electron beam bundle passes through the analysis sample 10, an observation image of the internal structure of the analysis sample 10 can be obtained by projecting it onto the image sensor 34 through the imaging lens system 33. A fluorescent screen may be used instead of the image sensor 34.

  As described above, according to the present embodiment, first, the etching groove 16 reaching the soluble film 12 is formed so as to surround the analysis target region 10R by irradiating the FIB 15A, 15B to the laminated film 10Z. That is, since the side surface 10W is formed by the FIB etching method, higher dimensional accuracy can be secured as compared with the photolithography method or the like.

  On the other hand, since the bottom surface 10B is formed by a chemical wet etching method (specifically, an etching solution 17 that can dissolve only the soluble film 12 out of the wafer 11, the soluble film 12, and the intermediate film 13Z). Even if the analysis target region 10R has a relatively large dimension (for example, 200 μm × 20 μm) (for example, 200 μm × 200 μm), the bottom 12B and its peripheral portion are dissolved and removed. Unlike the case where the bottom surface is formed by the FIB etching method, the bottom surface 10B parallel to the surface 14S can be formed, and the thickness of the entire analysis sample 10 can be reduced. Further, since the side surface 10W of the obtained analysis sample 10 is grasped and taken out, the surface 14S of the analysis target film pattern 14 can be prevented from being stained.

  Since the analysis target region 10R of the analysis sample 10 is analyzed using SEM or TEM, accurate analysis of the state of the surface 14S and the state in a plane parallel to the surface 14S is easily performed. be able to. In addition, when the sample 10 for analysis is cut | disconnected and a laminated cross section is formed, the analysis of the laminated cross section is also possible.

While the present invention has been described with reference to the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made. For example, in the above embodiment, a soluble film is formed using a metal material and an acidic solution is used as a solvent. However, the present invention is not limited to this. For example, a soluble film may be formed using silicon oxide (SiO ₂ ) and hydrofluoric acid may be used as a solvent. In that case, it is desirable to form the substrate and the intermediate film using silicon (Si). In addition, the substrate and the intermediate film can be formed using a metal material. In that case, for example, a soluble film may be formed using aluminum oxide (Al ₂ O ₃ ) and an alkaline solution may be used as a solvent. Or you may make it use an organic solvent as a solvent while forming a soluble film | membrane using an organic material. As a specific example, a novolak resist or an acrylic resist is used as the organic material, and an organic solvent containing at least N-methylpyrrolidone is used.

  In the above embodiment, the analysis target film is a single layer film or a laminated film made of metal. However, the present invention is not limited to this, and a resist film (organic functional film), diamond-like carbon (DLC), or others It may be a single layer film or a laminated film made of the insulating material.

  In the above embodiment, the etching groove is formed by irradiating the FIB to obtain the analysis target film pattern. However, the present invention is not limited to this, and the laser beam may be irradiated. Alternatively, an etching groove can be formed by milling after providing a photoresist mask having a predetermined shape.

  In the above embodiment, the case where the analysis sample is analyzed by irradiating the electron beam using SEM and TEM is described, but the present invention is not limited to this. For example, an analysis method for performing analysis by irradiating X-rays or ion beams can be used. Examples of such analysis techniques include X-ray photoelectron spectroscopy (XPS), secondary ion mass spectrometry (SIMS), or Rutherford backscattering analysis (RBS). Spectrometry).

  The sample preparation method and sample analysis method of the present invention can be suitably used for analysis of various thin film patterns included in electronic / magnetic devices such as semiconductor elements and magnetoresistive elements, for example.

It is a top view showing 1 process in the sample preparation method concerning one embodiment of the present invention. It is sectional drawing corresponding to the top view shown in FIG. FIG. 2 is a cross-sectional view illustrating a process following FIG. 1. FIG. 4 is a cross-sectional view illustrating a process following FIG. 3. FIG. 5 is a cross-sectional view illustrating a process following FIG. 4. FIG. 6 is a cross-sectional view illustrating a process following FIG. 5. It is sectional drawing showing the modification of the process shown in FIG. It is the schematic showing the structure of SEM used in the sample analysis method which concerns on one embodiment of this invention. It is the schematic showing the structure of TEM used in the sample analysis method which concerns on one embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sample for analysis, 10R ... Analysis object area, 10Z ... Laminated film, 11 ... Wafer, 12 ... Soluble film, 12B ... Bottom part, 13 ... Intermediate film pattern, 13Z ... Intermediate film, 14 ... Analysis object film pattern, 14S ... surface, 14Z ... analysis target film, 15 (15A, 15B) ... focused ion beam (FIB), 16 ... etching groove, 17 ... etching solution, 18 ... buffer tank, 19 ... flow path, 20 ... SEM, 22 ... scanning Coil, 23 ... objective lens, 24 ... focusing lens, 25 ... electron gun, 26 ... detector, 27 ... video amplifier, 28 ... cathode ray tube (CRT), 30 ... TEM, 31 ... electron gun, 32 ... irradiation lens system, 33: Imaging lens system, 34: Image sensor.

