JP3106846U - Sample holder for charged particle beam equipment - Google Patents

Abstract

【Task】
It solves the problem of processing unevenness and redeposition in the focused ion beam processing method, and improves analysis accuracy such as fine structure analysis and elemental analysis.
[Solution]
A sample holder for a charged particle beam apparatus having a function of rotating a sample stage on which a sample is fixed around a holder axis by 360 °, wherein the tip of the sample stage is rotationally corrected at right angles to the traveling direction of the focused ion beam. This is achieved by irradiating an ion beam.
Further, in the sample holder for the charged particle beam apparatus having a function capable of rotating 360 ° around the sample stage axis, the tip of the sample stage of the sample holder is rotationally corrected at right angles to the traveling direction of the focused ion beam. Thereafter, this is achieved by irradiating the sample fixed on the sample stage with an ion beam.
[Selection] Figure 5

Description

  The present invention relates to an apparatus for preparing and observing a sample for observation with an electron microscope. In particular, a fine sample piece is extracted from a sample by a focused ion beam (hereinafter referred to as FIB) processing apparatus, and the extracted fine sample piece is fixed to a sample stage. The present invention relates to a sample preparation method by FIB from an arbitrary direction of an extracted micro sample, and a sample holder for a charged particle beam apparatus that enables the sample preparation method.

  2. Description of the Related Art Conventionally, for example, a technique described in Patent Document 1 is known as a system for pretreatment of a sample by a focused ion beam apparatus and subsequent observation system. In this technique, the sample processed by the focused ion beam apparatus can be inserted into an observation apparatus such as a pretreatment apparatus or a transmission electron microscope (hereinafter referred to as TEM) without changing the sample. However, in these apparatuses, consideration is given to the method of processing and observing from an arbitrary direction, but when processing a sample using the FIB processing apparatus, the ion beam or the sample cross section that has passed near the sample cross section is used. No consideration is given to the so-called redeposition problem in which the scattered ion beam sputters the sample bottom or sample stage and reattaches to the sample processing surface as a contaminant. Further, in the composite material, no consideration is given to the problem of unevenness (hereinafter referred to as processing unevenness) generated on the processed surface because the sputtering rate varies depending on the element.

  Furthermore, a technique described in Patent Document 2 is known as a method for observing a cross section of an integrated circuit. In this technique, the problem of processing unevenness is considered, but the problem of redeposition is not considered, and the problem of processing unevenness and redeposition cannot be solved at the same time.

JP-A-6-103947 JP-A-9-186210

  An object of the present invention is to process a micro sample extracted by a focused ion beam processing method from an arbitrary direction. Accordingly, an object of the present invention is to provide a sample preparation method and a sample holder for a charged particle beam apparatus capable of solving the processing unevenness and the redeposition problem and improving the analysis accuracy such as fine structure analysis and elemental analysis.

  The object is to correct the rotation of the tip of the sample holder of the sample holder perpendicular to the traveling direction of the focused ion beam in the sample holder for the charged particle beam apparatus having a function capable of rotating 360 ° around the sample stage axis. This is achieved by irradiating the sample fixed to the sample stage with an ion beam.

  Further, the above object is to provide a charged particle beam apparatus sample holder having a function of rotating a sample stage to which a sample is fixed around the holder axis by 360 ° with respect to the traveling direction of the focused ion beam. This is achieved by irradiating an ion beam to a sample whose rotation is corrected at a right angle.

  By using the sample preparation method and the sample holder for the charged particle beam apparatus according to the present invention, it is possible to perform processing from an arbitrary direction by an ion beam without removing the minute sample piece from the sample stage. In addition, processing irregularities and redeposition problems are eliminated.

  In a sample holder for a charged particle beam apparatus having a function capable of rotating 360 ° around the sample stage axis, the tip of the sample stage of the sample holder is subjected to rotation correction at a right angle to the traveling direction of the focused ion beam, and then the sample Irradiate the sample fixed to the stage with an ion beam.

  Further, in the charged particle beam apparatus sample holder having a function of rotating the sample stage to which the sample is fixed 360 degrees around the holder axis, the tip of the sample stage is rotationally corrected at right angles to the traveling direction of the focused ion beam. The sample is irradiated with an ion beam.

  The present invention will be described below with reference to the drawings. FIG. 1 shows a configuration diagram of an FIB apparatus 1 according to an embodiment of the present invention. The FIB apparatus 1 body includes an ion gun 2, a condenser lens 3, a diaphragm 4, a scanning electrode 5, and an objective lens 6. In the sample chamber of the FIB apparatus 1, a secondary electron detector 9 above the sample holder 8 to which the sample 7 is attached, a deposition gun 10 for forming a protective film on the sample 7 and fixing the sample 7 to the sample stage. , A microprobe 11 for carrying a micro sample produced by FIB processing is attached. A scanning image display device 12 is connected to the secondary electron detector 9. The scanning image display device 12 is connected to the scanning electrode 5 via the scanning electrode control unit 13. The microprobe 11 is connected to a microprobe control device 14 for controlling the position of the microprobe 11. The sample holder 8 is connected to the holder control unit 15. The ion beam 16 emitted from the ion gun 2 is converged by the condenser lens 3 and the diaphragm 4, passes through the objective lens 6, and converges on the sample 7. The scanning electrode 5 above the objective lens 6 deflects and scans the ion beam 16 incident on the sample 7 in accordance with an instruction from the scanning electrode control unit 13. When the ion beam 16 is irradiated onto the sample 7, the sample 7 is sputtered and generates secondary electrons. The generated secondary electrons are detected by the secondary electron detector 9 and displayed on the scanning image display device 12. The gas emitted from the deposition gun 10 toward the sample 7 reacts with the ion beam 16 and is decomposed, and metal is deposited on the ion beam 16 irradiation region on the surface of the sample 7. This deposited film is used to form a protective film on the surface of the sample 7 before FIB processing and to fix a minute sample piece to the sample stage. The angle of the sample 7 can be changed on the optical axis of the ion beam 16 by a holder control unit 15 connected to the sample holder 8, and the sample 7 can be processed from various angles.

FIG. 2 shows a top view (a) and a cross-sectional view (b) of the tip of the sample holder 17 for a charged particle beam apparatus according to an embodiment of the present invention. The sample holder 17 has a mechanism in which a holder shaft 18 connected to the tip portion can rotate 360 ° around the shaft center, and further, the sample holder 17 has a shaft center perpendicular to the holder shaft 18 at the tip portion independently of the mechanism. A sample rotation shaft 19 having a mechanism capable of rotating 360 ° around is provided. The sample holder 17 has a structure in which a part of the structure of the sample holder 17 is released so that the ion beam 16 is not blocked when the ion beam 16 enters the FIB apparatus 1.

  3A and 3B are a side view (a) and a perspective view (b) of a sample stage 20 according to an embodiment of the present invention. A side view and a perspective view of a state in which the minute sample piece 21 is fixed to the sample stage 20 are shown in (c) and (d), respectively. The micro sample piece 21 is attached to the tip of the sample stage 20. The tip of the sample stage 20 has a flat shape so that the minute sample piece 21 can be easily fixed. A deposition film 22 is formed and adhered to the contact portion between the minute sample piece 21 and the sample stage 20 by using the deposition gun 10 of the FIB apparatus 1.

  FIG. 4 shows an example in which a sample stage 20 is fixed to a charged particle beam apparatus sample holder 17 according to an embodiment of the present invention. The sample rotating shaft 19 is hollow and can be mounted so as to insert the sample table 20.