Claims (19)

Forming a laminated film in which a soluble film, an intermediate film, and an analysis target film including an analysis target region are sequentially stacked on the substrate from the side of the substrate;
By selectively etching the laminated film using a dry etching method or a laser etching method, an etching groove reaching at least the soluble film is provided along the outer edge of the analysis target region, and the analysis target film pattern and the intermediate film Forming a pattern;
Using the solvent capable of dissolving only the soluble film among the substrate, the soluble film and the intermediate film, by dissolving and removing the soluble film at least in a portion in contact with the intermediate film pattern, the analysis object film pattern And a step of forming a sample for analysis comprising an intermediate film pattern. The sample preparation method according to claim 1, further comprising a step of taking out the analysis sample by grasping a side surface thereof. The sample preparation method according to claim 1, wherein the etching groove is formed by irradiation with a focused ion beam or a laser beam. The sample preparation method according to any one of claims 1 to 3, wherein the soluble film is dissolved and removed until the thickness is less than half. The sample according to any one of claims 1 to 4, further comprising a step of forming a buffer tank connected to the etching groove in a region excluding the analysis target region on the substrate. Manufacturing method. The sample preparation method according to claim 5, wherein the buffer tank is formed so as to occupy a region larger than the etching groove. The sample preparation method according to any one of claims 1 to 6, wherein the soluble film is formed using a metal material and an acidic solution is used as the solvent. The sample preparation method according to claim 7, wherein hydrochloric acid, nitric acid, aqua regia or sulfuric acid is used as the acidic solution. As the metal material, aluminum (Al), gold (Au), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), palladium (Pd), platinum (Pt), The sample preparation method according to claim 7 or 8, wherein a material containing at least one of rhodium (Rh), ruthenium (Ru), tantalum (Ta), and titanium (Ti) is used. The sample preparation method according to any one of claims 7 to 9, wherein the substrate and the intermediate film are formed using aluminum oxide (Al ₂ O ₃ ). The sample preparation method according to claim 1, wherein the soluble film is formed using silicon oxide (SiO ₂ ) and hydrofluoric acid is used as the solvent. The sample preparation method according to claim 11, wherein the substrate and the intermediate film are formed using silicon (Si). The sample preparation method according to any one of claims 1 to 6, wherein the soluble film is formed using aluminum oxide (Al ₂ O ₃ ), and an alkaline solution is used as the solvent. . The sample preparation method according to claim 1, wherein the soluble film is formed using an organic material, and an organic solvent is used as the solvent. The sample preparation method according to claim 14, wherein a novolac resist or an acrylic resist is used as the organic material, and an organic solvent containing at least N-methylpyrrolidone is used. The sample preparation method according to any one of claims 13 to 15, wherein the substrate and the intermediate film are formed using a metal material. As the metal material, aluminum (Al), gold (Au), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), palladium (Pd), platinum (Pt), 17. The sample preparation method according to claim 16, comprising using at least one of rhodium (Rh), ruthenium (Ru), tantalum (Ta), and titanium (Ti). A sample preparation process for preparing a sample for analysis;
A sample analysis step of analyzing the analysis sample using a scanning electron microscope or a transmission electron microscope,
The sample preparation process includes
Forming a laminated film in which a soluble film, an intermediate film, and an analysis target film including an analysis target region are sequentially stacked on the substrate from the side of the substrate;
By selectively etching the laminated film using a dry etching method or a laser etching method, an etching reaching at least the soluble film is provided along the outer edge of the analysis target region, and an analysis target film pattern and an intermediate layer are provided. Forming a film pattern;
Using the solvent capable of dissolving only the soluble film among the substrate, the soluble film and the intermediate film, by dissolving and removing the soluble film at least in a portion in contact with the intermediate film pattern, the analysis object film pattern And a step of forming a sample for analysis comprising an intermediate film pattern. The sample analysis method according to claim 18, wherein the sample preparation step further includes a step of taking out the analysis sample by grasping a side surface thereof.

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