FIG. 5 shows a tip portion of a sample stage 20 which is an embodiment of the present invention, and the processing method of the minute sample piece 21 will be described. As shown in FIG. 5A, the micro sample piece 21 extracted from the bulk material by using the micro probe 11 is bonded to the most distal portion of the sample stage 20 perpendicular to the ion beam optical axis by the deposition film 22. Fixed. When processing by FIB, as shown in FIG. 5B, the sample stage 20 is rotated by 90 °, and the ion beam 16 is irradiated from the side surface of the minute sample piece 21. The ion beam 16 traveling downward while sputtering the side surface of the minute sample piece 21 proceeds downward without sputtering the sample stage 20 and without reflecting upward. In this way, the sample stage 20 is processed with rotation correction perpendicular to the traveling direction of the ion beam 16 to prevent reattachment of the sputtered material from the sample bottom surface and the sample stage 20 to the processed surface. I can do it. Further, as shown in FIGS. 5 (c-1) to 5 (c-3), the rotation angle of the sample stage 20 is not fixed, but may be processed while changing the angle as needed. Since the sample stage 20 can be adjusted to an arbitrary angle, the traveling direction of the ion beam 16 is kept constant, and if the ion beam 16 is irradiated while changing the angle of the sample stage 20, there is no processing unevenness, and a flat sample surface is obtained. Can be processed.

FIG. 6 shows a tip portion of a sample stage 20 which is an embodiment of the present invention, and the processing method of the minute sample piece 21 will be described. As shown in FIG. 6A, the sample stage 20 is rotationally corrected at right angles to the traveling direction of the ion beam 16, and the side surface of the minute sample piece 21 extracted from the bulk material by using the microprobe 11 is used as the ion beam. It is bonded and fixed to the most distal portion of the sample stage 20 perpendicular to the 16 optical axes by a deposition film 22. If the FIB is processed in this state, it is possible to prevent the sputtered material from the sample bottom surface and the sample stage 20 from being reattached to the processed surface for the reason described above. As shown in FIG. 6B, when the sample stage 20 is rotated by 180 °, the ion beam 16 can be irradiated from the bottom surface of the minute sample piece 21. Thereby, for example, when a thin film sample is manufactured, the thin film can be easily manufactured even if the region to be analyzed or observed is deep from the sample surface. As shown in FIG. 6 (c-1) to FIG. 6 (c-3), the rotation angle of the sample stage 20 is not fixed but may be processed while changing the angle as needed. Since the sample stage 20 can be adjusted to an arbitrary angle, the traveling direction of the ion beam 16 is kept constant, and if the ion beam 16 is irradiated while changing the angle of the sample stage 20, there is no processing unevenness, and a flat sample surface is obtained. Can be processed. As shown in FIG. 6B, after the sample stage 20 is rotated by 180 ° and then irradiated with the ion beam 16 while changing the angle of the sample stage 20, there is no processing unevenness even from the bottom side of the sample, and the surface is flat. The sample surface can be processed. As shown in FIG. 6D, the sample stage 20 can be rotated 360 ° around the optical axis of the ion beam 16. Even if this mechanism is used, the same effects as in FIGS. 6B and 6C can be obtained.

  By using a combination of the rotating mechanism of the holder shaft 18 and the rotating mechanism of the sample rotating shaft 19, it is possible to irradiate the minute sample piece 21 with the ion beam 16 from any angle and to form a prism or cylinder or a thin film.

FIG. 7 is an explanatory diagram showing the main procedure of the sample preparation method shown in FIG.
(1) First, the micro sample piece 21 is extracted from the bulk material using the microprobe 11.
(2) The sample stage 20 inserted in the FIB sample chamber is rotationally corrected so as to be perpendicular to the ion beam optical axis.
(3) The bottom surface of the micro sample piece 21 is brought into contact with the most distal portion of the sample stage 20 perpendicular to the ion beam optical axis, and is adhered and fixed by the deposition film 22.
(4) The minute sample piece 21 is irradiated with the ion beam 16 and processed to a thickness of, for example, 100 nm. At this stage, the sample stage 20 is sputtered and redeposition occurs, but there is no need to worry about it. Further, for example, in the case of a sample made of a plurality of materials having different hardness, such as a semiconductor device, processing unevenness due to a difference in etching rate can be generated, but this is not necessary. Furthermore, this step can be omitted, and finally a sample can be prepared without processing unevenness and redeposition.
(5) The sample stage 20 is rotationally corrected so as to be perpendicular to the ion beam optical axis.
(6) The fine sample piece 21 processed to a thickness of, for example, 100 nm is irradiated with the ion beam 16 and finished. There is no sample stage 20 in the traveling direction of the ion beam 16, and no redeposition occurs. The redeposition that occurred in step (4) can be removed here. Further, since the irradiation angle of the ion beam 16 with respect to the minute sample piece 21 is changed, the processing unevenness can be removed. As shown in FIG. 5 (c-1) to FIG. 5 (c-3), the rotation angle of the sample stage 20 is not fixed, but may be processed while changing the angle as needed.

  The sample preparation method procedure shown in FIG. 6 is the same, and the sample preparation can be performed without processing unevenness and redeposition.

FIG. 8 is an example of the present invention, and an explanatory view of a minute sample piece 21 produced by the procedure of FIG. 7 is shown. FIG. 8A is a diagram after the process of FIG. 7D is completed. Processing unevenness 24 due to the difference in etching rate occurs below the cavity 23 in the traveling direction of the ion beam 16. FIG. 8 (b) shows FIG.
It is a figure after complete | finishing the process of (6). The processing unevenness 24 is removed. Also, no redeposition has occurred.

1 is a basic configuration diagram of an FIB apparatus according to an embodiment of the present invention. The top view and sectional drawing of the sample holder tip part for charged particle beam devices which are one example of the present invention. The side view and perspective view of the sample stand for charged particle beam apparatuses which are one Example of this invention. The side view of the sample holder front-end | tip part for charged particle beam devices which is one Example of this invention. Explanatory drawing of the sample processing method at the time of this invention implementation. Explanatory drawing of the sample processing method at the time of this invention implementation. The flowchart at the time of implementation of this invention. Electron micrograph at the time of implementation of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... FIB apparatus, 2 ... Ion gun, 3 ... Condenser lens, 4 ... Aperture, 5 ... Scan electrode, 6 ... Objective lens, 7 ... Sample, 8 ... Sample holder, 9 ... Secondary electron detector, 10 ... Deposition Gun 11, microprobe 12, scanning image display device 13 scanning electrode control unit 14 microprobe control device 15 holder control unit 16 ion beam 17 sample holder for charged particle beam device 18 DESCRIPTION OF SYMBOLS ... Holder axis, 19 ... Sample rotation axis, 20 ... Sample stage, 21 ... Fine sample piece, 22 ... Deposition film, 23 ... Cavity, 24 ... Unevenness of processing.

Claims (3)

  An ion source having a liquid metal, a high voltage power source for accelerating an ion beam emitted from the ion source, a lens for focusing the ion beam on the sample surface, and scanning the focused ion beam on the sample surface A focused ion beam processing apparatus having a sample chamber for inserting a deflector and a sample holder in which a sample is fixed, an electron source for emitting electrons, a high voltage power source for accelerating the electrons, focusing of electrons on the sample, In a common sample holder that can be used for both electron beam apparatuses having a function of observing a transmitted electron image, the sample piece fixed to the sample holder can be rotated at least 90 ° with respect to the traveling direction of the focused ion beam at any angle. And a step of processing a region to be analyzed or observed by irradiation with a focused ion beam while adding rotation correction. Folder.   2. The sample holder for a charged particle beam apparatus according to claim 1, wherein a tip of the sample holder of the sample holder is rotationally corrected at right angles to the traveling direction of the focused ion beam, and the sample piece can be fixed to the sample holder. Sample holder for charged particle beam equipment. 3. The sample holder according to claim 2, wherein the tip of the sample stage of the sample holder is rotationally corrected at right angles to the traveling direction of the focused ion beam, and the sample piece fixed to the sample stage is rotated 360 ° around the sample stage axis. A sample holder for a charged particle beam apparatus, comprising a step of processing a region to be analyzed or observed by focused ion beam irradiation while adding a rotation correction at an arbitrary angle.

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